Keywords: Decay heat; nuclear data; Monte Carlo; uncertainty; Molten Salt Reactors

Abstract
Decay heat is the heat released as a result of radioactive decays of fission products, minor actinides, and delayed neutron fission after reactor shutdown. Although this heat decreases over time, it can still release enough power to compromise reactor safety.
Consequently, decay heat must be managed from unloading to final repository of spent fuel. It also plays a critical role in safety system design of Gen IV reactors. Decay heat can be calculated using the summation method by summing individual radioactive nuclide
contributions. Isotopic decay heat contribution is calculated by multiplying its concentration as a function of cooling time, decay constant, and mean decay energy. Concentrations are computed using simulation tools that solve the Bateman equations. Decay data come from
experimental measurements, which inherently carry uncertainties. This PhD research aims to quantify the propagation of these uncertainties on decay heat calculations using a Monte Carlo approach that samples from fission yields and decay data to calculate mean decay
heat and the associated uncertainty. An in-house code, Cocodrilo, was developed to sample decay data from the ENDF-6 library. Additionally, the research includes benchmark comparisons of PWR assembly depletion calculations and MSFR neutronic studies as groundwork for the future.