Fission product release from commercial versus simulated fuels in LWR (light water reactor) accident studies

Experimental studies of fission product release from light water reactor (LWR) fuels have been conducted at Oak Ridge National Laboratory (ORNL). The principal objective of this project, which is supported by the US Nuclear Regulatory Commission (NRC), is to provide the fission product release data base for the severe-accident program that is required for sequence-dependent analyses. The results from these tests of commercial LWR fuel have been complemented by data from tests of simulated high-burnup fuel - unirradiated UO{sub 2} that contained fission product species in the forms and concentrations similar to the real fission products in irradiated fuel. Tests of simulated LWR fuel included both (a) the SASCHA project in the Federal Republic of Germany, which studied release from a simulated core melt of UO{sub 2}, Zircaloy, and stainless steel; and (b) tests of SASCHA-type fuel in the ORNL test apparatus. This review considers results in steam atmosphere from the SASCHA tests, the four ORNL tests of simulated fuel, and the first nine ORNL tests of highly irradiated fuel. Data from the ORNL simulated fuel tests and the three latest irradiated fuel tests have not been published previously.