JEFF, NEA WPEC Subgroup 27
Impact:
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.
Accuracy:
7.5% on the total gamma energy. 7.5% on the 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.
Review comment:
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.
Entry Status:
Work in progress (as of SG-C review of May 2018)
Pending new evaluation or validation (as of SG-C review of June 2019)
Pending new evaluation or validation (as of SG-C review of May 2021) with recommendations for priority validation of the latest evaluations
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
- A. Chyzh, et al., Total prompt g-ray emission in fission of U-235, Pu-239,241, and Cf-252, PRC 90 (2014) 014602, EXFOR 14361
- S. Oberstedt, et al., Future research program on prompt g-ray emission in nuclear fission, Eur. Phys. J. A (2015) 51:178
- A. Gatera, et al., Prompt-fission g-ray spectral characteristics from 239Pu(nth,f), PRC 95 (2017) 064609
Theory/Evaluation
- O. Serot et al., Prompt Fission Gamma Spectra and Multiplicities for JEFF-3.3, JEF/DOC-1828, JEFF Meeting, OECD, Paris (2017)
- D. Brown et al., ENDF/B-VIII.0: The 8th Major Release of the Nuclear Reaction Data Library with CIELO-project Cross Sections, New Standards and Thermal Scattering Data, NDS 148 (2018) 1
- I. Stetcu et al., Evaluation of the Prompt Fission Gamma Properties for Neutron Induced Fission of U-235,238 and Pu-239, NDS 163 (2020) 261
- A. Tudora, Prompt gamma-ray results of two deterministic modelings of prompt emission in fission, Eur. Phys. J. A 56 (2020) 128
Additional file attached:HPRLgammafission.pdf
Additional file attached:
| Request ID | 11 |
Type of the request | General request |
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 94-PU-239 | (n,f),(n,g) SIG,eta,alpha | 1 meV-1 eV | | 1 | Y |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action |
| Fission | Thermal reactors | 09-MAY-07 | 06-JUN-07 | Y |
Requester: Dr Luiz Carlos LEAL at IRSN, FR
Email: luiz.leal@irsn.fr
Project (context): Thermal reactors
Impact:
Improve the estimation of keff as well as the moderator temperature coefficient for thermal systems. In particular, this concerns MOX cores and Pu solutions.
References:
[1] A. Santamarina, Improvement of the Pu239 Evaluation for JEFF3, JEF/DOC-1158 (attached below)
[2] Russell D. Mosteller, "ENDF/B-VII, ENDF/B-VI, and JENDL-3.3 Results for Unreflected Plutonium Solutions and MOX Lattices", Joint International Topical Meeting on Mathematics & Computation and Supercomputing in Nuclear Applications (M&C + SNA 2007) Monterey, California, April 15-19, 2007, on CD-ROM, American Nuclear Society, LaGrange Park, IL (2007), Los Alamos report: LA-UR-06-6903
[3] D. Bernard, E. Fort, A. Courcelle, A. Santamarina, G. Noguère, "239Pu nuclear data improvements in thermal and epithermal neutron ranges, International Conference on Nuclear Data for Science and Technology 2007, Contrib #708.
[4] H.Weigmann, B.Keck, J.A.Wartena,P.Geltenbort, K.Schreckenbach, Int.Conf.on the Physics of Reactors: Operation, Design and Computation, Marseille, 23-27 Apr 1990.
Accuracy:
< 1 % for fission cross section and < 2 % for capture cross section
Justification document:
Recent benchmark calculations indicate that the shape of sig(n,g), sig(n,f), eta and/or alpha at low energy need to be revised. A similar problem was seen about 10 years ago with the U-235 cross section. In that case the shape of eta at low energy was found to be slightly varying with energy. It appears that a similar problem exists for Pu-239. Existing experimental data have not helped much to solve the puzzle. Measurements of these quantities in the range from 1 meV to 1 eV, including the 0.3 eV resonance, will be of utmost importance.
Comment from requester:
Existing measurements of the Pu-239 fission and capture cross sections (alpha) do not help to resolve a longstanding problem with thermal benchmarks regarding Pu-239. The measurements of Ref. [4] helped resolve a similar problem that previously existed for U-235.
Review comment:
Since the request refers to the resonance region, measurements would be needed to address this request. Quite different measurement samples and detectors would be required for the (n,f) and (n,g) cross section measurements with individual uncertainties that would be easily in excess of 1%. Therefore, to achieve the accuracy, measurements should aim at measuring either eta or alpha in function of energy striving for minimal systematic errors. Such an eta or alpha measurement would need to be combined with a precise fission cross section from an evaluation or an independent measurement. Calibrating a fission deposit mass to 1%, is possible, but poses a challenge. Interested experimental groups should consult Ref. [4].
Entry Status:
Work in progress (as of SG-C review of May 2018)
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
- D. Rochman et al., Cross-section measurements for 239Pu(n,f) and 6Li(n,a) with a lead slowing-down spectrometer, NIM A 564 (2006) 400, EXFOR 14108
- F. Tovesson, T.S. Hill, Cross Sections for 239Pu(n,f) and 241Pu(n,f) in the Range En = 0.01 eV to 200 MeV, Nuclear Science and Engineering 165 (2010) 224, EXFOR 14271
- 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
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
Additional file attached:
Additional file attached:jefdoc-1158.pdf
| Request ID | 32 |
Type of the request | High Priority request |
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 94-PU-239 | (n,g) SIG | 0.1 eV-1.35 MeV | | See details | Y |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action |
| Fission | Fast Reactors (VHTR) | 04-APR-08 | 12-SEP-08 | Y |
Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email:
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 Range | Initial versus target uncertainties (%) |
| | Initial | ABTR | SFR | EFR | GFR | LFR | ADMAB | VHTR |
| | | 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.
Review comment:
See appendix A of the attached report.
Entry Status:
Work in progress (as of SG-C review of May 2018)
Main 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
- R. Perez Sanchez et al., Simultaneous Determination of Neutron-Induced Fission and Radiative Capture Cross Sections from Decay Probabilities Obtained with a Surrogate Reaction (to infer the neutron-induced fission and radiative capture cross sections of
239Pu), Phys. Rev. Lett. 125 (2020) 122502
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
Additional file attached:SG26-report.html
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 |
Requester: Dr Roberto CAPOTE NOY at IAEA, AUT
Email: roberto.capotenoy@iaea.org
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
- M.T. Pigni, et al., n+235U resonance parameters and neutron multiplicities in the energy region below 100 eV, EPJ Web of Conferences 146, 02011 (2017)
- E. Fort et al., Evaluation of prompt nubar for 239Pu: Impact for applications of the fluctuations at low energy, Nuclear Science and Engineering 99, 375 (1988)
- Gwin et al., Measurements of the energy dependence of prompt neutron emission from 233U, 235U, 239Pu, and 241Pu for En = 0.005 to 10 eV relative to emission from spontaneous fission of 252Cf, Nuclear Science and Engineering 87, 381 (1984)
- R. Capote, et al., Prompt Fission Neutron Spectra of Actinides, Nuclear Data Sheets 131, 1-106 (2016)
- C. De Saint Jean (coordinator), Co-ordinated Evaluation of Plutonium-239 in the Resonance Region, Nuclear Energy Agency, International Evaluation Cooperation, NEA/WPEC-34, Report NEA/NSC/WPEC/DOC(2014)447 (2014)
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:
Work in progress (as of SG-C review of May 2018)
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
- F.J. Hambsch, et al., Prompt fission neutron emission in resonance fission of 239Pu, ND2004, Santa Fe (NM), USA, September 2004, AIP 769 (2005) 644
Theory/Evaluation
- J.E. Lynn, P. Talou and O. Bouland, Reexamining the role of the (n,gf) process in the low-energy fission of 235U and 239Pu, PRC 97 (2018) 064601
Additional file attached:
Additional file attached:
| Request ID | 115 |
Type of the request | High Priority request |
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 94-PU-239 | (n,tot) SIG | Thermal-5 eV | | 1 | Y |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action |
| Fission | Thermal reactors | 22-MAR-19 | 08-APR-19 | Y |
Requester: Dr Gilles NOGUERE at CAD-DER, FR
Email: gilles.noguere@cea.fr
Project (context):
Impact:
The use of new high-accuracy transmission data in the evaluation procedure will affect the partial cross sections and their uncertainties, whose impact on neutronic calculations may be significant. For the first resonance the uncertainty on capture is 2.5% in JEFF-3.3 and 4% in ENDF/B-VIII.0, whereas the sensitivity of keff to capture is close to 200 pcm/% for MOX fuel. Hence, any modifications of the resonance parameters and their uncertainties will have a sizeable impact on reactor applications.
Accuracy:
Accuracy and precision better than 1% are required for the first resonance.
Justification document:
New experimental setups are developed to measure the capture cross sections of actinides in the resolved resonance range. However, total cross sections are also important quantities for evaluation purposes.
The transmission data of the first resonance have all been measured in the 1950's (see attached figure).
Uncertainty information on these old measurements are scarce or lacking and does not help much to constrain the resonance parameters in the evaluation process, which is a pity given the high accuracy that can be reached on a transmission measurement (compared to capture). The attached figure illustrates how ENDF/B-VIII.0 and JEFF-3.3 differs, partly because of evaluators' choices, but also because of poor uncertainty information.
New high-accuracy transmission measurements of the first resonance will help improve the resonance parameters and reduce the uncertainty on the capture cross section.
Comment from requester:
Review comment:
Entry Status:
Work in progress (as of SG-C review of June 2019)
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
- C. de Saint Jean (coordinator), Co-ordinated Evaluation of Plutonium-239 in the Resonance Region, Nuclear Energy Agency, International Evaluation Cooperation, NEA/WPEC-34, Report NEA/NSC/WPEC/DOC(2014)447 (2014)
Additional file attached:HPRL_Request_Pu239_ntot_1stRes.png
Additional file attached:
