ID 40
Target 14-Si-28
Reaction (n,inl)
Quantity SIG - Cross section
Incident energy 1.4 MeV - 6 MeV
Accuracy 3-8 %
Field(s) Fission
Subfield Fast Reactors
Accepted date 15-Sep-2008
Status Archived
Latest review date 22-Apr-2022


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 Range Initial versus target uncertainties (%)
Initial GFR
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.

Entry status

Completed (as of SG-C review of May 2018) - The measurement performed at JRC-Geel [Negret:2013] and the latest evaluations (JEFF-3.3, ENDF/B-VIII.0) all match the requested accuracy.

Main recent references

Please report any missing information to hprlinfo@oecd-nea.org


  • 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)