| 1. |
- Hambsch, F. -J, et al.
(författare)
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Fission Fragment Yield, Cross Section and Prompt Neutron and Gamma Emission Data from Actinide Isotopes
- 2014
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Ingår i: Nuclear Data Sheets. - : Elsevier BV. - 0090-3752 .- 1095-9904. ; 119, s. E38-E41
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Tidskriftsartikel (refereegranskat)abstract
- Recent experimental investigations on major and minor actinides at the JRC-IRMM are presented. Fission-fragment distributions of isotopes with vibrational resonances in the sub-threshold fission cross section, i. e. U-234,U-238, have been measured. For U-234, the impact of an increased neutron multiplicity for the heavy fragments with higher incident neutron energies has been studied as observed in experiment and also recently theoretically predicted. The impact is found to be noticeable on post-neutron mass yields, which are the relevant quantities for a-priori waste assessments. The fission cross sections for Pu-240,Pu-242 at threshold and in the plateau region are being investigated within the ANDES project. The results show some discrepancies to the ENDF/B-VII. 1 evaluation mainly for Pu-242 around 1 MeV, where the evaluation exhibits a resonance-like structure not observed so clearly in the present work. The requested target accuracy in design studies of innovative reactor concepts like Gen-IV is in the range of a few percent. In order to be able to respond to requests for measurements of prompt neutron and gamma-ray emission in fission JRC-IRMM has also invested in setting up a neutron and gamma-ray detector array. The neutron array is called SCINTIA and has so far been tested with Cf-252(SF). For gamma-ray multiplicity and spectrum measurements of Cf-252(SF) and U-235(n(th), f) lanthanum- and cerium-halide detectors were successfully used.
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| 2. |
- Salvador-Castiñeira, P., et al.
(författare)
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Neutron-induced fission cross section of Pu 240 from 0.5 MeV to 3 MeV
- 2015
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Ingår i: Physical Review C. Nuclear Physics. - : American Physical Society (APS). - 0556-2813 .- 1089-490X. ; 92:1
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Tidskriftsartikel (refereegranskat)abstract
- Pu240 has recently been pointed out by a sensitivity study of the Organization for Economic Cooperation and Development (OECD) Nuclear Energy Agency (NEA) to be one of the isotopes whose fission cross section lacks accuracy to meet the upcoming needs for the future generation of nuclear power plants (GEN-IV). In the High Priority Request List (HPRL) of the OECD, it is suggested that the knowledge of the Pu240(n,f) cross section should be improved to an accuracy within 1-3 %, compared to the present 5%. A measurement of the Pu240 cross section has been performed at the Van de Graaff accelerator of the Joint Research Center (JRC) Institute for Reference Materials and Measurements (IRMM) using quasi-monoenergetic neutrons in the energy range from 0.5 MeV to 3 MeV. A twin Frisch-grid ionization chamber (TFGIC) has been used in a back-to-back configuration as fission fragment detector. The Pu240(n,f) cross section has been normalized to three different isotopes: Np237(n,f), 235U(n,f), and 238U(n,f). Additionally, the secondary standard reactions were benchmarked through measurements against the primary standard reaction 235U(n,f) in the same geometry. A comprehensive study of the corrections applied to the data and the associated uncertainties is given. The results obtained are in agreement with previous experimental data at the threshold region. For neutron energies higher than 1 MeV, the results of this experiment are slightly lower than the ENDF/B-VII.1 evaluation, but in agreement with the experiments of Laptev et al. (2004) as well as Staples and Morley (1998).
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| 3. |
- Salvador-Castiñeira, P., et al.
(författare)
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Neutron-induced fission cross sections of Pu 242 from 0.3 MeV to 3 MeV
- 2015
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Ingår i: Physical Review C. Nuclear Physics. - : American Physical Society. - 0556-2813 .- 1089-490X. ; 92:4
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Tidskriftsartikel (refereegranskat)abstract
- The majority of the next generation of nuclear power plants (GEN-IV) will work in the fast-neutron-energy region, as opposed to present day thermal reactors. This leads to new and more accurate nuclear-data needs for some minor actinides and structural materials. Following those upcoming demands, the Organisation for Economic Cooperation and Development Nuclear Energy Agency performed a sensitivity study. Based on the latter, an improvement in accuracy from the present 20% to 5% is required for the Pu242(n,f) cross section. Within the same project both the Pu240(n,f) cross section and the Pu242(n,f) cross section were measured at the Van de Graaff accelerator of the Joint Research Centre at the Institute for Reference Materials and Measurements, where quasimonoenergetic neutrons were produced in an energy range from 0.3 MeV up to 3 MeV. A twin Frisch-grid ionization chamber has been used in a back-to-back configuration as fission-fragment detector. The Pu242(n,f) cross section has been normalized to three different isotopes: Np237(n,f), U235(n,f), and U238(n,f). A comprehensive study of the corrections applied to the data and the uncertainties associated is given. The results obtained are in agreement with previous experimental data at the threshold region up to 0.8 MeV. The resonance-like structure at 0.8 to 1.1 MeV, visible in the evaluations and in most previous experimental values, was not reproduced with the same intensity in this experiment. For neutron energies higher than 1.1 MeV, the results of this experiment are slightly lower than the Evaluated Nuclear Data File/B-VII.1 evaluation but in agreement with the experiment of Tovesson et al. (2009) as well as Staples and Morley (1998). Finally, for energies above 1.5 MeV, the results show consistency with the present evaluations.
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