Burnup Credit Implementation for PWR UOX Used Fuel Assemblies in France: From Study to Practical Experience

Abstract

Burnup credit for used fuel assemblies, in particular, pressurized water reactor uranium oxide, has been a major focus of research in France for more than 30 years. As a result, a wealth of knowledge and experience has been gained. The first implementation of burnup credit in France used the “50-leastirradiated-cm” method approved by the French safety authority in the early 1980s. However, because of the continuous increase in fuel enrichment, the industry is interested in reducing the conservatisms of this method by taking into consideration more realistic hypotheses, such as the introduction of fission products and a nonuniform axial burnup profile. To address this concern, a working group, bringing together several French nuclear companies and institutions [AREVA, CEA (Commissariat à l’Energie Atomique et aux Energies Alternatives), EDF (Electricité de France), and IRSN (Institut de Radioprotection et de Sûreté Nucléaire)], was created in 1997. This paper presents the results of the working group’s discussions and studies on all the issues pertaining to the use of burnup credit. In addition, the practical experience of AREVA TN (a division of AREVA dealing with radioactive materials transport and storage throughout the entire nuclear fuel cycle) with transport casks, using input from these results, is described.