NEA Nuclear Data High Priority Request List, HPRL


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Request ID40 Type of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 14-SI-28 (n,inl) SIG  1.4 MeV-6 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors 15-SEP-08 15-SEP-08 

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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).
This request is specific to the gas-cooled fast reactor.

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
2.23 - 6.07 MeV 14 3 4
1.35 - 2.23 MeV 50 6 8

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:
Completed (as of SG-C review of May 2018)

Main recent references:
Please report any missing information to


  • A. Negret et al., Cross sections for inelastic scattering of neutrons on 28Si and comparison with the 25Mg(a,n)28Si reaction, PRC 88 (2013) 034604, EXFOR 23173
  • A. Negret et al., Neutron inelastic scattering measurements for background assessment in neutrinoless double beta decay experiments, PRC 88 (2014) 027601


  • M. Herman et al., COMMARA-2.0 Neutron Cross Section Covariance Library, Report BNL-94830-2011, Brookhaven National Laboratory (2011)