| Request ID | 2 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 8-O-16 | (n,a),(n,abs) SIG | 2 MeV-20 MeV | See details | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fission | Material recycl, adv. reactors | 21-SEP-05 | 12-SEP-08 | Y | |
Requester: Mr Arnaud COURCELLE at SACLAY, FR
Email: arnaud.courcelle@cea.fr
Project (context): LWR, Material recycling and NEA WPEC Subgroup 26
Impact:
In light water reactors oxygen is present in UOX, MOX and water. The sensitivity coefficient (dk/k)/(dσ/σ)=-3.5 pcm/%. A 30% uncertainty results in an uncertainty for keff of 100 pcm. This important effect was identified by Subgroup 22 of WPEC which investigated the underprediction of the reactivity of light water reactors with the most recent nuclear data evaluations.
A second point concerns helium production which is of importance for the performance of fuel pins and clads. The O-16(n,α) reaction accounts for 25% of the total helium production and contributes 7% to its uncertainty.
A third point concerns the calibration of neutron source strengths using the manganese-sulfate bath technique (NIST). The final requested uncertainty of 1% on neutron source calibrations is very near the 0.5% uncertainty contributed by this reaction.
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 (n,a) : 5% in the whole range.
For (n,abs): 9.9 % (2.23 - 6.07 MeV) and 12.1 % (6.07 - 19.6 MeV).
Justification document:
See reference 1 attached: Need for O16(n,alpha) Measurement and Evaluation in the range 2.5 - 10 MeV A. Courcelle et al. (August 2005) and references therein.
See also 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), and
And "Nuclear data for improved LEU-LWR reactivity predictions", WPEC Vol. 22 (link to Report).
Comment from requester:
The required accuracy concerns the normalisation of the cross section.
A sensitivity analysis is also presented for keff in a fast reactor.
Considerable differences exist among evaluations and measurements are discrepant. Recent C-13(α,n) and C-13(α,α) measurements are identified that provide detailed knowledge about the inverse reaction. Together with an R-matrix analysis this may be used to improve the evaluation for the O-16(n,α) reaction. Feedback has been obtained from evaluators at ORNL, LANL and KAPL.
Review comment:
A direct measurement is in preparation using an ionisation chamber with the time projection technique. The measurement aims at providing benchmark data for the R-matrix analysis near the main resonance (En ~ 5 MeV).
A poor resolution measurement should be sufficient to check the normalisation of the R-matrix result, since resonance self-shielding is not an issue.
The recent results for the C-13(α,n) correspond to 4.8-12 MeV neutrons. This covers a part of the region of interest, but not the important range from 2.35 to 4.8 MeV.
The status of the IRMM measurements was presented as a poster in the ND2007 conference, by V. Khriatchkov, G. Giorginis, V. Corcalciuc, M. Kievets, "The cross section of the 16O(n,a)13C reaction in the MeV energy range", contribution 481, ND2007, Nice, April 2007.
The achieved accuracy is estimated to be 30%.
The request is well motivated and the response for follow-up is very encouraging.
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:Need for O16(n,alpha).pdf
| Request ID | 3 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 94-PU-239 | (n,f) prompt g | Thermal-Fast | Eg=0-10MeV | 7.5 | Y |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fission | LWR | 28-APR-06 | 12-MAY-06 | Y | |
Requester: Prof. Gerald RIMPAULT at CAD-DER, FR
Email: gerald.rimpault@outlook.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 ID | 4 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 92-U-235 | (n,f) prompt g | Thermal-Fast | Eg=0-10MeV | 7.5 | Y |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fission | LWR, Gen-IV | 10-MAY-06 | 12-MAY-06 | Y | |
Requester: Prof. Gerald RIMPAULT at CAD-DER, FR
Email: gerald.rimpault@outlook.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
Theory/Evaluation
Additional file attached:HPRLgammafission.pdf
Additional file attached:
| Request ID | 5 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 72-HF-0 | (n,g) SIG | 0.5 eV-5.0 keV | 4 | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fission | LWR | 28-APR-06 | 16-APR-07 | ||
Requester: Dr Gilles NOGUERE at CAD-DER, FR
Email: gilles.noguere@cea.fr
Project (context): JEFF
Impact:
In nuclear industry hafnium is used as neutron absorbing material to regulate the fission process. Interpretations of critical experiments with UOx fuel conducted by CEA in the AZUR zero-power reactors has shown systematic underestimation of the reactivity worth that may be attributed to an overestimated natural hafnium capture cross section in the epi-thermal energy range [1,2].
Accuracy:
Requested accuracy can be found in the CEA Report "Correlations entre données nucleaires et experiences integrales a plaques, le cas du hafnium", Jean-Marc Palau, CEA-R-5843 (1997). The target accuracy on the effective capture integral has to be lower than 4%
Justification document:
[1] David Bernard, "Determination des incertitudes liés aux grandeurs neutroniques d'interet des reacteurs a eau presurisee a plaques combustibles et application aux etudes de conformite", University Blaise Pascal, Clermont-Ferrand II, France (2001).
[2] G. Noguere, A. Courcelle, J.M. Palau, O.Litaize, "Low neutron energy cross sections of the hafnium isotopes", JEFDOC-1077.pdf, OECD-NEA, Issy-les-Moulineaux, France (2005).
[3] G. Noguere, A. Courcelle, P. Siegler, J.M. Palau, O. Litaize, "Revision of the resolved resonance range of the hafnium isotopes for JEFF-3.1", Technical note CEA Cadarache NT-SPRC/LEPH-05/2001 (2005).
Comment from requester:
Neither the JENDL3.3 nor the JEFF3.1 libraries, that were recently issued, solve the problem. In fact, this was observed for JENDL3.3 before the JEFF3.1 file was constructed. As a result the JEFF3.1 file has been produced with this problem in mind taken into consideration the recent data from Trbovich et al. obtained at RPI [3]. Finally, a 400 pcm underestimation remains that is likely due to interfering isotopic contributions in the resolved energy region. New high resolution measurements appear needed, and would be particularly valuable if they can distinguish the contributions of different isotopes.
Review comment:
Calculations on the AZUR configuration using the JEFF3.1 library give a Hf reactivity worth of about -300 pcm [2].
Entry Status:
Completed (as of SG-C review of May 2018) - The measurements performed at RPI [Trbovich:2009] and JRC-Geel [Ware:2010] allowed to significantly improve the Hf isotopes in JEFF, which now gives satisfactory results for reactivity worth due to Hf data [Noguere:2009].
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
Theory/Evaluation
Additional file attached:JEFDOC-1077.ppt
Additional file attached:NT_Hafnium.pdf
| Request ID | 8 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 1-H-2 | (n,el) DA/DE | 0.1 MeV-1 MeV | 0-180 Deg | 5 | Y |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fission | Heavy Water Reactors | 25-JUL-06 | 16-APR-07 | Y | |
Requester: Kenneth KOZIER at CNLCR, CAN
Email:
Project (context): Critical experiments with high enriched uranyl fluoride in heavy water
Impact:
Different representations of the energy-angle neutron elastic scattering probability distributions (at energies <3.2 MeV) used in various releases of the ENDF/B-VI and JENDL-3.3 evaluated data libraries for deuterium cause differences of about: (1) 1000 pcm in simulations [1,2] of critical experiments involving solutions of high enriched uranyl fluoride solutions in heavy water (specifically the HST-004 and HST-020 series of measurements in the NEA ICSBEP handbook), and (2) 60 pcm in the calculation bias observed [2] in simulations of heavy-water coolant void reactivity (CVR) experiments performed in ZED-2. Moreover, both the HST and ZED-2 simulation results show a rising trend with neutron leakage, suggesting that further revision of the deuterium data evaluations may be needed. Modern measurements may help resolve a small positive bias of about 150 pcm in the simulation of ZED-2 heavy-water CVR experiments (corresponding to about 10% of the calculated CVR).
Accuracy:
About 5%, depending on energy and angle. At 220 keV, existing experimental data have uncertainties of about 16% and differ from the evaluated library values by about 35% at backward angles near 180 degrees. At 500 keV, some experimental data have uncertainties of about 5%, but differ from the library values by up to 50% at 180 degrees. At 1.0 MeV, existing experimental data have uncertainties of about 5%, but differ from the library values by up to 33% near 180 degrees. ENDF/B-VI.8 and JENDL-3.3 differ by about 15% at 180 degrees over this energy range. It is estimated that a 5% uncertainty would correspond to a reactivity uncertainty of about 300 pcm in the context of the HST simulations and about 20 pcm in the ZED-2 CVR simulations, and would be adequate to resolve the current discrepancy between results obtained using the ENDF-B/VI.8 (also VII) and JENDL-3.3 deuterium data files.
Justification document:
The available angular scattering experimental data for deuterium were reviewed [3, attached] and found to be 25 to more than 50 years old, sparse and inconsistent, particularly at backward angles near 180 degrees. The experimental data frequently differ from the evaluated library values by several standard deviations, especially at extreme backward and forward angles. In addition to the HST and ZED-2 simulation results [1,2], the neutronic importance of the deuterium scattering data has been investigated in empirical sensitivity studies of simple systems [4, attached], which suggest that the differences arise at energies up to about 1.0 MeV. A recent TSUNAMI sensitivity analysis of the CVR for an Advanced CANDU Reactor (ACR-700) type lattice cell showed [5] a large sensitivity to the deuterium elastic scattering cross section (34% change in CVR per % change in the cross section), although this methodology does not currently address the angular dependence.
References:
1. R.D. Mosteller, J.M. Campbell and R.C. Little, Reactivity Impact of ENDF/B-VI Cross Sections for Deuterium in Heavy-Water Solution Benchmarks, LA-UR-05-0330, 2005 Annual Meeting of the American Nuclear Society, June 5 - 9, 2005, San Diego, CA.
2. R.D. Mosteller, K.S. Kozier, J.M. Campbell and R.C. Little, ''Reactivity Impact of Deuterium Cross Sections for Heavy-Water Benchmarks'', LA-UR-05-0787, proceedings of the International Topical Meeting on Mathematics and Computation, Supercomputing, Reactor Physics, and Nuclear and Biological Applications, Avignon, France, September 12-15, 2005.
3. L.W. Townsend, ''Neutron-Deuterium Cross Section Evaluation'', Final Technical Report, AECL Purchase Order 217739, March 31, 2006 (copy attached).
4. K.S. Kozier, ''Sensitivity of MCNP5 Calculations for a Spherical Numerical Benchmark Problem to the Angular Scattering Distributions for Deuterium'', proceedings of the PHYSOR-2006 ANS Topical Meeting: Advances in Nuclear Analysis and Simulation, Vancouver, BC, September 10-14, 2006 (copy attached; to be issued).
5. M.L. Williams, J.C. Gehin and K.T. Clarno, ''Sensitivity Analysis of Reactivity Responses Using One-Dimensional Discrete Ordinates and Three-Dimensional Monte Carlo Methods'', proceedings of the PHYSOR-2006 ANS Topical Meeting: Advances in Nuclear Analysis and Simulation, Vancouver, BC, September 10-14, 2006 (to be issued).
6. J.P. Svenne, L. Canton, K. Kozier, and L. Townsend, "Re-evaluating low-energy neutron-deuteron elastic scattering using
three-nucleon theory", International Conference on Nuclear Data for Science and Technology 2007, Contrib. #208.
7. K.S. Kozier, "Assessment of evaluated (n,d) energy-angle elastic scattering distributions using MCNP simulations of critical measurements and simplified calculation benchmarks", International Conference on Nuclear Data for Science and Technology 2007, Contrib. #594
Comment from requester:
Additional sensitivity studies are in progress. We are also looking into the possibility of having someone review the theoretical basis for the two distinctly different quantum mechanical formalisms used by ENDF/B & JENDL for the deuterium elastic scattering energy-angle distributions, and potentially undertake some new Faddeev three-body model calculations.
Review comment:
At the ND2007 in Nice two contributions were presented summarising the status at the time of the conference (April 2007, refs. 6 and 7). Theoretical calculations by L. Canton solving the AGS three-body equations using the Bonn-B nuclear potential tend to support the higher degree of backscattering in the ENDF/B-IV.4 evaluation. A 5% experimental accuracy for the differential cross section at 180 degrees would be sufficient to discriminate between ENDF/B-VI.4 and theory on the one hand and ENDF/B versions VI.5 to VII.0 on the other hand.
Possibilities for experimental efforts are being investigated in the US and in Europe. Further theoretical efforts are planned to study the impact of three body forces and the use of other nucleon-nucleon potentials on the angular distribution.
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:AECL Final Technical Report.pdf
Additional file attached:Full_paper_152003.pdf
| Request ID | 12 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 92-U-235 | (n,g) SIG,RP | 100 eV-1 MeV | 3 | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fission | FBR, Thermal reactors | 29-AUG-07 | 06-NOV-07 | ||
Requester: Dr Yasunobu NAGAYA at JAEA, JPN
Email: nagaya.yasunobu@jaea.go.jp
Project (context): JENDL, NEA WPEC Subgroup 29
Impact:
U-235 cross sections are very important not only for major thermal reactors but for FBRs because lots of critical experiments for FBRs have been performed at critical assemblies where UO2 fuels are used as driver fuels. Experimental data obtained at such critical assemblies have a great impact on design work for FBRs. Recent studies show that calculated sodium void reactivity worths for BFS experiments underestimate the experimental results by 30-50% [1].
The significant discrepancies not only exceed the target accuracy of 20% for a FBR design but also deteriorate the design accuracy estimated with the cross-section adjustment and bias factor techniques. Thus such experimental data cannot be employed in these techniques.
Accuracy:
The requested accuracies (relative one standard deviation) are given for energy-averaged cross sections as follows:
Energy interval and accuracy
100eV - 500eV: 5%
500eV - 1keV: 5%
1keV -2.25keV: 5%
2.25keV- 5keV: 8%
5keV - 10keV: 8%
10keV - 20keV: 8%
20keV - 30keV: 8%
30keV - 40keV: 3%
40keV - 90keV: 3%
90keV -200keV: 3%
200keV-400keV: 3%
400keV-900keV: 3%
900keV - 1MeV: 3%
(It is assumed that the resolved resonance region is below 2.25 keV and the unresolved resonance region is between 2.25 keV and 30 keV. The boundaries for the resonance regions are the same as for JENDL-3.3.)
Justification document:
Reference 1: first attached document, O. Iwamoto, "WPEC Subgroup Proposal" JAEA, March 9 (2007).
Reference 2: second attached document, viewgraph for Dr. Iwamoto's proposal at the 19th WPEC meeting.
Comment from requester:
The re-evaluation of U-235 cross sections has been already proposed at the 19th WPEC meeting on 18 - 20 April 2007, at the NEA Headquarters, Issy-les-Moulineaux, France.
Review comment:
The proposal seems well motivated. Concerns were expressed in view of the recent changes to the evaluation that emerged from the activities of NEA/WPEC Subgroup 22 "Nuclear Data for Improved LEU-LWR Reactivity Predictions" and ENDF/B-VII benchmarking. The wider impact that new evaluations of U-235 will have, should be considered and duly accounted for by new efforts. Although, the sensitivity of the cross section for the target application is well argued, the documentation does not reveal if the problem must be uniquely attributed to the capture cross section of U-235 in the specified energy range.
Entry Status:
Work in progress (as of SG-C review of May 2018)
Completed (as of SG-C review of June 2019) - The request was related to an issue in the keV region identified by the JENDL project in the early 2000's. Some preliminary evaluation work was performed in the framework of WPEC/SG29 [Iwamoto:2011]. The new measurements performed at LANSCE [Jandel:2012], RPI [Danon:2017] and n_TOF [Balibrea:2017] have been used in the CIELO evaluation [Capote:2018]. The issue is now solved in all major libraries (JENDL-4.0, JEFF-3.3, ENDF/B-VIII.0).
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
Theory/Evaluation
Validation
Additional file attached:U235proposal.pdf
Additional file attached:Viewgraph.U235proposal.pdf
| Request ID | 15 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 95-AM-241 | (n,g),(n,tot) SIG | Thermal-Fast | See details | ||
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fission | LWR, Thermal | 08-NOV-07 | 10-SEP-08 | Y | |
Requester: Dr Osamu IWAMOTO at JAEA, JPN
Email: iwamoto.osamu@jaea.go.jp
Project (context): JENDL and WPEC subgroup 26
Impact:
The thermal value for the total cross section is inconsistent with the best value for the capture cross section. This inconsistency should be removed (JENDL). Current inconsistencies in the measured total cross section for the main low energy resonances should be removed and a capture measurement should be made to demonstrate consistency.
Design phases of selected reactor and fuel cycle concepts require improved data and methods in order to reduce margins for both economical and safety reasons. A first indicative nuclear data target accuracy assessment was made within WPEC Subgroup 26 (SG-26). The assessment indicated a list of nuclear data priorities for each of the systems considered (ABTR, SFR, EPR, GFR, LFR, ADMAB, VHTR, EPR). These nuclear data priorities should all be addressed to meet target accuracy requirements for the integral parameters characterizing those systems (see the accompanying requests originating from SG-26).
Accuracy:
For JENDL: A new measurement with a total uncertainty of 5% for the thermal total cross section would be required to resolve the issue.
For SG-26: Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties.
Energy Range Uncertainty (%) Â Initial GFR ADMAB
67.4 -183 keV 7 4 2 24.8 -67.4 keV 8 3 2 9.12 -24.8 keV 7 3 2 2.03 -9.12 keV 7 3 2 0.454-2.03 keV 7 3 3
Justification document:
[1] Toru YAMAMOTO, "Analysis of Core Physics Experiments of High Moderation Full MOX LWR", Proc. of the 2005 Symposium on Nuclear Data, February 2-3, 2006, JAEA, Tokai, Japan, pp.7-13, JAEA-Conf 2006-009 (2006). (See attached document)
OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (Link to WPEC Subgroup 26 Report in PDF format, 6 Mb).
Comment from requester:
Given the present state of knowledge the above target accuracies are very tight. However, any attempt that significantly contributes to reducing the present accuracy for this quantity is strongly encouraged. Any such attempt will significantly enhance the accuracy with which reactor integral parameters may be estimated and will therefore impact economic and safety margins.
Review comment:
New experimental work is ongoing at IRMM in collaboration with CEA. Recent capture measurements have taken place at Los Alamos. There appear to be no large discrepancies in thermal capture measurements dating from 2000 as long as it is clearly distinguished whether the isomer contribution is included or not. Sample material available at IRMM is not compatible with an accurate measurement of the total cross section at thermal energy.
Entry Status:
Work in progress (as of SG-C review of May 2018)
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
Theory/Evaluation
Additional file attached:Yamamoto_T(MOX-LWR)2006.pdf
Additional file attached:
| Request ID | 18 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 92-U-238 | (n,inl) SIG | 65 keV-20 MeV | Emis spec. | See details | Y |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fission | Fast Reactors EFR,SFR,ABTR... | 28-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 238U(n,inel) is an important issue that emerges for five of the eight cases studied. The most stringent requirements for this case arise from the GFR and the LFR.
Improvements of the nuclear data for 238U(n,inel) are important for estimates of keff for the GFR, LFR, ABTR and SFR (in order of significance), the peak power of a GFR and the void coefficient of an SFR.
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 ABTR SFR EFR GFR LFR 6.07-19.6 MeV 29 12 7 2.23-6.07 MeV 20 3 5 4 2 3 1.35-2.23 MeV 21 4 5 4 2 2 0.498-1.35 MeV 12 7 6 5 2 2 67.4-183 keV 11 7 9 7 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. This request is of high priority.
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 ID | 19 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 94-PU-238 | (n,f) SIG | 9 keV-6 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: 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 Range Initial versus target uncertainties (%) Initial SFR EFR GFR LFR ADMAB 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
Validation
Additional file attached:SG26-report.html
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: 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 Range Initial versus target uncertainties (%) Â 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
Theory/Evaluation
Validation
Additional file attached:SG26-report.html
Additional file attached:
| Request ID | 22 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 95-AM-242M | (n,f) SIG | 0.5 keV-6 MeV | See details | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing 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 Range Initial versus target uncertainties (%) Â Initial SFR LFR ADMAB
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
Validation
Additional file attached:SG26-report.html
Additional file attached:
| Request ID | 25 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 96-CM-244 | (n,f) SIG | 65 keV-6 MeV | See details | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing 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 Range Initial versus target uncertainties (%) Â Initial SFR EFR GFR LFR ADMAB
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
Theory/Evaluation
Validation
Additional file attached:SG26-report.html
Additional file attached:
| Request ID | 27 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 96-CM-245 | (n,f) SIG | 0.5 keV-6 MeV | See details | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing 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 Range Initial versus target uncertainties (%) Initial SFR EFR GFR LFR ADMAB 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 ID | 29 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 11-NA-23 | (n,inl) SIG | 0.5 MeV-1.3 MeV | Emis spec. | See details | Y |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fission | Fast Reactors (SFR) | 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 void coefficient for the 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 Range Target versus initial uncertainties (%) Â Initial ABTR SFR EFR
1.35 - 2.23 MeV 13 9 0.498 - 1.35 MeV 28 10 4 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)
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
Validation
Additional file attached:SG26-report.html
Additional file attached:
| Request ID | 32 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 94-PU-239 | (n,g) SIG | 0.1 eV-1.35 MeV | See details | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fission | Fast Reactors (VHTR) | 04-APR-08 | 12-SEP-08 | Y | |
Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr
Project (context): NEA WPEC Subgroup 26
Impact:
Design phases of selected reactor and fuel cycle concepts require improved data and methods in order to reduce margins for both economical and safety reasons. A first indicative nuclear data target accuracy assessment was made within WPEC Subgroup 26 (SG-26). The assessment indicated a list of nuclear data priorities for each of the systems considered (ABTR, SFR, EPR, GFR, LFR, ADMAB, VHTR, EPR). These nuclear data priorities should all be addressed to meet target accuracy requirements for the integral parameters characterizing those systems (see the accompanying requests originating from SG-26).
Requested accuracy is required to meet target accuracy for k-eff for all fast reactors and the VHTR. Requirements become more stringent when inelastic cross sections would be allowed less stringent target accuracies (eg for inelastic of 243Am, 238U, but also 239Pu) Details are provided in the OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).
Accuracy:
Energy Range Initial versus target uncertainties (%)  Initial ABTR SFR EFR GFR LFR ADMAB VHTR   λ=1 λ≠1,a λ≠1,b λ=1 λ≠1,a λ≠1,b λ=1 λ≠1,a λ=1 λ≠1,a λ=1 λ≠1,a λ=1 λ≠1,a λ=1 λ≠1,a
0.498 - 1.35 MeV 18 10 7 5 11 8 7 7 5 7 5 7 5 183 - 498 keV 12 6 4 3 7 5 4 5 4 4 3 5 4 67.4 - 183 keV 9 5 4 3 6 4 4 5 3 6 4 4 3 5 3 24.8 - 67.4 keV 10 6 4 3 7 5 4 5 4 5 4 5 3 5 4 9.12 - 24.8 keV 7 6 4 3 6 4 4 5 3 4 3 5 3 5 3 2.03 - 9.12 keV 16 7 5 4 7 5 4 4 3 3 2 6 4 4 3 0.10 - 0.54 eV 1.4 0.8 0.7
Justification document:
OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).
Comment from requester:
Given the present state of knowledge the above target accuracies are very tight. However, any attempt that significantly contributes to reducing the present accuracy for this quantity is strongly encouraged. Any such attempt will significantly enhance the accuracy with which reactor integral parameters may be estimated and will therefore impact economic and safety margins.
Review comment:
See appendix A of the attached report.
Entry Status:
Work in progress (as of SG-C review of May 2018)
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
Theory/Evaluation
Validation
Additional file attached:SG26-report.html
Additional file attached:
| Request ID | 33 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 94-PU-241 | (n,g) SIG | 0.1 eV-1.35 MeV | See details | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fission | Fast Reactors (VHTR) | 04-APR-08 | 12-SEP-08 | Y | |
Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr
Project (context): NEA WPEC Subgroup 26
Impact:
Design phases of selected reactor and fuel cycle concepts require improved data and methods in order to reduce margins for both economical and safety reasons. A first indicative nuclear data target accuracy assessment was made within WPEC Subgroup 26 (SG-26). The assessment indicated a list of nuclear data priorities for each of the systems considered (ABTR, SFR, EPR, GFR, LFR, ADMAB, VHTR, EPR). These nuclear data priorities should all be addressed to meet target accuracy requirements for the integral parameters characterizing those systems (see the accompanying requests originating from SG-26).
Requested accuracy is required to meet target accuracies for keff and burnup for the Very High Temperature Reactor (VHTR). Details are provided in the OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).
Accuracy:
Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties. The weighting factor λ is explained in detail in the accompanying document. Changes from the reference value of λ=1 show the the possible allowance for other target uncertainties. Two cases (A and B) are distinguished for λ≠1 (see Table 24 of the report).
Energy Range Initial versus target uncertainties (%)  Initial SFR ADMAB VHTR PWR   λ=1 λ≠1,a λ≠1,b λ=1 λ=1 λ≠1,a λ=1 λ≠1,a
0.498 - 1.35 MeV 32 14 15 13 8 183 - 498 keV 21 11 11 10 7 0.10 - 0.54 eV 7 2 3 3 4
Justification document:
OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).
Comment from requester:
Given the present state of knowledge the above target accuracies are very tight. However, any attempt that significantly contributes to reducing the present accuracy for this quantity is strongly encouraged. Any such attempt will significantly enhance the accuracy with which reactor integral parameters may be estimated and will therefore impact economic and safety margins.
Review comment:
See appendix A of the attached report.
Entry Status:
Work in progress (as of SG-C review of May 2018)
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Theory/Evaluation
Validation
Additional file attached:SG26-report.html
Additional file attached:
| Request ID | 34 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 26-FE-56 | (n,inl) SIG | 0.5 MeV-20 MeV | Emis spec. | See details | Y |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fission | ADMAB and SFR | 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).
Somewhat different requested accuracy is required to meet target accuracies for keff, peak power and void coefficient for the Accelerator-Driven Minor Actinides Burner (ADMAB) and for keff for the 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. The weighting factor λ is explained in detail in the accompanying document. Changes from the reference value of λ=1 show the the possible allowance for other target uncertainties. Two cases (A and B) are distinguished for λ≠1 (see Table 24 of the report).
Energy Range Initial versus target uncertainties (%) Initial ABTR SFR EFR LFR ADMAB 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
6.07 - 19.6 MeV 13 9 11 13 2.23 - 6.07 MeV 7 4 5 7 3 3 1.35 - 2.23 MeV 25 6 7 10 3 4 7 7 7 4 6 2 2 0.498 - 1.35 MeV 16 8 9 13 3 4 6 8 9 4 5 2 2
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:
Experimental work was recently completed at IRMM. The impact of the new experimental results is studied at CEA/Cadarache. Uncertainties below 5% will require a major further improvement.
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 ID | 35 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 94-PU-241 | (n,f) SIG | 0.5 eV-1.35 MeV | See details | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing 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 Range Initial versus target uncertainties (%) Initial ABTR SFR EFR GFR LFR ADMAB VHTR EPR 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
Validation
Additional file attached:SG26-report.html
Additional file attached:
| Request ID | 36 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 92-U-238 | (n,g) SIG | 20 eV-25 keV | See details | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fission | Fast and Thermal Reactors | 15-SEP-08 | 15-SEP-08 | ||
Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr
Project (context): CEA Cadarache
Impact:
Design phases of selected reactor and fuel cycle concepts require improved data and methods in order to reduce margins for both economical and safety reasons. A first indicative nuclear data target accuracy assessment was made within WPEC Subgroup 26 (SG-26). The assessment indicated a list of nuclear data priorities for each of the systems considered (ABTR, SFR, EPR, GFR, LFR, ADMAB, VHTR, EPR). These nuclear data priorities should all be addressed to meet target accuracy requirements for the integral parameters characterizing those systems (see the accompanying requests originating from SG-26).
Accuracy:
Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties. The weighting factor λ is explained in detail in the accompanying document. Changes from the reference value of λ=1 show the the possible allowance for other target uncertainties. Two cases (A and B) are distinguished for λ≠1 (see Table 24 of the report).
Energy Range Initial versus target uncertainties (%) Initial ABTR SFR EFR GFR LFR VHTR EPR λ=1 λ≠1,a λ≠1,b λ=1 λ≠1,a λ≠1,b λ=1 λ≠1,a λ=1 λ≠1,a λ=1 λ≠1,a λ=1 λ≠1,a λ=1 λ≠1,a
9.12 - 24.8 keV 9 3 2 2 4 3 3 3 2 2 1 2 2 5 4 2.03 - 9.12 keV 3 1 1 22.6 - 454 eV 2 1 1 1 1
Justification document:
1. OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).
2. OECD/NEA WPEC Subgroup 7 (SG-7) Final Report: "Nuclear data standards" (link to WPEC Subgroup 7 Report in PDF format, 450kb).
Comment from requester:
Given the present state of knowledge the above target accuracies are very tight. However, any attempt that significantly contributes to reducing the present accuracy for this quantity is strongly encouraged. Any such attempt will significantly enhance the accuracy with which reactor integral parameters may be estimated and will therefore impact economic and safety margins.
Review comment:
In this particular case high accuracy is required throughout the energy range. Only the groups shown above have initial uncertainties larger than the target uncertainties. The low initial uncertainty is a result of the standards evaluation (see SG-7 report above). Concerns have been raised that despite the excellent efforts of this subgroup an independent check is in order to verify the present view on required corrections to experimental work for the unresolved resonance range.
Entry Status:
Completed (as of SG-C review of May 2018) - New time-of-flight measurements have been performed worldwide, e.g., at LANSCE [Ullmann:2014], JRC-Geel [Kim:2016] and n_TOF [Mingrone:2017;Wright:2017]. These experimental data have been used in the CIELO evaluation [Sirakov:2017,Capote:2018] and for the evaluation of the standards [Carlson:2018]. The CIELO evaluated data have been adopted in ENDF/B-VIII.0 and JEFF-3.3; the evaluated uncertainties match the requested accuracy.
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
Theory/Evaluation
Validation
Additional file attached:SG26-report.html
Additional file attached:
| Request ID | 37 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 94-PU-240 | (n,f) SIG | 0.5 keV-5 MeV | See details | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing 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 Range Initial versus target uncertainties (%) Initial SFR EFR GFR LFR ADMAB 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
Theory/Evaluation
Validation
Additional file attached:SG26-report.html
Additional file attached:
| Request ID | 38 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 94-PU-240 | (n,f) nubar | 200 keV-2 MeV | See details | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing 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 Range Initial versus target uncertainties (%) Initial SFR EFR GFR LFR ADMAB 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
Validation
Additional file attached:SG26-report.html
Additional file attached:
| Request ID | 39 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 94-PU-242 | (n,f) SIG | 200 keV-20 MeV | See details | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing 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 Range Initial versus target uncertainties (%) Initial SFR EFR GFR LFR ADMAB 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
Validation
Additional file attached:SG26-report.html
Additional file attached:
| Request ID | 40 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 14-SI-28 | (n,inl) SIG | 1.4 MeV-6 MeV | See details | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fission | Fast Reactors | 15-SEP-08 | 15-SEP-08 | ||
Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr
Project (context): CEA Cadarache
Impact:
Design phases of selected reactor and fuel cycle concepts require improved data and methods in order to reduce margins for both economical and safety reasons. A first indicative nuclear data target accuracy assessment was made within WPEC Subgroup 26 (SG-26). The assessment indicated a list of nuclear data priorities for each of the systems considered (ABTR, SFR, EPR, GFR, LFR, ADMAB, VHTR, EPR). These nuclear data priorities should all be addressed to meet target accuracy requirements for the integral parameters characterizing those systems (see the accompanying requests originating from SG-26).
This request is specific to the gas-cooled fast reactor.
Accuracy:
Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties. The weighting factor λ is explained in detail in the accompanying document. Changes from the reference value of λ=1 show the the possible allowance for other target uncertainties. Two cases (A and B) are distinguished for λ≠1 (see Table 24 of the report).
Energy Range Initial versus target uncertainties (%) Initial GFR λ=1 λ≠1,a
2.23 - 6.07 MeV 14 3 4 1.35 - 2.23 MeV 50 6 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:
Completed (as of SG-C review of May 2018) - The measurement performed at JRC-Geel [Negret:2013] and the latest evaluations (JEFF-3.3, ENDF/B-VIII.0) all match the requested accuracy.
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
Theory/Evaluation
Additional file attached:SG26-report.html
Additional file attached:
| Request ID | 41 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 82-PB-206 | (n,inl) SIG | 0.5 MeV-6 MeV | See details | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing 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).
This request is specific to the SFR and ADMAB lead-cooled systems.
Accuracy:
Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties. The weighting factor λ is explained in detail in the accompanying document. Changes from the reference value of λ=1 show the the possible allowance for other target uncertainties. Two cases (A and B) are distinguished for λ≠1 (see Table 24 of the report).
Energy Range Initial versus target uncertainties (%)  Initial LFR ADMAB   λ=1 λ≠1,a λ=1 λ≠1,a
6.07 - 19.6 MeV 18 7 9 2.23 - 6.07 MeV 5 3 4 1.35 - 2.23 MeV 14 5 7 0.498- 1.35 MeV 11 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:
Data have been taken at IRMM for using the (n,n’g)-technique. Experimental results have been included in a new evaluation. The experimental uncertainties are better than 5% in most of the energy range of interest and therefore the request is nearly met. Complementary data for the neutron emission spectrum (angular distribution) would be of interest.
Entry Status:
Pending new evaluation or validation (as of SG-C review of May 2018)
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
Theory/Evaluation
Additional file attached:SG26-report.html
Additional file attached:
| Request ID | 42 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 82-PB-207 | (n,inl) SIG | 0.5 MeV-6 MeV | See details | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing 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).
This request is specific to the SFR and ADMAB lead-cooled systems.
Accuracy:
Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties. The weighting factor λ is explained in detail in the accompanying document. Changes from the reference value of λ=1 show the the possible allowance for other target uncertainties. Two cases (A and B) are distinguished for λ≠1 (see Table 24 of the report).
Energy Range Initial versus target uncertainties (%)  Initial LFR ADMAB   λ=1 λ≠1,a λ=1 λ≠1,a
6.07 - 19.6 MeV 18 7 9 2.23 - 6.07 MeV 5 3 4 1.35 - 2.23 MeV 14 5 7 0.498- 1.35 MeV 11 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:
Data have been taken at IRMM for using the (n,n’g)-technique. Experimental results have been included in a new evaluation. The experimental uncertainties are better than 5% in most of the energy range of interest and therefore the request is nearly met. Complementary data for the neutron emission spectrum (angular distribution) would be of interest.
Entry Status:
Pending new evaluation or validation (as of SG-C review of May 2018)
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
Theory/Evaluation
Additional file attached:SG26-report.html
Additional file attached:
| Request ID | 44 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 93-NP-237 | (n,f) SIG | 200 keV-20 MeV | 2-3 | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing 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:
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:
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
Validation
Additional file attached:1-s2.0-S0306454906000296-main.pdf
Additional file attached:
| Request ID | 45 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 19-K-39 | (n,p),(n,np) SIG | 10 MeV-20 MeV | 10 | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fusion | 17-MAY-17 | 11-JUL-17 | Y | ||
Requester: Dr Stanislav SIMAKOV at KARLSRUHE, GER
Email: stanislav.simakov@partner.kit.edu
Project (context): IFMIF and DONES material test facilities, and fusion power plants
Impact:
The 39K(n,p) reaction produces 39Ar with decay half-life of 269 years and makes the dominant contribution to the long-lived radioactive inventories in NaK. The latter is considered as a coolant of specimens in the accelerator driven irradiation facilities that are designed now for the fusion material testing (IFMIF [1], DONES [2] ...). Together with the competing reaction 39K(n,np)38Ar they also determine the total amount of Argon gas which impact on the thermal and mechanical properties of sealed specimens containers [3].
The current poor knowledge of these two reactions questions whether NaK could be used in the IFMIF and DONES design. Additionally, since potassium is present in cement and concrete, the 39K(n,p)39Ar reaction impacts on the long-term radioprotection and shielding issues in IFMIF/DONES testing vaults and future fusion power plants.
Accuracy:
The continuous Argon gas leakage through cracks in the welding of sealed containers or their accidental rupture is a complex process. Because of this complexity, the sensitivity analyses quantifying the required accuracy of the cross sections have never been done. However, considering the potentially high impact and the poor knowledge of these cross sections, a request for 10% accuracy is a reasonable requirement that will be practically achievable by utilizing the current techniques. This requirement is supported by the fusion and general nuclear data users.
Justification document:
At 14 MeV neutron energy 3 measurements by proton spectroscopy and activation [4-6] reported 3 times larger value for 39K(n,p)39Ar reaction cross section than measurement by AMS [7]. For competing reaction 39K(n,np)38Ar the situation is vice versa. See Ref. [3] for more information.
The main evaluated libraries are similarly discrepant depending on which experiment they follow.
The new measurement is needed first at 14 MeV to resolve this contradiction.
References
Comment from requester:
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
Additional file attached:effdoc-1318.pdf
Additional file attached:
| Request ID | 97 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 24-CR-50 | (n,g) SIG | 1 keV-100 keV | 8-10 | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fission | 20-JAN-18 | 05-FEB-18 | Y | ||
Requester: Dr Roberto CAPOTE NOY at IAEA, AUT
Email: roberto.capotenoy@iaea.org
Project (context):
Impact:
Neutron absorption in the Cr isotopes of structural materials affects the criticality of fast reactor assemblies [Koscheev2017]. These cross sections are also of interest for stellar nucleosynthesis [Kadonis10].
Accuracy:
8-10% in average cross-sections and calculated MACS at 10, 30, 100 keV.
Selected criticality benchmarks with large amounts of Cr (e.g., PU-MET-INTER-002, and HEU-COMP-INTER-005/4=KBR-15/Cr) show large criticality changes of the order of 1000 pcm due to 30% change in Cr-53 capture in the region from 1 keV up to 100 keV [Trkov2018]. On the other side different evaluations (e.g., BROND-3.1, ENDF/B-VII.1, ENDF/B-VIII.0 and JEFF-3.3) for Cr-53(n,g) are discrepant by 30% in the same energy region. For Cr-50, evaluated files show better agreement at those energies but they are lower than Mughabghab evaluation of the resonance integral by 35%. These discrepancies are not reflected in estimated uncertainty of the evaluated files (e.g., JEFF-3.3 uncertainty is around 10% which is inconsistent with the observed spread in evaluations). Due to these differences we request new capture data with 8-10% uncertainty to discriminate between different evaluations and improve the C/E for benchmarks containing Chromium and/or SS.
Justification document:
Criticality benchmarks can test different components of stainless steel (SS), including Cr which is a large component of some SS. Currently, a large part of the uncertainty in SS capture seems to be driven by uncertainty in Cr capture [Koscheev2017]. Indeed, some benchmarks highly sensitive to Cr (as a component of SS) indicate a need for much higher capture in Cr for both Pu and U fueled critical assemblies (e.g., HEU-COMP-INTER-005/4=KBR-15/Cr and PU-MET-INTER-002=ZPR-6/10).
Capture in natural Cr is driven by capture on Cr-50 and especially in odd Cr-53.
For Cr-53(n,g) there is a very large spread in MACS(30) values in different libraries compared to recommended KADoNiS 1.0 [Kadonis10] value of 41 +/- 10 mb (the latter is 25% larger). Existing measurements from the 70s are even larger being close to 60 mb with 30% uncertainty.
Note also discrepancies in resonance integrals (in barns) between evaluated libraries and ATLAS [Mughabghab2006] for both Cr-50(n,g) and Cr-53(n,g)
| Reaction | ENDF/B-VII.1 | BROND-3.1 | ATLAS 2006 |
|---|---|---|---|
| Cr-50(n,g) | 7.21 | 7.21 | 11.7 +/- 0.2 |
| Cr-53(n,g) | 8.42 | 11.2 | 12.3 |
Finally, the re-evaluation for ENDF/B-VIII.0 of the ORNL TOF measurement on enriched Cr-53 target [Guber2011] contradicts the increase suggested in Ref. [Koscheev2017] where preliminary data have been used.
Such contradictions need to be resolved thanks to new measurements and evaluation.
References
Comment from requester:
- Cr-50(n,g) may be measured by activation or TOF. An accurate activation measurement at 5 and 25 keV may help in solving the puzzle of Cr capture.
- Cr-53(n,g) can only be measured by TOF. There is no publication of the final analysis of the ORNL TOF measurement using enriched Cr-53 sample.
- Lead Slowing Down Spectrometer (LSDS) measurements of Cr-50, Cr-53 and Cr-52 enriched samples and of Cr-nat sample could be extremely important to validate and select a proper evaluation of Cr capture cross section below 100 keV. These measurements are strongly encouraged as complementary to TOF and feasible activation measurements.
Review comment:
Entry Status:
Work in progress (as of SG-C review of May 2018)
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
Theory/Evaluation
Validation
Additional file attached:Trkov2018.pdf
Additional file attached:
| Request ID | 98 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 24-CR-53 | (n,g) SIG | 1 keV-100 keV | 8-10 | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fission | 20-JAN-18 | 05-FEB-18 | Y | ||
Requester: Dr Roberto CAPOTE NOY at IAEA, AUT
Email: roberto.capotenoy@iaea.org
Project (context):
Impact:
Neutron absorption in the Cr isotopes of structural materials affects the criticality of fast reactor assemblies [Koscheev2017]. These cross sections are also of interest for stellar nucleosynthesis [Kadonis10].
Accuracy:
8-10% in average cross-sections and calculated MACS at 10, 30, 100 keV.
Selected criticality benchmarks with large amounts of Cr (e.g., PU-MET-INTER-002, and HEU-COMP-INTER-005/4=KBR-15/Cr) show large criticality changes of the order of 1000 pcm due to 30% change in Cr-53 capture in the region from 1 keV up to 100 keV [Trkov2018]. On the other side different evaluations (e.g., BROND-3.1, ENDF/B-VII.1, ENDF/B-VIII.0 and JEFF-3.3) for Cr-53(n,g) are discrepant by 30% in the same energy region. For Cr-50, evaluated files show better agreement at those energies but they are lower than Mughabghab evaluation of the resonance integral by 35%. These discrepancies are not reflected in estimated uncertainty of the evaluated files (e.g., JEFF-3.3 uncertainty is around 10% which is inconsistent with the observed spread in evaluations). Due to these differences we request new capture data with 8-10% uncertainty to discriminate between different evaluations and improve the C/E for benchmarks containing Chromium and/or SS.
Justification document:
Criticality benchmarks can test different components of stainless steel (SS), including Cr which is a large component of some SS. Currently, a large part of the uncertainty in SS capture seems to be driven by uncertainty in Cr capture [Koscheev2017]. Indeed, some benchmarks highly sensitive to Cr (as a component of SS) indicate a need for much higher capture in Cr for both Pu and U fueled critical assemblies (e.g., HEU-COMP-INTER-005/4=KBR-15/Cr and PU-MET-INTER-002=ZPR-6/10).
Capture in natural Cr is driven by capture on Cr-50 and especially in odd Cr-53.
For Cr-53(n,g) there is a very large spread in MACS(30) values in different libraries compared to recommended KADoNiS 1.0 [Kadonis10] value of 41 +/- 10 mb (the latter is 25% larger). Existing measurements from the 70s are even larger being close to 60 mb with 30% uncertainty.
Note also discrepancies in resonance integrals (in barns) between evaluated libraries and ATLAS [Mughabghab2006] for both Cr-50(n,g) and Cr-53(n,g)
| Reaction | ENDF/B-VII.1 | BROND-3.1 | ATLAS 2006 |
|---|---|---|---|
| Cr-50(n,g) | 7.21 | 7.21 | 11.7 +/- 0.2 |
| Cr-53(n,g) | 8.42 | 11.2 | 12.3 |
Finally, the re-evaluation for ENDF/B-VIII.0 of the ORNL TOF measurement on enriched Cr-53 target [Guber2011] contradicts the increase suggested in Ref. [Koscheev2017] where preliminary data have been used.
Such contradictions need to be resolved thanks to new measurements and evaluation.
References
Comment from requester:
- Cr-50(n,g) may be measured by activation or TOF. An accurate activation measurement at 5 and 25 keV may help in solving the puzzle of Cr capture.
- Cr-53(n,g) can only be measured by TOF. There is no publication of the final analysis of the ORNL TOF measurement using enriched Cr-53 sample.
- Lead Slowing Down Spectrometer (LSDS) measurements of Cr-50, Cr-53 and Cr-52 enriched samples and of Cr-nat sample could be extremely important to validate and select a proper evaluation of Cr capture cross section below 100 keV. These measurements are strongly encouraged as complementary to TOF and feasible activation measurements.
Review comment:
Entry Status:
Work in progress (as of SG-C review of May 2018)
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
Theory/Evaluation
Validation
Additional file attached:Trkov2018.pdf
Additional file attached:
| Request ID | 99 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 94-PU-239 | (n,f) nubar | Thermal-5 eV | 1 | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing 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
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
Theory/Evaluation
Additional file attached:
Additional file attached:
| Request ID | 102 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 64-GD-155 | (n,g),(n,tot) SIG | Thermal-100 eV | 4 | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fission | LWR | 07-FEB-18 | 09-MAY-18 | Y | |
Requester: Mr Cristian MASSIMI at UBOLOGNA, ITY
Email: cristian.massimi@unibo.it
Project (context):
Impact:
In nuclear industry gadolinium is used as neutron absorber having the highest thermal absorption cross section among all stable elements thanks to Gd-155 and especially Gd-157 isotopes. It is commonly used, in PWR or BWR, as burnable absorber in fresh fuel to compensate an excess of reactivity or as emergency shutdown poison in CANDU reactors. RPI measurements of the Gd-157 thermal capture cross-section [1] differ by 10% from the ENDF/B-VI.8 value and, thus, in ENDF/B-VII.1 [2] the low energy cross section uncertainty was increased by up to a factor 2, i.e. from about 2-4% to 4-6%. There is no significant change in the latest ENDF/B-VIII.0 evaluation of these two isotopes. A sensitivity and uncertainty analysis was performed by ENEA to quantify the maximum impact of the uncertainty of the gadolinium isotopes cross sections on the criticality of a LWR system [3-5]. It showed that, in systems with a high number of gadolinium fuel pins, neutron capture of odd gadolinium isotopes contribution to keff uncertainty ranks high, just after the major U-235 and U-238 contributions.
Accuracy:
Sensitivity and uncertainty analyses show that keeping the cross section uncertainty below 4% mitigates the impact on keff uncertainty at high-burnup, which is important for a good estimation of the residual reactivity penalty of a fuel assembly at the end of life.
Justification document:
Despite their importance, the capture cross sections of the odd Gd isotopes have not been extensively studied and are not known with the accuracy required by present-day nuclear industry. In the thermal energy range these cross sections contribute more than 99% to the total cross section. Complementary accurate transmission measurements are also required to constrain the capture cross section. Table 1 in Ref. [4] illustrates current discrepancies for 157Gd capture cross-section at thermal energy. Such contradictions should be clarified thanks to new measurements and evaluation.
References
Comment from requester:
Beyond nuclear industry, nuclear astrophysics can benefit from the accurate knowledge of 155- and 157-Gd(n,g) cross section up to a few keV, as the even-Gd isotopes play an important role in the s-process nucleosynthesis. Therefore a consistent analysis of all Gd-nat isotopes from thermal up to a few keV is of high interest for both astrophysics and nuclear data evaluation purpose.
Review comment:
Entry Status:
Pending new evaluation or validation (as of SG-C review of May 2018)
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
Theory/Evaluation
Validation
Additional file attached:ENEA_RdS_PAR2015_078.pdf
Additional file attached:jefdoc-1835.pdf
| Request ID | 103 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 64-GD-157 | (n,g),(n,tot) SIG | Thermal-100 eV | 4 | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fission | LWR | 07-FEB-18 | 09-MAY-18 | Y | |
Requester: Mr Cristian MASSIMI at UBOLOGNA, ITY
Email: cristian.massimi@unibo.it
Project (context):
Impact:
In nuclear industry gadolinium is used as neutron absorber having the highest thermal absorption cross section among all stable elements thanks to Gd-155 and especially Gd-157 isotopes. It is commonly used, in PWR or BWR, as burnable absorber in fresh fuel to compensate an excess of reactivity or as emergency shutdown poison in CANDU reactors. RPI measurements of the Gd-157 thermal capture cross-section [1] differ by 10% from the ENDF/B-VI.8 value and, thus, in ENDF/B-VII.1 [2] the low energy cross section uncertainty was increased by up to a factor 2, i.e. from about 2-4% to 4-6%. There is no significant change in the latest ENDF/B-VIII.0 evaluation of these two isotopes. A sensitivity and uncertainty analysis was performed by ENEA to quantify the maximum impact of the uncertainty of the gadolinium isotopes cross sections on the criticality of a LWR system [3-5]. It showed that, in systems with a high number of gadolinium fuel pins, neutron capture of odd gadolinium isotopes contribution to keff uncertainty ranks high, just after the major U-235 and U-238 contributions.
Accuracy:
Sensitivity and uncertainty analyses show that keeping the cross section uncertainty below 4% mitigates the impact on keff uncertainty at high-burnup, which is important for a good estimation of the residual reactivity penalty of a fuel assembly at the end of life.
Justification document:
Despite their importance, the capture cross sections of the odd Gd isotopes have not been extensively studied and are not known with the accuracy required by present-day nuclear industry. In the thermal energy range these cross sections contribute more than 99% to the total cross section. Complementary accurate transmission measurements are also required to constrain the capture cross section. Table 1 in Ref. [4] illustrates current discrepancies for 157Gd capture cross-section at thermal energy. Such contradictions should be clarified thanks to new measurements and evaluation.
References
Comment from requester:
Beyond nuclear industry, nuclear astrophysics can benefit from the accurate knowledge of 155- and 157-Gd(n,g) cross section up to a few keV, as the even-Gd isotopes play an important role in the s-process nucleosynthesis. Therefore a consistent analysis of all Gd-nat isotopes from thermal up to a few keV is of high interest for both astrophysics and nuclear data evaluation purpose.
Review comment:
Entry Status:
Pending new evaluation or validation (as of SG-C review of May 2018)
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
Theory/Evaluation
Validation
Additional file attached:ENEA_RdS_PAR2015_078.pdf
Additional file attached:jefdoc-1835.pdf
| Request ID | 114 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 83-BI-209 | (n,g)Bi-210g,m BR | 500 eV-300 keV | 10 | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| ADS,Fission | 26-OCT-18 | 09-NOV-18 | Y | ||
Requester: Dr Alexey STANKOVSKIY at SCK-CEN, BLG
Email: alexey.stankovskiy@sckcen.be
Project (context): MYRRHA and Gen-IV reactors with lead-bismuth coolants
Impact:
Polonium-210, a rather short-lived alpha emitter (half-life 138.4 days), determines the radiological burden associated with the use of lead-bismuth heavy metal coolants of fast reactors, MYRRHA accelerator-driven system currently designed at SCK•CEN, Belgium is one of the examples. It is produced via neutron capture on 209Bi forming the ground state of 210Bi (half-live 5 days) which rapidly decays into 210Po. 210Bi has also long-lived (3 My) metastable state that can also be produced via neutron capture and that decays to 206Tl. Thus the knowledge of branching ratio between these two neutron capture channels is important to accurately predict the inventory of Polonium-210.
Accuracy:
10% on the capture cross sections both to ground and metastable states of 210Bi.
The analysis performed in [Fiorito2018] reveals high sensitivity of 210Po production to the neutron capture cross section at first (801.6 eV) and neighbouring resonances up to 10 keV, as well as to the data around 100-300 keV where the neutron spectrum is peaked. The spread in prediction of 210Po concentration between nuclear data libraries reaches 40% while the propagation of existing covariance data for the capture cross section results in uncertainties between 5 and 20%. Furthermore, the covariance data on the branching ratio are not provided in the evaluated data files although they are likely to contribute significantly to the final 210Po concentration uncertainty.
Justification document:
Significant differences between evaluations were observed in the neutron capture cross section and branching ratio, which were proved to pose a severe constraint for the correct 210Po content prediction in MYRRHA and other lead-bismuth cooled reactor concepts. The covariance matrices found in the 209Bi evaluations result in different uncertainty profiles and energy correlations. The 210Po concentration uncertainty (intended as one standard deviation) after one irradiation cycle of MYRRHA is ranging between 5% and 20%. This level of uncertainty does not cover the deviation between 210Po concentration values assessed with the evaluated files coming from different libraries, even when three standard deviations are considered. Furthermore, branching ratio covariances were not propagated since they are not provided in the evaluated files, although they are likely to add a significant uncertainty contribution to the polonium content.
Significant efforts are necessary to reduce the discrepancies between evaluated data. In particular, accurate measurements should be carried out to obtain the reliable branching ratio not only at thermal energies and for the first resonance at about 800 eV, but also in the energy ranges of interest for lead-bismuth-cooled reactors such as MYRRHA, as made clear by the sensitivity plots in [Fiorito2018].
Because of the disagreement between libraries, a consistent evaluation for the branching ratios should be elaborated that also includes the energy-dependent behaviour in the resonance region and above. Although the BROND-3.1 [Blokhin2016] evaluation seems providing most accurate branching ratio among evaluated libraries, it also relies only on few experimental energy points [Saito2003, Saito2004, Borella2008, Borella2011] in the range 800 eV – 10 keV. The future evaluation thus should be supported by additional experimental measurements.
References
Comment from requester:
Review comment:
In addition to 209Bi(n,g) branching ratio or activation measurements, complementary transmission measurements may be needed to fix the resonance parameters in the re-evaluation of the 209Bi capture cross section. Moreover, integral benchmarks dedicated to 209Bi activation/cooling in representative spectra are required to better assess the performance of evaluated data.
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
Experiments
Additional file attached:
Additional file attached:
| Request ID | 115 | Type of the request | High Priority request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 94-PU-239 | (n,tot) SIG | Thermal-5 eV | 1 | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing 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
Additional file attached:HPRL_Request_Pu239_ntot_1stRes.png
Additional file attached:
