| Abstract: | A correlation for RIA fuel failure threshold has been derived and compared with recent experimental data. The correlation can be used for UO2 and MOX fuel and at hot zero power and cold zero power transients, account taken for the different initial enthalpy and for the lower ductility at cold conditions. It can also be used for non-zero power transients, provided that a term accounting for the start-up power is incorporated. A probabilistic approach has been attempted for the cold zero power case. For LOCA, a correlation has been derived expressing the LOCA limit as a function of the hydrogen accumulated in the cladding during base irradiation. However, LOCA experimental data exhibit a significant scatter, possibly because results depend on details in the conduct of the tests. Consequently, predictions of LOCA limits vs. burn-up are affected by appreciable uncertainty, and more data derived from testing of high burn-up cladding specimens are needed in order to reach firm conclusions. |
