Title: Neutron-induced Fission Cross Section of 240,242Pu
Citation: PHYSICS PROCEDIA vol. 64 p. 177-182
Publisher: ELSEVIER BV
Publication Year: 2015
JRC N°: JRC105084
ISSN: 1875-3892
URI: http://www.sciencedirect.com/science/article/pii/S1875389215001406
DOI: 10.1016/j.phpro.2015.04.024
Type: Articles in periodicals and books
Abstract: A sensitivity analysis for the new generation of fast reactors [Salvatores (2008)] has shown the importance of improved cross section data for several actinides. Among them, the 240,242Pu(n,f) cross sections require an accuracy improvement to 1-3% and 3-5%, respectively, from the current level of 6% and 20%. At the Van de Graaff facility of the Institute for Reference Materials and Measurements (JRC-IRMM) the fission cross section of the two isotopes was measured relative to two secondary standard reactions, 237Np(n,f) and 238U(n,f), using a twin Frisch-grid ionization chamber. The secondary standard reactions were benchmarked through measurements against the primary standard reaction 235U(n,f) in the same geometry. Sample masses were determined by means of low-geometry alpha counting or/and a 2π Frisch-grid ionization chamber, with an uncertainty lower than 2%. The neutron flux and the impact of scattering from material between source and target was examined, the largest effect having been found in cross section ratio measurements between a fissile and a fertile isotope. Our 240,242Pu(n,f) cross sections are in agreement with previous experimental results and slightly lower than present evaluations. In case of the 242Pu(n,f) reaction no evidence for a resonance at En=1.1 MeV was found.
JRC Directorate:Nuclear Safety and Security

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