Methodology for the evaluation of fission gas release in lead fast reactor

The Lead cooled Fast reactor is a reactor design option selected within GEN-IV initiative. GEN-IV reactor concepts have to fulfill four strategic goals, namely: sustainability, economics, safety and reliability, proliferation resistance and physical protection. Fast spectrum nuclear reactors enable a much more reduction of uranium consumption. To increase the operability of the reactor, sufficient reactivity reserve has to be assured by the core designer. Hence the nuclear fuel has to be designed to withstand high burn up. Increasing the burn up the gas release issue become more and more important, thus a correct and reliable evaluation of fission gas release during normal operation and in case of accident is of a major importance. In the former case statistical analysis may complement more classical mechanistic evaluations; in the latter case different computational tools may be involved. Best estimate methodology may imply use of different codes. Namely to perform a realistic assessment of the fuel behavior, especially in case of accident conditions, a chain of codes has to be adopted if an analyst wants to adopt a suitable tool per different disciplines.