2012 Deep River Science Academy Summer Lecture

GENERATION IV SUPERCRITICAL WATER-COOLED REACTOR

M. Yetisir

Deep River, 2012 July 12

UNRESTRICTED | ILLIMITÉ

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

UNRESTRICTED | ILLIMITÉ

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

UNRESTRICTED | ILLIMITÉ

How does nuclear plant work?

UNRESTRICTED | ILLIMITÉ

How does nuclear plant work?

What is a Gen IV Reactor

Produce Power Transfer and Transport Energy UNRESTRICTED | ILLIMITÉ

Convert to Electricity

How does nuclear plant work?

Not! UNRESTRICTED | ILLIMITÉ

How does nuclear plant work?

UNRESTRICTED | ILLIMITÉ

What is a Gen IV Reactor? Generation I : Early prototype nuclear power reactors Shippingport Douglas

(PWR) – First nuclear power plant

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

UNRESTRICTED | ILLIMITÉ

What is a Gen IV Reactor? Generation IV : Next generation power plants

- AP-1000 - ESBWR - Douglas Point NDP - EC6

UNRESTRICTED | ILLIMITÉ

Gen IV Reactors1

The primary goals are to

1 Gen



Improved safety



improve proliferation resistance,



minimize waste and natural resource utilization, and



lower cost to build and operate

IV reactors are being developed by a group of nations under the cooperative international initiative

called “The Generation IV International Forum (GIF)” UNRESTRICTED | ILLIMITÉ

10

What are Gen IV Reactors?

Very-high-temperature

reactor (VHTR)

Supercritical-water-cooled Molten-salt Gas-cooled

reactor (SCWR)

reactor (MSR) fast reactor (GFR)

Sodium-cooled Lead-cooled

fast reactor (SFR)

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.

UNRESTRICTED | ILLIMITÉ

11

Gen IV Supercritical Water-Cooled Reactor

UNRESTRICTED | ILLIMITÉ

What is Supercritical Fluid?

UNRESTRICTED | ILLIMITÉ

What is Supercritical Fluid?

UNRESTRICTED | ILLIMITÉ

Why Supercritical Water as Coolant? 55

Cycle Efficiency [%]

Ultra-Supercritical 50

Supercritical

Benefit: Significantly Improved (up to 40%) cycle efficiency as compared to current LWRs

45

40

35

30 CANDU 6 (5 MPa, 265ºC)

17 MPa, 540ºC

25 MPa, 550ºC

27 MPa, 590ºC

29 MPa, 610ºC

Canadian 35 MPa, SCWR (25 710ºC MPa, 625ºC)

Steam Pressure and Temperature

CANDU 6 (265 C) < 33% Steam Cycle efficiency

UNRESTRICTED | ILLIMITÉ

Supercritical water-coooled reactor:

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

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.

UNRESTRICTED | ILLIMITÉ

Multi-disciplinary Development

Reactor Fuel

Physics

Design

Thermalhydraulics Materials

and Chemistry

Instrumentation Balance Safety

and Control

of Power

Systems

Design

and Integration

UNRESTRICTED | ILLIMITÉ

17

A Typical CANDU Design

UNRESTRICTED | ILLIMITÉ

Canadian SCWR – Design Evolution 1

CANDU style horizontal and vertical designs with feeders and online fuelling option. UNRESTRICTED | ILLIMITÉ

Canadian SCWR – Design Evolution 2

Simplified designs with reduced feeders and no-feeders with batch fuelling. Low pressure moderator is maintained. UNRESTRICTED | ILLIMITÉ

Canadian SCWR (Gen IV)

UNRESTRICTED | ILLIMITÉ

21

Canadian SCWR – An example of design choices

UNRESTRICTED | ILLIMITÉ

22

High Efficiency Fuel Channel (HEC)

25 MPa, 625ºC

350ºC

(figure from I. Pioro et al.)

UNRESTRICTED | ILLIMITÉ

23

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) UNRESTRICTED | ILLIMITÉ

181.4

24

Canadian SCWR Reactor Core

UNRESTRICTED | ILLIMITÉ

25

UNRESTRICTED | ILLIMITÉ

26

UNRESTRICTED | ILLIMITÉ

27

UNRESTRICTED | ILLIMITÉ

28

UNRESTRICTED | ILLIMITÉ

29

UNRESTRICTED | ILLIMITÉ

30

Canadian SCWR Reactor Core

UNRESTRICTED | ILLIMITÉ

31

UNRESTRICTED | ILLIMITÉ

32

Canadian SCWR Reactor Buildings

SHIELD BUILDING

CONTAINMENT BUILDING From Feedwater Pumps at 350°C

To HP Turbine at 25 MPa and 625°C

UNRESTRICTED | ILLIMITÉ

33

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) 

UNRESTRICTED | ILLIMITÉ

34

Moderator-based Safety Systems

RESERVE WATER POOL

MODERATOR MAKEUP TANK

PASSIVE MODERATOR COOLING SYSTEM (PMCS)

ACTIVE MODERATOR COOLING SYSTEM (AMCS)

UNRESTRICTED | ILLIMITÉ

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

Active MCS

UNRESTRICTED | ILLIMITÉ

Suppression Pool

Active ECC System

37

Containment Building and Reserve Water Pool

UNRESTRICTED | ILLIMITÉ

38

Containment Building and Reserve Water Pool

UNRESTRICTED | ILLIMITÉ

39

Shield Building, Containment Building and Air Coolers

UNRESTRICTED | ILLIMITÉ

40

Reactor Buildings and Safety Systems

UNRESTRICTED | ILLIMITÉ

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. 

UNRESTRICTED | ILLIMITÉ

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

UNRESTRICTED | ILLIMITÉ

43

AECL - OFFICIAL USE ONLY / À USAGE EXCLUSIF -

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) 

UNRESTRICTED | ILLIMITÉ

45