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 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 ID32 Type of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 94-PU-239 (n,g) SIG  0.1 eV-1.35 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing 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 RangeInitial versus target uncertainties (%)
  InitialABTR SFREFRGFRLFRADMABVHTR
   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 ID33 Type of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 94-PU-241 (n,g) SIG  0.1 eV-1.35 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing 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 RangeInitial versus target uncertainties (%)
  InitialSFR ADMABVHTRPWR
   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 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 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:



Request ID115 Type of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 94-PU-239 (n,tot) SIG  Thermal-5 eV  1 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Thermal reactors 22-MAR-19 08-APR-19 Y

Requester: Dr Gilles NOGUERE at CAD-DER, FR
Email: gilles.noguere@cea.fr

Project (context):

Impact:

The use of new high-accuracy transmission data in the evaluation procedure will affect the partial cross sections and their uncertainties, whose impact on neutronic calculations may be significant. For the first resonance the uncertainty on capture is 2.5% in JEFF-3.3 and 4% in ENDF/B-VIII.0, whereas the sensitivity of keff to capture is close to 200 pcm/% for MOX fuel. Hence, any modifications of the resonance parameters and their uncertainties will have a sizeable impact on reactor applications.

Accuracy:

Accuracy and precision better than 1% are required for the first resonance.

Justification document:

New experimental setups are developed to measure the capture cross sections of actinides in the resolved resonance range. However, total cross sections are also important quantities for evaluation purposes.

The transmission data of the first resonance have all been measured in the 1950's (see attached figure).

Uncertainty information on these old measurements are scarce or lacking and does not help much to constrain the resonance parameters in the evaluation process, which is a pity given the high accuracy that can be reached on a transmission measurement (compared to capture). The attached figure illustrates how ENDF/B-VIII.0 and JEFF-3.3 differs, partly because of evaluators' choices, but also because of poor uncertainty information.

New high-accuracy transmission measurements of the first resonance will help improve the resonance parameters and reduce the uncertainty on the capture cross section.

Comment from requester:

Review comment:

Entry Status:
Work in progress (as of SG-C review of June 2019)

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

  • C. de Saint Jean (coordinator), Co-ordinated Evaluation of Plutonium-239 in the Resonance Region, Nuclear Energy Agency, International Evaluation Cooperation, NEA/WPEC-34, Report NEA/NSC/WPEC/DOC(2014)447 (2014)

Additional file attached:HPRL_Request_Pu239_ntot_1stRes.png
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