ID 19
Type H - High priority request
Target 94-Pu-238
Reaction (n,f)
Quantity SIG - Cross section
Incident energy 9 keV - 6 MeV
Accuracy 3-24 %
Field(s) Fission
Subfield Fast Reactors (ADMAB)
Accepted date 11-Sep-2008
Status Work in progress
Latest review date 28-Apr-2022



Project (context)

NEA WPEC Subgroup 26


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).

The request for the improved cross section and uncertainties for 238Pu(n,f) emerges for five of the eight cases studied. The most stringent requirements for this case arise from the SFR, LFR and ADMAB.
Improvements of the nuclear data for 238Pu(n,f) are important for estimates of keff for the SFR, LFR, ADMAB and GFR (in order of significance), the peak power of ADMAB and the void coefficient of an SFR.

Requested accuracy is required to meet target accuracy for burnup for an Accelerator-Driven Minor Actinides Burner (ADMAB). Details are provided in the SG-26 report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" ( WPEC Subgroup 26 Report in PDF format, 6 Mb ).


Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties.

Energy Range Initial versus target uncertainties (%)
2.23 - 6.07 MeV 21 6   7 8 7
1.35 - 2.23 MeV 34 6 24 8 7 6
0.498 - 1.35 MeV 17 3 10 5 3 3
183 - 498 keV 17 4 12 6 3 4
67.4 - 183 keV 9 5     5  
24.8 - 67.4 keV 12 6   7 6  
9.12 - 24.8 keV 11 7   7 7  


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

Work in progress (as of SG-C review of May 2018)

Main recent references

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



  • M.B. Chadwick et al., ENDF/B-VII.1 Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data, p.2937 in NDS 112 (2011) 2887
  • Pu-238 evaluation was proposed to be part of INDEN (CIELO follow-up) initial program of work (as of Dec. 2017)


Additional file(s)

  1. International Evaluation Co-operation, Volume 26 - 6.05 MB PDF