PALO VERDE NUCLEAR GENERATING STATION

Transcription

1 PALO VERDE NUCLEAR GENERATING STATION Introduction to Plant Systems Lesson Plan Engineering Training (Program) Date: May 17, 2012 LP Number: NGT95C Rev Author: Ben Acosta Title: Introduction to Plant Systems Teaching Review: Duration : 32 Hours Teaching Approval:

2 Engineering Training (Program) Page: 2 of 90 INITIATING DOCUMENTS: INPO Guidelines for Training and Qualification of Engineering Personnel Engineering Training Program Description REQUIRED TOPICS NONE CONTENT REFERENCES NGT95 Plant Systems Student Handout Lesson Plan Revision Data May 17, 2012 Ben Acosta Added Learning Objective to cover Nuclear Instruments Excore & Incore Instrumentation (EO 1.1.6). Tasks and Topics Covered The following tasks are covered in NGT95 Introduction to Plant Systems: Task or Topic Number* Lesson: k Task Statement NGT95 Introduction to Plant Systems Using equipment location and arrangement drawings, identify and locate major plant equipment in various buildings and parts of buildings. Total tasks or topics: 1

3 Engineering Training (Program) Page: 3 of 90 TERMINAL OBJECTIVE: 1.1 The student will be presented with basic functions that major systems provide for plant operation, and the general locations of major plant equipment and then be able to, state the system function and identify the major components. Mastery of the material will be demonstrated by passing a written exam with a minimum score of 80% State the purpose of the Reactor core and identify the major components State the purpose of the Reactor Coolant System and identify the major components State the purpose of the Chemical & Volume Control System and identify the major components State the function of the Containment Building State the purpose of the Safety Injection system and identify the major components. State the purpose of the Excore Neutron Monitoring System (SE) and the Incore Instrumentation (RI), identify major components State the purpose of the Plant Protection System and identify the major components State the purpose of the Steam Generator and identify the major components State the purpose of the Main Steam System and identify the major components State the purpose of the Main Turbine system and identify the major components State the purpose of the Main Generation system and identify the major components State the purpose of the 13.8 KV Non Class Electrical Distribution system and identify the major components State the purpose of the 4.16KV Non Class Electrical Distribution system and identify the major components State the purpose of the 4.16KV Class Electrical Distribution system and identify the major components State the purpose of the Class IE standby generation system and identify the major components State the purpose of the Condensate system and identify the major components State the purpose of the Feedwater system and identify the major components State the purpose of the Auxiliary Feedwater and identify the major components State the purpose of the Circulating Water System and identify the major components State the purpose of the Plant Cooling Water system and identify the major components State the purpose of the Turbine Cooling Water system and identify the major components.

4 Engineering Training (Program) Page: 4 of State the purpose of the Nuclear Cooling Water system and identify the major components State the purpose of the Normal Chilled Water system and identify the major components State the purpose of the Essential Spray Pond system and identify the major components State the purpose of the Essential Cooling Water system and identify the major components State the purpose of the Essential Chilled Water system and identify the major components State the purpose of the Spent Fuel Pooling Cooling system and identify the major components State the purpose of the Instrument Air system and identify the major components. INFORMATION IN SHADED AREA IS ADDITIONAL INFORMATION AND IS NOT TESTABLE FOR NGT95.

5 Engineering Training (Program) Page: 5 of 90 Site Layout and Plant Overview PVNGS is a desert site of approximately 4100 acres, situated about 50 miles west of downtown Phoenix, Arizona, contains three standardized Combustion Engineering System 80 pressurized water nuclear power plants, a water processing facility with its attendant storage pond, two evaporation ponds, a large electrical switchyard, a twin gas turbine auxiliary electrical generation plant, and assorted support structures and office buildings. The Palo Verde plants have a "plant north" that does not coincide exactly with geographic north, but makes location of components practical on drawings. For our plants, the east - west axis coincides with the long axis of the Turbine Building, so plant north is toward the cooling towers. WINTERSBURG RD. DELIVERY ENTRANCE N W E S PARKING LOT 3 Palo Verde Site Layout WAREHOUSE LOOP WAREHOUSE COMBO SHOP U2 COOLING TOWERS G MAIN GATE NORTH ANNEX UNIT 2 U1 COOLING TOWERS OSB Protected Area Access UNIT 1 E D OSB F WATER RECLAMATION FACILITY LOW LEVEL RADWASTE STORAGE CENTRAL PROCESSING FACILITY - Medical/Fitness for Duty VANPOOL PARKING LOT 1 POND SOUTH ST. EAST ST. VEHICLE MAINTENANCE FACILITY DRY CASK STORAGE AREA GAS TURBINE GENERATORS CHEMICAL STORAGE FACILITY WATER WAY WATER STORAGE RESERVOIR U3 COOLING TOWERS NORTH ST. UNIT 3 WEST ST. OSB SERVICE BLDG. DAWPS A C B CONTRACTOR OVERFLOW PARKING SRP SWITCHYARD 7/30/01 VISITOR S ENTRANCE ADMIN COMPLEX BLDGS. A & B ENERGY INFORMATION CENTER / PARKING LOT PARKING LOT B

6 Engineering Training (Program) Page: 6 of 90 T.Obj 1.1 The student will be presented with basic functions that major systems provide for plant operation, and the general locations of major plant equipment and then be able to, state the system function and identify the major components. Mastery of the material will be demonstrated by passing a written exam with a minimum score of 80%. Main Idea The reactor, steam generators, and primary piping in general are in the Containment Building, a hemispherically domed reinforced concrete cylinder surrounded with post-tensioned bridge wire tendons. Immediately plant south of the containment building is the Auxiliary Building, containing equipment to maintain the volume and chemical composition of the primary system coolant. The Fuel Building contains facilities for preparing and storing new fuel prior to use and for storing and cooling spent fuel after removal from the reactor. The Radwaste Building contains the systems to separate, monitor, package, and release radionuclides, while the Control Building contains the control room, instrumentation, cabling, and various control-related support equipment to control the plant in normal and abnormal circumstances. The Diesel Building contains two diesel generator sets to provide emergency power, while the balance of the steam plant; including turbines, condenser, and feedpumps are found in the Turbine Building. Obviously there are more structures and tankage in the actual plant, but this introduction is intended only to provide a simplified skeleton upon which to hang subsequent systems and components as we examine them. The CE System 80 design consists of a pressurized light water reactor fueled with Zircalloy clad uranium oxide fuel and cooled by two closed loop steam generators connected in parallel with the reactor vessel. The system includes four Reactor Coolant Pumps to provide circulation of primary coolant, and a Pressurizer to maintain system pressure and, consequently, required subcooling margins. Thermal energy generated in the reactor core passes through the two steam generators and turns water in the secondary system to high pressure steam. Secondary steam drives a main generator by means of one high pressure and three low pressure turbines mounted in series on a single turbine shaft. As a general rule, significant quantities of radionuclides are confined to the primary system and its various supporting systems, so the overall plant resembles a conventional non-nuclear steam plant with a remote heat source.

7 Engineering Training (Program) Page: 7 of 90 EO State the purpose of the Reactor core and identify the major components. Main Idea Purpose: The purpose of the reactor core is to produce 3990 Mw of thermal power. Major Components: The reactor core is composed of 241 fuel assemblies and 89 control element assemblies. The fuel assemblies are arranged to approximately a right circular cylinder with an equivalent diameter of inches and an active length of 150 inches. The fuel assembly, which provides for 236 fuel rod positions (16 X 16 array), consists of 5 guide tubes welded to 10 of eleven spacer grids and is closed at the top and bottom by end fittings. Each guide tube displaces four fuel rod positions and provides channels which guide the CEAs over their entire length of travel. In-core instrumentation is installed in the central guide tube of selected fuel assemblies through the bottom head of the reactor vessel. Lateral support and positioning of the fuel rods are provided by leaf spring spacer grids welded to the guide tubes. The fuel assemblies sit on the lower support structure and are restrained from upward movement by the Upper Guide Structure (UGS) tubes on the bottom of the UGS assembly. The fuel assemblies consist of the following major components: Fuel Spacer Grids (11 per assembly) Upper End Fitting Holddown Plate Lower End Fitting Guide Tubes (5 per assembly) Fuel Rods (236 per assembly) Burnable Poison Rods (0, 12, or 16 per selected assembly) The outer guide tubes, spacer grids and end fittings form the structural frame of the assembly. Control Element Assemblies and Control Element Drive Mechanisms The control element assemblies provide a mechanical means to shutdown the reactor and regulate reactor power (core reactivity during startup and shutdown). The control rods are withdrawn from the core to achieve the critical condition and they are inserted into the core when a reactor shutdown is initiated. A total of 89 control element assemblies are provided in the core. They are divided into three groups: regulating (control) groups, part strength rod groups and shutdown groups. There are five regulating groups designated 1, 2, 3, 4 and 5; two part strength rod groups designated P1 and P2; and two shutdown groups designated A and B. The control element assemblies are also divided into three basic types as follows: Forty-eight are twelve element (fingered) full length CEA's Twenty-eight are four element full length CEA's Thirteen are four element part strength CEA's

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9 Engineering Training (Program) Page: 9 of 90 Reactor Vessel and Internals The reactor is a pressurized water type which uses four cold leg and two hot leg coolant loops. The fuel assemblies are arranged to approximately a right circular cylinder with an equivalent diameter of inches and an active length of 150 inches. The reactor coolant enters the four inlet nozzles of the reactor vessel, flows downward between the reactor vessel wall and the core barrel, passes through the flow skirt section where the flow distribution is equalized and goes into the lower plenum. The coolant then flows upward through the core removing heat from the fuel rods. The heated coolant enters the core outlet region where the coolant flows outside of the control element assembly shroud tubes to the reactor vessel outlet nozzles. The control element assembly shroud tubes protect the individual neutron absorber elements of the CEAs from the effects of coolant cross flow above the core.

10 Engineering Training (Program) Page: 10 of 90 EO State the purpose of the Reactor Coolant System and identify the major components. Main Idea Purpose: The purpose of the Reactor Coolant System (RCS) is to: 1. To transfer thermal energy from the reactor core to the steam generator, where steam is produced for use in the main turbine. 2. To serve as the secondary barrier to the release of fission products from the reactor core to the environs. 3. To provide sufficient core cooling during all normal plant evolutions and expected transients to preclude significant fuel damage. Major Components: The reactor coolant system (RCS) circulates water in a closed cycle, removing heat from the reactor core and internals and transferring it to a secondary system. The steam generation provides the interface between the reactor coolant (primary) system and the main steam (secondary) system. The steam generators are vertical u-tube heat exchangers with an integral economizer in which heat is transferred from the reactor coolant to the main steam system. Reactor coolant is prevented from mixing with the secondary steam by the steam generator tubes and the steam generator tube sheet, making the RCS a closed system thus forming a barrier to the release of radioactive materials from the core of the reactor to the containment building. The Reactor Coolant System is a semi-closed loop cooling system with a continuous bleed and feed interface and a Chemical and Volume Control System for maintenance of Reactor Coolant chemistry and volume. The major components of the RC system are the Reactor Vessel, two parallel heat transfer loops (each containing one Steam Generator and two Reactor Coolant Pumps) and a Pressurizer connected to the loop 1 Hot Leg of the Reactor Vessel outlet pipes. The system also includes interconnecting piping to auxiliary systems, safety valves, valves and instrumentation necessary for operation and control. The Reactor Vessel serves as the common link between the two parallel heat transfer loops. It also contains and supports the reactor core and directs the flow of coolant through the core. During normal operation, the Reactor Coolant is circulated through the Reactor Vessel and Steam Generators by the Reactor Coolant Pumps. The Reactor Coolant is heated as it passes through the reactor vessel by energy produced by the fissioning fuel in the core and it is cooled in the Steam Generators as it gives up heat to the secondary system to form steam. The Reactor Coolant also serves as a neutron moderator in the core and contains a soluble neutron absorber (boron) for reactivity control. The Reactor Coolant is maintained in a subcooled condition by maintaining a high system pressure of 2250 psia.

11 Engineering Training (Program) Page: 11 of 90 Pressurizer (Pzr) The Pressurizer is connected to the Reactor Coolant System in the loop 1 hot leg by the Pressurizer surge line and in the loop 1 cold legs by the spray lines. The Pressurizer performs the following functions: Maintains Reactor Coolant System in the subcooled condition. Acts as a surge volume to minimize pressure changes during load transients. Ensures primary system integrity by preventing overpressurization. During load changes, the Reactor Coolant expands or contracts in response to the balance between heat input and heat removal in the Reactor Coolant System. Without the Pressurizer, even small load changes would cause extreme pressure changes within the Reactor Coolant System. The Reactor Coolant System pressure is maintained and controlled by the Pressurizer where steam and water are maintained in thermal equilibrium. During full-load operation, the Pressurizer volume is almost evenly divided between saturated water and saturated steam. Steam is formed by energizing immersion heaters in the Pressurizer, or is condensed by a subcooled Pressurizer spray as necessary to maintain operating pressure (normally about 2250 psia) and limit pressure variations due to plant transients. Since this pressure (2250 psia) is significantly higher than the pressure corresponding to the saturation temperature of the water passing through the other parts of the Reactor Coolant System, no boiling occurs except in the Pressurizer.

12 Engineering Training (Program) Page: 12 of 90 Overpressure protection for the RCS is provided by four spring-loaded ASME Code safety valves. These valves discharge to the Reactor Drain Tank where the steam is released under water to be condensed and cooled. If the steam discharge exceeds the capacity of the tank, the tank is relieved to the Containment via a rupture disc installed in the tank. In addition to this overpressure protection, a vent system is provided that permits the operator to vent the Reactor Vessel Head or Pressurizer steam space from the control room under post-accident conditions. The system provides a redundant vent path either to the containment directly or to the Reactor Drain Tank. Pressurizer Safety Valves The valves are set to open at 2475 psia, + 25 psia with a 3% accumulation. The blowdown factor is 5%. The combined capacity of the valves is equal to or greater than the maximum surge rate resulting from a complete loss of load without a reactor trip and without any other control functions (i.e. pzr. spray actuation) other than the lifting of the SG safety valves.

13 Engineering Training (Program) Page: 13 of 90 Steam Generators (RCE-E01A, E01B) Two steam generators (RCE-E01A and -E01B) are designed to transfer 4013 MWT from the RCS to the secondary system, producing approximately 18.0 x 10 6 lb/hr of 1031 psia saturated steam when provided with 450 F feedwater. Moisture separators and steam driers in the shell side of the steam generator limit the moisture content of the steam to 0.1 % wt during normal operation at full power. The steam generators are vertical u-tube heat exchangers with an integral economizer in which heat is transferred from the reactor coolant to the main steam system. Reactor coolant is prevented from mixing with the secondary steam by the steam generator tubes and the steam generator tube sheet, making the RCS a closed system thus forming a barrier to the release of radioactive materials from the core of the reactor to the containment building. The steam generators are capable of sustaining the following design transients without exceeding code allowable stress limits: Ten cycles of hydrostatic testing of the secondary side at 1-1/4 times design pressure (test condition). A restriction of steam generator tube secondary side to primary side differential pressure also exists and must not exceed 895 psid. Temperature shall be maintained in accordance with the technical specifications. Four thousand differential pressure transients of 85 psi across the primary divider plate in either direction caused by starting and stopping reactor coolant pumps (normal condition). The steam generator was designed to ensure that critical vibration frequencies are well out of the range expected during normal operation and during abnormal conditions. The tubing and tubing supports are designed and fabricated with considerations given to both secondary side flow induced vibration and reactor coolant pump induced vibrations. In addition, the steam generator assemblies are designed to withstand the blowdown forces resulting from the severance of a steam nozzle. The steam generator assemblies are also designed to withstand the severance of any one of the feedwater nozzles. The two accidents are not considered simultaneously. A steam generator tube rupture incident is a penetration of the barrier between the reactor coolant system and the main steam system. The integrity of this barrier is significant from the standpoint of radiological safety in that a leaking steam generator tube allows the transfer of reactor coolant into the main steam system. Radioactivity contained in the reactor coolant would mix with water in the shell side of the affected steam generator. This radioactivity would be transported by steam to the turbine and then to the condenser or directly to the condenser via the turbine steam bypass system. Non-condensable radioactive gases in the condenser are removed by the main condenser air removal system and discharged to atmosphere. Experience with nuclear steam generators indicates that the probability of complete severance of a tube is remote. A double ended rupture has never occurred in a steam generator of this design. The more probable modes of failure, which result in smaller penetrations, are those involving the occurrence of pinholes or small cracks in the tubes, and of cracks in the seal welds between the tubes and tube sheet. The concentration of radioactivity in the secondary side of the steam generators is dependent upon the concentration of radionuclides in the reactor coolant, the primary to secondary leak rate, and the rate of steam generator blowdown. The recirculation water within the steam generators contains volatile additives necessary for proper chemistry control. The vertical, U-tube, recirculating steam generators are equipped with integral economizers. Each steam generator and its associated reactor coolant pumps are isolated from potential containment building missiles by reinforced concrete walls. The steam generators are supported vertically on conical skirts welded to the bottom of their primary chambers, and horizontally by shock absorbing snubbers and keys attached to the steam drums. Each conical skirt is bolted to a sliding base which rests on low friction bearings and allows unrestrained RCS thermal expansion. Two keyways within the sliding base mate with embedded keys to guide steam generator movement during RCS expansion and contraction, and, together with stop and anchor bolts, limit movement of the steam generator bottom during seismic events and following a LOCA.

14 Engineering Training (Program) Page: 14 of 90 Primary Chamber The primary chamber is located at the bottom of the steam generator. It forms part of the RCS pressure boundary and directs reactor coolant flow through the steam generator. The primary chamber is divided into two plenums (inlet and outlet) by a divider plate and stay tube. The stay tube is a hollow, cylindrical tube located in the center of the steam generator. It aids in separating the primary chamber inlet and outlet plenums, the economizer and evaporator regions on the steam generator secondary side, and supports the tube sheet. The divider plate is attached to the stay tube using tongue and groove joints to allow flexibility between it, the primary chamber, and the tube sheet. One nozzle is provided in the inlet plenum and two in the outlet plenum. Flow from the associated reactor coolant loop hot leg enters through the 42 inch ID SG inlet nozzle, passes through the tube sheet and U-tubes, and returns to the reactor coolant pump suction legs via the two 30 inch ID SG outlet plenum nozzles. Two 16 inch primary manways and four instrument nozzles are provided. The primary chamber is constructed of carbon steel with stainless steel cladding on inner surfaces to minimize corrosion. Its design temperature and pressure are 650 F and 2500 psig, respectively. Tube Sheet and U-Tubes The tube sheet and U-tubes form the boundary between the steam generator primary and secondary sides. The tube sheet is a 23.5 inch thick steel plate clad on the primary side with inconel (Ni-Cr-Fe) (Inconel 690) for corrosion resistance. 25,160 holes are machined in the tube sheet to accept the U-tubes. A two inch drilled passage is provided for blowdown of the steam generator area just above the tube sheet (plus blowdown). The steam generator U-tubes (12,580) are arranged in a bundle to maximize heat transfer and structural stability while minimizing flow resistance. The tubes are constructed of Inconel 690 (Ni-Cr-Fe), each has an outside diameter of 0.75 inches and a wall thickness of The average tube length is approximately 58 feet. The tube ends are inserted in the tube sheet, explosively expanded, and then welded to the tube sheet to prevent leakage. The tubes are supported throughout their length by a series of tube support plates arranged in an "egg crate" design. Additional vertical, horizontal, and batwing strips are provided for tube support in the bend region. This design allows maximum open flow area to limit mechanical or flow induced vibrations.

15 Engineering Training (Program) Page: 15 of 90 Reactor Coolant Pumps The functions of the Reactor Coolant Pumps are as follows: Provide the head necessary to maintain required flow through the Reactor Coolant System during normal operation. Add heat to the primary system during plant heatups. Four Reactor Coolant Pumps are provided, one in each cold leg. The pumps are vertical single-stage, centrifugal type, each driven by a 12,000 hp, squirrel cage induction motor. Each pump has a capacity of 114,400 gpm at a discharge head of 365 ft. Reactor Coolant Pump motors are powered from Non Class 13.8 KV switchgear (NAN S01/S02). Thrust Bearing Assembly - During normal operation there is an upward thrust exerted on the pump due to pressure in the RCS. A downward thrust is developed by the impeller pumping action when the pump is running. At NOP, the net thrust of these two forces is 1.5 x 10 5 lbs. in the upward direction. Shaft Seal Assembly - A shaft seal assembly is provided to act as a pressure boundary between the reactor coolant system and containment while minimizing leakage along the pump shaft. The seal assembly consists of three tandem mechanical pressure reduction seals and an auxiliary impeller. Impeller - The six bladed, radial flow impeller is used to impart a velocity head to the reactor coolant. The combination of the six impeller blades and the eleven diffuser blades minimize hydraulic forces in the pump. Socket head cap screws hold the impeller nut in place. Proper positioning of the impeller is accomplished by using a spacer. Diffuser & Suction Pipe The diffuser is an 11 blade, two piece, removable type which converts the velocity head developed by the pump impeller into a pressure head. The suction pipe separates the suction & discharge sides of the pump.

16 Engineering Training (Program) Page: 16 of 90 EO State the purpose of the Chemical & Volume Control System and identify the major components. Main Idea Purpose: The Chemical and Volume Control System controls the purity, volume, and boric acid content of the reactor coolant. The Chemical and Volume Control System provides for the following functions: Maintains Reactor Coolant System chemistry and purity during normal operation and shutdown modes. Maintains the RCS inventory during normal system operations. Provides a means for continuous removal of noble gases from the RCS. Controls the boron concentration of the RCS in order to obtain optimum Control Element Assembly positioning, and to compensate for reactivity changes associated with major changes in reactor coolant temperature, core burnup, and xenon concentration variations. Provides the boron concentration necessary to obtain the shutdown margin required for maintenance, emergencies, or refueling operations. Receives, stores, and separates borated water waste for reuse and/or discharge to the Liquid Radwaste System. Provides auxiliary spray to the pressurizer in the RCS for maintaining control of reactor coolant pressure during final stages of shutdown and to allow for cooling of the pressurizer. Provides continuous measurement of the RCS boron concentration and fission product activity. Provides water to the reactor coolant pump seals and controls the bleedoff from the pump seals. Provides the source of borated water used for safety injection following a loss of coolant accident, and is also the source for borated water used to fill the refueling pool during refueling operations. Provides borated water for makeup needed by the spent fuel pool. Provides makeup water to various auxiliary equipment. Receive and contains discharges from drains and relief valves from the Reactor Coolant System, Safety Injection System, and Shutdown Cooling System. Compensate for small amounts of RCS leakage. Provide a source of borated water to Engineered Safety Features equipment. Provide Shutdown Cooling purification flow.

17 Engineering Training (Program) Page: 17 of 90 Major Components: The coolant purity level and boron concentration of the RCS is controlled by continuous processing of a bypass stream of reactor coolant. The RCS volume, pressurizer level, is maintained using the letdown and charging features of the CVCS. The CH System includes the following subsystems: Letdown and Charging Reactor Coolant Pump Controlled Bleedoff, Seal Injection, and Chemical Addition Reactor Makeup and Refueling Water Radioactive Collection, Processing, and Storage Boric Acid Reclamation

18 Engineering Training (Program) Page: 18 of 90 Letdown and Charging Subsystem Reactor coolant is letdown from the RCS just upstream of reactor coolant pump 2B. The temperature and pressure of this flow must be reduced to meet CVCS downstream component design and operational requirements. The letdown flow passes through a delay coil (to allow for decay of N-16 activity), then through two normally open isolation valves and then through the regenerative heat exchanger. This shell-and-tube heat exchanger reduces the letdown temperature. Heat is transferred from the letdown coolant flowing through the heat exchanger tubes to reactor coolant makeup (charging) flow, which passes through the heat exchanger shell. The regenerative heat exchanger thus performs two functions; it cools letdown flow and heats charging flow. Letdown flow exiting the regenerative heat exchanger passes through the containment and an isolation valve on the Auxiliary Building side of containment, then through one or both of the letdown flow control valves. These valves are positioned in response to signals from the pressurizer level controller. The shutdown cooling purification system taps into letdown upstream of the letdown heat exchanger which permits purification during shutdown conditions. Letdown flow then passes through the tube side of the letdown heat exchanger. Nuclear cooling water, flowing through the heat exchanger shell, provides the cooling medium. Two backpressure control valves, installed downstream of the letdown heat exchanger, maintain upstream system pressure at approximately 450 psig to prevent flashing in the letdown line. Flow, at normal letdown pressure and temperature, passes through one of two purification filters. These filters remove insoluble impurities to reduce crud buildup on equipment. A portion of the letdown flow is then routed to the boronometer for sampling. The boronometer indicates coolant boron concentration and the radiation monitor indicates coolant fission product activity. Letdown flow is automatically bypassed around the boronometer upon presence of a high temperature condition (140 F), thus protecting the instrument from high temperature. There are three ion exchangers, each of which is capable of passing maximum letdown flow (150 gpm). Two of the three ion exchangers are purification ion exchangers and the third is a deborating ion exchanger. One of the two purification ion exchangers is continuously in service removing dissolved ionic materials and particulates. The second purification ion exchanger is used periodically to remove lithium from the reactor coolant as necessary for ph control. This unit's lithium capacity becomes exhausted during one core cycle. It is then used for continuous purification during the following core cycle. The deborating ion exchanger is used near the end of core life to remove boron. Due to the low boron concentration, this method of removal is preferred near the end of core life because it minimizes the liquid waste accumulation. Letdown flow is automatically bypassed around the purification ion exchanger(s) upon presence of a high temperature condition (140 F) to protect them from high temperature. Outlet flow from the ion exchangers passes through a common strainer installed to collect any resin particles (fines) which may be released. Normal letdown flow is directed to the volume control tank or back to the shutdown cooling system during shutdown conditions. Letdown enters the VCT through a spray nozzle located in the tank's gas space. The VCT normally operates with a 34% to 44% liquid level. The gas space is filled with hydrogen during normal operation to scavenge oxygen and thus aid reactor coolant chemistry control. The hydrogen pressure in the tank is maintained at approximately psig. The VCT acts as a surge tank for the RCS to accommodate small mismatches between actual and programmed pressurizer level, collects RCP bleedoff, and provides net positive suction head for the charging pumps. In the event a high water level is reached in the VCT, excess water is diverted to the HUT Charging Subsystem of the CVCS Three reciprocating charging pumps (rated at 44 gpm each) are installed in parallel just downstream of the volume control tank. One is always in service; one is normally in service, and the third is in standby. The Letdown and Charging Subsystem is normally operated in automatic control. Charging pump control is provided by the pressurizer level controller to balance the letdown and charging rates and maintain pressurizer level within a programmed band.

19 Engineering Training (Program) Page: 19 of 90 A portion of the charging flow, about 26 gpm, is directed to the RCP Seal Injection Subsystem and the balance, 62 gpm, is sent to the RCS. Charging flow to the RCS passes through the shell side of the regenerative heat exchanger, where it is heated by RCS letdown flow in the tube side. The charging then enters RCS loop 2A between RCP 2A and the reactor vessel. A pressurizer auxiliary spray line just upstream of the charging line `A' isolation valve is used to supply pressurizer spray during conditions when normal spray is not functional. Reactor Coolant Pump Controlled Bleedoff, and Seal Injection A portion of the charging flow is used to supply RCP seal injection. This flow passes through a temperature protection isolation valve which automatically isolates seal injection flow as the temperature downstream of the seal injection heat exchanger decreases to 70 F or increases above 150 F. This is necessary to prevent RCP seal damage. It is preferred to have no seal injection flow than to have the flow too cold or too hot. Two seal injection filters are installed just downstream of the heat exchanger. One filter is normally in service removing particulate materials to prevent seal damage, and the other is isolated. The seal injection line then divides into four branches, one for each RCP. An automatic flow control valve, installed in the supply line to each RCP, regulates the flow at approximately 6.6 gpm to each pump. A portion of the flow is directed into the RCS to flush the lower pump bearings. Controlled bleedoff from the RCP seals (normally approximately gpm per pump) flows to the volume control tank via a common header. An alternate return path to the reactor drain tank via a relief valve is provided. Reactor Makeup and Refueling Water Subsystem The Reactor Makeup and Refueling Water Subsystem consists of the following major components: Reactor makeup water tank Reactor makeup water pumps (2) Refueling water tank Boric acid makeup pumps (2) Boric acid batch tank The reactor makeup water tank provides storage for demineralized water. It receives pure water from the following sources: Demineralized water storage tank Liquid Radwaste System recycle monitor tank Boric acid concentrator The reactor makeup water tank supplies the reactor makeup water pumps and is the backup source to the essential auxiliary feed pumps. The reactor makeup water pumps take suction on the makeup water tank and discharge to the reactor makeup supply header, the Boric Acid Batch Tank eductor or the chemical and volume control makeup system which supplies the volume control tank, or directly to the charging pump suctions. An in-line filter, installed at the pump's common discharge header, removes particulate materials. The Refueling Water Tank provides storage for the plant's borated water. It receives boric acid from either of the following sources: Boric acid batching tank Boric acid concentrator bottoms

20 Engineering Training (Program) Page: 20 of 90 The boric acid makeup pumps take suction on the refueling water tank through a remote-operated isolation valve and discharge to the volume control tank, the Boric Acid Batch Tank eductor, or directly to the charging pump suctions. An alternate path from the suction line of the boric acid makeup pumps goes directly to the suction of the charging pumps. A third path is from the B Train supply to the Engineered Safety Feature Pumps with RWT water, to the suction of the charging pumps. The Spent Fuel Pool may also supply borated water to the suction of the Charging Pumps through the BAMP piping. An in-line filter is installed at boric acid makeup pump's common discharge header to remove particulate materials. The flow of borated and non-borated makeup to the VCT or the charging pump suction is regulated by makeup flow control valves. The valves regulate the quantities of borated and non-borated water added by positioning the flow control valves. The valves are installed in the discharge lines of the RMWPs and the BAMPs. The boric acid batch tank provides boric acid solution to the refueling water tank. Electric heaters and a mixer, located in the tank, maintain the boron in solution. The BABT eductor can receive motive fluid from either the RMWPs or the BAMPs. The BABT eductor acts as a jet pump and drains the concentrated boric acid solution from the BABT into the motive fluid flow at a predetermined rate. Radioactive Collection, Processing, and Storage Subsystem The water used in this subsystem is collected from three general areas: Letdown flow diverted from the volume control tank during feed and bleed operations from shutdowns, startups, and boron dilution over core life; Reactor drain tank contents consisting of reactor coolant quality water collected from various equipment and valve leakoffs, drains, and reliefs located within containment; Equipment drain tank contents consisting of reactor coolant quality water collected from various equipment and valve leakoffs, drains, and reliefs located outside containment. Letdown flow which has been diverted from the volume control tank because of a high water level condition in the volume control tank enters the subsystem just downstream of the reactor drain filters and upstream of the pre-holdup ion exchanger temperature bypass valve. Contents of the reactor drain tank and equipment drain tank are processed via the reactor drain pumps through applicable isolation valves. The discharge of the reactor drain pumps passes through the reactor drain filter and either the pre-holdup ion exchanger temperature bypass valve or the pre-holdup ion exchanger. Normal flow is through the pre-holdup ion exchanger and its strainer which removes resin, lithium, and other ionic radionuclides. When the pre-holdup ion exchanger temperature reaches 140 F, the pre-holdup ion exchanger is automatically bypassed to prevent resin damage. Boric Acid Reclamation Subsystem The Boric Acid Reclamation Subsystem operates as necessary when the contents of the holdup tank are to be processed. Under normal conditions, holdup tank contents are pumped by the holdup pumps to the boric acid concentrator. However, if the holdup tank radiation level or gas concentration is too high, the holdup pumps discharge back through the reactor drain filter pre-holdup ion exchanger and gas stripper for reprocessing. Operation of the boric acid concentrator increases the boron concentration of the boric acid concentrator bottoms to a level greater than the refueling water tank, where the borated water is sent for reuse. If sufficient contamination is present in the boric acid concentrator bottoms, they are pumped to the Solid Radwaste System for processing. The distillate (steam which has been condensed and cooled in the process flow) is sent to the reactor makeup water tank via the boric acid condensate ion exchanger, which prevents boron carryover into the reactor makeup water tank.

21 Engineering Training (Program) Page: 21 of 90 EO State the function of the Containment Building. Main Idea Purpose: The containment houses the Reactor Coolant System and constitutes a major barrier to the release of fission product activity to the environment. The functional requirements for the containment design are: The containment must withstand the peak pressure and time varying thermal gradient resulting from postulated accidents. The containment must be leaktight in order to minimize leakage of airborne radioactive materials. Provisions are included for approximately 150 piping and electrical penetrations as well as two personnel/equipment access points. The containment must provide biological shielding during normal operations and under accident conditions. Major Components: In terms of geometry, the containment consists of a flat base slab, a right cylinder, and a hemispherical dome. The containment is constructed of reinforced concrete pre-stressed by post-tensioned tendons in the cylinder. Prestressed means that the concrete is stressed prior the application of the operational load, and post-tensioning refers to tendons that applied after the concrete has hardened. With an interior height of 206.5' and an interior diameter of 146', the containment has a free volume of 2.6 million cubic feet. The base mat contains a central cavity and a tunnel around the perimeter for instrumentation and inspection. Overall the base mat has a thickness of 10.5'. The containment walls vary in thickness from 4.0' at the wall springline to 3.5' at the apex of the dome. The walls are clad with a 1/4" welded steel plate liner to prevent leakage. The safety analysis shows that the containment meets the requirements of the ASME Boiler and Pressure Vessel Code, Section III Division 2 (concrete containments). The calculations included load factors in computing ultimate loads to provide a factor of safety against variation in loads, assumptions in structural analysis, simplifications in calculations, and effects of construction sequence and methods. Load factors are the ratios by which the anticipated loads are multiplied in the design process in order to assure that they are conservatively estimated, and that deformation behavior of the structure is elastic (low strain). The load factor approach makes a rational evaluation of the isolated factors that must be considered to assure an adequate safety margin. This approach places the greatest conservatism on those loads most subject to variation and those most directly controlling the safety of the structure. The civil general design criteria classifies loads as either normal operating or accident/extreme environmental. The criteria specify various combinations of loads which must be evaluated as well as the appropriate load factors. The safety analysis considered a range of postulated accidents to determine the limiting challenges to the containment structure. Load factors for the abnormal category demonstrate that the containment has the capacity to withstand pressure loadings at least 50% greater than those calculated for the postulated LOCA or MSLB. The containment can also withstand a load greater than 25% of a limiting accident concurrent with an Operating Basis Earthquake or a Safe Shutdown Earthquake. In addition, the structure will withstand a 100 year wind (105 mph) and design basis tornado. The latter includes translational wind speeds of 60 mph, tangential winds of 240 mph, and a barometric pressure drop of 2.25 psi in less than 2 seconds.

22 Engineering Training (Program) Page: 22 of 90 The containment design conditions are 60 psig for internal pressure and 300 F. The UFSAR indicates that the large break LOCA presents the worst case. For a double-ended slot break in a RCP discharge line having an area of 9.82 square feet, the resulting peak containment pressure was 49.5 psig, and the peak temperature was 298 F. The Main Steam Line break inside containment was less limiting; however, the maximum local containment temperature of 370 F achieved during the MSLB was used a design basis for demonstrating compliance with Equipment Qualification requirements. In addition, the pressure in three containment subcompartments resulting from a LOCA were calculated to demonstrate that the interior walls were capable of withstanding accident loadings. To evaluate the containment structure under external loads, two events were considered: misoperation of the containment purge equipment and inadvertent containment spray actuation. Both events involve the creation of external load by drawing a vacuum in containment. The first event occurs if a containment purge discharge fan is operated without its associated supply fan. The analysis shows that the equivalent differential pressure produced is only a few inches of water. In the containment spray event, a vacuum is produced as the containment air is cooled by the spray. The resulting pressure -2.6 psig was bounded by the design pressure of -4.0 psig. Containment Design Parameters Inside Diameter (ft) 146 Inside Height (ft) 206 Net Free Volume (ft 3 ) 2,620,000 Concrete Thickness, Dome (ft) 3.5 Concrete Thickness, Cylindrical Walls (ft) 4 Concrete Thickness, Buttress Section (ft) 6.5 Concrete Thickness, Basement (ft) Design Pressure, External (psid) 4 Design Pressure, Internal (psig) 60 Design Temperature, High Mean, During Normal Ops (F) 120 Design Temperature, Maximum Design Basis Accident (F) 300 Design Leak Rate (% net free volume per 60 psig) 0.1

23 Engineering Training (Program) Page: 23 of 90 EO State the purpose of the Safety Injection system and identify the major components. Introduction Safety Injection The Safety Injection System can be broken into 3 functional areas or systems; Emergency Core Cooling (Safety Injection), Residual Heat Removal (Shutdown Cooling) and Containment Heat Removal (Containment Spray System). The relationship between the systems is that all are used for some phase of plant cooldown on a loss of coolant accident. The SI System is the first system to respond to this condition by injecting borated water into the Reactor Coolant System by means of Safety Injection Pumps and/or Safety Injection Tanks. The Shutdown Cooling System supplements other heat rejection equipment to reduce temperature in post shutdown periods to the refueling temperature (125 F). The Containment Spray System introduces borated water into the containment atmosphere to reduce containment pressure and temperature in the event of a pipe rupture and removes iodine from the containment atmosphere. Main Idea Purpose: Emergency Core Cooling (Safety Injection) The functions of the Safety Injection System are: Inject borated water into the RCS to flood and cool the core in the event of a LOCA thus preventing a significant amount of cladding failure along with subsequent release of fission products into the containment. Remove heat from the core for extended periods of time following a LOCA. Inject borated water into the RCS to increase shutdown margin following a rapid cooldown of the system due to a steam line rupture.

24 Engineering Training (Program) Page: 24 of 90 During a loss of coolant, a Safety Injection Actuation Signal is generated by low pressurizer pressure and/or high containment pressure. Once activated the SI System delivers borated water to the Reactor Coolant System by means of active pumps and/or passive injection tanks. The Refueling Water Tank provides the initial source of cooling water. When the tank is depleted, the SI pump suction switches to the containment sumps, and RCS fluid lost through the break is recycled to conserve inventory. In addition, borated water injected into the RCS by SI also increases shutdown margin following a rapid cooldown of the system due to a steam line rupture. The Safety Injection System has an active component and a passive component. The passive component consists of 4 Safety Injection Tanks each connected to one of the RCS Cold Legs. A SIT is a tank containing a large volume of borated water with a nitrogen gas cover pressure of approximately 600 psig. Each SIT is normally isolated from the RCS by a check valve held shut by RCS pressure. The SITs are called passive since no electrical power is necessary to cause the injection. IF RCS pressure falls below SIT pressure (<600 psig) the check valves open and borated water flows to the RCS due to the SIT nitrogen pressure. The active components of Safety Injection System consist of 2 trains of HPSI Pumps, LPSI Pumps, and their injection valves. The pumps and valves are powered by Class IE power sources and auto START/OPEN upon receipt of a Safety Injection Actuation Signal. The HPSI and LPSI pumps take a suction on the borated Refueling Water Tank and inject into the RCS cold legs. Each HPSI pump injects to all four cold legs and has the capability of being lined up to the associated hot legs. The LPSI pumps inject into two cold legs each. Shutdown Cooling The functions of the Shutdown Cooling System are: Supplement other heat rejection equipment as necessary to reduce the temperature of the RCS in post-shutdown periods from approximately 350 F to the refueling temperature (125 F) and to maintain the refueling temperature for extended periods of time. Supplement other heat rejection equipment in cooling the plant and bringing it to cold shutdown operation following a steam line break or small break LOCA. Remove heat from containment following a LOCA by shifting heat exchangers to the recirculation mode. Supplement the cooling capacity of the Fuel Pool Cooling and Cleanup System during refueling operations. Transfer water between the refueling water tank and refueling pool when filling and draining the refueling pool. The Shutdown Cooling System supplements other heat rejection equipment to reduce temperature in post shutdown periods to the refueling temperature (125 F). During normal operations, it is used to remove decay heat when the reactor shut down, and the steam generators are not available. The Shutdown Cooling System consists mainly of components of the Safety Injection System and the Containment Spray System, including: LPSI pumps Shutdown Cooling Heat Exchangers CS pumps Loop Injection Valves Suction valves connected to the RCS Hot legs.

25 Engineering Training (Program) Page: 25 of 90 The SDCS is a recirculation heat removal system designed to transfer RCS heat to the SDCHX for removal by the Essential Cooling Water System and then to the Essential Spray Pond System. The SDCS is put into service after the RCS pressure and temperature have been reduced to approximately 400 psia and 300 F respectively. A SDCS loop takes a suction on an RCS Hot leg through three suction isolation valves. Between the second and third isolation valves on each loop is a relief valve used for Low Temperature Overpressure Protection. From the suction valves SDC flow enters the LPSI pump. The discharge of the LPSI pump is valved to the SDCHX and returns to the RCS by the LPSI Loop Injection valves. Flow and temperature is controlled by manipulation of the SDCHX outlet and bypass valves. The capability exists to supply SDCS flow with the CS pump. The CS pump can be used either in parallel with the LPSI pump or instead of the LPSI Pump. Administrative limits are placed on using the CS pump for SDCS to ensure containment spray operability is maintained. Containment Spray The functions of the Containment Spray System are: Introduce a cool spray of borated water into the containment atmosphere in the event of a LOCA or a steam line rupture within the containment to reduce containment pressure and temperature and limit the leakage of airborne activity from the containment. Remove iodine from the containment atmosphere Provide additional flow during shutdown cooling operations to maintain the desired cooldown rate at lower RCS temperatures. Remove heat from containment following a LOCA by shifting heat exchangers to the recirculation mode. The containment serves as a major barrier to the release of radioactive fission products. During a LOCA, the addition of thermal energy from steam causes the containment temperature and pressure to increase. This may result in overpressurization and subsequent failure of the containment (leakage in excess of design bases). The Containment Spray System reduces containment pressure by condensing steam through the introduction of relatively cool borated water into containment atmosphere. The spray also reduces offsite dose consequences by removing iodine from the containment atmosphere. The Containment Spray System consists of the following major components: Containment Spray Pumps. Containment Spray Headers. Shutdown Cooling Heat Exchangers Spray Isolation Valves.

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27 Engineering Training (Program) Page: 27 of 90 EO: State the purpose of the Excore Neutron Monitoring System (SE) and the Incore Instrumentation (RI), identify major components and state their function Main Idea Excore Neutron Monitoring Instrumentation (SE) Purpose The purposes of the excore nuclear instrumentation system (SE) are to: Provide continuous monitoring of neutron flux from source levels, 2 x 10-8 up to 200% of full power. Provide an indication in the main control room representative of neutron flux for all levels of reactor operations including source level startups. Provide auxiliary outputs proportional to the rate of change of power. Provide (in the power operating range) signals to the plant protection system (SB) for departure from nucleate boiling ratio (DNBR) protection, power level, and local power density (LPD). Provide (in the power operating range) signals to the loose parts and vibration monitoring system for use in detecting core support barrel motion. Provide (in the power operating range) signals to the reactor regulating system for use during automatic turbine load following operations. Provide instrumentation and annunciators in the main control room for the rate of change of power level. Provide audio (by remote speakers) count rate information in the main control room and containment to monitor neutron flux at low power levels. Provide annunciators in the main control room to alert the operator of a boron dilution event during shutdown subcritical modes of operation. To monitor neutron flux for 182 days after a loss of coolant accident or main steam line break. Major Components The excore nuclear instrumentation system (SE) provides a means of measuring reactor power level by monitoring neutron flux leakage (which is proportional to power) from the reactor vessel. The equipment includes: Neutron detectors located around the reactor vessel Pre-amplifiers (when required) located outside the reactor biological shield Pre-amplifiers for post-accident excores Signal processing drawers (located out-of-containment) Remote indicators, recorders, and controls located in the main control room area and remote shutdown area.

28 Engineering Training (Program) Page: 28 of 90 Neutron flux is monitored from source levels through full power operation, and signal outputs are provided for reactor control, reactor protection and for information display. Two startup, two control, and four safety channels of instrumentation are furnished and provide outputs. The neutron detectors are mounted in holder assemblies, which are located in instrument wells (thimbles) external to the reactor vessel. Eight instrument wells are required, one per channel. The SE system is designed for the following performance functions in order to meet various NRC design criteria and requirements: The SE system safety channels are designed to provide continuous reactor power monitoring from the source range to 200% of full reactor power. The SE system log safety channels are designed to monitor the rate of change of reactor power. The SE system startup channels are designed to monitor the neutron flux in the source range. The SE system is designed to provide for the boron dilution alarm system (BDAS). The SE system is designed to provide reactor power signals for operator information and control channel signals for control functions (RRS, SBCS, and FWCS).

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30 Engineering Training (Program) Page: 30 of 90 BF 3 Detector (SEN-NE-5 (Ch 1) and SEN-NE-6 (Ch 2)) Each startup channel detector assembly is comprised of two sections of BF 3 proportional counters mounted side by side in an overall can. Each section consists of two parallel elements with a 26 inch active length, with each element comprised of a cylindrical aluminum shell electrically connected to a common signal. A fine tungsten wire is strung coaxially within this chamber, and the space between these two electrodes is filled with boron trifluoride gas, highly enriched in the isotope boron 10, B 10. A large potential, typically 2000 volts, is applied between the tungsten anode and the aluminum cathode. When a thermal neutron enters the chamber, the B 10, which has a high affinity (large neutron absorption cross section) for thermal neutrons, interacts with the neutron in the following way: 5B N 1 5 B 11* 3 Li α e MeV (Gamma and Kinetic Energy) The decay of the excited B 11 nucleus into a lithium nucleus and a helium nucleus (alpha particle) liberates 2.78 Mev of energy, most of which goes into the kinetic energy of the two particles. These particles quickly dissipate their energy by stripping the BF 3 gas of electrons. In this respect, a BF 3 proportional counter is very similar to a fission chamber. However, unlike the fission chamber, the proportional counter accelerates the electrons resulting from particle interaction towards the center electrode to the point where they possess sufficient energy to strip still more electrons from the fill gas. The result is an avalanche effect in which the charge from each initiating event is multiplied several fold, so that the charge ultimately collected at the anode may be several orders of magnitude larger than that produced by the initial neutron interaction. Gas amplification is proportional to applied voltage, roughly doubling for every 150 volt increase. It is therefore possible to increase the charge out of a detector (or the voltage pulse amplitude from a detector pre-amplifier pair) simply by increasing detector high voltage. This cannot be done with a fission chamber operating in the ionization chamber mode because there is no gas amplification. The term proportional counter derives from the proportionality between the size of the input event and the output event, so that relative magnitude of initial events can be preserved, although the output amplitude (which is voltage dependent) is larger by some factor. Dual Section BF3

31 Engineering Training (Program) Page: 31 of 90 Uncompensated Ionization Chamber (SEN-NE-7 (Ch 1) and SEN-NE-8 (Ch 2)) A potential of -800 VDC is placed across the chamber active volume, and the UIC operates in the ionization region (there is no gas amplification). The chamber is boron lined and operates according to the following reaction: 5B N 1 5 B 11* 3 Li α e MeV (Gamma and Kinetic Energy) The incident thermal neutron reacts with the boron lining producing lithium and helium (alpha) ions. The ions dissipate their energy through ionization of the fill gas as they cross the inter-electrode space. The number of ions reaching the electrode is equal to the number of ions produced in the above reaction. Nearly all ions produced are collected to form a DC output current, which is linearly proportional to neutron flux. Individual section outputs are sent to the control channel for processing. Uncompensated Ion Chamber

32 Engineering Training (Program) Page: 32 of 90 Fission Chamber SEA-NE-1A (Ch A), SEA-NE-1B (Ch B), SEA-NE-1C (Ch C), SEA-NE-1D (Ch D) Each fission chamber (figure 2-8) consists of a 40 inch long active volume comprised of concentric aluminum cylinders. The space between these cylinders is filled with a nitrogen/argon mixture. One of the electrodes is coated with uranium U235, a highly enriched fissionable isotope. A large voltage is maintained across this chamber, typically VDC. The detectors operate by means of the following reaction: 0N U 235 FF1 + FF MeV (Gamma and kinetic energy) FF = Fission Fragment Chamber operation depends upon the interaction of neutrons, which have escaped from the reactor vessel with the uranium coating in the fission chamber. The number of neutrons escaping the vessel is proportional to reactor power. These neutrons are thermalized by the moderating material surrounding the detector thimbles, and are subsequently absorbed by the U235, resulting in fission. The fission results in two fission fragments of smaller mass, carrying approximately 168 MeV of energy. Neutrons released within the chamber during the fission process escape with only negligible probability of interaction with other uranium atoms because of the small quantity of fissionable material within the chamber itself. The fission fragments travel through the gas volume, giving up their kinetic energy by stripping fill gas atoms of electrons, with the number of electrons actually stripped being proportional to the energy of the original fission fragments. The large voltage across the chamber prevents the free electrons from recombining with the fill gas positive ions, sweeping these electrons to the positive (less negative) detector electrode, while the positive gas ions travel more slowly to the negative electrode. The electron collection results in a pulse of variable amplitude, depending on the amount of fission fragment energy actually dissipated in the chamber volume. These pulses can be coupled to a pre-amplifier and counted by the signal processing electronics, or integrated to yield a DC current signal. The former method is employed in a wide range logarithmic channel, the latter in the power range linear channel. Fission Chamber

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34 Engineering Training (Program) Page: 34 of 90 Incore Neutron Monitoring Instrumentation (RI) Purpose To measure the neutron flux at a large number (305 typical) of localized areas in the core for the purpose of evaluating numerous operating characteristics such as power distribution, flux tilt, and peaking factors. To monitor the coolant temperature at the core exit to provide an indication of the trending of core uncovering and recovering. Major Components The fixed incore instrumentation system consists of the following major components: Detector (neutron) Background detector Thermocouple Support hardware Incore amplifiers Amplifier high speed multiplexer There are 61 fixed incore instrumentation detector assemblies, each consisting of five self-powered rhodium detectors, one background detector, a core exit thermocouple (CET) and one dry movable detector calibration tube. The entire assembly is covered with a solid tubular oversheath. The elements of the assembly pass through a sealing device called the seal plug, which allows the element to traverse the reactor pressure boundary without permitting coolant leakage. The elements terminate at a multi-pin connector which mates with a connector on the field cables and a quick disconnect fitting on the end of the movable detector guide tube. The reactor has 61 fixed incore assembly locations, each equipped with five rhodium detectors and one full length background detector. The rhodium detectors are placed axially along the movable detector calibration tube at 10, 30, 50, 70, and 90% of active core height.

35 Engineering Training (Program) Page: 35 of 90 The background detector is identical to the rhodium detectors except that the rhodium has been removed. The detector provides periodic confirmation of correction coefficients to the plant computer and is used in the fixed incore amplifiers to compensate for signal errors induced in the signal wire. The core exit thermocouples (CETs) provide direct input to the qualified safety parameter display system (QSPDS). These temperatures are used to determine if there is an approach to inadequate core cooling during core uncovering and recovering

36 Engineering Training (Program) Page: 36 of 90 EO State the purpose of the Plant Protection System and identify the major components. Plant Protection System The Palo Verde Plant Protection System (PPS) is divided into three sub-systems; Reactor Protection System (RPS) Engineered Safety Features Actuation System (ESFAS) Supplementary Protection System (SPS) Each of these subsystems performs specific functions within the overall scope and purpose of the PPS. The RPS provides fifteen automatic reactor trips. Thirteen of these are analog inputs. The Core Protection Calculators provide two digital contact inputs. Manual reactor trip is also available. The ESFAS provides seven safety functions and automatic actuation signals for the two safety related equipment groups (trains). Manual actuation of individual or multiple equipment trains is afforded as well. The SPS provides a single reactor trip function from pressurizer pressure analog inputs. Main Idea Major Components and their function: Reactor Protection System The Reactor Protection System portion of the Plant Protection System provides a rapid and reliable shutdown of the reactor to protect the core and the reactor coolant system pressure boundary from potentially hazardous operating conditions. Shutdown is accomplished by the generation of reactor trip signals. The trip signals open the Reactor Trip Switchgear breakers, de-energizing the Control Element Drive Mechanism coils, allowing all Control Element Assemblies to drop into the core by the force of gravity.

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38 Engineering Training (Program) Page: 38 of 90 The RPS provides trips for the following conditions: 1. Variable Overpower - >111% (preset ceiling) or >10.6%/minute (rapid power increase) 2. High Logarithmic Power Level - >0.01% (bypassed on power increase) 3. High Local Power Density - >21 kw/ft 4. Low Departure from Nucleate Boiling Ratio - < High Pressurizer Pressure - >2383 psia 6. Low Pressurizer Pressure - <1837 psia 7. High Steam Generator Water Level - SG 1 - >91% nr 8. High Steam Generator Water Level - SG 2 - >91% nr 9. Low Steam Generator Water Level - SG 1 - <44% wr 10. Low Steam Generator Water Level - SG 2 - < 44% wr 11. Low Steam Generator Pressure - <960psia 12. High Containment Pressure - >3.0 psig 13. Low Reactor Coolant Flow - SG psid 14. Low Reactor Coolant Flow - SG psid

39 Engineering Training (Program) Page: 39 of Manual Trip Engineering Safety Features Actuation System The ESFAS portion of the Plant Protection System provides the following actuation signals to the Engineered Safety Features equipment when the applicable monitored variables reach levels requiring protective action: 1. Containment Isolation Actuation Signal (CIAS) 2. Containment Spray Actuation Signal (CSAS) 3. Main Steam Isolation Signal (MSIS) 4. Safety Injection Actuation Signal (SIAS) 5. Recirculation Actuation Signal (RAS) 6. Auxiliary Feedwater Actuation Signal 1 (AFAS) 7. Auxiliary Feedwater Actuation Signal 2 (AFAS)

40 Engineering Training (Program) Page: 40 of 90 Safety Injection Actuation Signal The Technical Specification require that an SIAS will be generated at both of the following: decreasing pressurizer pressure of <1837 psia (ceiling-variable setpoint) increasing high containment pressure of > 3.0 psig. The low pressurizer pressure function also trips the reactor via the RPS. The high containment pressure actuation is also shared with the corresponding reactor trip. Pretrip alarms are provided to alert the operator that a trip value is being approached. SIAS is required in the event of a Loss of Coolant Accident, Main Steam Line Break, or Steam Generator Tube Rupture. It actuates the components required for injection of borated water into the Reactor Coolant System and emergency core cooling, thereby ensuring adequate shutdown margin and minimizing core fuel damage. Containment Isolation Actuation Signal The CIAS is also generated on either low pressurizer pressure or high containment pressure. The setpoints and actuation functions are the same as those for SIAS and the corresponding RPS trips. An SIAS, CIAS and reactor trip will occur simultaneously. Pretrip alarms are provided; Low PZR Press Pre-Trip at 1880 psia; High Containment Press Pre-Trip 2.5 psig. The CIAS initiates isolation of selected process lines penetrating the containment. By isolating the containment; the release of radioactive material to atmosphere is minimized for accidents involving fuel damage and the associated fission product releases. Energy release to the containment which could lead to over-pressurization and potential failure is limited in the event of main feedwater or steam system piping ruptures. Containment Spray Actuation Signal The Tech Specs require that a CSAS be initiated on an increasing (HI-HI) containment pressure of 8.5 psig. Since CSAS occurs at a higher containment pressure than the SIAS & CIAS actuations, both SIAS & CIAS should also be present during any containment spray actuation. Pretrip alarms are provided at 6.0 psig. The CSAS actuates the Containment Spray Systems in the event of a LOCA or MSLB. The cool borated spray water removes heat from the containment atmosphere to limit and reduce post accident containment pressure. Recirculation Actuation Signal The Tech Specs require that a RAS be generated on a decreasing Refueling Water Tank level of 7.4%, following an SIAS. Pretrip alarms are provided at 11% RWT level. The RAS is provided to initiate recirculation of borated water from the containment sump. This provides for long term post-accident Emergency Core Cooling using the Safety Injection System. Following SIAS actuation, the RWT serves as the source of borated water for core injection and containment spray. When the RWT water inventory is depleted, an RAS will cause the ESF systems to automatically shift their suction to the containment sump. The sump, being full of water previously pumped from the RWT for core injection and containment spray, can now serve as the borated water supply for long term core cooling. Main Steam Isolation Signal The Tech Specs require that a MSIS be generated by the ESFAS when any of the following conditions occur: A decreasing SG No. 1 or SG No. 2 pressure of <960 psia An increasing level in SG No. 1 or SG No. 2 level of > 91% (NR) An increasing Containment Pressure of > 3.0 psig. The MSIS will isolate the Main Steam, Main Feedwater, Sample and Blowdown lines on both steam generators regardless of which SG (if either) was responsible for the actuation. In the event of a MSLB, the MSIS will limit the energy release to containment and prevent excessive containment pressures. By isolating both Steam Generators, only the damaged SG can release its energy. It also prevents a complete blowdown of both SGs and the resulting loss of heat sink for the reactor core.

41 Engineering Training (Program) Page: 41 of 90 Auxiliary Feedwater Actuation Signal Separate AFAS signals are developed for each Steam Generator: AFAS-1 for SG-1 and AFAS-2 for SG-2. Tech Specs require that an AFAS be initiated for a particular steam generator when it has a decreasing level of < 25.8% WR and its pressure is < 185 psid below the other Steam Generator. The SG pressure instrumentation channels are compared in the AFAS circuitry. As long as pressures in both SGs are about equal, both will be considered intact. If, however, pressure in the two SGs differs by more than 185 psi, the one with the lower pressure will be considered ruptured and will not receive an AFAS actuation. The following pre-trip alarms are provided; Low SG Level at 28.7% WR SG1/SG2 Differential Pressure Pre-Trip 124 psid The AFAS will start the auxiliary feedwater pumps and open the auxiliary feedwater valves to the intact steam generator, maintaining a minimum water inventory for decay heat removal. This provides protection for a loss of normal feedwater flow. Under certain conditions, the actuation signal may be initiated by the Diverse Auxiliary Feedwater Actuation System. Once actuated, the auxiliary feedwater pumps will remain operating until the actuation has been reset and the pumps manually secured. The actuated valves will cycle open and shut automatically 25.8% WR, 40.8% WR) to maintain level in the appropriate SG. Each aux. feedwater train can feed either SG individually or both SGs simultaneously. Manual Actuation Manual initiation of both the A and B safety equipment trains for either SIAS, CIAS, CSAS, MSIS, RAS, AFAS-1 or AFAS-2 may be accomplished from B05, using either of two adjacent sets of actuation switches. These switches open the trip path lock-outs once actuated. Manual actuation of individual safety equipment trains for each actuation signal can be done from the Aux. Relay Cabinets. Manual actuation of the MSIS (both trains) can also be accomplished from the Remote Shutdown Panel. Supplementary Protection System The SPS provides initiation and annunciation of a reactor trip. The SPS augments the RPS by providing a separate trip logic and diverse initiation of a reactor trip. The SPS trip is initiated on High pressurizer pressure (2409 psia) to protect the Reactor Coolant Pressure Boundary against the overpressurization which could otherwise result from an Anticipated Transient Without Scram (ATWS) event. An Anticipated Transient Without Scram is an expected operational transient (such as a loss of condenser vacuum, loss of feedwater, or loss of offsite power) which is accompanied by a failure of the Reactor Protection System to trip the reactor. The trip signal opens the reactor trip switchgear and CEDM M-G set output contactors, either one of which will de-energize the CEDM coils allowing all CEAs to drop into the core. The SPS also provides independent monitoring and indication of Reactor Coolant System pressurizer pressure and RTSG breaker status.

42 Engineering Training (Program) Page: 42 of 90 EO State the purpose of the Steam Generator and identify the major components. Main Idea Purpose: The Steam Generator (SG) produces the steam that drives the main turbine. Steam Generator During normal operation, reactor coolant leaving the core of the reactor vessel enters the 2 "hot legs", one per loop, and flows to the steam generators. Hot leg temperatures range between 564 F (at zero power) and 615 F (at full power). This hot reactor coolant enters the steam generator through the inlet nozzle in the steam generator primary head. The steam generator is a shell and U-tube heat exchanger with an integral economizer. It operates with reactor coolant on the tube side and secondary coolant on the shell side. Primary (reactor) coolant flows through the U-tubes giving up its heat to the secondary feedwater in the shell side of the steam generator. The heat added by the reactor coolant causes the feedwater (secondary coolant) to boil thus generating steam for turbine operation. The primary (reactor coolant) and secondary (feedwater and steam) systems are separated and do not come in contact with each other. This design prevents radioactive contamination of the secondary system. Reactor coolant leaves the steam generator through two outlet nozzles at a "cold leg" temperature of approximately 557 F. A vertical divider plate separates the inlet and outlet plenums of the primary head. Each outlet supplies the "suction leg" piping of the reactor coolant pumps. Two steam generators transfer the heat generated in the reactor coolant (RC) system to the secondary coolant, forming 99.9% quality steam for use in the main turbine. Major Components: Each Steam Generator consists of the following major components: Primary chamber Tube sheet and U-tubes (12,580) Secondary side shell Feedwater ring Economizer Wrapper plate Moisture separators (194) Steam dryers (142) Steam nozzles (2) Blowdown nozzles and piping, Wet lay-up recirc. pump (1)

43 Engineering Training (Program) Page: 43 of 90 EO State the purpose of the Main Steam System and identify the major components. Main Idea Purpose: The function of the main steam supply system is to deliver steam from the steam generators to the high-pressure turbine over a range of flows and pressures covering the entire operating range from system warmup to valves-wideopen conditions. The system also provides steam to the moisture separator/ reheaters, the feedwater pump turbines, and the steam seal system for the main and the feedwater pump turbines. Major Components: The four Main Steam Supply Lines, two per steam generator, penetrate the containment and enter the Main Steam Support Structure. The Main Steam Safety Valves, Atmospheric Dump Valves, and Main Steam Isolation Valves are located in the MSSS. Five Main Steam Safety Valves, one Atmospheric Dump Valve and one Main Steam Isolation Valve are installed in each steam line. The Main Steam Safety and Atmospheric Dump Valves are located upstream of the Main Steam Isolation Valves to ensure Steam Generator over pressure protection is provided at all times. The safety valves are spring-operated and open sequentially with increasing pressure. The Atmospheric Dump Valves are air-operated and may be opened/closed by the Control Room operator to control pressure or primary plant cooldown in the event the Main Condenser and/or Steam Bypass Control System are not available. A connection is provided on one of the main steam lines of each steam generator upstream of the Main Steam Isolation Valves for adding nitrogen gas to the Steam Generators during shutdown conditions. This is necessary to minimize corrosion. The nitrogen gas is vented to the Containment Purge System prior to startup. A connection is provided on one of the Main Steam Lines of each steam generator upstream of the MSIVs for supplying steam to the Train A Auxiliary Feed (AF) pump turbine. This arrangement ensures steam and thus feedwater will be available for primary plant cooldown during emergency conditions. The MSIVs can be positioned to isolate the Steam Generators from the Main Steam System. They may be operated from the control room and close automatically upon receipt of a Main Steam Isolation Signal. Each Steam Generator supplies 8.96 x 10 6 lbm/hr steam flow at saturated conditions of 1039 psia and 549 F. The four Main Steam Lines provide a total steam flow of 17.9 x 10 6 lbm/hr and are cross-connected downstream of the MSIVs to equalize steam generator load and pressure. The following steam loads are supplied from the cross-connect header and downstream main steam piping: Main turbine (high pressure) Main feedwater pump turbines Steam Bypass Controls System Auxiliary Steam System Gland Sealing steam Reheat steam to 2nd stage heater.

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45 Engineering Training (Program) Title: EO NGT95 Introduction to Plant Systems Page: 45 of 90 Lesson Plan #: NGT95C State the purpose of the Main Turbine system and identify the major components. Main Idea Purpose: The Main Turbine System provides a means of converting the thermal energy received from the Nuclear Steam Supply System into mechanical energy to drive the Main Generator at a constant speed over the entire generator load range. Major Components Steam from the two Steam Generators is supplied to the Main Turbine and for startup of the Feedwater Pump Turbines when Main Turbine load is less than 470 MW (35% of full load). When turbine load is greater than 470 MW, the pump turbines are supplied by reheat steam. Steam from the Main Steam System enters the high-pressure turbine through four stop and four governing control valves. Crossties are provided both upstream and downstream of the stop valves to provide pressure equalization with one or more stop valves closed. A portion of the main steam is used for second-stage reheat in the Moisture Separator Reheater. The steam exiting the MSR is used to supply the Low Pressure Turbines.

46 Engineering Training (Program) Page: 46 of 90 There are two steam extraction points in the High Pressure Turbine. Steam from the first (3rd Stage) extraction point is used for seventh point feedwater heating and first stage reheat of the MSR. Steam from the second extraction point (5th Stage) is used for sixth point feedwater heating. After expanding through the HPT, the exhaust steam flows through the MSR to remove entrained moisture and to superheat the steam, thus improving cycle efficiency. The drying and reheating processes, which takes place before the Low Pressure Turbine inlets, not only improves the cycle efficiency and but it also minimizes erosion of the LPT buckets (due to excessive exhaust wetness). A portion of the HPT exhaust (Cold Reheat) is used for fifth point feedwater heating before going through the MSR s. After the steam passes through the MSR s a portion of the reheated steam (Hot Reheat) is directed into the MFWPT s which drive the Steam Generator Feedwater Pumps. The remainder of the reheated steam is routed equally to the three LPT s through Combined Reheat Stop and Intercept Valves. In each LPT, there are four steam extraction points for the remaining four stages of feedwater heating. 8th Stage extraction provides heating to #4 Feedwater Heater, 9th Stage extraction provides heating to #3 Feedwater Heater, 11th Stage extraction provides heating to #2 Feedwater Heater, 12th Stage extraction provides heating to #1 Feedwater Heater. After expansion in the LPT, the steam is discharged to the Main Condensers. In addition to the external MSR s, the last three LPT stages are designed to remove any condensed moisture and drain it to the next lowest extraction. The moisture from the external MSR s is drained to MSR Drain Tanks and from there to the Heater Drain Tank and subsequently is pumped into the Feedwater System. Similarly, the condensate in the reheaters is drained to the HDT and is pumped into the Feedwater System. Moisture Separator Reheaters The Moisture Separator Reheaters mechanically remove entrained moisture from the High Pressure Turbine exhaust steam and reheat the dried steam to a temperature near the initial live steam temperature. A portion of the reheated steam is directed into the Feedwater Pump Turbine. The remainder of the reheated steam is then passed on to the Low Pressure Turbines. Steam from the two Main Steam Generators is supplied to the Main Turbine. When generator loads above 15 percent have been sustained, the MSR s are placed in service. Exhaust steam from the High Pressure Turbine flows through the MSR s. The drying and reheating processes, which takes place before the Low Pressure Turbine inlets, improves the cycle efficiency and minimizes erosion of the Low Pressure Turbine buckets (due to excessive exhaust wetness). A portion of the reheated steam is directed into the Feedwater Pump Turbines which drive the Steam Generator Feedwater Pumps. The remainder of the reheated steam is routed to the three Low-Pressure Turbines. The Low Pressure Turbines exhaust into the Main Condenser. Extraction steam from the High Pressure Turbine third stage is used for heating steam for the First Stage Reheater. The heating steam for the Second Stage Reheater is supplied from the main steam lines. Moisture removal from the cycle is achieved by both external moisture separators and internal stage moisture removal in the Low Pressure Turbine elements. Each Moisture Separator Reheater has three drain tanks associated with it, a Moisture Separator Reheater Drain Tank, a 1st Stage Reheater Drain Tank, and a 2nd Stage Reheater Drain Tank. Since there are four MSR s, there are four such groups supplied. The MSR Drain Tank receives drains from the MSR shell that contains the moisture removal vanes. The MSR Drain Tanks drain to the Heater Drain Tanks through their normal level control valve. On a high level in the drain tank, the tank will drain to the Condenser. The tank is vented back to the MSR. The 1st Stage Reheater Drain Tank receives drain from the 1st stage reheater tube bundle. The drain tank normally drains to the 6th Stage Feedwater Heater, on a high level the tank will drain to the Condenser. The tank is normally vented back to the 1st stage tube bundle, during Purge operations the tank is vented to the Condenser. The 2nd Stage Reheater Drain Tank receives drain from the 2nd stage reheater tube bundle. The drain tank normally drains to the 7th Stage Feedwater Heater, on a high level the tank will drain to the Condenser. The tank is normally vented back to the 2nd stage tube bundle, during Purge operations the tank is vented to the Condenser.

47 Engineering Training (Program) Page: 47 of 90 Steam Bypass Control System The purpose of the Steam Bypass Control System is to maximize plant availability by making full utilization of the capacity of the Turbine Bypass Valves to remove Nuclear Steam Supply System thermal energy. This objective is achieved by the selective use of the Turbine Bypass Valves to release steam and thereby to avoid unnecessary Reactor trips by preventing the opening of Pressurizer or Steam Generator Safety Valves. The SBCS provides a means for controlling NSSS thermal conditions during heatup, cooldown and after unit trips by the accommodation of load rejections, and other conditions which result in excess NSSS energy. By using the SBCS in conjunction with the Reactor Power Cutback System and the Reactor Regulating System, the Turbine Bypass Valve and Condenser capacities can accommodate 100% Turbine load rejections without lifting Primary or Secondary Safety Valves.

48 Engineering Training (Program) Page: 48 of 90 EO State the purpose of the Main Generation system and identify the major components. Main Idea Purpose: The functions of the Main Generation System are to: Convert mechanical power from the main turbine to electric power and step up the voltage for transmission by the Extra High Voltage transmission system. Provide normal operating power for non-safety-related auxiliaries of the nuclear generating unit. Major Components: The Main Generation System consists of the main generator an isolated phase bus a unit auxiliary transformer a bank of main step-up transformers

49 Engineering Training (Program) Page: 49 of 90 The Main Generator converts mechanical power received from the main turbine to electrical power. The Main Generation System, is started by pressurizing the generator with hydrogen, starting the isophase bus and generator stator cooling, bringing the turbine up to speed, applying field excitation, and synchronizing the generator to the system. The generator output voltage, nominally 24 kv, is applied to the isolated phase bus which, in turn, supplies the transformers. The Unit Auxiliary Transformer converts the 24 kv to 13.8 kv and provides power to both 13.8 kv nonclass IE buses using a dual secondary winding system. This is the normal system configuration for normal operation. The Main Transformer raises generator voltage to a nominal 525 kv for transmission to power utilization points for industrial, commercial and residential use. The main generator is located in the Turbine Building at the 176 elevation. The Unit Auxiliary Transformer wall and the Main Step-up Transformers are plant south of the Turbine Building. The Isolated Phase Bus is located from the main generator terminals inside the Turbine Building and continues through the Turbine Building wall to the Unit Auxiliary Transformer and the Main Step-up Transformer.

50 Engineering Training (Program) Page: 50 of 90 Main Generator Cooling The main generator rotor is cooled by a flow of hydrogen gas between the rotor and stator and through the ventilation passages in the rotor body. The internal components of the main generator excitation system are also cooled by hydrogen gas. The hydrogen is cooled by coolers located in the generator casing. Hydrogen is circulated through the shell side of the cooler and throughout the generator casing by two axial fans mounted on the shaft at each end of the generator rotor. The hydrogen coolers are cooled by the Turbine Cooling Water System. Hydrogen is used as a cooling medium in large generators, it conducts heat better than air because its molecules move much faster. It is less dense causing less windage (friction, resistance) loss while still adequately cooling. When kept dry, it will not cause oxidation in the generator. Because a hydrogen based system must be kept pure; dust, dirt, and other contaminant build ups are kept at a minimum. All these qualities together permit the generator to run a higher load and greater efficiency without overheating. The major disadvantage to a hydrogen based cooling system is its explosive potential. Hydrogen will burn in air if the hydrogen to air ratio is 19:1 or less. The hydrogen to air ratio in the generator is maintained at approximately 97:1 thus precluding explosive probabilities. Hydrogen will burn if the concentration in air is between 4 and 46%. Concentrations between 46 and 75% will explode. The support system must be capable of keeping the generator full of gas at above 90% purity and 75 psig pressure. It must also be well sealed to prevent oxygen from entering. During generator filling, there must be an intermediate gas used to ensure that hydrogen and oxygen do not come together. Once H 2 purity is greater than 90% and H 2 pressure is raised to 75 psig the H 2 regulator is placed in service and H 2 pressure is maintained by automatic makeup through the H 2 pressure regulator to maintain 75 psig in the generator. The regulator is manually adjusted to the set pressure. The hydrogen used for generator cooling is itself cooled using two shell and tube type coolers located in the generator casing. Hydrogen is circulated through the shell side of the coolers and throughout the casing by two axial fans mounted on the shaft. The Turbine Cooling Water System provides the heat removal medium on the tube side. Each cooler is capable of carrying 80% of the generators required cooling load and maintain machine hydrogen temperature between 48 C maximum and 30 C minimum. Temperature is controlled by measuring the H 2 temperature in the generator and adjusting the turbine cooling water outlet temperature control valve on the hydrogen cooler to maintain a setpoint temperature of 35 C. Generator H 2 gas pressure is automatically maintained by a pressure regulator manually set to maintain 75 psig of H 2 gas in the generator. The hydrogen gas is also circulated through a gas dryer to remove moisture. The moisture in the gas adheres to the absorber which can then be removed by applying heat and creating a vacuum using the Seal Oil System vacuum pump. A color indicator provides (light pink) indication that the dryer needs reactivation. The Generator Seal Oil System (SO) prevents the escape of hydrogen gas from the enclosed generator casing along the rotor shaft. A shaft seal is provided at each end of the generator where vacuum treated oil from the vacuum tank is fed between the seal rings and the shaft preventing hydrogen from leaking past the seals. SO receives oil from the lube oil system, degassifies the oil, delivers it to the shaft seal, collects the drain oil from the seals, removes absorbed gases, and returns the oil to the lube oil system. If the lube oil system is lost as indicated by a drop in bearing header pressure, valves will align to allow closed loop operation to ensure seal maintenance.

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52 Engineering Training (Program) Page: 52 of 90 EO State the purpose of the 13.8 KV Non Class Electrical Distribution system and identify the major components. Main Idea Purpose & Major Components: The 13.8-kV Non-Class IE power system receives off-site power from the 525-kV switchyard and power from the unit auxiliary transformer. Distribution of the power is to station auxiliary loads from the 13.8-kV switchgear. The Non-Class IE, 13.8 kv power system consists of one kv startup transformer, and six 13.8 kv switchgear per unit. In addition two 13.8 kv switchgear serve the water reclamation plant. The unit auxiliary transformer (MAN-X02) of the Main Generator System (MA) supplies the normal source of power for 13.8 kv switchgear buses NAN-S01 and -S02. The buses NAN-S01 and S02, in turn, distribute that power to nonsafety related motors above 3500 hp and other non-safety related station auxiliaries via the normal service transformers (NBN-X01 & X02). The non-class 1E start-up transformers each have two 13.8 kv secondary windings connected to 13.8 switchgear which are arranged so that each startup transformer can provide power to the 13.8 kv auxiliary loads of all three units. The normal switching arrangement provides for each start-up transformer supplying power to two 13.8 kv intermediate buses (NAN-S05 & NAN-S06) of two different units. This arrangement is employed so that offsite power supply requirements can be met with one start-up transformer out of service. The 13.8-kV switchgear buses, NAN-S03 and -S04, receive power from the intermediate buses and supply offsite power for the ESF transformers. They also supply an alternate source of power for 13.8-kV buses NAN-S01 and -S02 respectively. Intermediate buses also supply power to two 13.8 kv buses AW-NRN-S01 and AW-NRN-S02. This system supplies many large motors, such as, the circulating water pumps and reactor coolant pumps, as well as load centers. The 13.8-kV AC non-class IE circuit breakers are equipped with panel mounted control switches for both local and remote control. Provisions are made for manual closing, tripping and automatic tripping. In addition, the alternate supply breakers for buses NAN-SO1 and -SO2 have an automatic closing function that activates a fast transfer on loss of normal power. Although normally operated from the control room, these breakers can be tripped locally in an emergency. Each breaker control switch has two positions: TRIP, which opens the breaker, and CLOSE, which closes it. A trip of any one of the generators results in a loss of the associated unit auxiliary transformer power source and initiates an automatic fast bus transfer to the startup transformer source. Following a generator trip, a fast bus transfer, between NAN-SO1 and -SO3 or NAN-SO2 and -SO4, is accomplished by simultaneous tripping of the normal auxiliary transformer supply breaker and closing of the bus-tie breaker. The Normal Service Transformer (NBN-X01, X02), Startup Transformer (NBN-X01, X02, X03), 4.16 kv & 13.8 kv Switchgear, including the components therein, have maximum and minimum rated operating temperatures. The environmental air in the plant areas where the normal service transformer and the startup transformer are located must be maintained within these temperature limits to assure the equipment will perform within rating during its normal life. These ratings include the normal transformers & startup transformers kva rating, the continuous and short circuit interrupting current ratings of the circuit breakers, and the accuracy of operating current and operating times of the protective relays, meters and instruments included within the switchgear.

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54 Engineering Training (Program) Page: 54 of 90 EO State the purpose of the 4.16KV Non Class Electrical Distribution system and identify the major components. Main Idea Purpose and Major Components: The 4.16-kV AC Non-Class IE Power system, receives power from the 13.8-kV intermediate buses through two cooling tower makeup and blowdown transformers and the in-plant 13.8 kv buses through the normal service transformer. The power is distributed to all in- plant and cooling tower Non Class IE 4.16-kV loads. Only Non-Safety related loads are supplied by the Non-Class IE 4.16-kV ac system. The Non-Class IE AC system is that part of the onsite power system that provides power to those systems that are not required for a forced or safe shut down. The Non-Class IE AC system distributes power at 13.8-kV, 4.16-kV, 480 volts and 208/120 volts for non-safety related loads. Only non-safety-related loads are supplied by the Non-Class IE AC system. During normal plant operation, power for the onsite Non-Class IE AC system is supplied through the unit auxiliary transformer connected to the generator isolated phase bus. Two offsite sources are provided to meet startup, shutdown, and post-shutdown requirements of the units. Each unit's non-class IE power system is divided into two parts arranged so that the possibility of a forced shutdown due to loss of one part will be minimized. Each of the two parts supplies a load group including approximately half of the unit auxiliaries. Three startup transformers connected to the 525 kv switchyard are shared between Units 1, 2 and 3 and are connected to kv buses of the units. Each startup transformer is capable of supplying 100% of the startup or normally operating loads of one unit on one of its secondary windings, simultaneously with the engineered safety feature loads associated with two load groups of another unit on its other secondary winding. The non-class IE ac buses normally are supplied through the unit auxiliary transformer, and the class IE buses normally are supplied through the startup transformers. In the event of failure of the unit auxiliary transformer, turbine trip, generator trip, main step-up transformer failure or reactor trip, an automatic fast transfer of the 13.8 kv buses to the startup transformers is initiated to provide power to the auxiliary loads. Transfers of all buses can be initiated by the operator from the control room. Preferred power for Class IE buses is supplied from the startup transformers through the 13.8-kV switchgear and the 13.8-kV to the 4.16-kV ESF transformers. The 4.16-kV AC Power System consists of six transformers (four non-class IE and two class IE) and their respective switchgear. Each receives 13.8-kV power. Normal Service Transformers convert non-class IE, 13.8-kV power to kv Non-Class IE power. During normal operation, transformer supply is from the unit generator through the auxiliary transformer; however, during startup or upon loss of the unit generator, it is supplied by off-site power through busses NAN-S03 and -S04. Two Normal Service Transformers, NBN-X01 and -X02, supply 4.16-kV power to switchgear NBN-S01 and -S02. They, in turn, distribute the power to non-safety related 4.16-kV motors and associated loads. These buses are connected by a bus-tie breaker to provide each with an alternate source of power. In the event of a loss of power to the 4.16-kV non-class IE bus, operation of the bus undervoltage device sheds the bus motor loads. Upon re-establishment of power, the motor loads are reconnected to the bus in accordance with their system requirements.

55 Engineering Training (Program) Page: 55 of 90 EO State the purpose of the 4.16KV Class Electrical Distribution system and identify the major components. Main Idea Purpose: The function of the 4.16 kv AC Class IE Power System is to distribute electrical power at 4.16 kv AC to all 4.16 kv AC Class IE (safety-related) loads. The Class IE System also supplies power to selected loads that are not safety related, but are important to the plant. The 4.16 kv AC System receives preferred (off-site) power through two Engineered Safety Features service transformers or standby power from two diesel generators, and distributes power to two redundant load groups in the Class IE System. Major Components: The Class IE 4.16 kv AC Power System is comprised of two 4.16 kv switchgear buses (PBA-S03 and PBB-S04), two ESF service transformers (NBN-X03 and NBN-X04) and twenty eight 4.16 kv AC circuit breakers (fourteen breakers on each bus). The two 4.16 kv AC buses are normally supplied electrical power from the preferred off-site power source through the ESF service transformers. These two transformers convert Non-Class IE 13.8 kv preferred off-site power to 4.16 kv Class IE power, with each transformer furnishing one Class IE load group. Load Group 1 (PBA-S03) supplies safety train 'A' and Load Group 2 (PBB-S04 bus) supplies safety train 'B'. A safety train is defined as that equipment considered essential for a safe shutdown of the reactor. These two trains are provided for redundant protection. Under normal circumstances during all plant conditions, transformer NBN-X03 supplies bus PBA-S03 and transformer NBN-X04 supplies bus PBB-S04 with one exception. The exception is that, during plant modes 5 and 6, both trains can be employed but only one is required. If either transformer is not available, the bus normally supplied by that transformer can be fed by the other transformer. Feeding a bus from the cross-train source is not normally done; but, during abnormal/emergency conditions the cross-train bus may be supplied from the unaffected transformer; or, during modes 5 or 6, maintenance may be performed on an ESF transformer (or other equipment upstream from the ESF transformer) by transferring the bus it normally serves to the cross-train transformer source. Standby power can be supplied to the safety train 'A' bus (PBA-S03) by the diesel-generator PEA-G01 and to the safety train 'B' bus (PBB S04) by the diesel-generator PEB-G02. The 4.16 kv Class IE power system receives control signals from the Engineered Safety Feature Actuation system. The ESFAS senses and processes signals received from key process variables and, in the case of Loss of Power to the 4.16 kv Class IE System, generates the necessary output actuation signals to shed all 4.16 kv Class IE loads, automatically start and sequentially load the diesel generators. The 4.16 kv switchgear possesses the current carrying ability and the short circuit interrupting capability to perform all the switching duties it will be called on to do by the ESFAS system, the protective relaying systems or the manual switching it may be called on to perform. This capability ensures the integrity of the system's power supply.

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57 Engineering Training (Program) Page: 57 of 90 EO State the purpose of the Class IE standby generation system and identify the major components. Main Idea Purpose & Major Components: The Class IE standby generation system provides an independent source of onsite power for each of the two trains of engineered safety features equipment in each unit. The Standby Generation Class IE Power System, along with the diesel generator mechanical systems, provides an independent standby source of on-site AC power to the two trains of Engineered Safety Features equipment in the event of loss of preferred power. The Station Blackout Gas Turbine Generation System consists of non-safety related generators, 13.8 kv switchgear and associated power distribution system used to deliver alternating current power from the gas turbine-driven generators to the units to cope with a Station Blackout at one unit. Supplies AC power from the GTGs to the blacked out unit to cope with a SBO for a duration of four hours. Power distribution is effected by manual closure of circuit breakers. Two diesel generators provide standby power for the 4.16kV AC Class IE buses. The diesel generators are connected to the bus only during emergency plant conditions (e.g. Loss of Power) or during system testing. Each diesel generator is exclusively connected to a safety features bus and there is no automatic capability for cross-connecting. Standby power can be supplied to the safety train `A' bus (PBA-S03) by the diesel-generator PEA-G01 and to the safety train `B' bus (PBB-S04) by the diesel-generator PEB-G02. During normal operation, the diesel is maintained in a standby condition with an automatic start feature if a loss of power signal, auxiliary feedwater actuation signal, safety injection actuation signal or containment spray actuation signal is received. Upon receipt of a loss of power signal, the diesel will automatically start, come up to speed and voltage, close to bus and sequence loads. Upon receipt of an AFAS, SIAS, or CSAS, the generator will start, but will not automatically align itself to the Class IE bus, unless there is also a loss of power. The generator automatically operates on its own without manual control from operator. The operator can manually control the generator and will do so when it is removed from the bus and placed in standby condition. The Standby Generation Class IE Power System is capable of supplying the vital ESF loads necessary to reliably and safely shut down the affected unit or mitigate the consequences of a loss of coolant accident concurrent with loss of preferred power. Physical separation, electrical isolation, and redundancy is provided in the system so that any type of single failure or fault will not prevent the ESF systems from performing their functions. Each diesel generator and its associated equipment is designed to operate during and after a safe shutdown earthquake; each diesel generator and its associated equipment is housed in a separate room which is a Seismic Category I structure. Each diesel generator has a continuous rating (5500 kw) greater than the sum of the required ESF loads (single train) caused by a LOCA and a loss of preferred power supply. Each diesel generator is connected exclusively to a single 4.16 kv AC ESF bus; interlocks are provided to prevent paralleling the diesel generators with each other and lockouts prevent the diesel from tying on to a faulted bus. The 4.16 kv Class IE power system receives power from the diesel generator and also receives control signals from the Balance of Plant-Engineered Safety Feature Actuation System. Upon the occurrence of an abnormality or emergency operation, the senses and processes signals received, generates the necessary output actuation signals to shed all 4.16 kv Class IE loads and, on a loss of power, automatically starts and sequentially loads the diesel generators.

58 Engineering Training (Program) Page: 58 of 90 An SBO at PVNGS is the loss of all AC power at one unit. This means the loss of preferred (offsite) power together with the loss of the standby emergency AC power (i.e., the Class IE diesel generators). During an SBO, the NE System provides AAC power to selected emergency loads. AAC power is connected to the unit's non-class IE 13.8 kv bus on the high side of the Engineered Safety Features service transformer E-NBN-X03 by manually closing circuit breakers. The AAC power source is designed to provide and maintain AC power within voltage and frequency limits to the selected emergency loads of the blacked out unit for 4 hours. This includes being capable of being started and commence loading within one hour of initiation of a SBO and carry the required loads for the remaining three hours of the SBO. An engineering study has shown that the blacked out unit can successfully cope without 4.16 kv power for at least one hour. Two GTGs are located outside the protected area, plant east of Unit 1 and south of the Water Reclamation Facility near the WRF boundary. Power cables are provided to each unit in buried conduit duct banks. Each GTG can provide and maintain emergency loads at the blacked out unit at rated voltage and frequency. Both GTG's are started during an SBO or LOOP with one carrying the NAN-S07 bus and the other in standby. The electrical control and power distribution equipment for the GTGs are housed in the turbine control building/room located adjacent to the GTGs. The AAC power system is equipped with a completely independent start system capable of a black start. The starting system is a battery backed 24VDC power source that is electrically independent from the PVNGS units' power systems. The system will start a separate diesel engine which drives a hydraulic start pump to start the turbine. NE System 13.8 kv switchgear and power distribution cable deliver power from the GTGs to each unit's 13.8 kv bus kv switchgear AE-NAN-S07 is located near the GTGs in the TCR. The associated 13.8 kv circuit breakers are closed from the TCR in the event of a SBO. Circuit breaker E-NAN-S03AB tying the AAC bus to the high side of the ESF service transformer is located in its own cubicle outdoors next to the E-NAN-S03 switchgear on the south side of the unit's turbine building. The breaker is closed manually locally. Protective relays are provided throughout the NE System to selectively isolate faulted equipment and circuits from unfaulted equipment and circuits with isolation as close to the fault as possible. The Unit 1, 2 and 3 non-safety related 13.8 kv buses receive AAC power upstream of the Train A Class IE 4.16 kv bus interface. The AAC power source is not directly connected to Train B; however, PVNGS design provides for crosstying Train A to Train B at the safety related 4.16 kv level of each unit. GTG auxiliary systems are powered from 480V MCC AE-NHN-M73 located in the TCR. Power to this MCC is normally supplied from station MCC AE-NHN-M56 located outside the power block. However, during a SBO and operation of a GTG, the MCC is powered from step down transformer AE-NAN-S07A off the generator switchgear. An automatic transfer switch AE-NHN-U5607 is provided to transfer the power feed to the TCR 480V MCC when normal power is restored. Step down transformer AE-NAN-X05 provides 120/240VAC power to the switchgear and miscellaneous loads. The AAC power source is designed as non-class IE and meets the requirements of 10CFR50.63 and Regulatory Guide

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60 Engineering Training (Program) Page: 60 of 90 EO State the purpose of the Condensate system and identify the major components. Introduction The Condensate System consists of the Main Condenser, three Condensate Pumps and three trains of Low Pressure Feedwater Heaters. Each train of LP FW heaters is comprised of four heat exchangers. The Main Condenser is a large heat exchanger with circulating water passing through the tubes and Turbine exhaust steam and various equipment drains on the shell side being condensed and collected. The main condenser collects and stores the condensed water in the condenser hotwell. The hotwell is a reservoir of condensate ready for processing and reuse in the Steam Generators. The Condensate pumps take a suction on the hotwell. The Condensate pumps can discharge the condensate to the Condensate Polishing Demineralizers or the Circulating Water canal. The Polishing Demineralizers can be bypassed. Condensate out of the Polishing Demineralizers enters the LP heater trains where the condensate passes through the tubes being heated by Extraction Steam on the heaters shell sides. The condensate exits the fourth LP heater and provides partial suction pressure for the FW pumps. The CD System condenses used steam and drains, pressurizes, conditions and heats the condensate for the FW pumps suction for ultimate makeup to the S/G s. Main Idea Purpose: Condensate System major functions are to: Provide a means of condensing the turbine exhaust system. Receive steam and feedwater miscellaneous vents and drains. Store deaerated condensate for return to the steam cycle. Provide the first four stages of regenerative feedwater heating. Provide hotwell draw off to the condensate storage tank. Provide seal water to the Feedwater pumps. Provide feedwater pumps seal water. Provide main turbine hood sprays. Provide discharge to the circulating water canal. Provides cooling water to the steam generator blowdown heat exchanger.

61 Engineering Training (Program) Page: 61 of 90 Major Components: The Condensate System begins at the Condenser and comprises all components, piping, valves and instrumentation up to the suction of the Feedwater pumps with the exception of the CD Polishing Demineralizers. The Condenser absorbs heat from Turbine exhaust steam and miscellaneous vents and drains on the condenser shell side. A water seal is provided between the LP turbine exhaust hoods and the condenser to allow for differences in thermal expansion of the equipment. LP turbine and feedwater pump turbine exhaust and LP Feedwater Heater drains are the major condenser inputs during normal heater operation. During abnormal conditions (e.g., load rejection, turbine trip), the Turbine Bypass System discharges up to approximately 40 percent (by design) full steam flow to the condenser (approximately 60% by testing). Three 50% capacity CD pumps with controls and indication in the main control room take a suction on the Condenser Hotwells through the CD pump strainers which act to protect the pumps from foreign material. The CD pumps are equipped with mini-flow recirc lines which recirculate water from the discharge side of the CD pumps back to the condenser. These mini-flow lines prevent the CD pumps from overheating. A low recirc flow alarm is provided to alert the operator to a low flow condition. The CD and ED pumps provide the NPSH to the suction of the Feedwater pumps. LP Feedwater Heaters preheat the condensate going to the Feedwater System to increase system efficiency. The heaters are located downstream of the CD pumps and just before the suction of the Feedwater Pumps. They receive the condensate after it passes through/around the CD polishing demineralizers. Condensate is used to provide water to the seal water header, the feedwater pumps seals, the condensate storage tank through the hotwell draw off, the main turbine hood sprays for cooling the turbine low pressure hoods, cooling water flow to the steam generator blowdown heat exchanger and discharge of condensate to the circulating water canal when condensate inventory needs to be reduced. Steam entering the condenser gives up heat to the circulating water flowing through the condenser tubes, condenses, and is collected in the hotwell. Each condenser section hotwell is divided into two halves, corresponding to the two CW flow paths. This feature allows continued operation (at reduced power) while one CW flow path is isolated for maintenance (e.g., to repair tube leaks). Air and non-condensable gases are continuously removed from the condenser by the Condenser Air Removal System to reduce turbine backpressure and increase efficiency. When required, makeup water is added automatically to the hotwell from the Condensate Storage and Transfer System.

62 Engineering Training (Program) Page: 62 of 90 The condensate pumps A, B, and C take suction on the condenser hotwells via two headers. CD pump A takes suction on hotwells 2A, 2B, and 2C; pump C takes suction on hotwells 1A, 1B, and 1C, and pump B can be aligned to either or both headers. An inline strainer is installed at each pump suction to prevent foreign material from damaging the pumps and entering the system supply piping. The CD pumps discharge to a common supply header which distributes flow through the LP feedwater heaters and to various service loads either directly or via the SC System condensate polishing demineralizers. The demineralizers are normally in service, to reduce condensate contaminants. To prevent the CD pumps from overheating, which would result in pump damage, the pumps are equipped with Mini-flow recirculation lines. The recirculation lines run from the discharge side of the pumps and back to the respective condenser sections. CD pump A recirculates back to Hotwell 2C. CD pump B recirculation can be directed to either Section 1C or 2C. Where the B pump returns its recirculation is a function of the position of the pumps suction valves. CD pump C recirculates back to Section 1C. Three sets of four LP feedwater heaters are installed to maximize plant efficiency by preheating the condensate with LP turbine extraction steam. The heaters in each set are arranged in series. The heaters are shell and straight-tube heat exchangers with condensate flowing through the tubes and LP turbine extraction steam on the shell sides. The feedwater heaters are located in the upper condenser volume above the tube bundles. Heated condensate leaving the LP feedwater heaters enters a common header and is directed to the feedwater pump suctions.

63 Engineering Training (Program) Page: 63 of 90 Excess condensate inventory is controlled through the hotwell level control draw off valve. Condenser hotwell level is controlled by discharging water through the hotwell level draw off valve to the condensate storage tank. The draw off valve is located downstream of the condensate polishing demineralizers. Hotwell makeup is supplied by automatic makeup valves. The flow is established due to the vacuum in the condenser. If there is not a vacuum in the condenser, the manual valves can be used for hotwell makeup. To allow feed and condensate system startup recirculation, warmup, and cleanup, a line is installed from the outlets of the last High Pressure feedwater heaters back to the main condenser. This line is sized for approximately 50% of the maximum condensate rated flow. The flow path starts at the Condenser Hotwell and flows to the condensate pumps. The CD pumps provide the motive force to circulate condensate through the Condensate Polishing Demineralizers and the LP feedwater heater trains to the suction of the Feedwater Pumps. At the Feedwater Pumps, one of the bypass valves is open and the other closed. Both FW Pump discharge valves are closed. Flow goes through the FW Pump bypass, through the HP Feedwater Heaters and then back to the three condensers. In addition to the Startup Recirculation line, a line connects to the shell side of the 4A, 4B and 4C LP Feedwater heaters from the Auxiliary Steam System. This line is capable of admitting sufficient steam to raise the feedwater temperature to 175 F. The hotwell condensate can be pumped to the circulating water canal. This would be done if there is not enough capacity in the CST. This is accomplished by running A or C condensate pump and opening the respective valve to the circulating water canal. Caution must be exercised to prevent decreasing the hotwell level to the condensate pump low level trip setpoint.

64 Engineering Training (Program) Page: 64 of 90 EO State the purpose of the Feedwater system and identify the major components. Main Idea Purpose: The Main Feedwater System uses two steam turbine driven pumps to increase the pressure of condensate at the discharge of the low pressure feedwater heaters and heater drain pumps for water makeup to the steam generators. The high pressure feedwater is heated by two trains of high pressure feedwater heaters. Each train has three stages of feedwater heating. The discharge of the feedwater heaters is to the feedwater regulating valves. The feedwater regulating valves and turbine driven feedwater pumps speed determine the amount of feedwater that is fed to the steam generators. Major Components: The Main Feedwater System consists of the piping, SG Feedwater Pumps, HP Heaters, valves, controls, instrumentation, and associated equipment which supply feedwater to the Main Steam Generators. The Main Feedwater System receives the majority of its water from the Condensate System. This common supply branches into two parallel networks supplying a suction for the two 65% capacity feedwater pumps, both of which are turbine-driven, variable-speed pumps. The balance of the feedwater is supplied by the Feedwater Heater Extraction Steam and Drains System, each having an individual Heater Drain pump injecting water into the suction header of the associated feedwater pump. Branch connections in the discharge piping of each line provide minimum pump recirculation flow. A control valve regulates this flow and discharges to the condenser. The feedwater pumps discharge into a common header which, in turn, branches into two parallel heater trains. Each train has three stages of high pressure heaters. Either HP Heater Train can be isolated by means of motor-operated valves installed in the inlet and outlet piping. An 18 inch heater train bypass line provides the capability of 25% flow when one heater train is bypassed. This, combined with the 75% capacity available through the operating heater train, allows operation at up to 90% generated power (due to a change in efficiency resulting from lower feedwater temperatures) during single train failure. The parallel heater flow comes together in a common outlet header which provides mixing of the feedwater. This mixing equalizes the temperature of the feedwater, which is important when one train is isolated. The outlet header branches into two parallel 24 inch headers which carry water to the feedwater control valves and into the steam generators. The Feedpump Turbine System consists of two single flow, multi-stage turbines. Each turbine is capable of driving a feedwater pump at a speed sufficient to supply 65% of main feedwater system capacity. There are two FW pumps per unit which serve both steam generators. The FWPTs are located adjacent to the feedwater pumps on El. 110 ft in the Turbine Building. They are first placed on the turning gear before steam is admitted to the turbine wheels. Steam is admitted during secondary side startup before placing the feedwater pumps in service. Turbine speed is normally controlled by the Main Feedwater Control System which is part of the Reactor Control System. Turbine speed can also be manually controlled from the control room. The Turbines are each rated at 16,555 hp/5640 RPM and 17,638 hp/5774 RPM. A normal operating speed of 4,400 to 5,774 RPM is expected with a speed limiter setting of 5,889 RPM. The overspeed trip setpoint is 6,350 RPM provided by a nominal 110% overspeed mechanical trip mechanism.

65 Engineering Training (Program) Page: 65 of 90 Each flow train (A, B) includes a turbine and the following accessory components: LP stop valve LP control valve HP stop valve HP control valve Piping and drain valves Instrumentation (including electronic governor) Protective devices Lubricating and control oil system Turning gear Steam supply for the FWPTs comes from three sources. The two normal sources are main steam from the SG System and reheat steam from the MT System moisture separator reheaters. The other source is auxiliary steam from the Auxiliary Steam System. Main steam flows through the high pressure stop valve and the high pressure control valve. Steam from the moisture separator reheaters flows through the low pressure stop valve and the low pressure control valve. Low pressure steam is used for normal operation (e.g., each FW pump delivering 50% flow) and high pressure steam is used at startup and to supplement the low pressure system during periods of light loads, or overload, on the main turbine. Auxiliary steam is used during secondary side startup and for FWPT testing.

66 Engineering Training (Program) Page: 66 of 90 Stop valves admit and stop steam flow to the turbine and control valves throttle steam flow to control turbine speed. Both types of valves are operated by high pressure hydraulic control oil. The Turbine Steam Seal and Drain System provides shaft sealing steam to the A and B FWPTs. The Lube Oil System provides the lubricating and hydraulic control oil for the main feedwater pumps and FWPTs. The oil is cooled by the Turbine Cooling Water System. The FWPTs exhaust to the "A" condenser section. FWPT drains are directed to the "A" and "B" condenser sections. Each FWPT has a turning gear which provides slow speed turbine shaft rotation to evenly cool/heat the rotor to prevent bowing. The turning gear also allows for inspection alignment and enables easier breakaway when placing steam on the turbine. Besides the overspeed trip, the FWPTs will trip on turbine bearing low oil pressure, feedwater pump bearing low oil pressure, turbine exhaust low vacuum, active thrust bearing wear high, inactive thrust bearing wear high, feedwater pump low suction pressure or feedwater pump high discharge pressure. One feedwater pump is placed in service prior to exceeding 3% power, approximately the capacity of one auxiliary feedwater pump. The second feedwater pump is placed in service at approximately 50% power. Steam generator water level is automatically or manually controlled at power by changing the speed of the feedwater pump turbine which changes the output of the feedwater pump. Each feedwater pump has a design capacity of 22,314 gpm at 2,424 TDH. Normal operating temperature of the feedwater is approximately 347 F.

67 Engineering Training (Program) Page: 67 of 90 EO State the purpose of the Auxiliary Feedwater and identify the major components. Main Idea Purpose: The functions of the Auxiliary Feedwater System are as follows: Maintain water inventory in the steam generators during emergency operation when the Feedwater System is inoperable. Provide fill to the Steam Generators during startup. Maintain water inventory in The Steam Generators during startup, normal shutdown, and hot standby conditions. Maintain level in the Steam Generators under accident conditions to permit a Reactor Coolant System cooldown at a maximum rate of 75 F/h to a temperature of 350 F. The Auxiliary Feedwater System provides an independent means of supplying Feedwater to the Steam Generators in addition to the Main Feedwater System. Its function is to maintain water inventory in the Steam Generators for reactor residual heat removal during those phases of plant operation when the FW System is inoperable. The AF System provides a sufficient reserve of feedwater to permit the plant to operate at hot standby for 8 hours followed by an orderly plant cooldown, at a rate not to exceed 75 F/h, to the point where the Shutdown Cooling System may be initiated. The AF System also provides and maintains steam generator water inventory during normal startup, shutdown, and hot standby. Major Components: The Auxiliary Feedwater System consists of three pumps: one non-essential motor-driven pump (AFN-P01), one essential motor-driven pump (AFB-P01) and one essential turbine-driven pump (AFA-P01) and their associated valves, piping, controls and instrumentation.

68 Engineering Training (Program) Page: 68 of 90 The primary source of Auxiliary Feedwater is the 550,000 gallon Condensate Storage Tank (CST). Of this supply, 300,000 gallons are specifically designated for Auxiliary Feedwater. 195,000 gallons provide sufficient emergency feedwater reserve to allow an orderly plant cooldown to Shutdown Cooling System initiation, while the rest of the water furnishes sufficient reserve for maintaining the hot standby condition for 8 hours. The CST level is maintained by makeup water from the Demineralized Water System. The Reactor Makeup Water Tank provides a backup for the CST as a supply source of Auxiliary Feedwater and has a capacity of 480,000 gallons. The RMWT tank can be manually aligned as necessary to the two essential pumps only. The Non-Essential Pump is manually aligned and controlled to deliver water to both Steam Generators during normal plant startup, shutdown and hot standby. During normal power generation, the two essential pumps are aligned and placed in a standby condition. Should an accident occur (i.e., Main Steam/Main Feedwater line break, etc.) that would cause an Auxiliary Feedwater Actuation Signal due to low SG level, the essential pumps are started automatically upon receipt of an AFAS signal. The non-essential AFP can be manually aligned to provide Auxiliary Feedwater should abnormal and/or emergency conditions occurs. If the essential motor driven pump is running when a loss of power occurs, it will be Shed (Breaker Open) and restarted sequentially (Breaker Closed) when the Diesel Generator picks up the load. When the Turbine-Driven Pump receives the AFAS signal, the Main Steam Supply Valves open to supply the turbine with steam. Both supply valves are motor operated and can be manually positioned by operating switches on the Remote Shutdown Panel (located in the Control Building at the 100 foot level) and on Control Room Panel B06. Each essential pump is capable of supplying 1010 gpm flow at a discharge pressure of 1425 psig into one or both Main Steam Generators via the Main Feedwater Downcomer supply lines. Both Essential Pump Flow Regulating Valves are controlled by steam generator level. After conditions stabilize, the operator has the capability of manually controlling the flow. The flow will be at a sufficient rate to permit a Reactor Coolant System cooldown at a maximum rate of 75 F/h to a temperature of 350 F at which point the Shutdown Cooling System may be activated. The Non-Essential Pump can be manually activated and operated during the following conditions: Startup Normal Shutdown Hot Standby The Non-Essential Pump takes suction on the CST through two redundant, motor-operated suction isolation valves and delivers water to both Steam Generators via the Main Feedwater supply lines. The Non-Essential Auxiliary Feedwater supply lines join the Main Feedwater lines upstream of the Main Feedwater Downcomer Control Valves. During normal plant operations, the pump is in an isolated condition due to its Seismic Category II consideration, but is available for manual start and alignment if needed. The Essential Pumps take suction on the CST or the RMWT and discharge through motor-operated crossover valves into the Main Feedwater downcomer supply lines. The crossover valves allow each Auxiliary Feedwater pump to supply both Steam Generators. In the event that an AFAS signal is received, the Essential Pumps will automatically start and supply the required water to the affected steam generator(s).

69 Engineering Training (Program) Page: 69 of 90 EO State the purpose of the Circulating Water System and identify the major components. Main Idea Purpose: The Circulating Water System is a closed loop system that cools the main condenser to condense the steam and discharges the heat to the atmosphere through the cooling towers. The CW System also discharges the heat from the Plant Cooling Water System to the cooling towers. Makeup water is supplied by the Cooling Tower Makeup and Blowdown System. The CW System is in service whenever steam is admitted to the main condenser. The CW System supplies water to cool the condenser to condense the steam leaving the final stages of the turbine. The volume of water pumped exceeds that pumped by any other system in the plant. The heat picked up from the condenser and PW System is routed to the cooling towers which discharge the heat to the atmosphere. Major Components: Cooling is accomplished with three round mechanical draft cooling fans. The CW System is in service whenever steam is admitted to the turbine, which first occurs during secondary side startup before the turbine is placed on turning gear. The CW fans and pumps are shutdown when no longer needed, which occurs during cold shutdown after the turbine is placed on turning gear. Circulating water returning from the cooling towers enters the CW intake structure. The intake canal/structure is partitioned into four bays, one for each CW pump. Each bay is provided with a stationary trash screen and a removable stop-gate. The CW pumps take suction on their associated bays and discharge through motor-operated butterfly valves to two supply headers. The pumps are started from the control room. CW Pumps A and B serve one supply header and Pumps C and D serve the other. A cross-connect line with a normally open, motor-operated valve is provided between the two supply headers to minimize the consequences of a single CW pump failure. The main condenser consists of three sections. Each section includes two independent tube bundles. Each CW supply header provides cooling flow to one tube bundle in each condenser section. Thus, two parallel flow paths are provided through the main condenser, each consisting of one tube bundle per section with the three sections arranged in series. The two CW flow paths leaving the main condenser C section tube bundles are combined and directed to the cooling towers via a common return header. The cooling tower fans provide the air flow necessary to ensure the evaporative cooling process takes place. The fans are started from the control room. The CW return header divides into three lines, each supplying one cooling tower. The circulating water is cooled by direct contact with air drawn through the towers by the cooling tower fans. A portion of the CW is lost through evaporation and drift as it falls from the upper level of the cooling tower to the bottom. The remainder collects in the cooling tower basins and returns to the CW intake structure via the intake canal. The CW System blown down and makeup water is added from the Cooling Tower Makeup and Blowdown System to maintain the desired CW intake water level and water quality. Chemicals are added by the Chlorine Injection System as necessary to meet chemistry specifications. Small circulating water sample pumps take suction from and discharge to the intake canal to pump circ water to sample stations for chemical analysis. Sampling of the CW System also occurs in the turbine building by way of the Secondary Chemical Control System.

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71 Engineering Training (Program) Page: 71 of 90 EO State the purpose of the Plant Cooling Water system and identify the major components. Main Idea Purpose: The purposes and capabilities of the Plant Cooling Water System are to: Remove heat from the Turbine Cooling Water System, the Nuclear Cooling Water System, and the Condenser Air Removal Pump seal coolers, and rejects the heat to the Circulating Water System. Fill the condenser water boxes and CW System during startup or after condenser maintenance. Provide water to the CW screen wash area hose connections. Provide water to the Chlorine Injection System acid injection static mixers. Major Components: The PW System supplies water to cool the TC and NC heat exchangers and the AR vacuum pump seal coolers. The heat picked up is routed to the CW System cooling towers which discharge the heat to the atmosphere. PW and CW share circulating water as their cooling medium.

72 Engineering Training (Program) Page: 72 of 90 The PW System is one of the first systems be placed in service during secondary side startup. It is used to fill the CW System piping and the condenser water boxes. It is continuously in service during all modes of operation unless shutdown for maintenance. Two 100 percent redundant PW pumps take suction from the CW intake canal structure to feed the PW heat loads. Each pump is housed in an individual pump well adjacent to the CW pumps. The pumps are started from the main control room. One pump is normally operating and the other is on standby. The second PW pump will auto start on low discharge header pressure. Cooling water from the intake structure is pumped in parallel through the tube sides of the TC and NC heat exchangers and the condenser AR pump seal coolers. Return water is injected back to the CW System between the condenser and the cooling towers or, if the CW pumps are out of service, or the common return header is not available, return water is directed to the No. 2 cooling tower. PW flow to the heat exchangers is modulated by manual valve manipulation. These heat loads are all shell and tube heat exchangers with PW flowing through the tubes and process flow on the shell side. One NC heat exchanger and one TC heat exchanger are normally in service, receiving flow, and the others are isolated. The AR pump seal water coolers are in service when their associated pumps are operating. Three Air Removal pumps are normally required during power generation. Because of possible radioactive contamination of the NC system through leaks in various nuclear-related components in the system, the design operating pressure of the PW System is higher than the design operating or transient pressures of the NC System. This pressure differential ensures against radioactive contamination of the PW System and outside environment

73 Engineering Training (Program) Page: 73 of 90 EO State the purpose of the Turbine Cooling Water system and identify the major components. Main Idea Purpose: The TC System circulates treated demineralized cooling water in a closed loop to collect heat from the plant equipment and reject it to the Plant Cooling Water System. Major Components: The TC System consists of the following major components: TC pumps (2) Heat Loads TC heat exchangers (2) Surge tank Chemical addition tank Piping and valves. Two turbine cooling water pumps, TCN-P01A and B, are provided to circulate the required cooling water through the system. The pumps are motor-driven, horizontal centrifugal type, each rated at 100-percent capacity. Each pump is powered from a different bus to minimize the consequences of a loss of a single bus. The pumps are located in the Turbine Building 100' North East end. Either pump can be started in the control room by manual switches HS-21 and -22 or at the switchgear room (the control room switches are normally used). The pumps, which consists of an impeller within a casing, are connected to their motor shafts by a flexible coupling. Liquid is directed to the center (eye) of the impeller via two suction chambers and is thrown to the rim by centrifugal force as the motor shaft turns the impeller. The liquid leaves the impeller at high velocity which is converted to static pressure in the pump discharge casing nozzle. The pumps take suction on TC return flow just downstream of the TC heat exchangers and discharge through check valves and isolation valves to the common supply header. One pump normally is operating and the other is in standby. The standby pump starts automatically if the in-service pump's discharge pressure decreases below its low discharge setpoint. Two 100-percent capacity turbine cooling water heat exchangers, TCN-E01A and B, transfer heat from the TC System to the PW System. The heat exchangers are single-pass, counter-flow, shell and straight-tube type. The Heat Exchangers are located in the yard just north of the Turbine Building. PW water flowing through the tubes receives heat from the TC water flowing through the shell side. The heat exchanger shell is constructed of carbon steel and the tubes are titanium. One heat exchanger is normally in service and the other is isolated except during the summer when two heat exchangers are needed to provide the proper cooling. Relief valves are provided on the shell and tube sides to prevent over-pressurization.

74 Engineering Training (Program) Page: 74 of 90 The following equipment are heat loads on the Turbine Cooling Water system: Turbine lube oil coolers (2) EHC fluid coolers (2) Circulating Water Pump motor lube oil coolers (4) Heater Drain Pump lube oil coolers (2) Air compressor jacket coolers and after-coolers and service air system jacket coolers (3) Feedwater pump turbine lube oil coolers (2) Condensate pump motor lube oil coolers (3) Gland steam packing exhauster (1) Isolated phase bus cooling coils (1) Generator hydrogen coolers (2) duplex Generator Stator Coolers (2) Non-Nuclear related sample coolers (4)

75 Engineering Training (Program) Page: 75 of 90 EO State the purpose of the Nuclear Cooling Water system and identify the major components. Main Idea Purpose: The Nuclear Cooling Water System is a closed-loop system serving nuclear related, normal operating non-safety related components, and the safety related fuel pool heat exchangers. It circulates treated demineralized water to collect heat from the plant equipment and reject it to the PW System through heat exchangers. The NC System thus acts as a buffer between contaminated or potentially contaminated systems and the environment. Major Components: The supply header distributes cooling flow to the system heat loads which are arranged in parallel. NC System flow leaving the heat loads is directed to the NC heat exchangers. NC water leaving the heat exchangers returns to the suction of the NC pumps. NC flow is modulated either by motor-operated valves (e.g., the normal chillers), by a temperature control valve (e.g., the letdown heat exchanger), or by manual valve manipulation.

76 Engineering Training (Program) Page: 76 of 90 Only one of the two NC pumps and one of the two NC heat exchangers normally operates; the redundant pump and heat exchanger are in standby. The second NC pump will auto start on low discharge header pressure. The supply header distributes cooling flow to the system heat loads which are arranged in parallel. NC System flow leaving the heat loads is directed to the NC heat exchangers. NC water leaving the heat exchangers returns to the suction of the NC pumps. The NC System is normally in service during all modes of plant operation (when PW is in service). During outages, NC may have to be taken out of service temporarily for maintenance, or if the PW System is taken out of service. Whenever NC is not available (i.e., following a loss of offsite power or system failure), backup cooling to the NC System priority heat loads is provided by the Essential Cooling Water System. The following heat loads are cooled by the NC System. The "Priority" heat loads are those cooled by the safety related EW System when the NC System is not available. Priority Heat Loads Normal Chillers Nuclear Sample Coolers CEDM Normal ACUs RCP HP coolers, seal coolers and thrust bearing coolers; RCP motor air coolers and lube oil coolers Spent Fuel Pool Heat Exchangers Non-Priority Heat Loads Letdown Heat Exchanger Radwaste Evaporator Boric Acid Concentrator Waste Gas Compressors Non-Nuclear Sample Coolers Auxiliary Steam Vent Condenser Gas Stripper Auxiliary Steam Radiation Monitoring Cooling Coil NC System water chemistry is controlled to minimize corrosion. Chemicals are added as necessary to meet water quality specifications. These chemicals are added via the chemical addition tank and are flushed into the system using a portion of the NC pump discharge flow. Makeup water is supplied from the Demineralized Water Makeup System. NC System pressure (at the NC heat exchanger inlet) is maintained below PW System pressure to prevent potentially contaminated nuclear cooling water leakage into the PW System and the environment. In addition, the NC System is provided with a continuously operating radiation monitor which alarms in the control room on detection of high radiation.

77 Engineering Training (Program) Page: 77 of 90 EO State the purpose of the Normal Chilled Water system and identify the major components. Main Idea Purpose: The Normal Chilled Water System is a closed-loop system that supplies chilled water to the cooling coils of the airhandling units of the Normal Heating, Ventilating, and Air-Conditioning systems for the Containment, Control, Auxiliary, and Radwaste buildings, and for the coolers of the non-nuclear process sampling system. The WC System is in service during all modes of plant operation. Major Components: The basic refrigeration cycle starts in the chiller where the temperature of the chilled water is lowered. Freon is used as a refrigeration medium to remove heat from the chilled water in the chiller. As the low temperature, low pressure liquid freon is expanded into the chiller it absorbs heat from the chilled water. Upon expansion, the freon absorbs its latent heat of vaporization and changes state to a vapor.

78 Engineering Training (Program) Page: 78 of 90 The freon vapor then enters the compressor where it is compressed, increasing both its temperature and pressure. As a relatively high temperature, high pressure vapor, the freon gives up its latent heat of condensation to the cooling water in the condenser. In doing so, it once again changes state to a liquid. This now relatively high pressure, low temperature liquid freon is allowed to expand, and therefore depressurize, in the chiller. When this expansion occurs, the freon absorbs its latent heat of vaporization from the chilled water, lowering the temperature of the chilled water and beginning the basic refrigeration cycle again. The low temperature chilled water is pumped to the air cooling units and air handling units located in areas where essential components are installed. The heat given off by these components during operation is absorbed by the chilled water in the cooling coils of the ACUs and AHUs. This maintains the space temperature cool enough for continued operation of the installed equipment. The now relatively high temperature chilled water is returned to the chiller to be cooled once again during the basic refrigeration cycle. The following heat loads are served by the WC System: o o o o o o o o o o o o o o Containment refueling purge normal & Containment power access purge normal Auxiliary building normal Access control area normal CEDM control cabinet room normal Charging pump room normal Charging pump room normal Containment normal Radwaste building control room normal Control building normal Control room normal Auxiliary building sample coolers Polishing demineralizer sample coolers Non-nuclear process sampling cooler Generator collector housing cooler Blowdown demineralizer sample cooler

79 Engineering Training (Program) Page: 79 of 90 EO State the purpose of the Essential Spray Pond system and identify the major components. Main Idea Purpose: The Essential Spray Ponds are the Ultimate Heat Sink for the unit; they remove the heat from the EW System and diesel generator cooling loads. Each Essential Spray Pond Pump takes suction on its associated pond and discharges through piping to its heat loads. The Essential Spray Pond System consists of two independent, redundant safety related flow trains. Each train takes suction from and returns water to its Spray Pond. One flow train supplies cooling water required for plant shutdown to safety Train A EWHX and safety Train A diesel generator cooling water heat exchangers, the other flow train supplies cooling water to the same items in safety Train B. The heat is rejected to the Essential Spray Ponds which provide the unit with its Ultimate Heat Sink. Either flow train can supply sufficient cooling water to allow a safe plant shutdown independent of the other flow train. The two SP flow trains are fully redundant with one exception: the combined volume from both spray ponds is required for long term operation without makeup water, this would be necessary during a Loss of Coolant Accident. The SP System is normally not in operation during normal power generation except to cool the EWHX s when the EW System is in service or for chemistry circulation. It is usually operated during plant shutdowns or when the Diesel Generators are in service. When in use, one SP flow train is normally operating and the other flow train is in standby. Following a major leak in one flow train, the damaged train can be removed from service and the other placed into service. Major Components: Each flow train includes the following major components: Essential spray pond Essential spray pond pump Heat loads Filtration and chemical addition equipment Piping and valves

80 Engineering Training (Program) Page: 80 of 90 The heat loads for each flow train include a EWHX and the coolers/heat exchangers on one Diesel Generator. SP cooling water flows through the tube side of the heat exchangers. After passing through the heat loads, the cooling water is returned to the associated spray pond where it is sprayed into the air to maximize cooling. A portion of the water spray evaporates and the remainder falls into the pond to be recycled. Water may be added to the spray ponds from the Domestic Water System (preferred source) or the station reservoir (non-preferred source) to make up for evaporation losses. Nominal operating parameters include a SP pump discharge pressure of psig and a delta flow rate between pump discharge flow and return flow to spray pond of less than 775 gpm. Provision is made for bypassing the spray nozzles should ambient temperatures permit. Technical Specifications require average pond water temperature to be less than or equal to 89 F. SP System pressure is maintained higher than EW System pressure to prevent leakage from the EW System to the SP System in the event of an EWHX tube leak. This minimizes the potential for environmental contamination. Filtration and chemical addition equipment are provided for each Essential Spray Pond. The filtration equipment is operated continuously to remove particulate material from the spray ponds. This is necessary because the ponds are not covered. A filtration pump takes suction on its associated Spray Pond and discharges to a head tank. The water then gravity drains through sand filter units and returns to the associated pond. Spray Pond water chemistry is controlled to minimize corrosion and biological growth which could reduce heat transfer. The chemical addition equipment include 4 tanks and 4 sets of pumps to add four different chemical additives separately to spray pond A Train and B Train. The four chemical additives are: hypochlorite (to minimize biological growth), sulfuric acid (for ph control), a dispersant (for scale and deposit control), and a corrosion inhibitor (to minimize system corrosion). Each chemical addition tank is shared by Train A and Train B. To recirculate the chemicals which are added, the SP System is operated about three times a week.

81 Engineering Training (Program) Page: 81 of 90 EO State the purpose of the Essential Cooling Water system and identify the major components. Main Idea Purpose: The Essential Cooling Water System has the following purposes: Removes heat from all essential components required for normal and emergency shutdown of the plant (with the exception of the diesel generator units) and rejects the heat to the Essential Spray Ponds through the EW heat exchanger. Provides cooling water for the fuel pool cooling heat exchangers, reactor coolant pumps, CEDM normal Air Cooling Units, nuclear sample coolers and normal chillers when the Nuclear Cooling Water System is not available. Provides an intermediate barrier between the Reactor Coolant System and the Essential Spray Pond System to reduce the possibility of radioactive leakage to the environment. Major Components: The Essential Cooling Water System consists of two independent, redundant, closed loop, safety-related flow trains. One flow train supplies cooling water required for plant shutdown to safety Train A shutdown heat exchanger and essential chiller, the other flow train supplies cooling water to the same items in safety Train B. The EW System can also provide cooling to certain components normally cooled by the Nuclear Cooling Water System. The EW system operates as necessary during normal power operations and shutdown and during accident conditions. The EW system rejects plant heat loads to the Essential Spray Pond System which then rejects the heat to the ultimate heat sink. The EW System is operated monthly for normal surveillance testing for determination of operability. One flow train also operates as necessary during normal power generation. When in normal cooldown use (i.e., during plant shutdown), one EW flow train is normally operating to cool one operating shutdown cooling train, and the other flow train is in standby. In the event of a major leak in one flow train, the damaged flow train is removed from service and the other is placed in service. Each flow train includes the following major components: Surge tank EW pump Heat loads EW heat exchanger Chemical addition tank Piping and valves (including the EW/NC cross-tie valves).

82 Engineering Training (Program) Page: 82 of 90 A surge tank is connected to each EW flow train near the suction of the EW pump. The surge tank provides a volume for expansion and contraction of the system's contents due to temperature changes, ensures adequate NPSH for the EW pump, and provides a means of detecting leakage into or out of the EW System. Each EW pump discharges to its associated heat loads. The normal heat loads for each flow train include an essential chiller and a shutdown heat exchanger. The essential cooling water then flows through the shell side of the EW heat exchanger where Essential Spray Pond System flow absorbs heat as it passes through the heat exchanger tubes. The essential cooling water then returns to the EW System pump suction to repeat the cycle. At the EW heat exchanger, EW System pressure is designed to be lower than SP System pressure to prevent leakage from the EW System to the SP System in the event of an EW heat exchanger tube leak. This minimizes the potential for environmental contamination. Any leakage from the SP System into the EW System will be detected as a level increase in the EW surge tank level. Both EW System trains cross connect independently with the NC System to act as a backup cooling source for their respective fuel pool cooling heat exchangers; normally closed manual isolation valves are on the EW tie lines to the fuel pool heat exchangers. Both EW System trains also cross connect with the NC System, via a common line, to supply cooling water to the NC System priority heat loads (other than fuel pool heat exchangers) when the NC System is not available. The EW "A" loop is equipped with motor-operated isolation valves, while the EW "B" loop is equipped with manually operated isolation valves (these Train A and B valves are known as the cross-tie valves). EW System water chemistry is controlled to minimize corrosion. Nitrites and other chemicals are added as necessary to meet water quality specifications. These chemicals are added via each flow train's chemical addition tank, and are flushed into the system using a portion of the associated pump's discharge flow. Makeup water for the EW System is normally supplied from the Demineralized Water System. Water from the condensate storage tank is available as a backup supply.

83 Engineering Training (Program) Page: 83 of 90 EO State the purpose of the Essential Chilled Water system and identify the major components. Main Idea Purpose: The Essential Chilled Water System supplies chilled water to the essential air cooling units and air handling units in the Control Building and Auxiliary Building during essential equipment operation. The EC System consists of two 100 percent capacity, redundant, safety-related flow trains (Train A and Train B) which cannot be cross-connected. The EC System does not normally operate but instead starts automatically upon receipt of a proper signal when essential equipment operation is required. Major Components: The Essential Chilled Water System uses a circulating pump, piping and centrifugal chillers or cooling units to transfer heat from the Chilled Water System to the Essential Cooling Water System. These Chillers lower the temperature of the Chilled Water System allowing it to provide a cooling source to the air handling units and cooling units mentioned above. The Chillers remove heat from the Chilled Water System by the use of freon as a transfer medium. The freon, in the form of a vapor, is compressed increasing not only the pressure, but the temperature due to the heat of compression. This allows the freon to be at a high enough temperature to transfer heat out of the freon and into the Essential Cooling Water System. This causes the freon to condense into a liquid. When this high pressure and now relatively low temperature freon is now depressurized it changes back into a gas absorbing its latent heat of vaporization from the Chilled Water System. The Chilled water is then circulated through the system to the air handling and air cooling units which use cooling coils to cool the air of the areas required. The cooling units typically use three way valves that allow the cold Chilled water flow to either enter or bypass the cooling coils thereby allowing the units to control temperature. The loads are supplied cooling water in parallel then the chilled water flow returns to the chiller to be cooled again.

84 Engineering Training (Program) Page: 84 of 90 Heat loads served by the EC System are listed below: Control room essential AHUs Auxiliary feedwater pump room essential ACUs ECW pump room essential ACUs Electrical penetration room essential ACUs LPSI pump room essential ACUs HPSI pump room essential ACUs CS pump room essential ACUs DC equipment room essential ACUs

85 Engineering Training (Program) Page: 85 of 90 EO State the purpose of the Spent Fuel Pooling Cooling system and identify the major components. Main Idea Purpose: The PC System is one of two independent 100% capacity systems that are provided to cool the SFP and prevent thermal damage to spent fuel elements stored in the pool under normal and accident conditions. The other independent system is the Safety Injection System. The SI System is cross-connected to the PC Cooling System's common suction and discharge lines and can be aligned to use the Shutdown Cooling Heat Exchangers to cool the SFP water. Normally, the PC System is adequate to handle the spent fuel decay heat load and the SI System is isolated from the PC System by closed double isolation valves. Major Components: The PC Cooling System consists of two pumps and two heat exchangers piped in parallel. The cooling system is provided only for the SFP. The pumps take suction on the SFP through a common suction header and discharge through the heat exchangers into a common discharge header that returns to the SFP. The suction line takes water from the upper part of the SFP (to assist natural convection cooling) and the discharge line delivers it to the lower part of the SFP. The heat exchangers are normally cooled by the Nuclear Cooling Water System but backup cooling is provided by the Essential Cooling Water System. Either of the two flow trains are capable of providing adequate heat removal during normal conditions. A line is installed between the discharge of the cooling pumps and the suction of the heat exchangers to allow cross-connecting the two trains.

86 Engineering Training (Program) Page: 86 of 90 Technical Specifications require at least 23 feet of water to be maintained over the top of irradiated fuel whenever the fuel is in the SFP. The design of the piping penetrating the SFP and internal to the pool is such that this requirement is met. Piping entering the SFP penetrates the pool high enough to prevent serious loss of water due to an external pipe break. Piping internal to the pool has siphon breaker holes to prevent loss of water by siphon action after an external break. Also, there are no drain lines at the bottom of the SFP. Two Essential Ventilation Systems are required by Technical Specifications to be operable whenever spent fuel is in the SFP. This requirement is met by the Fuel Building HVAC System. Normal makeup water to the Spent Fuel Pool is from the Refueling Water Tank, a borated water supply. Alternate makeup is available from the Recycle Monitor Tanks (non-borated supply) or from the Condensate Storage Tank another non-borated water supply. SFP chemistry is maintained per the chemistry specifications. In particular, boron concentrations in the SFP is maintained between ppm boron during all modes of operation. The boron ensures that there is a sufficient amount of negative reactivity in the SFP at all times. During Mode 6, the Refueling Pool chemistry is also maintained per chemistry specifications. The SFP may be used as a source of borated water to restore RCS shutdown margin in an emergency. The PC Cooling Pumps and Heat Exchangers are located on the 100'-0" elevation of the Fuel Building beneath the new fuel storage racks. PC Cooling System nominal operating conditions are 45 psig pump discharge pressure, 122 F heat exchanger outlet temperature and 2000 gpm flow rate with one pump running. The SFP high temperature limit is 145 F. Operation of the PC System alone, or the PC System in conjunction with Shutdown Cooling (if the PC System is unable to adequately cool the spent fuel) ensures that SFP temperatures are below this limit. This high limit of 145 F is a consideration for the resins in the Ion Exchangers when the PC Cleanup System is operating.