NEA Nuclear Data High Priority Request List, HPRL


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Request ID4 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 92-U-235 (n,f) prompt g  Thermal-Fast Eg=0-10MeV 7.5 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission LWR, Gen-IV 10-MAY-06 12-MAY-06 N

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Requester: Prof. Gerald RIMPAULT at CADARACHE, FR

Project (context): JEFF, NEA WPEC Subgroup 27

The four fast reactor systems of GenIV feature innovative core characteristics for which gamma-ray heating estimates for non-fuel zones require an uncertainty of 7.5% [1]. For the experimental Jules Horowitz Reactor (RJH) at Cadarache a similar requirement appears [2]. Recent studies show evidence of discrepancies on integral measurement in MASURCA, EOLE and MINERVE, from which it is clear that the expectations for GenIV systems and the RJH thermal reactor are not met [3]. Gamma-ray energy release is dominated by Pu-239 and U-235.

7.5% on the total gamma energy
7.5% on multiplicity
Best accuracy achievable for the gamma spectrum shape

Justification document:
Reference 1: G. Rimpault, Proc. Workshop on Nuclear Data Needs for Generation IV, April 2005, Antwerp, Belgium
Reference 2: D. Blanchet, Proc. M&C 2005, Int. Topical Meeting on Mathematics and Computation, Supercomputing, Reactor Physics and Nuclear and Biological Applications, Sep. 2005, Avignon, France
Reference 3: 'Needs for accurate measurements of spectrum and multiplicity of prompt gammas emitted in fission', G. Rimpault, A. Courcelle and D. Blanchet, CEA/Cadarache – DEN/DER/SPRC.

Comment from requester:
Forty percent of the total gamma-ray energy release results from prompt decay of fission products. No comprehensive analytic expressions exist and Hauser-Feshbach model calculations are involved and presently lack sufficient knowledge to warrant a solution of the problem. New measurements would be needed to guide new evaluation efforts. Present evaluations are based on measurements from the seventies.

Comments from evaluator/experimentalist:
NEA-WPEC initiated Subgroup 27 "Prompt photon production from fission products" in response to this problem. The subgroup co-ordinator is R. Jacqmin of CEA.

Comments for achieved accuracy:
Discrepancies observed for C/E ratios in various benchmarks range from 10 to 28%.

Review comment:
The request is well motivated and based on a considerable effort.

Additional file attached: HPRLgammafission.pdf