Implementing Experimental Data on the Accidential Behaviour of the WWER Cladding Obtained at the AEKI in the TRANSURANUS Fuel Performance Code

Abstract

The paper gives an overview of the recent WWER-specific development and validation of the TRANSURANUS fuel performance code in the range of accident conditions. The extension of the code applicability was achieved through the implementation of new correlations for plastic deformation, steam oxidation and failure of the Zr1%Nb (E110) cladding at high temperature up to 1200 oC. The development of the new correlations was based on a comprehensive database of steam oxidation tests, tensile tests, tube burst tests and ring compression tests carried out at the KFKI Atomic Energy Research Institute (AEKI). The most important results of the separate effect tests are summarized in the first part of the paper exposing the interference of oxygen uptake, mechanical strength and cladding ductility. The newly developed empirical correlations, presented in the second part of the paper, were incorporated into the TRANSURANUS code and validated against independent tube burst tests. The results of numerous post-test analyses and an example for the simulation of fuel rod performance in postulated large break loss of coolant accident (LOCA) are presented in the third and last part of the paper. Furthermore, a new method is introduced to evaluate the fuel rod embrittlement at the quenching of the core on the basis of a ductility parameter which is independent from any oxidation correlation.JRC.E.3-Materials researc