Work Exercises and Case Studies to Write Safety Evaluation Report

Transcription

1 Work Exercises and Case Studies to Write Safety Evaluation Report 2013

2 Contents Considerations for Writing SER Guideline for Case Study Examples of SAR and Regulatory Review Guide Review Exercise Attachment Introduction to AFWS

3 Considerations for Writing SER Clear statement why the staff did or did not decide the application (or part of the application) acceptable Do use simple, clear, and concise language Do use the active form rather than passive form Do write the SER that a person with a basic knowledge of engineering and science to understand(i.e., freshman in college) Do maximize the use of good precedents to achieve efficiency and consistency Do rely on relevant regulatory guidance and standards to achieve efficiency and consistency

4 Considerations for Writing SER Do not repeat content of the application in the SER Do not treat regulatory guidance as a regulatory requirement Do not provide suggestions for improving the application Do not expand the scope of the SER beyond the scope of the application Do not solely rely on a commitment in making a determination that requirements are met

5 Guideline for Case Study The subject of safety evaluation Auxiliary Feedwater System (Refer Attachment 1) Design & Functions Operation and Surveillance Understanding of Related Documents AFW Safety Analysis Report of an example plant design Relevant SAR Chapter of AFWS (Typically, Chap. 10.4, and 7.3) Technical Specification for Operation Piping & Instrument Diagram for AFWS Regulatory Review Guide for AFWS (If Any)

6 Example of AFWS SAR(1)

7 Example of AFWS SAR(2)

8 Example of AFWS P&ID -8-

9 Example of Technical Specification

10 Example of Review Guides for AFWS

11 Example of Review Guides for AFWS

12 Review Exercise Review Areas for Exercise (Narrowed Scope) Acceptance Criteria (NRC SRP ) 5. System capacity for removing residual heat(btp 10-1) 6. Permission of in-service inspection 7. Permission of periodic operational functional testing 8. Automatic initiation of the system 9. Availability of systems not reliant upon AC power

13 Overall Process of Regulatory Review Review of SAR based on the SRP Use of relevant sections of SRP Area of Review, Acceptance Criteria Request Additional Information(if Any) Regulatory questions on the licensee s information Information for confirmation and assurance, etc. Evaluation findings and Conclusions Technical rationale and Bases Drafting Safety Evaluation Report

14 Summarized Table of SER 1. SRP acceptance criteria : 5. System Capacity for removing.. Requirements Describe related requirements(law, Acceptance Criteria..) System Design Concise description of the design in cooperated in SAR, P&ID etc. RAIs Describe the needed information for confirmation etc. Conclusions Conclusions and/or findings, conditions as a results of reviewing the corresponding SAR

15 Attachment. 1 Introduction to Auxiliary Feedwater System 1. Basic Concept of Safety Design 2. ESF Overview 3. Auxiliary Feed Water System -15-

16 1. Basic Concept of Safety Design Target of Nuclear Safety Prevention of Radioactivity Release Protecting Barrier Fuel and Pellet integrity Reactor Coolant System Integrity Containment Integrity Essential Safety functions Sub- Criticality Core Cooling Heat Removal RCS Inventory RCS Integrity Containment Integrity -16-

17 1. Basic Concept of Safety Design Relationship between Safety functions and Safety Systems Safety Functions Reactivity Control Coolant Inventory Control Core Cooling Core Heat Removal Containment Integrity Plant Safety Systems Reactor Protection System (Accident Prevention) Chemical and Volume Control System (Operating) Safety Injection System (Accident Mitigation) High Pressure Injection System Low Pressure Injection System Safety Injection Tank Main Feedwater System (Operating) Auxiliary Feedwater System (Accident Mitigation) Residual Heat Removal System (Shutdown) Containment Spray System (Accident Mitigation) -17-

18 2. ESF Overview ESF Sub-System 1. Containment Isolation 2. Containment Heat Removal (Spray System) 3. Containment Combustible Gas Control 4. Control Room Emergency Ventilation 5. Fuel Building (FHB) HVAC Exhaust and ECCS Equipment Room HVAC Exhaust 6. Auxiliary Feedwater System 7. Emergency Core Cooling System(ECCS) High Pressure safety injection (HPSI) Low Pressure safety injection (LPSI) Safety injection Tanks (SIT) -18-

19 ESF Actuation System 2. ESF Overview Signal RWT Low Level Pzr Low Pres. Cont. Bldg Pres. SG Low Pres. SG Low Level MCR Rad. Level SFP Rad. Level Cont. Rad. Level Actuation System High Hi-Hi RAS SIAS CIAS CSAS MSIS AFAS CREVAS FBEVAS CPIAS Components & Action Emer. Diesel SI valves LPSI Pump HPSI Pump Cont. Isol. valves Cont. Spray Pump Isol. Steam &Feed Aux Feed Pump MCR Emer. Vent Fuel Bldg Emer. Vent Cont. Purge Isol. ECCS Room HVAC -19-

20 3. Auxiliary Feedwater System (AFWS) To provide an independent means of supplying secondary makeup water to the steam generator in the event of following events Loss of normal feedwater(main Feedwater) Secondary system pipe breaks or valve failure Steam generator tube rupture Any incidents which will result in a loss of normal onsite and offsite power Small LOCA -20-

21 Simplified Figure of AFS To remove the iodine and other radionuclides from the To remove the iodine and other radionuclides from the containment atmosphere in the event of postulated LOCA containment atmosphere in the event of postulated LOCA To reduce the temperature and pressure in the containment To reduce the temperature and pressure in the containment atmosphere in the event of postulated LOCA or MSLB atmosphere in the event of postulated LOCA or MSLB

22 3. Auxiliary Feedwater System AFWS consists of ; Two separate redundant trains(2x100%), each has A motor-driven pump A turbine-driven pump (optionally diesel-driven pump for certain plants) Cross-tie lines provided in the XX Unit-1 Associated valves, Piping, I&C Actuation Signal AFAS Steam Generator level low (72~90% 23.7%) and SG differential pressure ( psid) DPS(Diverse Protection System) Steam Generator level low (22.2% ) Manual DB Events required AFAS Feedline Break, SLOCA, SGTR, SLB(inside and outside Cont t) -22-

23 3. Auxiliary Feedwater System (cont.) The minimum flow must be delivered assuming the following failure modes; Minor secondary system pipe breaks or valve failures w/wo a concurrent loss of offsite power and the most limiting single failure in the AF train. SGTR w/wo a concurrent loss of offsite power and the most limiting single failure in the AF train Major secondary system pipe breaks w/wo a concurrent loss of offsite power and the most limiting single failure in the AF train Any incident that will result in loss of offsite power and normal ac power Small LOCA w/wo a concurrent loss of offsite power and the most limiting single failure in the AF train -23-