|Quantity||SIG/SPA - Cross section averaged over an incident particle energy spectrum|
|Status||Work in progress|
|Latest review date||22-Apr-2022|
Dr Roberto CAPOTE NOY at IAEA, AUTImpact
A better knowledge of the prompt fission neutron spectrum (PFNS) from Pu-239 thermal-neutron induced fission is important for high-burnup fuels and new generation reactors. This is especially true when considering neutron radiation damage from the PFNS high-energy tail, which can be improved thanks to the measurements of spectrum-averaged cross section (SACS) of well-known high-threshold dosimetry reactions.
Deficiency in Pu-239(n,f) PFNS at large outgoing energies may be responsible for the discrepancies shown in Fig. 178 above 7.5 MeV of average reaction energy, see Fig. 178 in Ref. .
3% cross-section ratio uncertainty relative to reference cross sectionsJustification document
No SACS measurements exist in Pu-239(nth,f) prompt neutron field. In the latest IAEA evaluation, the extrapolation of Pu-239(nth,f) PFNS to outgoing energies above 8 MeV is based on SACS estimated by interpolation between SACS measured in U-233, U-235 and Cf-252 prompt neutron fields, see page 74-76, Fig. 43 and Table XXVI in Ref. .
SACS measurements of high-threshold dosimetry reactions are requested to improve further the high-energy tail of Pu-239(nth,f) PFNS above 8 MeV of outgoing energy. These measurements should be performed relative to high-threshold reference cross sections: Al-27(n,a), Au-197(n,2n), Ni-58(n,p).Entry status
Work in progress (as of SG-C review of June 2019)Main recent references
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