Models and methods for the representation of decay and photon heat in spatial kinetics calculations

In nuclear fission systems, the primary contribution to the reactor power originates from the deposition of the kinetic energy of the fission fragments in the fissioning medium. Secondary, although not necessarily negligible, contributions to the reactor power arise from additional physical phenomena, including, but not limited to, the interactions of the radiation emitted in the radioactive decay of the fission products, as well as the prompt neutrons and photons produced in the fission event. The additional characteristics of the behaviour of the power due to these phenomena may be important to consider in design and safety studies, motivating their proper treatment in the numerical codes foreseen to be applied to such analyses. This work examines modelling and computational aspects of the effects of decay and photon heat in the context of space-time nuclear reactor dynamics calculation