The neutron-induced fission cross section of 233Pa : and the quest for clean and safe nuclear energy

Abstract: Neutron-induced fission of 233Pa has been investigated between 1.0 and 8.5 MeV, and the reaction cross section was determined. Due to the short half-life of 233Pa for ?-decay, fission events from the daughter product 233U affect the analysis of the protactinium experiment. In order to be able to correct for this contamination by ingrowing 233U, its fission cross section was measured as well in the same energy region.The result for the 233Pa(n,f) cross section is compared with previous theoretical evaluations and indirect cross section estimations extracted from fission probability data. The cross section data that were measured in this work are lower than all other values for this isotope. The 233U(n,f) cross section values are also compared to evaluations. The evaluations for the neutron-induced fission cross section of 233U(n,f) are based on a large set of experimental values, and are thus considered to be very accurate. A good agreement between the results obtained in this work and the evaluations is observed in this case.New model calculations, based on the statistical model for nuclear reactions, are compared to the experimental results for the 233Pa(n,f) cross section. These theoretical calculations describe the experimental results very accurately, and can be used to extract information about the fissioning system.The main motivation for this work is its relevance for the thorium-based nuclear fuel cycle, which has been proposed for advanced reactor facilities intended for safe power supply and transmutation of nuclear waste.