A BNR model for LWR fuel rod clad creep behaviour

Semi-theoretical model was developed for predicting creep strain under thermal out-of-pile and in-pile conditions of interest for LWR type fuel rods. The results of model calculations were compared with an isothermal experiment data and post-irradiation examinations as available. Discussion was also given to the difference in creep behaviour between irradiated and unirradiated fuel cladding, indicating that model equations are applicable for predicting creep strain of spent fuel claddings. Strain-hardening and fluence/time-hardening effects were modelled and discussed. (authors)