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Request ID37 Type of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 94-PU-240 (n,f) SIG  0.5 keV-5 MeV  See details Y
FieldSubfieldCreated dateAccepted dateOngoing actionArchived Date
 Fission Fast Reactors 15-SEP-08 15-SEP-08 Y

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Requester: Prof. Massimo SALVATORES at CADARACHE, FR

Project (context): CEA Cadarache

Design phases of selected reactor and fuel cycle concepts require improved data and methods in order to reduce margins for both economical and safety reasons. A first indicative nuclear data target accuracy assessment was made within WPEC Subgroup 26 (SG-26). The assessment indicated a list of nuclear data priorities for each of the systems considered (ABTR, SFR, EPR, GFR, LFR, ADMAB, VHTR, EPR). These nuclear data priorities should all be addressed to meet target accuracy requirements for the integral parameters characterizing those systems (see the accompanying requests originating from SG-26).

Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties. The weighting factor λ is explained in detail in the accompanying document. Changes from the reference value of λ=1 show the the possible allowance for other target uncertainties. Two cases (A and B) are distinguished for λ≠1 (see Table 24 of the report).

Energy RangeInitial versus target uncertainties (%)
λ=1 λ≠1,a λ≠1,b λ=1 λ≠1,a λ=1 λ≠1,a λ=1 λ≠1,a λ=1 λ≠1,a
2.23 - 6.07 MeV 5 3 3 3 3 3 3 3
1.35 - 2.23 MeV 6 3 3 2 3 3 3 3 3 3
0.498 - 1.35 MeV 6 2 2 2 4 3 2 3 2 2 2 2
0.454 - 2.03 keV 22 13 13 11 9 10

Justification document:
OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).

Comment from requester:
Given the present state of knowledge the above target accuracies are very tight. However, any attempt that significantly contributes to reducing the present accuracy for this quantity is strongly encouraged. Any such attempt will significantly enhance the accuracy with which reactor integral parameters may be estimated and will therefore impact economic and safety margins.

Additional file attached: SG26-report.html

Review comment:

Entry Status:
Work in progress (as of SG-C review of May 2018)
Pending new evaluation or validation (as of SG-C review of May 2021)

Main recent references:
Please report any missing information to


  • A.B. Laptev et al., Int. Conf. on Fission and Properties of Neutron-Rich Nuclei, Sanibel Island, USA, p.462, 2007, EXFOR 41487
  • F. Tovesson et al., Neutron induced fission of 240,242Pu from 1 eV to 200 MeV, PRC 79 (2009) 014613, EXFOR 14223
  • P. Salvador et al., Neutron-induced fission cross section of 240Pu from 0.5 MeV to 3 MeV, PRC 92 (2015) 014620, EXFOR 23281
  • F. Belloni et al., Neutron induced fission cross section measurements of 240Pu and 242Pu, EPJ Conf. 146 (2017) 04062
  • A. Stamatopoulos et al., Investigation of the 240Pu(n,f) reaction at the n_TOF/EAR2 facility in the 9 meV-6 MeV range, PRC 102 (2020) 014616, EXFOR 23458
  • Ongoing work from a JRC-PTB-NPL collaboration and from a CENBG-CEA-JRC collaboration (ANDES and EMRP projects)


  • D. Brown et al., ENDF/B-VIII.0: The 8th Major Release of the Nuclear Reaction Data Library with CIELO-project Cross Sections, New Standards and Thermal Scattering Data, NDS 148 (2018) 1
  • Pu-240 evaluation was proposed to be part of INDEN (CIELO follow-up) initial program of work (as of Dec. 2017)