Request ID3 Type of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 94-PU-239 (n,f) prompt g  Thermal-Fast Eg=0-10MeV 7.5 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission LWR 28-APR-06 12-MAY-06 Y

Requester: Prof. Gerald RIMPAULT at CAD-DER, FR
Email: gerald.rimpault@cea.fr

Project (context): 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)

Main references:
Please report any missing information to hprlinfo@oecd-nea.org

Experiments

Theory/Evaluation

Additional file attached:HPRLgammafission.pdf
Additional file attached:



Request ID4 Type of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 92-U-235 (n,f) prompt g  Thermal-Fast Eg=0-10MeV 7.5 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission LWR, Gen-IV 10-MAY-06 12-MAY-06 Y

Requester: Prof. Gerald RIMPAULT at CAD-DER, FR
Email: gerald.rimpault@cea.fr

Project (context): 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 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)

Main references:
Please report any missing information to hprlinfo@oecd-nea.org

Experiments

  • E. Kwan, et al., Prompt energy distribution of 235U(n,f) gamma at bombarding energies of 1–20 MeV, NIM A 688 (2012) 55, EXFOR 14413
  • A. Oberstedt et al., Improved values for the characteristics of prompt-fission g-ray spectra from the reaction 235U(nth,f), PRC 87 (2013) 051602(R), EXFOR 31729
  • 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
  • M. Lebois, et al., Comparative measurement of prompt fission g-ray emission from fast-neutron-induced fission of U-235 and U-238, PRC 92 (2015) 034618, EXFOR 23299
  • Ongoing work at IRMM-IPNO, S. Oberstedt, et al., Future research program on prompt g-ray emission in nuclear fission, Eur. Phys. J. A (2015) 51:178
  • Ongoing work at JAEA, see H. Makii et al., Measurement of High-Energy Prompt g-rays from Neutron-Induced Fission of 235U, FIESTA 2017

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 ID16 Type of the request General request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 95-AM-243 (n,f) prompt n  Eth-10 MeV  10 
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 ADS Fast fission spectra 08-NOV-07 10-SEP-08 Y

Requester: Mr Toshinobu SASA at JAEA, JPN
Email: toshinobu.sasa@cao.go.jp

Project (context): J-PARC

Impact:
It is necessary in the ADS design study. Obninsk scientists report important difference of fission neutron spectra from ENDF/B-VI evaluation at MeV energies.

Accuracy:

Justification document:
T. Sugawara, K. Sugino, T. Sasa, "SND2006-V.10: Design of MA-loaded Core Experiments using J-PARC", T. Fukahori (Ed.), Proc. of 2006 Symposium on Nuclear Data, Jan. 25-26, 2007, RICOTTI, Tokai-mura, Ibaraki-ken, Japan, ISBN978-4-89047-138-6, Nuclear Data Division, Atomic Energy Society of Japan (2007) [CD-ROM].

Comment from requester:

Review comment:

It appears that experimental work for the neutron-induced reaction will be near to impossible on account of the required amount of sample material. Could this work be carried out by using a transfer reaction?

The importance of the fission neutron spectrum is not contested. It is a significant problem also for the major actinides and for those it is a recurrent subject of debate. The present request is dubbed a general request since it is not backed by a direct sensitivity study. The methodology of such sensitivity studies was recently explored by WPEC Subgroup 26 (link to WPEC Subgroup 26 Report in PDF format, 6 Mb). In that report it is also mentioned that substantial uncertainties may result from the fission spectrum but that further work is required.

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

  • L.V.Drapchinsky, Measurements of the prompt neutron spectra of minor actinides - Fast neutron induced fission of 241Am and 243Am, thermal neutron induced fission of 243Cm, Report ISTC-1828-01 (2004), EXFOR 41589

Additional file attached:sugawara_t(MA-cores_JPARC).pdf
Additional file attached:



Request ID17 Type of the request General request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 96-CM-244 (n,f) prompt n  Eth-10 MeV  10 
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 ADS Fast fission spectra 08-NOV-07 10-SEP-08 Y

Requester: Mr Toshinobu SASA at JAEA, JPN
Email: toshinobu.sasa@cao.go.jp

Project (context): J-PARC

Impact:
It is necessary in the ADS design study. Obninsk scientists report important difference of fission neutron spectra from ENDF/B-VI evaluation at MeV energies.

Accuracy:

Justification document:
T. Sugawara, K. Sugino, T. Sasa, "SND2006-V.10: Design of MA-loaded Core Experiments using J-PARC", T. Fukahori (Ed.), Proc. of 2006 Symposium on Nuclear Data, Jan. 25-26, 2007, RICOTTI, Tokai-mura, Ibaraki-ken, Japan, ISBN978-4-89047-138-6, Nuclear Data Division, Atomic Energy Society of Japan (2007) [CD-ROM].

Comment from requester:

Review comment:

It appears that experimental work for the neutron-induced reaction will be near to impossible on account of the required amount of sample material. Could this work be carried out by using a transfer reaction?

The importance of the fission neutron spectrum is not contested. It is a significant problem also for the major actinides and for those it is a recurrent subject of debate. The present request is dubbed a general request since it is not backed by a direct sensitivity study. The methodology of such sensitivity studies was recently explored by WPEC Subgroup 26 (link to WPEC Subgroup 26 Report in PDF format, 6 Mb). In that report it is also mentioned that substantial uncertainties may result from the fission spectrum but that further work is required.

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

Additional file attached:sugawara_t(MA-cores_JPARC).pdf
Additional file attached:



Request ID19 Type of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 94-PU-238 (n,f) SIG  9 keV-6 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors (ADMAB) 31-MAR-08 11-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).

The request for the improved cross section and uncertainties for 238Pu(n,f) emerges for five of the eight cases studied. The most stringent requirements for this case arise from the SFR, LFR and ADMAB.
Improvements of the nuclear data for 238Pu(n,f) are important for estimates of keff for the SFR, LFR, ADMAB and GFR (in order of significance), the peak power of ADMAB and the void coefficient of an SFR.

Requested accuracy is required to meet target accuracy for burnup for an Accelerator-Driven Minor Actinides Burner (ADMAB). Details are provided in the SG-26 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 RangeInitial versus target uncertainties (%)
InitialSFREFRGFRLFRADMAB
2.23 - 6.07 MeV 21 6 7 8 7
1.35 - 2.23 MeV 34 6 24 8 7 6
0.498 - 1.35 MeV 17 3 10 5 3 3
183 - 498 keV 17 4 12 6 3 4
67.4 - 183 keV 9 5 5
24.8 - 67.4 keV 12 6 7 6
9.12 - 24.8 keV 11 7 7 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:

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

  • M.B. Chadwick et al., ENDF/B-VII.1 Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data, p.2937 in NDS 112 (2011) 2887
  • Pu-238 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 ID21 Type of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 95-AM-241 (n,f) SIG  180 keV-20 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors (ADMAB) 31-MAR-08 11-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).

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 RangeInitial versus target uncertainties (%)
  InitialSFR GFRLFRADMAB
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 ID22 Type of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 95-AM-242M (n,f) SIG  0.5 keV-6 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors (SFR) 31-MAR-08 11-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 keff for Sodium-cooled Fast Reactor in a TRU burning configuration, i.e., with a Conversion Ratio CR<1 (SFR). 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 RangeInitial versus target uncertainties (%)
  InitialSFR LFRADMAB
2.23 - 6.07 MeV 23 8
1.35 - 2.23 MeV 20 8
0.498- 1.35 MeV 17 4 6
83 - 498 - keV 17 3 8 5
67.4 - 183 - keV 17 3 5
24.8 - 67.4 keV 14 4 6
9.12 - 24.8 keV 12 4 6
2.03 - 9.12 keV 12 7
0.454- 2.03 keV 12 5

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

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:

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

  • 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 ID25 Type of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 96-CM-244 (n,f) SIG  65 keV-6 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors (ADMAB) 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:
Requested accuracy is required to meet target accuracies for keff, peak power and burnup for the 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" (Final Draft attached).

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 RangeInitial versus target uncertainties (%)
  InitialSFR EFR GFRLFRADMAB
6.07 - 2.23 MeV 31 8 12 3
2.23 - 1.35 MeV 44 8 13 14 3
1.35 - 0.498 MeV 50 5 20 8 6 2
498 - 183 keV 37 12 4
183 - 67.4 keV 48 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:
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:
Experimentally the fission probability of the compound nucleus (245Cm) may be studied in detail through the use of a transfer reaction. The fission cross section for n+244Cm may then be inferred from a theoretical estimate of the compound nucleus formation cross section. Probably, this will be adequate for the EFR and GFR requirements and it could be sufficient for the SFR and LFR, as well.

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

  • B.I. Fursov, Fast neutron induced fission cross sections of some minor actinides, ND1997 Proceedings, p.488 (1997), EXFOR 41343

Theory/Evaluation

Validation

Additional file attached:SG26-report.html
Additional file attached:



Request ID27 Type of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 96-CM-245 (n,f) SIG  0.5 keV-6 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors (ADMAB) 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, peak power and burnup for the 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 RangeInitial versus target uncertainties (%)
InitialSFREFRGFRLFRADMAB
2.23 - 6.07 MeV 31 7
1.35 - 2.23 MeV 44 14 6
0.498 - 1.35 MeV 49 9 43 16 11 3
183 - 498 keV 37 7 13 7 3
67.4 - 183 keV 48 7 42 11 7 3
24.8 - 67.4 keV 27 9 11 9 3
9.12 - 24.8 keV 14 9 3
2.03 - 9.12 keV 13 4
0.454 - 2.03 keV 13 5

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:

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

Additional file attached:SG26-report.html
Additional file attached:



Request ID35 Type of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 94-PU-241 (n,f) SIG  0.5 eV-1.35 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast and Thermal Reactors 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:
Distinct requests for this fission cross section are made at higher energies for fast reactor applications and also at lower energies for thermal reactor applications. Requested accuracy is required to meet target accuracy for k-eff for the GFR, SFR, LFR and ABTR and to meet k-eff and burnup for EFR. Requested accuracy is also required to meet target accuracy for k-eff for the VHTR and k-eff and burnup for the PWR. 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" (Final Draft attached).

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 RangeInitial versus target uncertainties (%)
InitialABTRSFREFRGFRLFRADMABVHTREPR
λ=1 λ≠1,b λ=1 λ≠1,b λ=1 λ≠1,a λ=1 λ=1 λ=1 λ=1 λ≠1,a λ=1 λ≠1,a
0.498 - 1.35 MeV 17 12 9 3 3 8 7 4 4 2
183 - 498 keV 14 9 7 3 2 7 6 3 3 2
67.4 - 183 keV 20 9 7 3 2 6 5 3 3 2
24.8 - 67.4 keV 9 3 3 6 6 3 3 2
9.12 - 24.8 keV 11 4 3 7 6 3 4 2
2.03 - 9.12 keV 10 5 5 8 7 2 5 2
0.454 - 2.03 keV 13 4 4 7 6 3 3
22.6 - 454 eV 19 9 8 5 7 6 8 5 6
0.54 - 4.00 eV 27 9 12 8 10

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

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 ID37 Type of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 94-PU-240 (n,f) SIG  0.5 keV-5 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors 15-SEP-08 15-SEP-08 Y

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 RangeInitial versus target uncertainties (%)
InitialSFREFRGFRLFRADMAB
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
2.23 - 6.07 MeV 5 3 3 3 3 3 3 3
1.35 - 2.23 MeV 6 3 3 2 3 3 3 3 3 3
0.498 - 1.35 MeV 6 2 2 2 4 3 2 3 2 2 2 2
0.454 - 2.03 keV 22 13 13 11 9 10

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:

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

  • A.B. Laptev et al., Int. Conf. on Fission and Properties of Neutron-Rich Nuclei, Sanibel Island, USA, p.462, 2007, EXFOR 41487
  • F. Tovesson et al., Neutron induced fission of 240,242Pu from 1 eV to 200 MeV, PRC 79 (2009) 014613, EXFOR 14223
  • P. Salvador et al., Neutron-induced fission cross section of 240Pu from 0.5 MeV to 3 MeV, PRC 92 (2015) 014620, EXFOR 23281
  • F. Belloni et al., Neutron induced fission cross section measurements of 240Pu and 242Pu, EPJ Conf. 146 (2017) 04062
  • A. Stamatopoulos et al., Investigation of the 240Pu(n,f) reaction at the n_TOF/EAR2 facility in the 9 meV-6 MeV range, PRC 102 (2020) 014616
  • Ongoing work from a JRC-PTB-NPL collaboration and from a CENBG-CEA-JRC collaboration (ANDES and EMRP projects)

Theory/Evaluation

  • 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
  • Pu-240 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 ID38 Type of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 94-PU-240 (n,f) nubar  200 keV-2 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors 15-SEP-08 15-SEP-08 Y

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 RangeInitial versus target uncertainties (%)
InitialSFREFRGFRLFRADMAB
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
1.35 - 2.23 MeV 3 2 2 2
0.498 - 1.35 MeV 4 2 2 1 3 2 2 2 1 1 2 2
183 - 498 keV 5 3 3 3 3 3

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:

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

  • Pu-240 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 ID39 Type of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 94-PU-242 (n,f) SIG  200 keV-20 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors 15-SEP-08 15-SEP-08 Y

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 RangeInitial versus target uncertainties (%)
InitialSFREFRGFRLFRADMAB
λ=1 λ≠1,b λ=1 λ≠1,a λ=1 λ≠1,a λ=1 λ≠1,a λ=1
6.07 - 19.6 MeV 37 15 14
2.23 - 6.07 MeV 15 5 5 6 6 7 8 7
1.35 - 2.23 MeV 21 5 4 5 6 7 7 5
0.498 - 1.35 MeV 19 4 3 11 9 4 4 4 4 4
183 - 498 keV 19 9 8

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:

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

  • 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:SG26-report.html
Additional file attached:



Request ID44 Type of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 93-NP-237 (n,f) SIG,DE  200 keV-20 MeV  2-3 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission fast reactors 11-MAY-15 18-MAY-15 

Requester: Dr Fredrik TOVESSON at LANL, USA
Email: tovesson@lanl.gov

Project (context): Los Alamos National Laboratory

Impact:

  • The Np-237 fission cross section has impact for certain fast nuclear reactor designs. A sensitivity study by Aliberti et al. [1] pointed to a target accuracy of 8% for this cross section for Sodium-cooled Fast Reactor of the Gen-IV type (high level waste recycling).
  • WPEC Subgroup-26 [2]: Present uncertainty (BOLNA) 6-8% from 0.5-6 MeV. Required uncertainty for an Accelerator Driven Minor Actinide Burner (ADMAB): 1.5-4 %.
  • For many measurements the 237Np(n,f) is a reference cross section that is valuable on account of its low fission threshold and moderate activity.

Accuracy:
Uncertainties of 2-3%

Justification document:
There is a discrepancy of about 6-9% between a recent measurement performed by the n_TOF collaboration and ENDF/B-VII (C. Paradela et al. [3]).
The higher n_TOF values are supported by a validation exercise by Leong et al. [4].
A recent independent result in the energy range from 4.8 to 5.6 MeV yields cross sections that in function of energy first agree with ENDF/B-VII and then with the n_TOF result (M. Diakaki et al. [5]).
Independently an issue was recently found when cross sections for Pu-isotopes referred to the 238U(n,f) cross section were compared to the same cross sections referred to the 237Np(n,f) cross section in the same measurement arrangement (P. Salvador et al. [6]).

Comment from requester:

The request is well motivated and of some concern also to reactor dosimetry when using spectral indices and/or reaction rates of 237Np fission chambers (IRDFF [7]).

References:
  • [1] G. Aliberti et al., Annals of Nuclear Energy 33 (2006) 700-733.
  • [2] M. Salvatores et al., Nuclear Science NEA/WPEC-26, www.oecd.org.
  • [3] C. Paradela et al., Phys. Rev. C 82 (2010) 034601; Korean Physical Society 59 (2011) 1519.
  • [4] L.S. Leong et al., Annals of Nuclear Energy 54 (2013) 36

Review comment:

Entry Status:
Completed (as of SG-C review of May 2018) - The request was related to a discrepancy between measurements performed at LANSCE [Tovesson:2007] and n_TOF [Paradela:2010]. New measurements using improved PPAC detectors have shown that the overestimation of the n_TOF data was caused by different roughness of the surface of the Np and U samples [Tassan-Got:2019].

Main references:
Please report any missing information to hprlinfo@oecd-nea.org

Experiments

Theory/Evaluation

  • M.B. Chadwick et al., ENDF/B-VII.0: Next Generation Evaluated Nuclear Data Library for Nuclear Science and Technology, NDS 107 (2006) 2931

Validation

Additional file attached:1-s2.0-S0306454906000296-main.pdf
Additional file attached:



Request ID47 Type of the request Special Purpose Quantity
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 90-TH-232 (n,f) SIG,SPA  252Cf(sf)  2-5 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Dosimetry Fast fission, D-T fusion 06-OCT-17 06-OCT-17 

Requester: Dr Stanislav SIMAKOV at KARLSRUHE, GER
Email: stanislav.simakov@partner.kit.edu

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:
New measurements of the spectrum-averaged cross section are requested to solve C/E discrepancy. See SPA_CE_Cf252.pdf below.

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:SPA_CE_Cf252.pdf



Request ID63 Type of the request Special Purpose Quantity
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 95-AM-241 (n,f) SIG,SPA  252Cf(sf)-235U(n,f)  2-5 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Dosimetry Fast fission, D-T fusion 06-OCT-17 06-OCT-17 

Requester: Dr Stanislav SIMAKOV at KARLSRUHE, GER
Email: stanislav.simakov@partner.kit.edu

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:



Request ID99 Type of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 94-PU-239 (n,f) nubar  Thermal-5 eV  1 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing 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

  1. 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)
  2. 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)
  3. 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)
  4. R. Capote, et al., Prompt Fission Neutron Spectra of Actinides, Nuclear Data Sheets 131, 1-106 (2016)
  5. 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: