JEFF
Impact:
In nuclear industry hafnium is used as neutron absorbing material to regulate the fission process. Interpretations of critical experiments with UOx fuel conducted by CEA in the AZUR zero-power reactors has shown systematic underestimation of the reactivity worth that may be attributed to an overestimated natural hafnium capture cross section in the epi-thermal energy range [1,2].
Accuracy:
Requested accuracy can be found in the CEA Report "Correlations entre données nucleaires et experiences integrales a plaques, le cas du hafnium", Jean-Marc Palau, CEA-R-5843 (1997). The target accuracy on the effective capture integral has to be lower than 4%
Justification document:
[1] David Bernard, "Determination des incertitudes liés aux grandeurs neutroniques d'interet des reacteurs a eau presurisee a plaques combustibles et application aux etudes de conformite", University Blaise Pascal, Clermont-Ferrand II, France (2001).
[2] G. Noguere, A. Courcelle, J.M. Palau, O.Litaize, "Low neutron energy cross sections of the hafnium isotopes", JEFDOC-1077.pdf, OECD-NEA, Issy-les-Moulineaux, France (2005).
[3] G. Noguere, A. Courcelle, P. Siegler, J.M. Palau, O. Litaize, "Revision of the resolved resonance range of the hafnium isotopes for JEFF-3.1", Technical note CEA Cadarache NT-SPRC/LEPH-05/2001 (2005).
Comment from requester:
Neither the JENDL3.3 nor the JEFF3.1 libraries, that were recently issued, solve the problem. In fact, this was observed for JENDL3.3 before the JEFF3.1 file was constructed. As a result the JEFF3.1 file has been produced with this problem in mind taken into consideration the recent data from Trbovich et al. obtained at RPI [3]. Finally, a 400 pcm underestimation remains that is likely due to interfering isotopic contributions in the resolved energy region. New high resolution measurements appear needed, and would be particularly valuable if they can distinguish the contributions of different isotopes.
Review comment:
Calculations on the AZUR configuration using the JEFF3.1 library give a Hf reactivity worth of about -300 pcm [2].
Entry Status:
Completed (as of SG-C review of May 2018) - The measurements performed at RPI [Trbovich:2009] and JRC-Geel [Ware:2010] allowed to significantly improve the Hf isotopes in JEFF, which now gives satisfactory results for reactivity worth due to Hf data [Noguere:2009].
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
- A.K.M. Meaze et al. (G.N. Kim), Measurement of the Total Neutron Cross-Sections and the Resonance Parameters of Natural Hafnium at the Pohang Neutron Facility, J. Korean Phy. Soc. 46 (2005) 401, EXFOR 31689
- K. Wisshak, et al., Fast neutron capture on the Hf isotopes: Cross sections, isomer production, and stellar aspects, PRC 73 (2006) 045807, EXFOR 22926
- M.J. Trbovich, et al., Hafnium resonance parameter analysis using neutron capture and transmission experiments, NSE 161 (2009) 303, EXFOR 14239
- T. Ware, Measurement and analysis of the resolved resonance cross sections of the natural hafnium isotopes, PhD thesis, University of Birmingham (2010); etheses.bham.ac.uk//id/eprint/807
- M. Budak, et al., Experimental determination of effective resonance energies for 158Gd(n,g)159Gd and 179Hf(n,g)180mHf reactions, ANE 38 (2011) 2550
Theory/Evaluation
Additional file attached:JEFDOC-1077.ppt
Additional file attached:NT_Hafnium.pdf
| Request ID | 12 |
Type of the request | High Priority request |
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 92-U-235 | (n,g) SIG,RP | 100 eV-1 MeV | | 3 | Y |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action |
| Fission | FBR, Thermal reactors | 29-AUG-07 | 06-NOV-07 | |
Requester: Dr Yasunobu NAGAYA at JAEA, JPN
Email: nagaya.yasunobu@jaea.go.jp
Project (context): JENDL, NEA WPEC Subgroup 29
Impact:
U-235 cross sections are very important not only for major thermal reactors but for FBRs because lots of critical experiments for FBRs have been performed at critical assemblies where UO2 fuels are used as driver fuels. Experimental data obtained at such critical assemblies have a great impact on design work for FBRs. Recent studies show that calculated sodium void reactivity worths for BFS experiments underestimate the experimental results by 30-50% [1].
The significant discrepancies not only exceed the target accuracy of 20% for a FBR design but also deteriorate the design accuracy estimated with the cross-section adjustment and bias factor techniques. Thus such experimental data cannot be employed in these techniques.
Accuracy:
The requested accuracies (relative one standard deviation) are given for energy-averaged cross sections as follows:
Energy interval and accuracy
100eV - 500eV: 5%
500eV - 1keV: 5%
1keV -2.25keV: 5%
2.25keV- 5keV: 8%
5keV - 10keV: 8%
10keV - 20keV: 8%
20keV - 30keV: 8%
30keV - 40keV: 3%
40keV - 90keV: 3%
90keV -200keV: 3%
200keV-400keV: 3%
400keV-900keV: 3%
900keV - 1MeV: 3%
(It is assumed that the resolved resonance region is below 2.25 keV and the unresolved resonance region is between 2.25 keV and 30 keV. The boundaries for the resonance regions are the same as for JENDL-3.3.)
Justification document:
Reference 1: first attached document, O. Iwamoto, "WPEC Subgroup Proposal" JAEA, March 9 (2007).
Reference 2: second attached document, viewgraph for Dr. Iwamoto's proposal at the 19th WPEC meeting.
Comment from requester:
The re-evaluation of U-235 cross sections has been already proposed at the 19th WPEC meeting on 18 - 20 April 2007, at the NEA Headquarters, Issy-les-Moulineaux, France.
Review comment:
The proposal seems well motivated. Concerns were expressed in view of the recent changes to the evaluation that emerged from the activities of NEA/WPEC Subgroup 22 "Nuclear Data for Improved LEU-LWR Reactivity Predictions" and ENDF/B-VII benchmarking. The wider impact that new evaluations of U-235 will have, should be considered and duly accounted for by new efforts. Although, the sensitivity of the cross section for the target application is well argued, the documentation does not reveal if the problem must be uniquely attributed to the capture cross section of U-235 in the specified energy range.
Entry Status:
Work in progress (as of SG-C review of May 2018)
Completed (as of SG-C review of June 2019) - The request was related to an issue in the keV region identified by the JENDL project in the early 2000's. Some preliminary evaluation work was performed in the framework of WPEC/SG29 [Iwamoto:2011]. The new measurements performed at LANSCE [Jandel:2012], RPI [Danon:2017] and n_TOF [Balibrea:2017] have been used in the CIELO evaluation [Capote:2018]. The issue is now solved in all major libraries (JENDL-4.0, JEFF-3.3, ENDF/B-VIII.0).
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
- M. Jandel et al., New Precision Measurements of the 235U(n,g) Cross Section, PRL 109 (2012) 202506, EXFOR 14149
- A. Wallner et al., Novel Method to Study Neutron Capture of 235U and 238U Simultaneously at keV Energies, Phys. Rev. Lett. 112 (2014) 192501, EXFOR 23170
- J. Balibrea et al., Measurement of the neutron capture cross section of the fissile isotope 235U with the CERN n_TOF Total Absorption Calorimeter and a fission tagging based on Micromegas detectors, NDS 119 (2014) 10
- Y. Danon, et al., Simultaneous measurement of 235U fission and capture cross sections from 0.01 eV to 3 keV using a gamma multiplicity detector, Nucl. Sci. and Eng. 187 (2017) 191
- J. Balibrea et al., Measurement of the neutron capture cross section of the fissile isotope 235U with the CERN n TOF total absorption calorimeter and a fission tagging based on micromegas detectors, EPJ Conferences 146 (2017) 11021
Theory/Evaluation
- R. Capote et al., IAEA CIELO Evaluation of Neutron-induced Reactions on 235U and 238U Targets, NDS 148 (2018) 254
Validation
- O. Iwamoto et al., Uranium-235 Capture Cross-section in the keV to MeV Energy Region, International evaluation cooperation, Report NEA/WPEC-29, OECD NEA (2011)
- M. Salvatores, et al., Methods and Issues for the Combined Use of Integral Experiments and Covariance Data: Results of a NEA International Collaborative Study, Nuclear Data Sheets 118 (2014) 38
- G. Palmiotti, et al., Combined Use of Integral Experiments and Covariance Data, Nuclear Data Sheets 118 (2014) 596
Additional file attached:U235proposal.pdf
Additional file attached:Viewgraph.U235proposal.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: 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 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 | 33 |
Type of the request | High Priority request |
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 94-PU-241 | (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: 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 accuracies for keff and burnup for the Very High Temperature Reactor (VHTR). 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:
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 Range | Initial versus target uncertainties (%) |
| | Initial | SFR | ADMAB | VHTR | PWR |
| | | λ=1 | λ≠1,a | λ≠1,b | λ=1 | λ=1 | λ≠1,a | λ=1 | λ≠1,a |
|
| 0.498 - 1.35 MeV | 32 | 14 | 15 | 13 | 8 | | | | |
| 183 - 498 keV | 21 | 11 | 11 | 10 | 7 | | | | |
| 0.10 - 0.54 eV | 7 | | | | | 2 | 3 | 3 | 4 |
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
Theory/Evaluation
- H. Derrien et al., Reevaluation and Validation of the 241Pu Resonance Parameters in the Energy Range Thermal to 20 eV, NSE 150 (2005) 109
- Pu-241 evaluation was proposed to be part of INDEN (CIELO follow-up) initial program of work (as of Dec. 2017)
Validation
Additional file attached:SG26-report.html
Additional file attached:
| Request ID | 36 |
Type of the request | High Priority request |
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 92-U-238 | (n,g) SIG | 20 eV-25 keV | | See details | Y |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action |
| Fission | Fast and Thermal Reactors | 15-SEP-08 | 15-SEP-08 | |
Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr
Project (context): CEA Cadarache
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).
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 Range | Initial versus target uncertainties (%) |
| Initial | ABTR | SFR | EFR | GFR | LFR | VHTR | EPR |
| | 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 |
|
| 9.12 - 24.8 keV | 9 | 3 | 2 | 2 | 4 | 3 | 3 | 3 | 2 | 2 | 1 | 2 | 2 | | | 5 | 4 |
| 2.03 - 9.12 keV | 3 | | | | | | | | | 1 | 1 | | | | | | |
| 22.6 - 454 eV | 2 | | | | | | | | | | | | | 1 | 1 | 1 | 1 |
Justification document:
1. 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).
2. OECD/NEA WPEC Subgroup 7 (SG-7) Final Report: "Nuclear data standards" (link to WPEC Subgroup 7 Report in PDF format, 450kb).
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:
In this particular case high accuracy is required throughout the energy range. Only the groups shown above have initial uncertainties larger than the target uncertainties. The low initial uncertainty is a result of the standards evaluation (see SG-7 report above). Concerns have been raised that despite the excellent efforts of this subgroup an independent check is in order to verify the present view on required corrections to experimental work for the unresolved resonance range.
Entry Status:
Completed (as of SG-C review of May 2018) - New time-of-flight measurements have been performed worldwide, e.g., at LANSCE [Ullmann:2014], JRC-Geel [Kim:2016] and n_TOF [Mingrone:2017;Wright:2017]. These experimental data have been used in the CIELO evaluation [Sirakov:2017,Capote:2018] and for the evaluation of the standards [Carlson:2018]. The CIELO evaluated data have been adopted in ENDF/B-VIII.0 and JEFF-3.3; the evaluated uncertainties match the requested accuracy.
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
- A. Wallner et al., Novel Method to Study Neutron Capture of 235U and 238U Simultaneously at keV Energies, PRL 112 (2014) 192501, EXFOR 23170
- J.L. Ullmann, et al., Cross section and g-ray spectra for 238U(n,g) measured with the DANCE detector array at the Los Alamos Neutron Science Center, PRC 89 (2014) 034603, EXFOR 14310
- H.I. Kim et al., Neutron capture cross section measurements for 238U in the resonance region at GELINA, EPJ A 52 (2016) 170, EXFOR 23302
- F. Mingrone et al., Neutron capture cross section measurement of 238U at the CERN n_TOF facility in the energy region from 1 eV to 700 keV, PRC 95 (2017) 034604, EXFOR 23234
- T. Wright et al., Measurement of the 238U(n,g) cross section up to 80 keV with the Total Absorption Calorimeter at the CERN n_TOF facility, PRC 96 (2017) 064601
Theory/Evaluation
- H. Derrien et al., R-Matrix Analysis of 238U High-Resolution Neutron Transmissions and Capture Cross Sections in the Energy Range 0 to 20 keV, NSE 161 (2009) 131
- R. Dagan et al., Impact of the Doppler Broadened Double Differential Cross Section on Observed Resonance Profiles, ND2013, NDS 118 (2014) 179
- Kopecky et al., Status of Evaluated Data Files for 238U in the Resonance region, JRC Technical Report, EUR 27504 EN (2015)
- I. Sirakov et al., Evaluation of cross sections for neutron interactions with 238U in the energy region between 5 keV and 150 keV, EPJ A 53 (2017) 199
- R. Capote et al., IAEA CIELO Evaluation of Neutron-induced Reactions on 235U and 238U Targets, NDS 148 (2018) 254
- A.D. Carlson et al., Evaluation of the Neutron Data Standards, NDS 148 (2018) 143
Validation
Additional file attached:SG26-report.html
Additional file attached:
| Request ID | 97 |
Type of the request | High Priority request |
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 24-CR-50 | (n,g) SIG | 1 keV-100 keV | | 8-10 | Y |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action |
| Fission | | 20-JAN-18 | 05-FEB-18 | Y |
Requester: Dr Roberto CAPOTE NOY at IAEA, AUT
Email: roberto.capotenoy@iaea.org
Project (context):
Impact:
Neutron absorption in the Cr isotopes of structural materials affects the criticality of fast reactor assemblies [Koscheev2017]. These cross sections are also of interest for stellar nucleosynthesis [Kadonis10].
Accuracy:
8-10% in average cross-sections and calculated MACS at 10, 30, 100 keV.
Selected criticality benchmarks with large amounts of Cr (e.g., PU-MET-INTER-002, and HEU-COMP-INTER-005/4=KBR-15/Cr) show large criticality changes of the order of 1000 pcm due to 30% change in Cr-53 capture in the region from 1 keV up to 100 keV [Trkov2018]. On the other side different evaluations (e.g., BROND-3.1, ENDF/B-VII.1, ENDF/B-VIII.0 and JEFF-3.3) for Cr-53(n,g) are discrepant by 30% in the same energy region. For Cr-50, evaluated files show better agreement at those energies but they are lower than Mughabghab evaluation of the resonance integral by 35%. These discrepancies are not reflected in estimated uncertainty of the evaluated files (e.g., JEFF-3.3 uncertainty is around 10% which is inconsistent with the observed spread in evaluations). Due to these differences we request new capture data with 8-10% uncertainty to discriminate between different evaluations and improve the C/E for benchmarks containing Chromium and/or SS.
Justification document:
Criticality benchmarks can test different components of stainless steel (SS), including Cr which is a large component of some SS. Currently, a large part of the uncertainty in SS capture seems to be driven by uncertainty in Cr capture [Koscheev2017]. Indeed, some benchmarks highly sensitive to Cr (as a component of SS) indicate a need for much higher capture in Cr for both Pu and U fueled critical assemblies (e.g., HEU-COMP-INTER-005/4=KBR-15/Cr and PU-MET-INTER-002=ZPR-6/10).
Capture in natural Cr is driven by capture on Cr-50 and especially in odd Cr-53.
For Cr-53(n,g) there is a very large spread in MACS(30) values in different libraries compared to recommended KADoNiS 1.0 [Kadonis10] value of 41 +/- 10 mb (the latter is 25% larger). Existing measurements from the 70s are even larger being close to 60 mb with 30% uncertainty.
Note also discrepancies in resonance integrals (in barns) between evaluated libraries and ATLAS [Mughabghab2006] for both Cr-50(n,g) and Cr-53(n,g)
| Reaction | ENDF/B-VII.1 | BROND-3.1 | ATLAS 2006 |
|---|
| Cr-50(n,g) | 7.21 | 7.21 | 11.7 +/- 0.2 |
| Cr-53(n,g) | 8.42 | 11.2 | 12.3 |
Finally, the re-evaluation for ENDF/B-VIII.0 of the ORNL TOF measurement on enriched Cr-53 target [Guber2011] contradicts the increase suggested in Ref. [Koscheev2017] where preliminary data have been used.
Such contradictions need to be resolved thanks to new measurements and evaluation.
References
- [Guber2011] K.H. Guber, et al., Journal of the Korean Physical Society 59(2), 1685-1688, 2011
- [Kadonis10] KADoNiS 1.0 (http://exp-astro.physik.uni-frankfurt.de/kadonis1.0)
- [Koscheev2017] V. Koscheev, et al., EPJ Conf. 146, 06025, 2017
- [Mughabghab2006] S.F. Mughabghab, Atlas of Neutron Resonances, 5th Edition, Elsevier, 2006
- [Trkov2018] A. Trkov, O. Cabellos and R. Capote, Sensitivity of selected benchmarks to Cr-53 and Cr-50 capture, January 2018
Comment from requester:
- Cr-50(n,g) may be measured by activation or TOF. An accurate activation measurement at 5 and 25 keV may help in solving the puzzle of Cr capture.
- Cr-53(n,g) can only be measured by TOF. There is no publication of the final analysis of the ORNL TOF measurement using enriched Cr-53 sample.
- Lead Slowing Down Spectrometer (LSDS) measurements of Cr-50, Cr-53 and Cr-52 enriched samples and of Cr-nat sample could be extremely important to validate and select a proper evaluation of Cr capture cross section below 100 keV. These measurements are strongly encouraged as complementary to TOF and feasible activation measurements.
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
Theory/Evaluation
Validation
- V. Koscheev et al., Use the results of measurements on KBR facility for testing of neutron data of main structural materials for fast reactors, EPJ Conferences 146 (2007) 06025
Additional file attached:Trkov2018.pdf
Additional file attached:
| Request ID | 98 |
Type of the request | High Priority request |
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 24-CR-53 | (n,g) SIG | 1 keV-100 keV | | 8-10 | Y |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action |
| Fission | | 20-JAN-18 | 05-FEB-18 | Y |
Requester: Dr Roberto CAPOTE NOY at IAEA, AUT
Email: roberto.capotenoy@iaea.org
Project (context):
Impact:
Neutron absorption in the Cr isotopes of structural materials affects the criticality of fast reactor assemblies [Koscheev2017]. These cross sections are also of interest for stellar nucleosynthesis [Kadonis10].
Accuracy:
8-10% in average cross-sections and calculated MACS at 10, 30, 100 keV.
Selected criticality benchmarks with large amounts of Cr (e.g., PU-MET-INTER-002, and HEU-COMP-INTER-005/4=KBR-15/Cr) show large criticality changes of the order of 1000 pcm due to 30% change in Cr-53 capture in the region from 1 keV up to 100 keV [Trkov2018]. On the other side different evaluations (e.g., BROND-3.1, ENDF/B-VII.1, ENDF/B-VIII.0 and JEFF-3.3) for Cr-53(n,g) are discrepant by 30% in the same energy region. For Cr-50, evaluated files show better agreement at those energies but they are lower than Mughabghab evaluation of the resonance integral by 35%. These discrepancies are not reflected in estimated uncertainty of the evaluated files (e.g., JEFF-3.3 uncertainty is around 10% which is inconsistent with the observed spread in evaluations). Due to these differences we request new capture data with 8-10% uncertainty to discriminate between different evaluations and improve the C/E for benchmarks containing Chromium and/or SS.
Justification document:
Criticality benchmarks can test different components of stainless steel (SS), including Cr which is a large component of some SS. Currently, a large part of the uncertainty in SS capture seems to be driven by uncertainty in Cr capture [Koscheev2017]. Indeed, some benchmarks highly sensitive to Cr (as a component of SS) indicate a need for much higher capture in Cr for both Pu and U fueled critical assemblies (e.g., HEU-COMP-INTER-005/4=KBR-15/Cr and PU-MET-INTER-002=ZPR-6/10).
Capture in natural Cr is driven by capture on Cr-50 and especially in odd Cr-53.
For Cr-53(n,g) there is a very large spread in MACS(30) values in different libraries compared to recommended KADoNiS 1.0 [Kadonis10] value of 41 +/- 10 mb (the latter is 25% larger). Existing measurements from the 70s are even larger being close to 60 mb with 30% uncertainty.
Note also discrepancies in resonance integrals (in barns) between evaluated libraries and ATLAS [Mughabghab2006] for both Cr-50(n,g) and Cr-53(n,g)
| Reaction | ENDF/B-VII.1 | BROND-3.1 | ATLAS 2006 |
|---|
| Cr-50(n,g) | 7.21 | 7.21 | 11.7 +/- 0.2 |
| Cr-53(n,g) | 8.42 | 11.2 | 12.3 |
Finally, the re-evaluation for ENDF/B-VIII.0 of the ORNL TOF measurement on enriched Cr-53 target [Guber2011] contradicts the increase suggested in Ref. [Koscheev2017] where preliminary data have been used.
Such contradictions need to be resolved thanks to new measurements and evaluation.
References
- [Guber2011] K.H. Guber, et al., Journal of the Korean Physical Society 59(2), 1685-1688, 2011
- [Kadonis10] KADoNiS 1.0 (http://exp-astro.physik.uni-frankfurt.de/kadonis1.0)
- [Koscheev2017] V. Koscheev, et al., EPJ Conf. 146, 06025, 2017
- [Mughabghab2006] S.F. Mughabghab, Atlas of Neutron Resonances, 5th Edition, Elsevier, 2006
- [Trkov2018] A. Trkov, O. Cabellos and R. Capote, Sensitivity of selected benchmarks to Cr-53 and Cr-50 capture, January 2018
Comment from requester:
- Cr-50(n,g) may be measured by activation or TOF. An accurate activation measurement at 5 and 25 keV may help in solving the puzzle of Cr capture.
- Cr-53(n,g) can only be measured by TOF. There is no publication of the final analysis of the ORNL TOF measurement using enriched Cr-53 sample.
- Lead Slowing Down Spectrometer (LSDS) measurements of Cr-50, Cr-53 and Cr-52 enriched samples and of Cr-nat sample could be extremely important to validate and select a proper evaluation of Cr capture cross section below 100 keV. These measurements are strongly encouraged as complementary to TOF and feasible activation measurements.
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
Theory/Evaluation
Validation
- V. Koscheev et al., Use the results of measurements on KBR facility for testing of neutron data of main structural materials for fast reactors, EPJ Conferences 146 (2007) 06025
Additional file attached:Trkov2018.pdf
Additional file attached: