The KWU PCI modelling approach

Abstract Since PCI fuel rod failures are generally attributed to stress corrosion cracking of the clad, mechanical as well as chemical aspects must be considered in PCI modelling. Transient fission gas release, amplified by a thermal feedback effect, is expected to be very important with regard to both aspects. In view of the limited possibilities to describe analytically the complex mechanisms contributing to PCI failures, KWU uses a semiempirical PCI approach to evaluate the experimental results from ramp tests and power reactor experience and to develop preliminary PCI failure criteria. In parallel to the empirical approach, systematic PCI investigations are performed. To calculate stresses and strains during ramps, including fuel and clad plasticity and creep, the code SENATOR has been developed. The ANSYS code is used for the calculation of local stress and strain effects.