Request ID2 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 8-O-16 (n,a),(n,abs) SIG  2 MeV-20 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing 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.

Comments from evaluator/experimentalist:
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.

Comments for achieved accuracy:
The achieved accuracy is estimated to be 30%.

Review comment:
The request is well motivated and the response for follow-up is very encouraging.

Additional file attached:SG26-report.html
Additional file attached:Need for O16(n,alpha).pdf



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

Requester: Prof. Gerald RIMPAULT at CADARACHE, FR
Email: gerald.rimpault@cea.fr

Project (context): JEFF, NEA WPEC Subgroup 27

Impact:
The four fast reactor systems of GenIV feature innovative core characteristics for which gamma-ray heating estimates for non-fuel zones require an uncertainty of 7.5% [1]. For the experimental Jules Horowitz Reactor (RJH) at Cadarache a similar requirement appears [2]. Recent studies show evidence of discrepancies on integral measurement in MASURCA, EOLE and MINERVE, from which it is clear that the expectations for GenIV systems and the RJH thermal reactor are not met [3]. Gamma-ray energy release is dominated by Pu-239 and U-235.

Accuracy:
7.5% on the total gamma energy. 7.5% on the multiplicity.
Best accuracy achievable for the gamma spectrum shape.

Justification document:
Reference 1: G. Rimpault, Proc. Workshop on Nuclear Data Needs for Generation IV, April 2005, Antwerp, Belgium
Reference 2: D. Blanchet, Proc. M&C 2005, Int. Topical Meeting on Mathematics and Computation, Supercomputing, Reactor Physics and Nuclear and Biological Applications, Sep. 2005, Avignon, France
Reference 3: 'Needs for accurate measurements of spectrum and multiplicity of prompt gammas emitted in fission', G. Rimpault, A. Courcelle and D. Blanchet, CEA/Cadarache - DEN/DER/SPRC.

Comment from requester:
Forty percent of the total gamma-ray energy release results from prompt decay of fission products. No comprehensive analytic expressions exist and Hauser-Feshbach model calculations are involved and presently lack sufficient knowledge to warrant a solution of the problem. New measurements would be needed to guide new evaluation efforts. Present evaluations are based on measurements from the seventies.

Comments from evaluator/experimentalist:
NEA-WPEC initiated Subgroup 27 "Prompt photon production from fission products" in response to this problem. The subgroup co-ordinator is R. Jacqmin of CEA.

Comments for achieved accuracy:
Discrepancies observed for C/E ratios in various benchmarks range from 10 to 28%.

Review comment:
The request is well motivated and based on a considerable effort.

Additional file attached:HPRLgammafission.pdf
Additional file attached:



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

Requester: Prof. Gerald RIMPAULT at CADARACHE, FR
Email: gerald.rimpault@cea.fr

Project (context): JEFF, NEA WPEC Subgroup 27

Impact:
The four fast reactor systems of GenIV feature innovative core characteristics for which gamma-ray heating estimates for non-fuel zones require an uncertainty of 7.5% [1]. For the experimental Jules Horowitz Reactor (RJH) at Cadarache a similar requirement appears [2]. Recent studies show evidence of discrepancies on integral measurement in MASURCA, EOLE and MINERVE, from which it is clear that the expectations for GenIV systems and the RJH thermal reactor are not met [3]. Gamma-ray energy release is dominated by Pu-239 and U-235.

Accuracy:
7.5% on the total gamma energy
7.5% on multiplicity
Best accuracy achievable for the gamma spectrum shape

Justification document:
Reference 1: G. Rimpault, Proc. Workshop on Nuclear Data Needs for Generation IV, April 2005, Antwerp, Belgium
Reference 2: D. Blanchet, Proc. M&C 2005, Int. Topical Meeting on Mathematics and Computation, Supercomputing, Reactor Physics and Nuclear and Biological Applications, Sep. 2005, Avignon, France
Reference 3: 'Needs for accurate measurements of spectrum and multiplicity of prompt gammas emitted in fission', G. Rimpault, A. Courcelle and D. Blanchet, CEA/Cadarache – DEN/DER/SPRC.

Comment from requester:
Forty percent of the total gamma-ray energy release results from prompt decay of fission products. No comprehensive analytic expressions exist and Hauser-Feshbach model calculations are involved and presently lack sufficient knowledge to warrant a solution of the problem. New measurements would be needed to guide new evaluation efforts. Present evaluations are based on measurements from the seventies.

Comments from evaluator/experimentalist:
NEA-WPEC initiated Subgroup 27 "Prompt photon production from fission products" in response to this problem. The subgroup co-ordinator is R. Jacqmin of CEA.

Comments for achieved accuracy:
Discrepancies observed for C/E ratios in various benchmarks range from 10 to 28%.

Review comment:
The request is well motivated and based on a considerable effort.

Additional file attached:HPRLgammafission.pdf
Additional file attached:



Request ID5 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 72-HF-0 (n,g) SIG  0.5-5.0 keV  4 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing 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 by 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.

Comments from evaluator/experimentalist:
Measurements on natural Hf were carried out by CEA at IRMM in the frame of the NUDAME (http://www.irmm.jrc.be/html/nudame/) transnational access scheme. Further work is planned at IRMM in collaboration with CEA, INRNE, U. Birmingham and Serco.

Comments for achieved accuracy:
Calculations on the AZUR configuration using the JEFF3.1 library give a Hf reactivity worth of about -300 pcm [2].

Review comment:

Additional file attached:JEFDOC-1077.ppt
Additional file attached:NT_Hafnium.pdf



Request ID8 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 1-H-2 (n,el) DA/DE  0.1 MeV-1 MeV 0-180 Deg 5 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Heavy Water Reactors 25-JUL-06 16-APR-07 

Requester: Kenneth KOZIER at CNLCR, CAN
Email: kenneth.kozier@cnl.ca

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.

Comments from evaluator/experimentalist:

Comments for achieved accuracy:

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.

Additional file attached:AECL Final Technical Report.pdf
Additional file attached:Full_paper_152003.pdf



Request ID12 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 92-U-235 (n,g) SIG,RP  100 eV-1 MeV  3 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing 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.
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.)

Accuracy:

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.

Comments from evaluator/experimentalist:

Comments for achieved accuracy:

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.

Additional file attached:U235proposal.pdf
Additional file attached:Viewgraph.U235proposal.pdf



Request ID15 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 95-AM-241 (n,g),(n,tot) SIG  Thermal  See details 
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission LWR, Thermal 08-NOV-07 10-SEP-08 Y

Requester: Mr Tsuneo NAKAGAWA at JAEA, JPN
Email: nakagawa.tsuneo@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 RangeUncertainty (%)
  InitialGFR 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.

Comments from evaluator/experimentalist:
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.

Comments for achieved accuracy:
See accuracy table.

Review comment:

Additional file attached:Yamamoto_T(MOX-LWR)2006.pdf
Additional file attached:



Request ID18 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 92-U-238 (n,inl) SIG  65 keV-20 MeV Emis spec. See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors EFR,SFR,ABTR... 28-MAR-08 11-SEP-08 

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 RangeInitial versus target uncertainties (%)
InitialABTR SFREFRGFRLFR
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.

Comments from evaluator/experimentalist:
See appendix A of the attached report.

Comments for achieved accuracy:
See accuracy table.

Review comment:
This request is of high priority.

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



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

Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr

Project (context): NEA WPEC Subgroup 26

Impact:
Design phases of selected reactor and fuel cycle concepts require improved data and methods in order to reduce margins for both economical and safety reasons. A first indicative nuclear data target accuracy assessment was made within WPEC Subgroup 26 (SG-26). The assessment indicated a list of nuclear data priorities for each of the systems considered (ABTR, SFR, EPR, GFR, LFR, ADMAB, VHTR, EPR). These nuclear data priorities should all be addressed to meet target accuracy requirements for the integral parameters characterizing those systems (see the accompanying requests originating from SG-26).

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

Requested accuracy is required to meet target accuracy for burnup for an Accelerator-Driven Minor Actinides Burner (ADMAB). Details are provided in the SG-26 report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).

Accuracy:
Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties.
Energy RangeInitial versus target uncertainties (%)
InitialSFREFRGFRLFRADMAB
2.23 - 6.07 MeV 21 6 7 8 7
1.35 - 2.23 MeV 34 6 24 8 7 6
0.498 - 1.35 MeV 17 3 10 5 3 3
183 - 498 keV 17 4 12 6 3 4
67.4 - 183 keV 9 5 5
24.8 - 67.4 keV 12 6 7 6
9.12 - 24.8 keV 11 7 7 7

Justification document:
OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).

Comment from requester:
Given the present state of knowledge the above target accuracies are very tight. However, any attempt that significantly contributes to reducing the present accuracy for this quantity is strongly encouraged. Any such attempt will significantly enhance the accuracy with which reactor integral parameters may be estimated and will therefore impact economic and safety margins.

Comments from evaluator/experimentalist:

Comments for achieved accuracy:
See accuracy table

Review comment:

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



Request ID21 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 95-AM-241 (n,f) SIG  180 keV-20 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors (ADMAB) 31-MAR-08 11-SEP-08 Y

Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr

Project (context): NEA WPEC Subgroup 26

Impact:
Design phases of selected reactor and fuel cycle concepts require improved data and methods in order to reduce margins for both economical and safety reasons. A first indicative nuclear data target accuracy assessment was made within WPEC Subgroup 26 (SG-26). The assessment indicated a list of nuclear data priorities for each of the systems considered (ABTR, SFR, EPR, GFR, LFR, ADMAB, VHTR, EPR). These nuclear data priorities should all be addressed to meet target accuracy requirements for the integral parameters characterizing those systems (see the accompanying requests originating from SG-26).

The request for improved cross sections and emission spectra and their accuracies for 241Am(n,f) emerges for four of the eight cases studied. The most stringent requirements for this case arises for the ADMAB, while for the SFR and LFR the needs are nearly met.

Requested accuracy is required to meet target accuracy for keff for Accelerator-Driven Minor Actinides Burner (ADMAB). Details are provided in the OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).

Accuracy:
Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties.

Energy RangeInitial versus target uncertainties (%)
  InitialSFR GFRLFRADMAB
6.07 - 19.6 MeV 13 6
2.23 - 6.07 MeV 12 7 3 2
1.35 - 2.23 MeV 10 6 3 1
0.498 - 1.35 MeV 8 6 3 5 1
183 - 498 keV 8 4

Justification document:
OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).

Comment from requester:
SFR: Sodium-cooled Fast Reactor in a TRU burning configuration, i.e., with a Conversion Ratio CR<1
EFR: European Fast Reactor with full recycling of MA and CR~1
GFR: Gas-cooled Fast Reactor also with full recycling of MA
LFR: Lead-cooled Fast Reactor as defined for an IAEA benchmark
ABTR: Advanced Burner Test Reactor Na-cooled core, recently studied within the GNEP initiative
ADMAB: Accelerator-Driven Minor Actinides Burner
PWR: Pressurized Water Reactor

Comments from evaluator/experimentalist:
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.

Comments for achieved accuracy:
See accuracy table

Review comment:

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



Request ID22 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 95-AM-242 (n,f) SIG  0.5 keV-6 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors (SFR) 31-MAR-08 11-SEP-08 

Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr

Project (context): NEA WPEC Subgroup 26

Impact:
Design phases of selected reactor and fuel cycle concepts require improved data and methods in order to reduce margins for both economical and safety reasons. A first indicative nuclear data target accuracy assessment was made within WPEC Subgroup 26 (SG-26). The assessment indicated a list of nuclear data priorities for each of the systems considered (ABTR, SFR, EPR, GFR, LFR, ADMAB, VHTR, EPR). These nuclear data priorities should all be addressed to meet target accuracy requirements for the integral parameters characterizing those systems (see the accompanying requests originating from SG-26).

Requested accuracy is required to meet target accuracy for keff for Sodium-cooled Fast Reactor in a TRU burning configuration, i.e., with a Conversion Ratio CR<1 (SFR). Details are provided in the OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).

Accuracy:
Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties.

Energy RangeInitial versus target uncertainties (%)
  InitialSFR LFRADMAB
2.23 - 6.07 MeV 23 8
1.35 - 2.23 MeV 20 8
0.498- 1.35 MeV 17 4 6
83 - 498 - keV 17 3 8 5
67.4 - 183 - keV 17 3 5
24.8 - 67.4 keV 14 4 6
9.12 - 24.8 keV 12 4 6
2.03 - 9.12 keV 12 7
0.454- 2.03 keV 12 5

Justification document:
OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).

Comment from requester:
SFR: Sodium-cooled Fast Reactor in a TRU burning configuration, i.e., with a Conversion Ratio CR<1
EFR: European Fast Reactor with full recycling of MA and CR~1
GFR: Gas-cooled Fast Reactor also with full recycling of MA
LFR: Lead-cooled Fast Reactor as defined for an IAEA benchmark
ABTR: Advanced Burner Test Reactor Na-cooled core, recently studied within the GNEP initiative
ADMAB: Accelerator-Driven Minor Actinides Burner
PWR: Pressurized Water Reactor

Given the present state of knowledge the above target accuracies are very tight. However, any attempt that significantly contributes to reducing the present accuracy for this quantity is strongly encouraged. Any such attempt will significantly enhance the accuracy with which reactor integral parameters may be estimated and will therefore impact economic and safety margins.

Comments from evaluator/experimentalist:

Comments for achieved accuracy:
See accuracy table

Review comment:

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



Request ID25 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 96-CM-244 (n,f) SIG  65 keV-6 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors (ADMAB) 04-APR-08 12-SEP-08 

Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr

Project (context): NEA WPEC Subgroup 26

Impact:
Requested accuracy is required to meet target accuracies for keff, peak power and burnup for the Accelerator-Driven Minor Actinides Burner (ADMAB). Details are provided in the OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (Final Draft attached).

Accuracy:
Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties.

Energy RangeInitial versus target uncertainties (%)
  InitialSFR EFR GFRLFRADMAB
6.07 - 2.23 MeV 31 8 12 3
2.23 - 1.35 MeV 44 8 13 14 3
1.35 - 0.498 MeV 50 5 20 8 6 2
498 - 183 keV 37 12 4
183 - 67.4 keV 48 7

Justification document:
OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).

Comment from requester:
SFR: Sodium-cooled Fast Reactor in a TRU burning configuration, i.e., with a Conversion Ratio CR<1
EFR: European Fast Reactor with full recycling of MA and CR~1
GFR: Gas-cooled Fast Reactor also with full recycling of MA
LFR: Lead-cooled Fast Reactor as defined for an IAEA benchmark
ABTR: Advanced Burner Test Reactor Na-cooled core, recently studied within the GNEP initiative
ADMAB: Accelerator-Driven Minor Actinides Burner
PWR: Pressurized Water Reactor

Comments from evaluator/experimentalist:
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.

Comments for achieved accuracy:
See accuracy table above.

Review comment:

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



Request ID27 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 96-CM-245 (n,f) SIG  0.5 keV-6 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors (ADMAB) 04-APR-08 12-SEP-08 

Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr

Project (context): NEA WPEC Subgroup 26

Impact:
Design phases of selected reactor and fuel cycle concepts require improved data and methods in order to reduce margins for both economical and safety reasons. A first indicative nuclear data target accuracy assessment was made within WPEC Subgroup 26 (SG-26). The assessment indicated a list of nuclear data priorities for each of the systems considered (ABTR, SFR, EPR, GFR, LFR, ADMAB, VHTR, EPR). These nuclear data priorities should all be addressed to meet target accuracy requirements for the integral parameters characterizing those systems (see the accompanying requests originating from SG-26).

Requested accuracy is required to meet target accuracies for keff, peak power and burnup for the Accelerator-Driven Minor Actinides Burner (ADMAB). Details are provided in the OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).

Accuracy:
Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties.

Energy RangeInitial versus target uncertainties (%)
InitialSFREFRGFRLFRADMAB
2.23 - 6.07 MeV 31 7
1.35 - 2.23 MeV 44 14 6
0.498 - 1.35 MeV 49 9 43 16 11 3
183 - 498 keV 37 7 13 7 3
67.4 - 183 keV 48 7 42 11 7 3
24.8 - 67.4 keV 27 9 11 9 3
9.12 - 24.8 keV 14 9 3
2.03 - 9.12 keV 13 4
0.454 - 2.03 keV 13 5

Justification document:
OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).

Comment from requester:
Given the present state of knowledge the above target accuracies are very tight. However, any attempt that significantly contributes to reducing the present accuracy for this quantity is strongly encouraged. Any such attempt will significantly enhance the accuracy with which reactor integral parameters may be estimated and will therefore impact economic and safety margins.

Comments from evaluator/experimentalist:
Work is planned at IRMM for low energies.

Comments for achieved accuracy:
See accuracy table.

Review comment:

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



Request ID29 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 11-NA-23 (n,inl) SIG  0.5 MeV-1.3 MeV Emis spec. See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors (SFR) 04-APR-08 12-SEP-08 

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 RangeTarget versus initial uncertainties (%)
  InitialABTR SFREFR
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.

Comments from evaluator/experimentalist:
Experimental work is planned at IRMM.

Comments for achieved accuracy:

Review comment:

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



Request ID32 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 94-PU-239 (n,g) SIG  0.1 eV-1.35 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors (VHTR) 04-APR-08 12-SEP-08 

Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr

Project (context): NEA WPEC Subgroup 26

Impact:
Design phases of selected reactor and fuel cycle concepts require improved data and methods in order to reduce margins for both economical and safety reasons. A first indicative nuclear data target accuracy assessment was made within WPEC Subgroup 26 (SG-26). The assessment indicated a list of nuclear data priorities for each of the systems considered (ABTR, SFR, EPR, GFR, LFR, ADMAB, VHTR, EPR). These nuclear data priorities should all be addressed to meet target accuracy requirements for the integral parameters characterizing those systems (see the accompanying requests originating from SG-26).

Requested accuracy is required to meet target accuracy for k-eff for all fast reactors and the VHTR. Requirements become more stringent when inelastic cross sections would be allowed less stringent target accuracies (eg for inelastic of 243Am, 238U, but also 239Pu) Details are provided in the OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).

Accuracy:
Energy RangeInitial versus target uncertainties (%)
  InitialABTR SFREFRGFRLFRADMABVHTR
   λ=1 λ≠1,a λ≠1,b λ=1 λ≠1,a λ≠1,b λ=1 λ≠1,a λ=1 λ≠1,a λ=1 λ≠1,a λ=1 λ≠1,a λ=1 λ≠1,a
0.498 - 1.35 MeV 18 10 7 5 11 8 7 7 5 7 5 7 5
183 - 498 keV 12 6 4 3 7 5 4 5 4 4 3 5 4
67.4 - 183 keV 9 5 4 3 6 4 4 5 3 6 4 4 3 5 3
24.8 - 67.4 keV 10 6 4 3 7 5 4 5 4 5 4 5 3 5 4
9.12 - 24.8 keV 7 6 4 3 6 4 4 5 3 4 3 5 3 5 3
2.03 - 9.12 keV 16 7 5 4 7 5 4 4 3 3 2 6 4 4 3
0.10 - 0.54 eV 1.4 0.8 0.7

Justification document:
OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).

Comment from requester:
Given the present state of knowledge the above target accuracies are very tight. However, any attempt that significantly contributes to reducing the present accuracy for this quantity is strongly encouraged. Any such attempt will significantly enhance the accuracy with which reactor integral parameters may be estimated and will therefore impact economic and safety margins.

Comments from evaluator/experimentalist:
See appendix A of the attached report.

Comments for achieved accuracy:
See accuracy table

Review comment:

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



Request ID33 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 94-PU-241 (n,g) SIG  0.1 eV-1.35 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors (VHTR) 04-APR-08 12-SEP-08 

Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr

Project (context): NEA WPEC Subgroup 26

Impact:
Design phases of selected reactor and fuel cycle concepts require improved data and methods in order to reduce margins for both economical and safety reasons. A first indicative nuclear data target accuracy assessment was made within WPEC Subgroup 26 (SG-26). The assessment indicated a list of nuclear data priorities for each of the systems considered (ABTR, SFR, EPR, GFR, LFR, ADMAB, VHTR, EPR). These nuclear data priorities should all be addressed to meet target accuracy requirements for the integral parameters characterizing those systems (see the accompanying requests originating from SG-26).

Requested accuracy is required to meet target accuracies for keff and burnup for the Very High Temperature Reactor (VHTR). Details are provided in the OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).

Accuracy:
Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties. The weighting factor λ is explained in detail in the accompanying document. Changes from the reference value of λ=1 show the the possible allowance for other target uncertainties. Two cases (A and B) are distinguished for λ≠1 (see Table 24 of the report).

Energy RangeInitial versus target uncertainties (%)
  InitialSFR ADMABVHTRPWR
   λ=1 λ≠1,a λ≠1,b λ=1 λ=1 λ≠1,a λ=1 λ≠1,a
0.498 - 1.35 MeV 32 14 15 13 8
183 - 498 keV 21 11 11 10 7
0.10 - 0.54 eV 7 2 3 3 4

Justification document:
OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).

Comment from requester:
Given the present state of knowledge the above target accuracies are very tight. However, any attempt that significantly contributes to reducing the present accuracy for this quantity is strongly encouraged. Any such attempt will significantly enhance the accuracy with which reactor integral parameters may be estimated and will therefore impact economic and safety margins.

Comments from evaluator/experimentalist:
See appendix A of the attached report.

Comments for achieved accuracy:

Review comment:

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



Request ID34 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 26-FE-56 (n,inl) SIG  0.5 MeV-20 MeV Emis spec. See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing 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 RangeInitial versus target uncertainties (%)
InitialABTRSFREFRLFRADMAB
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.

Comments from evaluator/experimentalist:
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.

Comments for achieved accuracy:

Review comment:

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



Request ID35 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 94-PU-241 (n,f) SIG  0.5 eV-1.35 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast and Thermal Reactors 04-APR-08 12-SEP-08 

Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr

Project (context): NEA WPEC Subgroup 26

Impact:
Distinct requests for this fission cross section are made at higher energies for fast reactor applications and also at lower energies for thermal reactor applications. Requested accuracy is required to meet target accuracy for k-eff for the GFR, SFR, LFR and ABTR and to meet k-eff and burnup for EFR. Requested accuracy is also required to meet target accuracy for k-eff for the VHTR and k-eff and burnup for the PWR. Details are provided in the OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (Final Draft attached).

Accuracy:
Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties. The weighting factor λ is explained in detail in the accompanying document. Changes from the reference value of λ=1 show the the possible allowance for other target uncertainties. Two cases (A and B) are distinguished for λ≠1 (see Table 24 of the report).

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

Justification document:
OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).

Comment from requester:
Given the present state of knowledge the above target accuracies are very tight. However, any attempt that significantly contributes to reducing the present accuracy for this quantity is strongly encouraged. Any such attempt will significantly enhance the accuracy with which reactor integral parameters may be estimated and will therefore impact economic and safety margins.

Comments from evaluator/experimentalist:
See appendix A of the attached report.

Comments for achieved accuracy:
See accuracy table.

Review comment:

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



Request ID36 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 92-U-238 (n,g) SIG  20 eV-25 keV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing 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 RangeInitial versus target uncertainties (%)
InitialABTR SFREFRGFRLFRVHTREPR
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.

Comments from evaluator/experimentalist:

Comments for achieved accuracy:
See accuracy details

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.

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



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

Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr

Project (context): CEA Cadarache

Impact:
Design phases of selected reactor and fuel cycle concepts require improved data and methods in order to reduce margins for both economical and safety reasons. A first indicative nuclear data target accuracy assessment was made within WPEC Subgroup 26 (SG-26). The assessment indicated a list of nuclear data priorities for each of the systems considered (ABTR, SFR, EPR, GFR, LFR, ADMAB, VHTR, EPR). These nuclear data priorities should all be addressed to meet target accuracy requirements for the integral parameters characterizing those systems (see the accompanying requests originating from SG-26).

Accuracy:
Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties. The weighting factor λ is explained in detail in the accompanying document. Changes from the reference value of λ=1 show the the possible allowance for other target uncertainties. Two cases (A and B) are distinguished for λ≠1 (see Table 24 of the report).

Energy RangeInitial versus target uncertainties (%)
InitialSFREFRGFRLFRADMAB
λ=1 λ≠1,a λ≠1,b λ=1 λ≠1,a λ=1 λ≠1,a λ=1 λ≠1,a λ=1 λ≠1,a
2.23 - 6.07 MeV 5 3 3 3 3 3 3 3
1.35 - 2.23 MeV 6 3 3 2 3 3 3 3 3 3
0.498 - 1.35 MeV 6 2 2 2 4 3 2 3 2 2 2 2
0.454 - 2.03 keV 22 13 13 11 9 10

Justification document:
OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).

Comment from requester:
Given the present state of knowledge the above target accuracies are very tight. However, any attempt that significantly contributes to reducing the present accuracy for this quantity is strongly encouraged. Any such attempt will significantly enhance the accuracy with which reactor integral parameters may be estimated and will therefore impact economic and safety margins.

Comments from evaluator/experimentalist:

Comments for achieved accuracy:
See accuracy details

Review comment:

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



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

Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr

Project (context): CEA Cadarache

Impact:
Design phases of selected reactor and fuel cycle concepts require improved data and methods in order to reduce margins for both economical and safety reasons. A first indicative nuclear data target accuracy assessment was made within WPEC Subgroup 26 (SG-26). The assessment indicated a list of nuclear data priorities for each of the systems considered (ABTR, SFR, EPR, GFR, LFR, ADMAB, VHTR, EPR). These nuclear data priorities should all be addressed to meet target accuracy requirements for the integral parameters characterizing those systems (see the accompanying requests originating from SG-26).

Accuracy:
Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties. The weighting factor λ is explained in detail in the accompanying document. Changes from the reference value of λ=1 show the the possible allowance for other target uncertainties. Two cases (A and B) are distinguished for λ≠1 (see Table 24 of the report).

Energy RangeInitial versus target uncertainties (%)
InitialSFREFRGFRLFRADMAB
λ=1 λ≠1,a λ≠1,b λ=1 λ≠1,a λ=1 λ≠1,a λ=1 λ≠1,a λ=1 λ≠1,a
1.35 - 2.23 MeV 3 2 2 2
0.498 - 1.35 MeV 4 2 2 1 3 2 2 2 1 1 2 2
183 - 498 keV 5 3 3 3 3 3

Justification document:
OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).

Comment from requester:
Given the present state of knowledge the above target accuracies are very tight. However, any attempt that significantly contributes to reducing the present accuracy for this quantity is strongly encouraged. Any such attempt will significantly enhance the accuracy with which reactor integral parameters may be estimated and will therefore impact economic and safety margins.

Comments from evaluator/experimentalist:

Comments for achieved accuracy:
See accuracy table

Review comment:

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



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

Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr

Project (context): CEA Cadarache

Impact:
Design phases of selected reactor and fuel cycle concepts require improved data and methods in order to reduce margins for both economical and safety reasons. A first indicative nuclear data target accuracy assessment was made within WPEC Subgroup 26 (SG-26). The assessment indicated a list of nuclear data priorities for each of the systems considered (ABTR, SFR, EPR, GFR, LFR, ADMAB, VHTR, EPR). These nuclear data priorities should all be addressed to meet target accuracy requirements for the integral parameters characterizing those systems (see the accompanying requests originating from SG-26).

Accuracy:
Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties. The weighting factor λ is explained in detail in the accompanying document. Changes from the reference value of λ=1 show the the possible allowance for other target uncertainties. Two cases (A and B) are distinguished for λ≠1 (see Table 24 of the report).

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

Justification document:
OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).

Comment from requester:
Given the present state of knowledge the above target accuracies are very tight. However, any attempt that significantly contributes to reducing the present accuracy for this quantity is strongly encouraged. Any such attempt will significantly enhance the accuracy with which reactor integral parameters may be estimated and will therefore impact economic and safety margins.

Comments from evaluator/experimentalist:

Comments for achieved accuracy:
See accuracy details

Review comment:

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



Request ID40 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 14-SI-28 (n,inl) SIG  1.4 MeV-6 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors 15-SEP-08 15-SEP-08 Y

Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr

Project (context): CEA Cadarache

Impact:
Design phases of selected reactor and fuel cycle concepts require improved data and methods in order to reduce margins for both economical and safety reasons. A first indicative nuclear data target accuracy assessment was made within WPEC Subgroup 26 (SG-26). The assessment indicated a list of nuclear data priorities for each of the systems considered (ABTR, SFR, EPR, GFR, LFR, ADMAB, VHTR, EPR). These nuclear data priorities should all be addressed to meet target accuracy requirements for the integral parameters characterizing those systems (see the accompanying requests originating from SG-26).
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 RangeInitial versus target uncertainties (%)
InitialGFR
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.

Comments from evaluator/experimentalist:
Data have been taken at IRMM for using the (n,n’g)-technique. Data analysis is ongoing.

Comments for achieved accuracy:
See accuracy details

Review comment:

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



Request ID41 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 82-PB-206 (n,inl) SIG  0.5 MeV-6 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors 15-SEP-08 15-SEP-08 Y

Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr

Project (context): CEA Cadarache

Impact:
Design phases of selected reactor and fuel cycle concepts require improved data and methods in order to reduce margins for both economical and safety reasons. A first indicative nuclear data target accuracy assessment was made within WPEC Subgroup 26 (SG-26). The assessment indicated a list of nuclear data priorities for each of the systems considered (ABTR, SFR, EPR, GFR, LFR, ADMAB, VHTR, EPR). These nuclear data priorities should all be addressed to meet target accuracy requirements for the integral parameters characterizing those systems (see the accompanying requests originating from SG-26).
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 RangeInitial versus target uncertainties (%)
  InitialLFRADMAB
   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.

Comments from evaluator/experimentalist:
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.
References:
1. L.C. Mihailescu, PHD thesis, report EUR 22343 EN, European Commission (2006)
2. D. Rochman, A. J. Koning, Pb and Bi neutron data libraries with full covariance evaluation and improved integral tests, Nucl. Instrum. Methods, A 589 (2008) 85

Comments for achieved accuracy:
See accuracy table

Review comment:

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



Request ID42 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 82-PB-207 (n,inl) SIG  0.5 MeV-6 MeV  See details Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast Reactors 15-SEP-08 15-SEP-08 Y

Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr

Project (context): CEA Cadarache

Impact:
Design phases of selected reactor and fuel cycle concepts require improved data and methods in order to reduce margins for both economical and safety reasons. A first indicative nuclear data target accuracy assessment was made within WPEC Subgroup 26 (SG-26). The assessment indicated a list of nuclear data priorities for each of the systems considered (ABTR, SFR, EPR, GFR, LFR, ADMAB, VHTR, EPR). These nuclear data priorities should all be addressed to meet target accuracy requirements for the integral parameters characterizing those systems (see the accompanying requests originating from SG-26).
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 RangeInitial versus target uncertainties (%)
  InitialLFRADMAB
   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.

Comments from evaluator/experimentalist:
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.
References:
1. L.C. Mihailescu, PHD thesis, report EUR 22343 EN, European Commission (2006)
2. D. Rochman, A. J. Koning, Pb and Bi neutron data libraries with full covariance evaluation and improved integral tests, Nucl. Instrum. Methods, A 589 (2008) 85

Comments for achieved accuracy:
See accuracy details

Review comment:

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



Request ID43 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 1-H-1 (n,el) SIG,DA  10 MeV-20 MeV 4 pi 1-2 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Standard impact on all subfields 29-APR-11 13-MAY-11 

Requester: Dr Allan D. CARLSON at NIST, USA
Email: allan.carlson@nist.gov

Project (context): NIST, Neutron Cross-Section Standards (www-nds.iaea.org/standards), CSEWG, WPEC

Impact:
This neutron cross section standard is perhaps the most important of the standards [1]. All of the other standards have been measured relative to it. Any improvement in this standard improves all standards and other cross sections that have been directly or indirectly measured relative to this standard. It helps form the basis of the neutron cross section libraries. There is very large leverage associated with improvements in this cross section. A problem at about 14 MeV is shown in reference [2].

[1] A.D. Carlson, et al., International Evaluation of Neutron Cross Section Standards, Nuclear Data Sheets 110 (2009) 3215-3324.
[2] N. Boukharouba, et al., Measurement of the n-p elastic scattering angular distribution at 14.9 MeV, Phys. Rev. C 82, 014001 (2010).
[3] N. Boukharouba, et al., Measurement of the n-p elastic scattering angular distribution at 10 MeV, Phys. Rev. C 65, 014004 (2001).

Accuracy:
1%-2% over most of the angular range. Very little data are available at small center-of-mass angles so the emphasis should be placed there.

Justification document:
The nature of the standards makes a simple answer to the question difficult. Since essentially all cross section data depend on the standards, any improvement in this standard will improve data for any neutronics calculation.
This neutron cross section standard is perhaps the most important of the standards. All of the other standards have been measured relative to it. Any improvement in this standard improves all standards and other cross sections that have been directly or indirectly measured relative to this standard. It helps form the basis of the neutron cross section libraries. There is very large leverage associated with improvements in this cross section.

Comment from requester:

Comments from evaluator/experimentalist:

Comments for achieved accuracy:

Review comment:

Arjan Plompen: New measurement efforts should seriously consider measuring the angular distribution for the outgoing neutron at the incident energies of 10 and 14.9 MeV tackled by the Ohio University collaboration while covering the forward angles and with good overlap with those data at backward angle [2,3]. Ideally they should answer the question concerning the degree of the Legendre polynomial required for the targeted uncertainty and allow the coefficients to be established accurately.

Don Smith: [...] improvements in the standards can almost always be justified. The H(n,n)H standard is certainly an important one. [...] this impacts on all technical areas but certainly more so at higher energies, e.g., in the HE tail of the fission neutron spectrum (or for fusion applications) [...]

Mark Chadwick: The sensivity of many experiments to this cross section is essentially one.

Allan Carlson in response to questions raised by Arjan Plompen:

A) It is very difficult to make absolute measurements of the hydrogen angular distribution with high accuracy. Instead it is much easier to make relative measurements. But to normalize the relative data to the hydrogen total elastic cross section requires either a rather complete measurement of the relative angular distribution or very good models to assist in the extrapolation to the angular region that was not measured (in the reference [2,3]). [...] it must be emphasized that this normalization aspect is very important.

B) It is disturbing that there are differences of 0.5 to 1% between the Arndt et al. and ENDF/B-VII evaluations of the total elastic cross section in the 10-20 MeV energy region. Part of this is because of the databases being used in the evaluations. For example, the Abfalterer et al. data were not used in the Arndt PWA analysis but they were included in the Hale (ENDF/B-VII) work. They had significant weight in the Hale evaluation due to the small experimental uncertainties so the evaluation is similar to those data. [...] It would be very valuable if each group used exactly the same database and compared their results.

C) Improvements in measurements of the total cross section are also worthwhile. The most recent work has used TOF techniques with white sources. These measurements are good but I would suggest that making a measurement at a single point with a (nearly) monoenergetic source for which very good background measurements are possible could provide even smaller uncertainty. In the 50’s and 60’s, a number of total cross section measurements were made in the MeV energy region with fraction of a percent uncertainties. I expect we could probably do a little better now. Note the detailed process described in Fast Neutron Physics for accurate total cross section measurements. An important point for the total cross section work (but not for the angular distribution work) is a very accurate determination of the energy of the neutrons. An error of 20 keV in the energy scale for a 1 MeV cross section measurement causes about a 1% error in the cross section. This effect is less however at higher neutron energies.

Additional file attached:
Additional file attached:



Request ID44 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 93-NP-237 (n,f) SIG,DE  200 keV-20 MeV   Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission fast reactors 11-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:
  • [1] G. Aliberti et al., Annals of Nuclear Energy 33 (2006) 700-733.
  • [2] M. Salvatores et al., Nuclear Science NEA/WPEC-26, www.oecd.org.
  • [3] C. Paradela et al., Phys. Rev. C 82 (2010) 034601; Korean Physical Society 59 (2011) 1519.
  • [4] L.S. Leong et al., Annals of Nuclear Energy 54 (2013) 36

Comments from evaluator/experimentalist:

Comments for achieved accuracy:

Review comment:

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



Request ID45 Status of the request High Priority request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 19-K-39 (n,p),(n,np) SIG  10 MeV-20 MeV  10 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fusion  17-MAY-17 11-JUL-17 

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

  • [1] F. Arbeiter et al., Nuclear Materials and Energy 9 (2016)59.
  • [2] A. Ibarra et al., Fusion Science and Technology 66 (2014) 252.
  • [3] S.P. Simakov, Y. Qiu, U. Fischer, EFFDOC-1318, JEFF Meeting, OECD, Paris, April 24-27, 2017.
  • [4] M. Bormann et al., Zeitschrift fuer Naturforschung A 15 (1960) 200.
  • [5] D.V. Aleksandrov, L.I. Klochkova, B.S. Kovrigin, Soviet Atomic Energy 39 (1975) 736 (translated from Atomnaya Energiya 39 (1975) 137).
  • [6] W. Schantl, PhD thesis, Institut für Radiumforschung und Kernphysik, University of Vienna, 1970.
  • [7] K.A. Foland, R.J. Borg, M.G. Mustafa, Nuclear Science and Engineering 95 (1987) 128.

Comment from requester:

Comments from evaluator/experimentalist:

Comments for achieved accuracy:

Review comment:

Additional file attached:effdoc-1318.pdf
Additional file attached: