On the use of the FALCON code for modeling the behaviour of high burn-up BWR fuel during the LS-1 pulse-irradiation test

Khvostov, G.*; Zimmermann, M.*; 杉山 智之; 更田 豊志

Proceedings of International Conference on the Physics of Reactors, Nuclear Power; A Sustainable Resource (PHYSOR 2008) (CD-ROM), 8 Pages, 2008/09

Fuel behavior in the RIA-simulating test LS-1, performed at the NSRR with high burnup BWR fuel of a burnup of 69 GWd/tU, is analyzed using the FALCON code coupled with the advanced GRSW-A model for fission gas release (FGR) and fuel swelling. The calculation results agreed reasonably with the measured FGR from the failed fuel rod; about 23% of total gas generation. The mechanisms for the significant FGR are analyzed and discussed in consideration of the predicted initial micro-structural state of the fuel after the base irradiation. The minor role of gaseous swelling in the early fuel failure in the test LS-1 is shown by calculation, which is due to premature brittle cracking of the highly hydrated cladding under the room temperature conditions of the test. However, a significant potential impact of the gaseous swelling on cladding strain-stress conditions is shown by the calculation when assuming a sufficient cladding ductility in the hypothetical test at high temperature.