Spent Fuel Response after a Postulated Loss of Spent Fuel Bay Cooling Accident
33rd Annual CNS Conference - 2012 June 10-13


Presented at:
33rd Annual CNS Conference
2012 June 10-13
Location:
Saskatoon, Canada
Session Title:
Safety & Licensing-2

Authors:
Hazen Hezhi Fan (Candu Energy Inc.)
Ron Aboud (Candu Energy Inc.)
Ed Choy (Candu Energy Inc.)
Wenjie Zhu (Candu Energy Inc.)
Hui Liu (Candu Energy Inc.)
  

Abstract

A study of the spent fuel behavior in a postulated severe accident is performed to understand the timings of actions and potential consequence associated with an unmitigated loss of cooling for an extended period of time. This study provides input to the “stress test” for Cernavoda CANDU® 6 plants, requested by WENRA/ENSREG. For extreme situations, in the light of the events which occurred at Fukushima in 2011, this work has assessed the spent fuel response after a postulated loss of spent fuel bay cooling accident, assuming that there is a prolonged loss of all electrical power and water make-up to the spent fuel bay. Assessment results indicate that hydrogen generation is insignificant as long as the spent fuel remains submerged. With a large amount of shield water in the CANDU spent fuel bay, as a passive inherent feature, it is estimated that the onset of spent fuel uncovering takes more than two weeks after loss of the spent fuel bay cooling for the spent fuel bay design with normal load. The potential consequence is also discussed after the water level drops below the first few layers of spent fuel bundles due to boil-off/evaporation. However, there is a significant amount of time to take corrective actions using a number of backup design provisions to prevent spent fuel bundle uncovering.

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