Some Aspects of Fuel Motion in the Unprotected Transient Overpower Accident in LMFBRs,

摘要

This paper addresses certain aspects of the fuel motion which would be associated with a hypothetical,unprotected,transient overpower accident (TOP) and loss-of-flow-driven TOP accident (LOF-D-TOP). Experimental results are cited that suggest a time lag between failure and fuel ejection for irradiated pins. This time interval is needed for development of large rupture areas. When fuel does reach the channel,rapid upward dispersal appears likely,but so does eventual flow blockage. Arguments are presented for the availability of sufficient driving forces for sodium expulsion in the LOF-D-TOP with negligible axial fuel motion. Results of calculations on plenum gas release are presented which indicate that gas driven voiding would not be a direct problem in either the TOP or LOF-D-TOP accident.