ROP margin improvement options for CANDU reactors

Over the past few years, Candu Energy Inc. (a wholly owned subsidiary of SNC-Lavalin Inc., which acquired the assets of Atomic Energy of Canada Limited's Commercial Reactor Division) has been continuously developing and evaluating various options to improve the regional overpower protection (ROP) margin in aged CANDU 600 MW (CANDU 6®) reactors. This paper presents results from applying a couple of margin improvement options to a generic aged CANDU 6 reactor, namely ROP detector layout optimization and application of a revised handswitch position designation. Application of these options requires no change to the ROP analysis methodology, statistical approach or acceptance criterion. As such, any increase in ROP margin associated with these options carries little or no licensing risk and are not expected to require more than one standard outage to implement.