NEA Nuclear Data High Priority Request List, HPRL

HPRL Main High Priority Requests (HPR) General Requests (GR) Special Purpose Quantities (SPQ) New Request SGC/HPRL Documents


Request ID35 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 94-PU-241 (n,f) SIG  0.5 eV-1.35 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast and Thermal Reactors 04-APR-08 12-SEP-08 

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

Project (context): NEA WPEC Subgroup 26

Impact:
Distinct requests for this fission cross section are made at higher energies for fast reactor applications and also at lower energies for thermal reactor applications. Requested accuracy is required to meet target accuracy for k-eff for the GFR, SFR, LFR and ABTR and to meet k-eff and burnup for EFR. Requested accuracy is also required to meet target accuracy for k-eff for the VHTR and k-eff and burnup for the PWR. 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" (Final Draft attached).

Accuracy:
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 (%)
InitialABTRSFREFRGFRLFRADMABVHTREPR
λ=1 λ≠1,b λ=1 λ≠1,b λ=1 λ≠1,a λ=1 λ=1 λ=1 λ=1 λ≠1,a λ=1 λ≠1,a
0.498 - 1.35 MeV 17 12 9 3 3 8 7 4 4 2
183 - 498 keV 14 9 7 3 2 7 6 3 3 2
67.4 - 183 keV 20 9 7 3 2 6 5 3 3 2
24.8 - 67.4 keV 9 3 3 6 6 3 3 2
9.12 - 24.8 keV 11 4 3 7 6 3 4 2
2.03 - 9.12 keV 10 5 5 8 7 2 5 2
0.454 - 2.03 keV 13 4 4 7 6 3 3
22.6 - 454 eV 19 9 8 5 7 6 8 5 6
0.54 - 4.00 eV 27 9 12 8 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.

Comments from evaluator/experimentalist:
See appendix A of the attached report.

Comments for achieved accuracy:
See accuracy table.

Review comment:

Additional file attached: SG26-report.html