Automated selection of nuclides and reactions of interest in a depletion simulation. Precision loss estimation for multiple outputs

Abstract To accelerate depletion calculations, it is common to only consider a selection of isotopes. Simulating only a limited number of nuclides leads inevitably to some bias on the outputs of the depletion simulation. Most methods used are either implicit or dedicated to specific cases. This paper presents a new method, based on physics consideration and an explicit algorithm, that automatically selects isotopes and reactions for a depletion calculation. This method uses the creation and simplification of a nucleus tree gathering and linking together all nuclides that can possibly be created during the depletion process. This is performed by recursively adding nuclides possibly created from nuclides previously in the tree through decay or nuclear reaction. After the creation of the tree, it can be simplified by automatically cutting nuclides and reaction out through 3 processes: half-life threshold, cross-section threshold and reaction type cut. Using these simplification processes, the presented method leads to important calculation cost reduction (up to 40%) with effect on outputs lower than 3 times their stochastic standard deviation.