Title: Reaction cross-sections, fission yields and prompt neutron emission from actinide targets
Citation: Actinide and Fission Product Partitioning and Transmutation p. 305-314
Publisher: Organisation for Economic Co-operation and Development (OECD)
Publication Year: 2012
JRC N°: JRC61966
ISBN: 978-92-64-99174-3
URI: http://www.oecd-nea.org/pt/iempt11/index.html
Type: Articles in periodicals and books
Abstract: A thorough understanding of the fission process for actinides is becoming an important necessity for the modelling of innovative concepts for radioactive waste minimisation based on either accelerator driven systems or fast reactors, e.g. Generation IV systems. There is a need for improved nuclear data especially in the fast neutron energy range and for minor actinides, which have not been investigated in great detail so far. Investigations for the understanding of the fission process are one focus in the research activities at JRC-IRMM. Recently, fission-fragment properties (mass, kinetic energy and angular distributions) for the isotopes 238U and 234U have been studied to improve the knowledge of fission yield data in the threshold region of the neutron-induced fission cross-section. These new and precise data have been used to improve neutron-induced reaction modelling for 238U(n,f). The prompt neutron emission in nuclear fission has also been studied for the spontaneous fission of 252Cf showing for the first time no drop in neutron multiplicity for low total kinetic energies as expected by theory. Also, the prompt fission neutron spectrum of 235U is being investigated in detail, both at thermal and for higher-energy incoming neutrons. In the case of 235U the available experimental data are inconsistent with each other and contradictory to theoretical predictions. The new accurate spectral data are used to determine a realistic prompt fission neutron spectrum which is used to calculate critical assemblies and Keff.. A second part of the work programme at JRC-IRMM focus on the precise measurement of resonance parameters present in the neutron-induced reaction cross-sections at incident neutron energies up to several hundreds of electronvolts. The present evaluated data for neutron-induced reactions in 241Am do not fulfil the requirements, as spelled out by the OECD/NEA subgroup 26 to predict accurately the behaviour of a reactor core while burning minor actinides. Therefore, high resolution capture and transmission measurements have been carried out at the time-of-flight facility GELINA on 241Am in an energy region from thermal energy up to 500 eV. A preliminary analysis indicates an underestimation of the capture cross section in the present evaluations.
JRC Directorate:Health, Consumers and Reference Materials

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