Decay heat is the heat released after the reactor shutdown as a result of radioactive decays of the fuel isotopes and delayed fissions. The determination of decay heat is a major safety issue for a reactor in operation or in accidental conditions but also for the transport of burnt fuel and nuclear waste management. It is in particular a key parameter for the design of the Generation IV reactors safety systems but also for the use of innovating fuels. Few decay heat measurements are available. Hence there is a real need to have reliable codes to estimate the decay heat associated with its uncertainty. The calculation of decay heat relies on the combination of reactor simulations to estimate the fuel inventory and on nuclear data
used as an input : decay properties of the fission products and actinides, fission yields and cross sections.
The Nuclear Structure and Energy group of the SUBATECH laboratory performs decay heat calculations with the Monte Carlo depletion code SERPENT2 developed by the VTT in Finland for fission pulses, PWR fuel assemblies but also Gen IV concepts.
Since 2015, the impact of new TAS measurements of the β- and γ mean decay energies of some key fission products
on the decay heat calculation of thermal/fast fission pulses has been calculated with the SERPENT2 code.