Decay Heat Benchmark for Uranium-Free Fuels With Minor Actinides

The decay heat (energy due to decay of unstable nuclei) is a small fraction of reactor power at nominal conditions, but after reactor shut-down it is the most important heat source. For taking this source into account in design and safety studies, recommendations are available for fuels of operating reactors, such as UOX and MOX. Fuels for EFIT (European Facility for Industrial Transmutation), unlike UOX and MOX, should contain a significant amount of Minor Actinides (MAs) that would influence decay heat. CEA, CIEMAT, ENEA, FZK (now KIT), PSI and SCK•CEN established a benchmark case and computed decay heat curves for MA-bearing fuels and a MOX-type fuel. The decay heat in the fuels with MAs is appreciably higher than in MOX, except for low burnup cases after short cooling times. This should be taken into account in the design of the decay heat removal system for EFIT. The obtained differences between the decay heat in MA-bearing and MOX fuels are supposed to be representative for the benchmark (or similar) conditions. More effort is needed to evaluate the uncertainties of the computed results.