| Request ID | 3 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 94-PU-239 | (n,f) prompt g | Thermal-Fast | Eg=0-10MeV | 7.5 | Y |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fission | LWR | 28-APR-06 | 12-MAY-06 | Y | |
Requester: Prof. Gerald RIMPAULT at CAD-DER, FR
Email: gerald.rimpault@outlook.fr
Project (context): JEFF, NEA WPEC Subgroup 27
Impact:
Accuracy:
Justification document:
Comment from requester:
Review comment:
Entry Status:
Main references: Experiments Theory/Evaluation Additional file attached:HPRLgammafission.pdf
Requester: Dr Roberto CAPOTE NOY at IAEA, AUT
Project (context):
Impact: Cf. Ref. [1,2]. A similar, but stronger than in U-235, resonance nubar effect is expected for Pu-239 due to the 1/2 GS spin.
Accuracy: Accuracy below 1% is required on the evaluated data. New measurements must strive to achieve a relative uncertainty below about 1% on the ratio to Cf-252(sf) nubar, as done in the best past experiments [3]. Statistical precision below about 1% at the resonances is required in order to unambiguously identify resonant fluctuations.
Justification document: A new evaluation of the PFNS [4] in the thermal energy range has determined a lower value of the average neutron energy than that reported in the existing evaluated nuclear data libraries. This value is in agreement with Rising et al and Neudecker independent evaluations. However, a number of thermal-solution benchmarks has shown that the combined use of the new Thermal Neutron Constants and a softer prompt fission neutron spectrum at thermal energy yields k-eff values that are larger than measurements by a margin that increases as the above-thermal-leakage fraction (ATLF) increases (see Ref. [5]). Therefore a reduced criticality is needed for high-leakages solutions. Such reduced criticality may arises due to the (n,gf) process in Pu-239 resonance nubar. Unfortunately, only measurements from the 70s and 80s are available, a critical region below 5 eV needs to be remeasured with higher incident-energy resolution and higher accuracy and precision to improve existing evaluated data files. References
Comment from requester: Additionally to changes in nubar changes in resonance parameters may be required. We cannot split those effects on studied criticality benchmarks.
Review comment:
Entry Status:
Main references: Experiments Theory/Evaluation
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 the multiplicity.
Best accuracy achievable for the gamma spectrum shape.
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.
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.
Discrepancies observed for C/E ratios in various benchmarks range from 10 to 28%. The request is well motivated and based on a considerable effort.
Work in progress (as of SG-C review of May 2018)
Pending new evaluation or validation (as of SG-C review of June 2019)
Please report any missing information to hprlinfo@oecd-nea.org
Additional file attached:
Request ID 99
Type of the request High Priority request
Target Reaction and process Incident Energy Secondary energy or angle Target uncertainty Covariance
94-PU-239 (n,f) nubar Thermal-5 eV 1 Y
Field Subfield Date Request created Date Request accepted Ongoing action
Fission 23-MAR-18 12-APR-18 Y
Email: roberto.capotenoy@iaea.org
Work in progress (as of SG-C review of May 2018)
Please report any missing information to hprlinfo@oecd-nea.org