| Request ID | 10 | Type of the request | General request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 79-AU-197 | (n,tot) SIG | 5 keV-200 keV | 5 | ||
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fusion,Science | Dosimetry | 18-MAY-07 | 06-JUN-07 | ||
Requester: Dr Roberto CAPOTE NOY at IAEA, AUT
Email: roberto.capotenoy@iaea.org
Project (context): Dosimetry
Impact:
Accuracy:
Justification document:
Comment from requester:
Review comment:
Entry Status:
Main references: Experiments Theory/Evaluation Validation Additional file attached:AU197_NTOT_RECENT.ps
Requester: Dr Gilles NOGUERE at CAD-DER, FR
Project (context):
Impact: The use of new high-accuracy transmission data in the evaluation procedure will affect the partial cross sections and their uncertainties, whose impact on neutronic calculations may be significant. For the first resonance the uncertainty on capture is 2.5% in JEFF-3.3 and 4% in ENDF/B-VIII.0, whereas the sensitivity of keff to capture is close to 200 pcm/% for MOX fuel. Hence, any modifications of the resonance parameters and their uncertainties will have a sizeable impact on reactor applications.
Accuracy: Accuracy and precision better than 1% are required for the first resonance.
Justification document: New experimental setups are developed to measure the capture cross sections of actinides in the resolved resonance range. However, total cross sections are also important quantities for evaluation purposes. The transmission data of the first resonance have all been measured in the 1950's (see attached figure). Uncertainty information on these old measurements are scarce or lacking and does not help much to constrain the resonance parameters in the evaluation process, which is a pity given the high accuracy that can be reached on a transmission measurement (compared to capture). The attached figure illustrates how ENDF/B-VIII.0 and JEFF-3.3 differs, partly because of evaluators' choices, but also because of poor uncertainty information. New high-accuracy transmission measurements of the first resonance will help improve the resonance parameters and reduce the uncertainty on the capture cross section.
Comment from requester:
Review comment:
Entry Status:
Main references: Additional file attached:HPRL_Request_Pu239_ntot_1stRes.png
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)
5%
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 dosimetry 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.
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.
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.
Completed (as of SG-C review of May 2018) - The JEFF-3.2 evaluation [Sirakov:2013] based on new JRC-Geel measurements [Sirakov:2014;Massimi:2014] is significantly below the target accuracy. The evaluation has been validated against the Grenoble LSDS integral experiment [Zerovnik:2013].
Please report any missing information to hprlinfo@oecd-nea.org
Additional file attached:AU197_WISHAK.ps
Request ID 115
Type of the request High Priority request
Target Reaction and process Incident Energy Secondary energy or angle Target uncertainty Covariance
94-PU-239 (n,tot) SIG Thermal-5 eV 1 Y
Field Subfield Date Request created Date Request accepted Ongoing action
Fission Thermal reactors 22-MAR-19 08-APR-19 Y
Email: gilles.noguere@cea.fr
Work in progress (as of SG-C review of June 2019)
Please report any missing information to hprlinfo@oecd-nea.org
Additional file attached:
