Station Blackout Scenario Analysis for the Enhanced CANDU 6 (EC6) Reactor Design
CNS 24th Nuclear Simulation Symposium - 2012 October 15-16

Presented at:
CNS 24th Nuclear Simulation Symposium
2012 October 15-16
Session Title:
Technical 6: Thermalhydraulics & Safety

F. Gao (Candu Energy Inc.)
A. Lee (Candu Energy Inc.)
A. Jiang (Candu Energy Inc.)


After the Fukushima accident in Japan in 2011, a thorough safety review of nuclear power plants (both current and new build designs) has been performed to confirm their plant provisions to deal with the Station Blackout (SBO) event.  The SBO event involves loss of alternating current (AC) electrical power sources and potential loss of the ultimate heat sink.  The safety reviews by the nuclear operators, regulators and nuclear power plant designers have confirmed the robustness of the current CANDU reactor designs and have identified improvements to plant features to further reduce the risk of radioactive releases to the environment.

This paper illustrates the robustness of the Enhanced CANDU 6 (EC6®) reactor design in preventing the onset of severe core damage and mitigating the consequences for typical SBO scenarios.  The EC6 reactor design has been enhanced over the current CANDU 6 reactor designs by including specific complementary design features, e.g., severe accident recovery and heat removal system (SARHRS), and more a robust containment design, to meet modern regulatory expectations (such as those described in the Canadian Nuclear Safety Committee (CNSC) regulatory document, RD-337).  The severe accident progression and consequence analyses for the SBO event using MAAP4-CANDU [1] is presented to illustrate the failure of multiple barriers that would have to occur (e.g., loss of emergency core cooling, loss of moderator cooling, loss of shield cooling) and the time available for actions to arrest the accident progression and mitigate the consequences.  The concurrent and/or consequential failure of these multiple barriers has a very low probability of occurrence for the EC6 design.

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