Current Studies Related to the use of Burnup Credit in France

AbstractIn order to avoid criticality risks, a large number of companies using spent fuels have designed their facilities considering the fuel as fresh. This choice has obviously led to considerable safety margins. In the early 1980s, a method was accepted by the French Safety Authorities allowing operators to consider the changes in the fuel composition during depletion with some very pessimistic hypotheses: only actinides were considered and the amount of burnup used in the studies was equal to the mean burnup in the 50 least-irradiated centimetres. This method was used for reprocessing, storage and transport. However, as many firms still want to optimise their processes (e.g. transport, storage, fuel reprocessing), the main companies involved in the French nuclear industry and IPSN set up a Working Group in order to define the way burnup could be taken into account in the criticality calculations, considering some fission products plus a more realistic axial profile of burnup. The first part of this ar...