JEFF
Impact:
G. Aliberti, G. Palmiotti and M. Salvatores, "The role of differential and integral experiments to meet requirements for improved nuclear data", Int. Conf. on Nuclear Data for Science and Technology, Nice, France, 2007.
Accuracy:
Requested accuracy for nuclear applications is widely discussed within the NEA WPEC Subgroup 26, " Nuclear Data Needs for Advanced Reactor Systems". For Pu-242, the requested accuracy on the capture cross section should be lower than 8% in the fast energy range. Interpretations with JEFF-3.1 of the PROFIL and PROFIL-2 experiments carried out in the fast reactor Phenix have shown the overestimation of about 14% of the capture cross section [1,2].
Justification document:
[1] G. Noguere, E. Dupont, J. Tommasi and D. Bernard, "Nuclear data needs for actinides by comparison with post irradiation experiments", Technical note CEA Cadarache, NT-SPRC/LEPH-05/204 (2005).
[2] J. Tommasi, E. Dupont and P. Marimbeau., "Analysis of Sample Irradiation Experiments in Phénix for JEFF-3.0 Nuclear Data Validation", Nucl. Sci. Eng. 154 (2006) 119-133.
[3] E. Rich, G. Noguere, C. De Saint Jean and O. Serot. "Averaged R-Matrix Modelling of the Pu-242 cross sections in the Unresolved Resonance Range", in Proceedings of the Int. Conf. on Nuclear Data for Science and Technology, Nice, France, 2007.
Comment from requester:
To improve the evaluation of the fast energy range in term of average parameters, new high-resolution capture and transmission measurements are needed. The total cross section above 1.5 keV is poorly known. Accurate average radiation width and strength function are required to solve some ambiguous results obtained between optical model calculations and the statistical analysis of the s-wave resonances [3].
Review comment:
NEA WPEC Subgroup-26 will shortly present more detailed requests related to Pu isotopes that are motivated from sensitivity studies of Generation-IV, GNEP and several reference concepts.
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)
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
- M.Q. Buckner et al., Absolute measurement of the 242Pu neutron-capture cross section, PRC 93 (2016) 044613, EXFOR 14456
- J. Lerendegui, et al., Radiative neutron capture on 242Pu in the resonance region at the CERN n_TOF-EAR1 facility, PRC 97 (2018) 024605
Theory/Evaluation
- M. Herman et al., COMMARA-2.0 Neutron Cross Section Covariance Library, Report BNL-94830-2011, Brookhaven National Laboratory (2011)
- Pu-242 evaluation was proposed to be part of INDEN (CIELO follow-up) initial program of work (as of Dec. 2017)
Validation
Additional file attached:
Additional file attached:Noguere-Pu242-Note-Technique.pdf
| Request ID | 15 |
Type of the request | High Priority request |
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 95-AM-241 | (n,g),(n,tot) SIG | Thermal-Fast | | See details | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action |
| Fission | LWR, Thermal | 08-NOV-07 | 10-SEP-08 | Y |
Requester: Dr Osamu IWAMOTO at JAEA, JPN
Email: iwamoto.osamu@jaea.go.jp
Project (context): JENDL and WPEC subgroup 26
Impact:
The thermal value for the total cross section is inconsistent with the best value for the capture cross section. This inconsistency should be removed (JENDL). Current inconsistencies in the measured total cross section for the main low energy resonances should be removed and a capture measurement should be made to demonstrate consistency.
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:
For JENDL: A new measurement with a total uncertainty of 5% for the thermal total cross section would be required to resolve the issue.
For SG-26: Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties.
| Energy Range | Uncertainty (%) |
| | Initial | GFR | ADMAB |
|
| 67.4 -183 keV | 7 | 4 | 2 |
| 24.8 -67.4 keV | 8 | 3 | 2 |
| 9.12 -24.8 keV | 7 | 3 | 2 |
| 2.03 -9.12 keV | 7 | 3 | 2 |
| 0.454-2.03 keV | 7 | 3 | 3 |
Justification document:
[1] Toru YAMAMOTO, "Analysis of Core Physics Experiments of High Moderation Full MOX LWR", Proc. of the 2005 Symposium on Nuclear Data, February 2-3, 2006, JAEA, Tokai, Japan, pp.7-13, JAEA-Conf 2006-009 (2006). (See attached 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:
New experimental work is ongoing at IRMM in collaboration with CEA. Recent capture measurements have taken place at Los Alamos. There appear to be no large discrepancies in thermal capture measurements dating from 2000 as long as it is clearly distinguished whether the isomer contribution is included or not. Sample material available at IRMM is not compatible with an accurate measurement of the total cross section at thermal energy.
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. Nakamura et al., Thermal-Neutron Capture Cross Section and Resonance Integral of Americium-241, JNST 44 (2007) 1500, EXFOR 22998
- M. Jandel et al., Neutron capture cross section of 241Am, PRC 78 (2008) 034609, EXFOR 14209
- C. Lampoudis et al., Neutron transmission and capture cross section measurements for 241Am at the GELINA facility, Eur. Phys. J. Plus (2013) 128:86, EXFOR 23139
- K. Fraval et al., Measurement and analysis of the 241Am(n,g) cross section with liquid scintillator detectors using time-of-flight spectroscopy at the n_TOF facility at CERN, PRC 89 (2014) 044609, EXFOR 23237
- H. Harada et al., Capture Cross-section Measurement of 241Am(n,g) at J-PARC/MLF/ANNRI, NDS 119 (2014) 61, EXFOR 23172
- K. Terada et al., Measurements of gamma-ray emission probabilities of 241,243Am and 239Np, JNST 53 (2016) 1881
- K. Hirose et al., Simultaneous measurement of neutron-induced fission and capture cross sections for 241Am at neutron energies below fission threshold, NIM A 856 (2017) 133, EXFOR 23338
- K. Terada et al., Measurements of neutron total and capture cross sections of 241Am with ANNRI at J-PARC, Journal of Nuclear Science and Technology 55 (2018) 1198
- E. Mendoza et al., Measurement and analysis of the 241Am neutron capture cross section at the n_TOF facility at CERN, PRC 97 (2018) 054616
- New capture measurement performed in 2017 at n_TOF EAR2
Theory/Evaluation
- G. Noguere et al., Partial-wave analysis of n+Am-241 reaction cross sections in the resonance region, PRC 92 (2015) 014607
- K. Mizuyama et al., Correction of the thermal neutron capture cross section of 241Am obtained by the Westcott convention, JNST 54 (2017) 74
- G. Zerovnik et al., Improving nuclear data accuracy of 241Am and 237Np capture cross sections, EPJ Conferences 146 (2017) 11035
- H. Harada et al., Improving nuclear data accuracy of the Am-241 capture cross-section, International Evaluation Cooperation, Volume 41, NEA/WPEC-41, report NEA/NSC/R(2020)2, 2020
Additional file attached:Yamamoto_T(MOX-LWR)2006.pdf
Additional file attached:
| Request ID | 102 |
Type of the request | High Priority request |
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 64-GD-155 | (n,g),(n,tot) SIG | Thermal-100 eV | | 4 | Y |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action |
| Fission | LWR | 07-FEB-18 | 09-MAY-18 | Y |
Requester: Mr Cristian MASSIMI at UBOLOGNA, ITY
Email: cristian.massimi@unibo.it
Project (context):
Impact:
In nuclear industry gadolinium is used as neutron absorber having the highest thermal absorption cross section among all stable elements thanks to Gd-155 and especially Gd-157 isotopes. It is commonly used, in PWR or BWR, as burnable absorber in fresh fuel to compensate an excess of reactivity or as emergency shutdown poison in CANDU reactors. RPI measurements of the Gd-157 thermal capture cross-section [1] differ by 10% from the ENDF/B-VI.8 value and, thus, in ENDF/B-VII.1 [2] the low energy cross section uncertainty was increased by up to a factor 2, i.e. from about 2-4% to 4-6%. There is no significant change in the latest ENDF/B-VIII.0 evaluation of these two isotopes. A sensitivity and uncertainty analysis was performed by ENEA to quantify the maximum impact of the uncertainty of the gadolinium isotopes cross sections on the criticality of a LWR system [3-5]. It showed that, in systems with a high number of gadolinium fuel pins, neutron capture of odd gadolinium isotopes contribution to keff uncertainty ranks high, just after the major U-235 and U-238 contributions.
Accuracy:
Sensitivity and uncertainty analyses show that keeping the cross section uncertainty below 4% mitigates the impact on keff uncertainty at high-burnup, which is important for a good estimation of the residual reactivity penalty of a fuel assembly at the end of life.
Justification document:
Despite their importance, the capture cross sections of the odd Gd isotopes have not been extensively studied and are not known with the accuracy required by present-day nuclear industry. In the thermal energy range these cross sections contribute more than 99% to the total cross section. Complementary accurate transmission measurements are also required to constrain the capture cross section. Table 1 in Ref. [4] illustrates current discrepancies for 157Gd capture cross-section at thermal energy. Such contradictions should be clarified thanks to new measurements and evaluation.
References
- G. Leinweber, et al., Nuclear Science and Engineering 154, 261-279 (2006)
- M. B. Chadwick et al., ENDF/B-VII.1 Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data, Nuclear Data Sheets 112, 2887-2996 (2011)
- F. Rocchi, 157Gd and 155Gd (n,g) cross section project, JEF/DOC-1835 (2017)
- F. Rocchi, A. Guglielmelli, D.M. Castelluccio and C. Massimi, Reassessment of gadolinium odd isotopes neutron cross sections: scientific motivations and sensitivity-uncertainty analysis on LWR fuel assembly criticality calculations, EPJ Nuclear Sci. Technol. 3, 21 (2017)
- F. Rocchi, A. Guglielmelli, S. Lo Meo, Implementation of a Cross Section Evaluation Methodology for Safety Margin Analysis: Application to Gadolinium Odd Isotopes, ENEA Report RdS/PAR2015/078 (2016)
Comment from requester:
Beyond nuclear industry, nuclear astrophysics can benefit from the accurate knowledge of 155- and 157-Gd(n,g) cross section up to a few keV, as the even-Gd isotopes play an important role in the s-process nucleosynthesis. Therefore a consistent analysis of all Gd-nat isotopes from thermal up to a few keV is of high interest for both astrophysics and nuclear data evaluation purpose.
Review comment:
Entry Status:
Pending new evaluation or validation (as of SG-C review of May 2018)
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
- G. Leinweber et al., Neutron capture and total cross-section measurements and resonance parameters of gadolinium, Nuclear Science and Engineering 154 (2006) 261
- B. Baramsai et al., Neutron resonance parameters in 155Gd measured with the DANCE g-ray calorimeter array, Phys. Rev. C 85 (2012) 024622
- H.D. Choi et al., Radiative capture cross sections of 155,157Gd for thermal neutrons, Nucl. Science and Eng. 177 (2014) 219
- Y.-R. Kang et al., Neutron capture measurements and resonance parameters of gadolinium, Nucl. Science and Eng. 180 (2015) 86
- M. Mastromarco, et al., Cross section measurements of 155,157Gd(n,g) induced by thermal and epithermal neutrons, Eur. Phys. J. A 55 (2019) 9
- Yong-uk Kye, et al., Resonance parameters of Gd isotopes derived from capture measurements at GELINA, Eur. Phys. J. A 56 (2020) 30
- R. Mucciola, et al., Results of time-of-flight transmission measurements for 155,157Gd at a 10m station of GELINA, IAEA INDC Report, INDC(EUR)-0037 (2020)
- A. Kimura, et al., Neutron capture and total cross-section measurements of 155Gd and 157Gd at ANNRI in J-PARC, EPJ Conf. 239 (2020) 01012
Theory/Evaluation
Validation
- F. Rocchi et al., Reassessment of gadolinium odd isotopes neutron cross sections: scientific motivations and sensitivity-uncertainty analysis on LWR fuel assembly criticality calculations, EPJ N 3 (2017) 21
- F. Rocchi et al., Sensitivity uncertainty analysis and new neutron capture cross-sections for gadolinium odd-isotopes to support nuclear safety, Annals of Nuclear Energy 132 (2019) 537
Additional file attached:ENEA_RdS_PAR2015_078.pdf
Additional file attached:jefdoc-1835.pdf
| Request ID | 103 |
Type of the request | High Priority request |
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 64-GD-157 | (n,g),(n,tot) SIG | Thermal-100 eV | | 4 | Y |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action |
| Fission | LWR | 07-FEB-18 | 09-MAY-18 | Y |
Requester: Mr Cristian MASSIMI at UBOLOGNA, ITY
Email: cristian.massimi@unibo.it
Project (context):
Impact:
In nuclear industry gadolinium is used as neutron absorber having the highest thermal absorption cross section among all stable elements thanks to Gd-155 and especially Gd-157 isotopes. It is commonly used, in PWR or BWR, as burnable absorber in fresh fuel to compensate an excess of reactivity or as emergency shutdown poison in CANDU reactors. RPI measurements of the Gd-157 thermal capture cross-section [1] differ by 10% from the ENDF/B-VI.8 value and, thus, in ENDF/B-VII.1 [2] the low energy cross section uncertainty was increased by up to a factor 2, i.e. from about 2-4% to 4-6%. There is no significant change in the latest ENDF/B-VIII.0 evaluation of these two isotopes. A sensitivity and uncertainty analysis was performed by ENEA to quantify the maximum impact of the uncertainty of the gadolinium isotopes cross sections on the criticality of a LWR system [3-5]. It showed that, in systems with a high number of gadolinium fuel pins, neutron capture of odd gadolinium isotopes contribution to keff uncertainty ranks high, just after the major U-235 and U-238 contributions.
Accuracy:
Sensitivity and uncertainty analyses show that keeping the cross section uncertainty below 4% mitigates the impact on keff uncertainty at high-burnup, which is important for a good estimation of the residual reactivity penalty of a fuel assembly at the end of life.
Justification document:
Despite their importance, the capture cross sections of the odd Gd isotopes have not been extensively studied and are not known with the accuracy required by present-day nuclear industry. In the thermal energy range these cross sections contribute more than 99% to the total cross section. Complementary accurate transmission measurements are also required to constrain the capture cross section. Table 1 in Ref. [4] illustrates current discrepancies for 157Gd capture cross-section at thermal energy. Such contradictions should be clarified thanks to new measurements and evaluation.
References
- G. Leinweber, et al., Nuclear Science and Engineering 154, 261-279 (2006)
- M. B. Chadwick et al., ENDF/B-VII.1 Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data, Nuclear Data Sheets 112, 2887-2996 (2011)
- F. Rocchi, 157Gd and 155Gd (n,g) cross section project, JEF/DOC-1835 (2017)
- F. Rocchi, A. Guglielmelli, D.M. Castelluccio and C. Massimi, Reassessment of gadolinium odd isotopes neutron cross sections: scientific motivations and sensitivity-uncertainty analysis on LWR fuel assembly criticality calculations, EPJ Nuclear Sci. Technol. 3, 21 (2017)
- F. Rocchi, A. Guglielmelli, S. Lo Meo, Implementation of a Cross Section Evaluation Methodology for Safety Margin Analysis: Application to Gadolinium Odd Isotopes, ENEA Report RdS/PAR2015/078 (2016)
Comment from requester:
Beyond nuclear industry, nuclear astrophysics can benefit from the accurate knowledge of 155- and 157-Gd(n,g) cross section up to a few keV, as the even-Gd isotopes play an important role in the s-process nucleosynthesis. Therefore a consistent analysis of all Gd-nat isotopes from thermal up to a few keV is of high interest for both astrophysics and nuclear data evaluation purpose.
Review comment:
Entry Status:
Pending new evaluation or validation (as of SG-C review of May 2018)
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
- G. Leinweber et al., Neutron capture and total cross-section measurements and resonance parameters of gadolinium, Nuclear Science and Engineering 154 (2006) 261
- H.D. Choi et al., Radiative capture cross sections of 155,157Gd for thermal neutrons, Nucl. Science and Eng. 177 (2014) 219
- Y.-R. Kang et al., Neutron capture measurements and resonance parameters of gadolinium, Nucl. Science and Eng. 180 (2015) 86
- M. Mastromarco, et al., Cross section measurements of 155,157Gd(n,g) induced by thermal and epithermal neutrons, Eur. Phys. J. A 55 (2019) 9
- Yong-uk Kye, et al., Resonance parameters of Gd isotopes derived from capture measurements at GELINA, Eur. Phys. J. A 56 (2020) 30
- R. Mucciola, et al., Results of time-of-flight transmission measurements for 155,157Gd at a 10m station of GELINA, IAEA INDC Report, INDC(EUR)-0037 (2020)
- A. Kimura, et al., Neutron capture and total cross-section measurements of 155Gd and 157Gd at ANNRI in J-PARC, EPJ Conf. 239 (2020) 01012
Theory/Evaluation
Validation
- F. Rocchi et al., Reassessment of gadolinium odd isotopes neutron cross sections: scientific motivations and sensitivity-uncertainty analysis on LWR fuel assembly criticality calculations, EPJ N 3 (2017) 21
- F. Rocchi et al., Sensitivity uncertainty analysis and new neutron capture cross-sections for gadolinium odd-isotopes to support nuclear safety, Annals of Nuclear Energy 132 (2019) 537
Additional file attached:ENEA_RdS_PAR2015_078.pdf
Additional file attached:jefdoc-1835.pdf