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)
Completed at thermal energies (as of SG-C review of May 2022) - SG41 has reviewed all available data, addressed discrepancies and produced recommendations for Am-241 nuclear data. These data have been incorporated into new evaluations.
Work in progress at fast energies (as of SG-C review of May 2022)
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 | 21 |
Type of the request | High Priority request |
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 95-AM-241 | (n,f) SIG | 180 keV-20 MeV | | See details | Y |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action |
| Fission | Fast Reactors (ADMAB) | 31-MAR-08 | 11-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).
The request for improved cross sections and emission spectra and their accuracies for 241Am(n,f) emerges for four of the eight cases studied. The most stringent requirements for this case arises for the ADMAB, while for the SFR and LFR the needs are nearly met.
Requested accuracy is required to meet target accuracy for keff for Accelerator-Driven Minor Actinides Burner (ADMAB). 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.
| Energy Range | Initial versus target uncertainties (%) |
| | Initial | SFR | GFR | LFR | ADMAB |
|
| 6.07 - 19.6 MeV | 13 | | | | 6 |
| 2.23 - 6.07 MeV | 12 | 7 | 3 | | 2 |
| 1.35 - 2.23 MeV | 10 | 6 | 3 | | 1 |
| 0.498 - 1.35 MeV | 8 | 6 | 3 | 5 | 1 |
| 183 - 498 keV | 8 | | | | 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:
SFR: Sodium-cooled Fast Reactor in a TRU burning configuration, i.e., with a Conversion Ratio CR<1
EFR: European Fast Reactor with full recycling of MA and CR~1
GFR: Gas-cooled Fast Reactor also with full recycling of MA
LFR: Lead-cooled Fast Reactor as defined for an IAEA benchmark
ABTR: Advanced Burner Test Reactor Na-cooled core, recently studied within the GNEP initiative
ADMAB: Accelerator-Driven Minor Actinides Burner
PWR: Pressurized Water Reactor
Review comment:
A collaboration between CENBG, IPN-Orsay and CEA have taken data for the reaction 243Am(3He,af) that may yield the fission probability of 242Am. 242Am is the compound nucleus for the 241Am(n,f) reaction. A theoretical estimate of the compound nucleus formation cross section for the latter reaction will than allow to infer the fission cross section. The final accuracy may be sufficient for 2-3 of the four systems.
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
- G. Kessedjian et al., Neutron-induced fission cross sections of short-lived actinides with the surrogate reaction method, Phys. Lett. B 692 (2010) 297, EXFOR 23076
- F. Belloni, et al., Measurement of the neutron-induced fission cross-section of 241Am at the time-of-flight facility n_TOF, EPJ A 49 (2013) 2, EXFOR 23148
- K. Hirose et al., Simultaneous measurement of neutron-induced fission and capture cross sections for 241Am at neutron energies below fission threshold, NIM A856 (2017) 133, EXFOR 23338
- New measurement performed at n_TOF EAR2
Theory/Evaluation
- P. Talou et al., Improved Evaluations of Neutron-Induced Reactions on Americium Isotopes, NSE 155 (2007) 84
Validation
Additional file attached:SG26-report.html
Additional file attached:
| Request ID | 63 |
Type of the request | Special Purpose Quantity |
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 95-AM-241 | (n,f) SIG/SPA | 252Cf(sf)-235U(n,f) | | 2-5 | Y |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action |
| Dosimetry | Fast fission, D-T fusion | 06-OCT-17 | 06-OCT-17 | |
Requester: Dr Stanislav SIMAKOV at KIT, GER
Email: intersurfen@gmail.com
Project (context): IRDFF project
Impact:
The International Reactor Dosimetry and Fusion File (IRDFF) aims at providing evaluated neutron dosimetry reactions validated for all applications related to fission reactors and fusion technology development [IAEA2017].
Accuracy:
2%-5%
Justification document:
Accurate cross sections as well as spectrum-averaged cross sections (SACS) in relevant and well-characterized neutron fields are essential for improvement and validation of the evaluated data [Simakov2017].
Comment from requester:
Measurements of the spectrum-averaged cross section are missing for validation purposes.
References
- [IAEA2017] IAEA CRP on Testing and Improving the International Reactor Dosimetry and Fusion File (IRDFF),
http://www-nds.iaea.org/IRDFFtest/.
- [Simakov2017] S. Simakov, et al., “Proposals for new measurements for IRDFF community and HPRL”, September 2017.
Review comment:
Non-threshold reactions measured in fast spectra such as the 252Cf(sf) and 235U(nth,f) spectrum tend to have their spectrum averaged cross section dominated by scattering contributions and ‘room-return’ neutrons. Experiments should be designed to minimize these contributions and maximize the reaction rate from the primary source. For new experiments best estimates must be provided by detailed Monte Carlo calculation of the spectrum realized in the experiment and the Monte Carlo model must be made available to IRDFF to facilitate validation of new proposals for the cross section. In all cases it is advised to publish both the fully corrected SACS and the measured reaction rates of the primary reaction and the monitor reactions used for normalization and validation of the model. The measured reaction rates must be provided with a full covariance matrix.
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
Additional file attached:Simakov2017.pdf
Additional file attached: