New feature of DARWIN/PEPIN2 inventory code: Propagation of nuclear data uncertainties to decay heat and nuclide density

•Decay heat sensitivity and uncertainty quantification are implemented in DARWIN/PEPIN2.•Sensitivity coefficient assessment is performed by direct perturbation method.•Comparison of decay heat uncertainty computed with main evaluations are provided.•Decay heat uncertainty study underlines the need of fission yield covariance data.•Effects of neutron flux perturbation on decay heat uncertainty are studied. DARWIN/PEPIN2 is a French inventory code that has been developped at CEA since the mid-1990s for fuel fission reactor, material neutron activation and material radioactive decay calculations. It takes into account both R&D and industrial application requirements. Today, DARWIN/PEPIN2.4.x is the last major release and deals with nuclear data uncertainties propagation to some quantities of interest outputs as atom density, activity and decay heat. The purpose of this paper is to outline this last capability. Methodology approach, calculation hypotheses and nuclear data uncertainty used are discussed as well as the computational implementation. The last part of this paper shows two illustrative uncertainty calculations related to fission pulse and PWR-UO2 fuel depletion configurations.