2012 Deep River Science Academy Summer Lecture GENERATION IV SUPERCRITICAL WATER-COOLED REACTOR

Transcription

1 2012 Deep River Science Academy Summer Lecture GENERATION IV SUPERCRITICAL WATER-COOLED REACTOR M. Yetisir Deep River, 2012 July 12

2 What is a Gen IV Reactor Contents How does nuclear plant work? What is a Gen IV reactor? Why supercritical water? What is supercritical water? What is supercritical water-cooled reactor (SCWR)? Current concepts for the Canadian SCWR

3 Acknowledgment Number of figures in this presentation is obtained from Wikipedia and various sources in Internet.

4 How does nuclear plant work?

5 How does nuclear plant work? What is a Gen IV Reactor Produce Power Transfer and Transport Energy Convert to Electricity

6 How does nuclear plant work? Not!

7 How does nuclear plant work?

8 What is a Gen IV Reactor? Generation I : Early prototype nuclear power reactors Shippingport (PWR) First nuclear power plant Douglas Point (CANDU) Generation II : Most existing power reactors PWR, BWR, CANDU, etc. Example - CANDU 6 Douglas Point NDP Calandria Vessel during shipment Generation III : Improved power reactors evolved from Gen II reactors APWR, ABWR, Enhanced CANDU 6 (EC6), ACR, etc. Gen III+ Reactors: AP-1000, ESBWR

9 What is a Gen IV Reactor? Generation IV : Next generation power plants - Douglas Point NDP - EC6 - AP ESBWR

10 Gen IV Reactors 1 The primary goals are to Improved safety improve proliferation resistance, minimize waste and natural resource utilization, and lower cost to build and operate 1 Gen IV reactors are being developed by a group of nations under the cooperative international initiative called The Generation IV International Forum (GIF) 10

11 What are Gen IV Reactors? Very-high-temperature reactor (VHTR) Supercritical-water-cooled reactor (SCWR) Molten-salt reactor (MSR) Gas-cooled fast reactor (GFR) Sodium-cooled fast reactor (SFR) Lead-cooled fast reactor (LFR) There are few SCWR concepts being developed worldwide. Canada is developing a pressure-tube SCWR because of its experience in pressure-tube reactors. 11

12 Gen IV Supercritical Water-Cooled Reactor

13 What is Supercritical Fluid?

14 What is Supercritical Fluid?

15 Cycle Efficiency [%] Why Supercritical Water as Coolant? Ultra-Supercritical Supercritical Supercritical water-coooled reactor: Benefit: Significantly Improved (up to 40%) cycle efficiency as compared to current LWRs CANDU 6 (5 MPa, 265ºC) 17 MPa, 540ºC CANDU 6 (265 C) < 33% Steam Cycle efficiency 25 MPa, 550ºC 27 MPa, 590ºC 29 MPa, 610ºC Steam Pressure and Temperature Canadian SCWR (25 MPa, 625ºC) 35 MPa, 710ºC Canadian SCWR (625 C) ~48% with moisture separator ~50% with reheat Known Technology: Supercritical fossil fuel plant technology has been well-established. Originally developed in the 1950s. More than 400 SC fossil plants are operating world-wide. Challenge: Reactor Core Design for the significantly increased operating temperature (up to 625 C) and pressures (~25MPa). 15

16 SCWR Design Challenges Design Challenges: Lower Material Strength by a factor of 2 to 3 Higher Pressure Load - Operating pressure incrases by a factor of 2.5 (from ~11MPa to 26 MPa) Higher Thermal Load Temperature gradient s(outlet-inlet) increase by a factor of 2 to 5.

17 Multi-disciplinary Development Reactor Physics Fuel Design Thermalhydraulics Materials and Chemistry Instrumentation and Control Balance of Power Safety Systems Design and Integration 17

18 A Typical CANDU Design

19 Canadian SCWR Design Evolution 1 CANDU style horizontal and vertical designs with feeders and online fuelling option.

20 Canadian SCWR Design Evolution 2 Simplified designs with reduced feeders and no-feeders with batch fuelling. Low pressure moderator is maintained.

21 Canadian SCWR (Gen IV) 21

22 Canadian SCWR An example of design choices 22

23 High Efficiency Fuel Channel (HEC) 25 MPa, 625ºC 350ºC (figure from I. Pioro et al.) 23

24 High Efficiency Fuel Channel (HEC) Fuel Channel Dimensions Liner Inside Diameter (mm) 136 Liner Thickness (mm) 0.7 Insulator Thickness (mm), Zirconia 10 Pressure Tube Thickness (mm) 12 Pressure Tube Outside Diameter (mm)

25 Canadian SCWR Reactor Core 25

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31 Canadian SCWR Reactor Core 31

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33 Canadian SCWR Reactor Buildings SHIELD BUILDING CONTAINMENT BUILDING From Feedwater Pumps at 350 C To HP Turbine at 25 MPa and 625 C 33

34 Inherent Safety Passive Moderator Heat Removal Heat rejected to the moderator is passively transferred to the Ultimate Heat Sink (supported by tests) Numerical studies indicate that no coremelt and walk-away safety target is feasible based on thermal radiation cooling of the core, with natural circulation decay heat removal using the low pressure moderator and inherently negative physics coefficients Test Facilities are being built to demonstrate the No Core Melt case. No-Diesel long-term decay heat removal is targeted through a combination of water reserves (short-term UHS) and air coolers (long term UHS) 34

35 Moderator-based Safety Systems RESERVE WATER POOL MODERATOR MAKEUP TANK PASSIVE MODERATOR COOLING SYSTEM (PMCS) ACTIVE MODERATOR COOLING SYSTEM (AMCS) 36

36 Coolant-based Safety Systems Reserve Water Pool Reserve Water Pool Ambient Air Coolers Isolation Condensers Containment Air Coolers Feedwater Gravity Driven Water Pool HP Turbine Control and Shutdown Systems Suppression Pool Suppression Pool Active MCS Active ECC System 37

37 Containment Building and Reserve Water Pool 38

38 Containment Building and Reserve Water Pool 39

39 Shield Building, Containment Building and Air Coolers 40

40 Reactor Buildings and Safety Systems 41

41 Simplicity Significant reduction of number of components as compared to present-day pressure-tube reactors (steam generators, fuelling machine, inlet feeders and fuel channel end fitting internals are eliminated) Calandria vessel is low pressure. Hence, control and shutoff rods penetrate the low-pressure calandria, not a pressure vessel at a SC pressure. Supercritical coolant is not in contact with in-core pressure bearing components. Inlet plenum is at a temperature close to those in present-day PWR operating temperatures. Not a high-risk technology. Refueling, fuel channel inspection and fuel channel replacement activities are simpler, because fuel channels can be accesses simply by removing the head of the inlet plenum. There are no internal components or penetrations at the inlet plenum. 42

42 Meets Gen IV Reactor Goals The primary goals for Gen IV reactors are satisfied by Enhanced safety through redundant and independent safety systems Passive Moderator Cooling System Passive Primary-Side and Containment Cooling Systems Lower cost to build and operate Supercritical steam with thermal efficiency > 45% (~40% greater than current CANDUs) Simplified design (significantly reduced number of components) increase reliability Minimize waste and improve natural resource utilization through the use of Thorium with an igniter (Plutonium or bred U233 or Enriched Uranium) Improved proliferation resistance U232 exists in spent fuel can easily be detected and has to be handled remotely 43

43 AECL - OFFICIAL USE ONLY / À USAGE EXCLUSIF - 44

44 Sustainability Thorium Fuel Heavy-water moderation in a pressure-tube design provides a great flexibility in the selection of nuclear fuel. Either enriched Uranium or Thorium can be used as fuel Current fuel is Thorium with an igniter (enriched Uranium, U-233 bred from Thorium or Reactor Grade Plutonium) 45