Molten material assessment for O6 mixed bundle channel feeder stagnation break in CANDU-6 reactor

摘要

A molten material assessment for O6 mixed-bundle channel feeder stagnation break in CANDU-6 reactor has been performed using CATHENA slave channel model. The feeder stagnation break size for the mixed-bundle channel is found to be the same as that for the standard bundle channel; the inlet feeder break area of 17.75 cm(sup 2). The predicted channel failure times based on the ballooning criterion for the stagnation feeder break accident are 11.6 s and 11.3 s for the mixed-bundle and standard bundle channel cases, respectively. The predicted total molten masses at 2 s after the channel failure are 20.0 kg and 20.1 kg of molten sheath and molten eutectic alloy for the mixed-bundle and standard bundle channel cases, respectively. For the full CANFLEX bundle channel case, the channel failure time and total molten mass at 2 s after the channel failure are predicted to be 11.7 s and 20.5 kg of molten sheath and molten eutectic alloy, respectively. No fuel melting is observed for any of the analysis cases. Both the 0.1 kg less molten mass for the mixed-bundle channel case and the 0.4 kg more molten mass for the full CANFLEX bundle channel compared to the standard bundle channel case are kept within bounds of the existing in-core damage and shutdown depth assessment in Reference 5, and therefore both calandria integrity and sub-criticality for the full or partial CANFLEX bundle CANDU-6 reactor are assured for the feeder break accidents. 1 tab., 5 figs., 7 refs. (Author). (Atomindex citation 28:019114)