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Request ID32 Type of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 94-PU-239 (n,g) SIG  0.1 eV-1.35 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors (VHTR) 04-APR-08 12-SEP-08 Y

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Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr

Project (context): NEA WPEC Subgroup 26

Impact:
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).

Requested accuracy is required to meet target accuracy for k-eff for all fast reactors and the VHTR. Requirements become more stringent when inelastic cross sections would be allowed less stringent target accuracies (eg for inelastic of 243Am, 238U, but also 239Pu) Details are provided in the 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).

Accuracy:

Energy RangeInitial versus target uncertainties (%)
  InitialABTR SFREFRGFRLFRADMABVHTR
   λ=1 λ≠1,a λ≠1,b 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 λ=1 λ≠1,a
0.498 - 1.35 MeV 18 10 7 5 11 8 7 7 5 7 5 7 5
183 - 498 keV 12 6 4 3 7 5 4 5 4 4 3 5 4
67.4 - 183 keV 9 5 4 3 6 4 4 5 3 6 4 4 3 5 3
24.8 - 67.4 keV 10 6 4 3 7 5 4 5 4 5 4 5 3 5 4
9.12 - 24.8 keV 7 6 4 3 6 4 4 5 3 4 3 5 3 5 3
2.03 - 9.12 keV 16 7 5 4 7 5 4 4 3 3 2 6 4 4 3
0.10 - 0.54 eV 1.4 0.8 0.7

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.

Additional file attached: SG26-report.html

Review comment:
See appendix A of the attached report.

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

Experiments

  • S. Mosby et al., Improved neutron capture cross section of Pu-239, PRC 89 (2014) 034610, EXFOR 14383
  • S. Mosby et al., 239Pu(n,g) from 10 eV to 1.3 MeV, NDS 148 (2018) 312
  • S. Mosby et al., Unifying measurement of 239Pu(n,g) in the keV to MeV energy regime, PRC 97 (2018) 041601
  • Ongoing work by a CENBG-CEA-IPNO+ collaboration on surrogate measurements, see R. Perez et al., The Surrogate Reaction Method Applied to 240Pu, FIESTA 2017

Theory/Evaluation

  • C. De Saint Jean et al., Coordinated Evaluation of Plutonium-239 in the Resonance Region, International Evaluation Cooperation, Volume 34, NEA/WPEC-34, OECD (2014)
  • M.B. Chadwick et al., CIELO Collaboration Summary Results: International Evaluations of Neutron Reactions on Uranium, Plutonium, Iron, Oxygen and Hydrogen, NDS 148 (2018) 189

Validation