Request ID1 Status of the request General request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 14-SI-28 (n,np) SIG  Threshold-20 MeV 4 pi 20 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fusion Material Recycling 21-SEP-05 23-MAR-07 

Requester: Dr Edward T. CHENG at GAT, USA
Email:

Project (context): Structural material for fusion power reactors

Impact:
SiC is a potential very low activation structural material for a fusion power reactor. Al-27 produced from neutron irradiation of Si generates Al-26 via the Al-27(n,2n) reaction. Al-26 is a long-lived radionuclide with a half life of 720,000 years emitting high energy gammas. The concentration of Al-26 in SiC determines whether the decommissioned fusion blanket qualifies for recycling.

Accuracy:
The request for 20% accuracy is based on what seemed feasible for the nuclear data community to achieve and probably would be sufficient for applications as well. It is not based on any sensitivity calculations.

Justification document:
The estimates consider waste generated by four full power years at 5 MW/m2 neutron wall load and are based on a particular scenario for waste handling using evaluations for Si-28(n,x)Al-27 provided by ENDF/B-VI and ADL-3 which are adopted in FENDL/A-2.0. Estimated concentration limits for Si are a factor 10 higher than earlier estimates, so that SiC would qualify as a truly low-activation material. The request asks for experimental data to validate these estimates and a subsequent re-evaluation. No direct experimental data exist.
Reference 1: E.T.Cheng, Jour. Nucl. Mat.,258-263(1998)1767
Reference 2: E.T. Cheng, Proc. of the Int. Conf. on Nuclear Data for Science and Technology, eds. G. Reffo, A. Ventura and C. Grandi, SIF, Bologna, 1158 (1997)

Comment from requester:
Two methods to measure this reaction cross section have been suggested by Herbert Vonach and others. These include (1) Measurement of Na24 activity with high-purity Si samples and intense neutron sources, and (2) Measurement of total production in Si and then subtracting the well known (n,p) cross sections to obtain the (n,n'p) values. An attempt to measure this cross section data at 14 MeV a few years ago failed due to the contamination of the Si samples with the impurity Al. The request for 20% accuracy is based on what seemed feasible for the nuclear data community to achieve and probably would be sufficient for applications as well. It is not based on any sensitivity calculations.

Comments from evaluator/experimentalist:

Comments for achieved accuracy:
The accuracy is not known. Estimates from present and earlier evaluations differ by a factor of ten.

Review comment:
The request appears to imply application to post-ITER fusion reactors in view of the high neutron dose required to generate relevant quantities of Al-26. Reference [1] refers primarily to the Si-28(n,np) reaction, whereas the production of Al-27 from Si-28 is important. This therefore also implies the (n,d) reaction since the respective thresholds are 12 and 9.7 MeV. Quantitative information is supplied that seems to suggest directly that 20% accuracy is of interest to the application. Stoichiometric SiC has 70 wt% of Si, whereas the scenario assumed for the estimates of Ref. [1] results in an upper limit of 85 wt% Si for recycling. This request qualifies as a General request primarily since the project end time is unspecified. The request will be reevaluated in 2010.

Additional file attached:
Additional file attached:



Request ID6 Status of the request General request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 92-U-233 (n,g) SIG  10 keV-1.0 MeV  9 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Fast reactors 28-APR-06 13-MAR-07 

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

Project (context): JEFF

Impact:
U-233 is the main isotope of relevance to the Th/U fuel cycle. Its most important cross section is the fission cross section. The direct impact of the U-233 capture cross section is rather limited on most reactor related parameters but breeding. However, reliable capture data are needed for the evaluation work.

Accuracy:
The target accuracy on the capture cross section in the unresolved resonance range should be better than 10%

Justification document:
Interpretations of the Profil and Profil-2 experiments [1] performed in the fast reactor Phenix of the CEA Marcoule have shown an underestimation of 9% the U-233 effective capture cross section available in the latest version of the European library JEFF-3.1. The accuracy of the capture data available in EXFOR is not suitable to perform a new evaluation.
References:
[1] J. Tommasi, E. Dupont and P. Marimbeau., "Analysis of Sample Irradiation Experiments in Phénix for JEFF-3.0 Nuclear Data Validation", Nucl. Sci. Eng. 154 (2006) 119-133
[2] J.C.Hopkins and B.C.Diven, "Neutron capture to fission ratios in U-233, U-235, Pu-239", Nucl. Sci. Eng. 12 (1962)169
[3] G. Noguere, E. Dupont, J. Tommasi and D. Bernard, "Nuclear data needs for actinides by comparison with post irradiation experiments", Technical note CEA Cadarache, NT-SPRC/LEPH-05/204 (2005) (see below).

Comment from requester:

Comments from evaluator/experimentalist:
Owing to the difficulty in measuring the U-233(n,g) cross section, new evaluation has to take into account the Profil results [3] (see below).
CENBG has proposed an experiment to study the ratio of the capture to the fission cross section at IRMM in the frame of the NUDAME transnational access scheme (http://www.irmm.jrc.be/html/nudame/).

Comments for achieved accuracy:
Owing to the integral trend given by the interpretation of PROFIL, the final accuracy on the effective capture cross section should be lower than 9%.

Review comment:
Adrien Bidaud, CENBG, Bordeaux, independently investigated the sensitivity of the regeneration of U-233 to various cross sections. Sensitivities were evaluated considering a molten salt reactor under the constraints of criticality and isotopic equilibrium. Large sensitivities are observed for the capture cross section and for nu-bar. He concludes that "Any effort done to confirm the neutron yields and the capture cross section or at least to confirm their uncertainty would be very much appreciated." The energy range of interest is below that of the current request.

Additional file attached:
Additional file attached:NT-Profil.pdf



Request ID7 Status of the request General request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 26-FE-56 (n,xn) SIG,DDX  7 MeV-20 MeV 1MeV-20MeV 30 
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission,ADS Shielding, Medical, SNS 13-JUL-06 16-APR-07 

Requester: Prof. Arjan KONING at NRGPETTEN, NED
Email:

Project (context): JEFF, Model calculations

Impact:
New double differential experimental data for the Fe(n,xn) reaction will allow a crucial test of the pre-equilibrium models underlying neutron transport libraries for spallation neutron sources. They will thereby enhance the confidence in neutron transport calculations for spallation neutron sources such as envisioned for accelerator driven systems.

Accuracy:
30% for the double-differential spectra

Justification document:
A global pre-equilibrium analysis from 7 to 200 MeV based on the optical model potential, A.J. Koning and M.C. Duijvestijn, Nucl. Phys. A744, 15 (2004).

Comment from requester:
There are hundreds of (p,xp) and (p,xn) spectra in the 20-200 MeV range available, several (n,xp) spectra, but there are basically no double-differential (n,xn) spectra available. The presence of such data would heavily constrain the pre-equilibrium model paraneters and thereby result in a much better prediction of neutron-induced spectra in the entire 50-200 MeV range. Since high-energy spectra are rather structureless the choice of target is less essential.

Comments from evaluator/experimentalist:

Comments for achieved accuracy:

Review comment:
A recent effort was made by a collaboration between the University of Uppsala and LPC Caen to obtain (n,xn) double differential data for Pb-208 (to be published).

Additional file attached:
Additional file attached:



Request ID9 Status of the request General request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 92-U-233 (n,g) nubar,SIG  Thermal-10 keV  .5 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Molten Salt Reactors 19-APR-07 19-APR-07 

Requester: Dr Adrien BIDAUD at LPSC, FR
Email: bidaud@lpsc.in2p3.fr

Project (context): JEFF

Impact:
U-233 is the main isotope of relevance to the Th/U fuel cycle. The present request concerns the viability of Th/U fueled molten salt reactors which requires that the amount of U-233 generated equals that which is destroyed.

Accuracy:
0.5% in nubar, 5% for the (n,g) cross section

Justification document:
Uncertainties on the predicted regeneration gain inferred from the uncertainties of the nuclear data have been estimated showing a 4200 pcm uncertainty for a regeneration gain designed to be 200 pcm, i.e. very close to a complete balancing of production and destruction of U-233. The main culprits are nubar contributing 2200 pcm and the capture cross section contributing 3260 pcm. A target accuracy of 2000 pcm is required to facilitate defining the reprocessing scheme for a molten salt reactor.
Reference:
A. Bidaud, Impact of Nuclear Data Uncertainties on a GEN IV Thorium Reactor at Equilibrium (attached document).
CEA Technical Note NT-SPRC/LEPH-05/204, G. Noguere et al (attachment 2).

Comment from requester:
Owing to the difficulty in measuring the U-233(n,g) cross section, a new evaluation could be done on the basis of the Profil results (see CEA Technical Note NT-SPRC/LEPH-05/204).

Comments from evaluator/experimentalist:
Any effort done to reduce the uncertainties on neutron yields and capture cross section down to less than 1% and about 5% respectively or at least to confirm their uncertainty would be very much appreciated. If the uncertainty on RG could be reduced down to 2000pcm, the needed reprocessing scheme could be designed with more confidence, and then the research on specific goals such as minor actinide and protactinium extraction could be prioritized.

Comments for achieved accuracy:
Nubar is currently known to 1%, the capture cross section to 10%. The above mentioned target uncertainties implies that the desired accuracies for improved data are approximately half these numbers.

Review comment:

Additional file attached:U233_MSR_Impact.pdf
Additional file attached:NT-Profil.pdf



Request ID10 Status of the request General request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 79-AU-197 (n,tot) SIG  5 keV-200 keV  5 
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Science,Fusion Dosimetry 18-MAY-07 06-JUN-07 

Requester: Dr Roberto CAPOTE NOY at IAEA, AUT
Email: roberto.capotenoy@iaea.org

Project (context): Dosimetry

Impact:
INDC(NDS)-0507 Summary Report of Consultants’ Meeting Review the Requirements to Improve and Extend the IRDF library (International Reactor Dosimetry File (IRDF-2002)), IAEA Headquarters, Vienna, Austria 20-21 April 2006, prepared by L.R. Greenwood and Alan L. Nichols (IAEA, Vienna, January 2007)

Accuracy:
5%

Justification document:
Gold is an extremely important material in nuclear applications: the capture on gold is a standard neutron cross-section, gold has been proposed as a high energy neutron dosimeter (see below), Au-197(n,2n) is a reactor dosimetric reaction considered in all recent IRDF files, etc. Reactions on gold are also of interest for nuclear model code testing as gold is a mono-isotopic element being amenable to detailed calculations.
Taken from INDC(NDS)-0507 "... proposed high energy dosimetry reactions 197Au(n,2n)196Au, 197Au(n,3n)195Au, and 197Au(n,4n)194Au require the extension of the gold evaluation up to 60 MeV"
To our surprise we found large discrepancies in the measured total cross section data of gold in the 5-200 keV energy range (URR) as can be seen from the attached plots. The only existing evaluation (Young et al in red in the figures) has been carried out in the early nineties and has been adopted for all subsequent libraries with minor modifications. This evaluation follows the Seth et al. data measured in 1965, which is in contradiction with several new measurements (for example Purtov 1994 and Wishak 1995-2006). The spread of the Wishak measurements is puzzling.

Comment from requester:
A new dispersive coupled-channel optical model potential (5 keV - 200 MeV) derived using the requested data (plus the existing database above 200 keV) will have a direct impact on future evaluations of neutron induced reactions on gold.

Comments from evaluator/experimentalist:
While considerable data exist for the 5-200 keV total cross section, there is considerable scatter in these data. The measurement range is well suited for time-of-flight facilities and may also be accessed with quasi-monoenergetic beams using the Li(p,n) neutron source reactions. For a transmission measurement optimal conditions are obtained with a transmission factor close to 0.5, which implies that getting a sample might be costly, but purity and chemical issues should not be concerns. A measurement which overlaps with the region of the Au capture standard (200 keV to 2.5 MeV) would be of interest to allow a consistency check.

Comments for achieved accuracy:

Review comment:

Additional file attached:AU197_NTOT_RECENT.ps
Additional file attached:AU197_WISHAK.ps



Request ID11 Status of the request General request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 94-PU-239 (n,f),(n,g) SIG,eta,alpha  1 meV-1 eV  1 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission Thermal reactors 09-MAY-07 06-JUN-07 

Requester: Dr Luiz Carlos LEAL at IRSN, FR
Email: luiz.leal@irsn.fr

Project (context): Thermal reactors

Impact:
Improve the estimation of keff as well as the moderator temperature coefficient for thermal systems. In particular, this concerns MOX cores and Pu solutions.

References:
[1] A. Santamarina, Improvement of the Pu239 Evaluation for JEFF3, JEF/DOC-1158 (attached below)
[2] Russell D. Mosteller, "ENDF/B-VII, ENDF/B-VI, and JENDL-3.3 Results for Unreflected Plutonium Solutions and MOX Lattices", Joint International Topical Meeting on Mathematics & Computation and Supercomputing in Nuclear Applications (M&C + SNA 2007) Monterey, California, April 15-19, 2007, on CD-ROM, American Nuclear Society, LaGrange Park, IL (2007), Los Alamos report: LA-UR-06-6903
[3] D. Bernard, E. Fort, A. Courcelle, A. Santamarina, G. Noguère, "239Pu nuclear data improvements in thermal and epithermal neutron ranges, International Conference on Nuclear Data for Science and Technology 2007, Contrib #708.
[4] H.Weigmann, B.Keck, J.A.Wartena,P.Geltenbort, K.Schreckenbach, Int.Conf.on the Physics of Reactors: Operation, Design and Computation, Marseille, 23-27 Apr 1990.

Accuracy:
< 1 % for fission cross section and < 2 % for capture cross section

Justification document:
Recent benchmark calculations indicate that the shape of sig(n,g), sig(n,f), eta and/or alpha at low energy need to be revised. A similar problem was seen about 10 years ago with the U-235 cross section. In that case the shape of eta at low energy was found to be slightly varying with energy. It appears that a similar problem exists for Pu-239. Existing experimental data have not helped much to solve the puzzle. Measurements of these quantities in the range from 1 meV to 1 eV, including the 0.3 eV resonance, will be of utmost importance.

Comment from requester:
Existing measurements of the Pu-239 fission and capture cross sections (alpha) do not help to resolve a longstanding problem with thermal benchmarks regarding Pu-239. The measurements of Ref. [4] helped resolve a similar problem that previously existed for U-235.

Comments from evaluator/experimentalist:
Since the request refers to the resonance region, measurements would be needed to address this request. Quite different measurement samples and detectors would be required for the (n,f) and (n,g) cross section measurements with individual uncertainties that would be easily in excess of 1%. Therefore, to achieve the accuracy, measurements should aim at measuring either eta or alpha in function of energy striving for minimal systematic errors. Such an eta or alpha measurement would need to be combined with a precise fission cross section from an evaluation or an independent measurement. Calibrating a fission deposit mass to 1%, is possible, but poses a challenge. Interested experimental groups should consult Ref. [4].

Comments for achieved accuracy:

Review comment:

Additional file attached:
Additional file attached:jefdoc-1158.pdf



Request ID13 Status of the request General request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 24-CR-52 (n,xd),(n,xt) SIG  Threshold-65 MeV  20 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fusion IFMIF, First wall 23-OCT-07 07-NOV-07 

Requester: Dr Robin A. FORREST at CCFE, UK
Email:

Project (context): JEFF, EFF

Impact:
See attached report EFF/DOC-1015, "Preparatory work for the evaluation of Cr-52 high energy neutron data for EFF", P. Pereslavtsev.

Accuracy:
No experimental data are available for this reaction apart from one point at 14 MeV. Therefore, new experimental results with 20% accuracy are still valuable.

Justification document:
The reactions that need to be considered are Cr-52(n,d+n'p)V-51 and Cr-52(n,t+n'd)V-50. These are important both for modelling and for fusion technology applications. They are discussed in the UKAEA FUS 509 document (Handbook of activation data) available for download: ukaea-fus-509.pdf (8.6 Mb).

Comment from requester:
Attempts to measure the split in (n,d) and (n,np) to the production of 51V and the split in (n,t), (n,nd) and (n,2np) contributions to the production of 50V would be valuable.

Comments from evaluator/experimentalist:
In view of the stable end product both for the (n,d) and (n,nd) reaction, double differential measurements detecting the deuteron are recommended. Such measurements may also provide important additional data for modeling in the form of (n,xp) and (n,xt) double differential cross sections. Measurements with the 'activation-technique' would need to employ a combination of two reactions. Such measurements are complicated, since traces of natural vanadium are a major source of contamination and because the induced activity will be very low. Accelerator Mass Spectrometry is deemed not feasible on account of the background resulting from the wide spread use of vanadium in structural parts. In view of these difficulties it is unlikely that experimentally the cross section for the production of a specific isotope will be accessible. Modeling would have to be invoked.

Comments for achieved accuracy:
According to the attached report a single measurement at 14 MeV exists. Above that energy two recent evaluations divergence by nearly a factor 2.

Review comment:
Cr-52 has been under re-evaluation several times in the recent past. For this particular reaction it appears that no progress can be made without new experimental data. In view of the predicted trends in the cross section, it appears that the emphasis of new experimental work should be in the domain above 14 MeV. However, the energy range between threshold (8441 keV) and 14 MeV may be important in an actual fusion reactor.

Additional file attached:effdoc-1015.pdf
Additional file attached:



Request ID14 Status of the request General request
TargetReaction and processIncident EnergySecondary energy or angleTarget uncertaintyCovariance
 94-PU-242 (n,g),(n,tot) SIG  0.5 eV-2.0 keV  8 Y
FieldSubfieldDate Request createdDate Request acceptedOngoing action
 Fission SFR 06-JUL-07 07-NOV-07 

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

Project (context): JEFF

Impact:
G. Aliberti, G. Palmiotti and M. Salvatores, "The role of differential and integral experiments to meet requirements for improved nuclear data", Int. Conf. on Nuclear Data for Science and Technology, Nice, France, 2007.

Accuracy:
Requested accuracy for nuclear applications is widely discussed within the NEA WPEC Subgroup 26, " Nuclear Data Needs for Advanced Reactor Systems". For Pu-242, the requested accuracy on the capture cross section should be lower than 8% in the fast energy range. Interpretations with JEFF-3.1 of the PROFIL and PROFIL-2 experiments carried out in the fast reactor Phenix have shown the overestimation of about 14% of the capture cross section [1,2].

Justification document:
[1] G. Noguere, E. Dupont, J. Tommasi and D. Bernard, "Nuclear data needs for actinides by comparison with post irradiation experiments", Technical note CEA Cadarache, NT-SPRC/LEPH-05/204 (2005).
[2] J. Tommasi, E. Dupont and P. Marimbeau., "Analysis of Sample Irradiation Experiments in Phénix for JEFF-3.0 Nuclear Data Validation", Nucl. Sci. Eng. 154 (2006) 119-133.
[3] E. Rich, G. Noguere, C. De Saint Jean and O. Serot. "Averaged R-Matrix Modelling of the Pu-242 cross sections in the Unresolved Resonance Range", in Proceedings of the Int. Conf. on Nuclear Data for Science and Technology, Nice, France, 2007.

Comment from requester:
To improve the evaluation of the fast energy range in term of average parameters, new high-resolution capture and transmission measurements are needed. The total cross section above 1.5 keV is poorly known. Accurate average radiation width and strength function are required to solve some ambiguous results obtained between optical model calculations and the statistical analysis of the s-wave resonances [3].

Comments from evaluator/experimentalist:

Comments for achieved accuracy:

Review comment:
NEA WPEC Subgroup-26 will shortly present more detailed requests related to Pu isotopes that are motivated from sensitivity studies of Generation-IV, GNEP and several reference concepts.

Additional file attached:
Additional file attached:Noguere-Pu242-Note-Technique.pdf



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

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

Project (context): J-PARC

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

Accuracy:

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

Comment from requester:

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

Comments for achieved accuracy:

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

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



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

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

Project (context): J-PARC

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

Accuracy:

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

Comment from requester:

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

Comments for achieved accuracy:

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

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