Research of fission yields evaluation and measurements within the ALFONS project

Abstract

Both commercial nuclear power plants and research facilities need nuclear data for daily operation and experimentations. The fission yields, based on evaluations and experimental values are used to know the composition of the spent fuel, safety measures, decay heat, burnup calculations or delayed neutrons for example. The evaluation of three of the main fission yields libraries (ENDF, JEFF and JEDNL) has been done by analyzing them individually and making comparisons between the different sources. The literature review shows that the libraries are not all optimal and can be improved by new measurements and evaluations. The different investigations presented in this report are based on several criteria such as half life, yield value, cross section for absorption, decay chain or delayed neutrons emission. Fission fuels such as Uranium 235, Plutonium 239 and Americium 243 have been analyzed for different incident neutron energies. The results show that there are a few large uncertainties and discrepancies between the databases for some specific isotopes. Nevertheless, the libraries are sufficiently complete and precise for the current applications. New measurements and evaluations can be made to improve the quality of the libraries, for example on Iodine 129, Xenon 135, Gadolinium 157, Samarium 149 or Iodine 137. This is planned with a new measurement setup called IGISOL in Jyväskylä, Finland.