Review of the Licensing Basis for RIA and LOCA Transients in Light of New Evidence on High Burnup Fuel Behavior

The fuel of power reactors can be damaged by both rapid reactivity insertion accidents (RIA) and by Loss of Coolant Accidents (LOCA) due to the break of a coolant pipe. The consequences of such postulated accidents with a very low probability can be mitigated by dedicated safety systems. Yet, the possible consequences need to be assessed as part of the safety evaluation in the framework of the reactor licensing process as these transients form part of the so-called design basis. Most importantly, coolability of the reactor core must be demonstrated. The current paper reviews the important fuel related phenomena that may occur during such transients and their relation to the current licensing basis. Finally, possible changes in light of new experimental evidence from high burnup fuel behavior tests are discussed.