A refuelling strategy of CANFLEX-RU fuel in CANDU reactors

The refuelling strategy of CANFLEX-RU (=RUFIC, Recovered Uranium Fuel In CANDU) as a CANDU high-burnup fuel for CANDU 6 reactors is studied to determine the achievable characteristics of the fuel and reactor operations. In this study, 4-, 2-, and 3-bundle shifts of 0.92 w/o RUFIC fuel in a CANDU 6 reactor were individually evaluated through 1200 FPD refuelling simulations. The computer code system used is WIMS-AECL/DRAGON/ RFSP. The 4-bundle shift case shows that the peak maximum channel power of 7228 kW seems too high to maintain the available operating margins, whereas the 2-bundle shift case shows that a sufficient operating margin could be secured. However, since the channel-refuelling rate (channels/day) of the 2-bundle shift case is twice that of the 4-bundle shift, the 3-bundle shift of the RUFIC fuel was also studied. As a result, it is found that all the operating parameters in the 3-bundle shift case are achievable for the CANDU 6 reactor operation, and the channel-refuelling rate of 2.88 channels/day seems to be attractive compared to that of 4.32 channels/day in the 2-bundle shift case. (author)