GENERATION III AND III NUCLEAR POWER PLANT DESIGNS

GENERATION III AND III+ NUCLEAR POWER PLANT DESIGNS ACR-1000 (Advanced CANDU Reactor) Dr. Şule Ergün Hacettepe University Department of Nuclear Engineering March 2008, Istanbul

Outline • CANDU Concept • CANDU Development • ACR-1000 – Technical Description • Conclusion

CANDU Concept Pressurized Heavy Water Reactor (CANadian Deterium Uranium)

CANDU Development • CANDU 6 • ACR-700 • ACR-1000

CANDU Development • The CANDU Design: – Modular horizontal fuel channels – Simple fuel bundle design – Separated coolant from moderator – Cool, low pressure heavy water moderator – On-power fuelling – Passive shutdown systems

ACR-1000 • Low enriched fuel • Light water coolant • Higher steam pressure • Smaller reactor core • High capacity factor • Over 60 year life • Larger thermal margins

ACR-1000 Evolution in Core Size CANFLEX Fuel Bundle

ACR-1000 • Safety Enhancements – Enhanced passive safety – Factor of ten improvement in severe core damage frequency • Improved Construction – Shorter construction schedule – Reduce cost by 25% or more

ACR-1000 • ECC System: – Initial injection from pressurized ECI tanks located inside Reactor Building (RB) – Long Term Cooling (LTC) System provides pumped recovery – LTC System also provides maintenance cooling after normal shutdown

ACR-1000 Frequency for internal events: ~ 3 x 10 -7/ reactor year

ACR-1000 • Severe accident mitigation: – Passive Core Make-Up Tanks keep HTS full to assure thermosyphoning capability – Reserve Water System (RWS) supply by gravity to SGs provides inventory for long-term thermosyphoning – Passive make-up to HTS from ECI and RWS delay accident progression – Passive make-up to moderator and calandria vault from RWS delay accident progression – Passive spray system supplied from RWS delays containment failure

Conclusion • The ACR-1000 innovations include: – A compact core design which reduces heavy water inventory and results in lower costs and reduced emissions – Use of light water as reactor coolant, resulting in reduction of systems for heavy water coolant cleanup and recovery and simplification of containment atmosphere cleanup systems – Use of low enriched uranium fuel, contained in advanced CANFLEX ACR fuel bundles

Conclusion – Efficient means for burning other fuel types such as mixed oxides (MOX) and thorium fuels – Increased fuel safety margins – Improved plant thermal efficiency through use of higher pressures and higher temperatures in the coolant and steam supply systems – Enhanced accident resistance and core damage prevention features – Enhanced operability and maintainability