Impact: Neutron absorption in the Cr isotopes of structural materials affects the criticality of fast reactor assemblies [Koscheev2017]. These cross sections are also of interest for stellar nucleosynthesis [Kadonis10].
Accuracy: 8-10% in average cross-sections and calculated MACS at 10, 30, 100 keV. Selected criticality benchmarks with large amounts of Cr (e.g., PU-MET-INTER-002, and HEU-COMP-INTER-005/4=KBR-15/Cr) show large criticality changes of the order of 1000 pcm due to 30% change in Cr-53 capture in the region from 1 keV up to 100 keV [Trkov2018]. On the other side different evaluations (e.g., BROND-3.1, ENDF/B-VII.1, ENDF/B-VIII.0 and JEFF-3.3) for Cr-53(n,g) are discrepant by 30% in the same energy region. For Cr-50, evaluated files show better agreement at those energies but they are lower than Mughabghab evaluation of the resonance integral by 35%. These discrepancies are not reflected in estimated uncertainty of the evaluated files (e.g., JEFF-3.3 uncertainty is around 10% which is inconsistent with the observed spread in evaluations). Due to these differences we request new capture data with 8-10% uncertainty to discriminate between different evaluations and improve the C/E for benchmarks containing Chromium and/or SS.
Justification document: Criticality benchmarks can test different components of stainless steel (SS), including Cr which is a large component of some SS. Currently, a large part of the uncertainty in SS capture seems to be driven by uncertainty in Cr capture [Koscheev2017]. Indeed, some benchmarks highly sensitive to Cr (as a component of SS) indicate a need for much higher capture in Cr for both Pu and U fueled critical assemblies (e.g., HEU-COMP-INTER-005/4=KBR-15/Cr and PU-MET-INTER-002=ZPR-6/10). Capture in natural Cr is driven by capture on Cr-50 and especially in odd Cr-53. For Cr-53(n,g) there is a very large spread in MACS(30) values in different libraries compared to recommended KADoNiS 1.0 [Kadonis10] value of 41 +/- 10 mb (the latter is 25% larger). Existing measurements from the 70s are even larger being close to 60 mb with 30% uncertainty. Note also discrepancies in resonance integrals (in barns) between evaluated libraries and ATLAS [Mughabghab2006] for both Cr-50(n,g) and Cr-53(n,g) Finally, the re-evaluation for ENDF/B-VIII.0 of the ORNL TOF measurement on enriched Cr-53 target [Guber2011] contradicts the increase suggested in Ref. [Koscheev2017] where preliminary data have been used. Such contradictions need to be resolved thanks to new measurements and evaluation. References
Reaction ENDF/B-VII.1 BROND-3.1 ATLAS 2006 Cr-50(n,g) 7.21 7.21 11.7 +/- 0.2 Cr-53(n,g) 8.42 11.2 12.3
Comment from requester:
- Cr-50(n,g) may be measured by activation or TOF. An accurate activation measurement at 5 and 25 keV may help in solving the puzzle of Cr capture.
- Cr-53(n,g) can only be measured by TOF. There is no publication of the final analysis of the ORNL TOF measurement using enriched Cr-53 sample.
- Lead Slowing Down Spectrometer (LSDS) measurements of Cr-50, Cr-53 and Cr-52 enriched samples and of Cr-nat sample could be extremely important to validate and select a proper evaluation of Cr capture cross section below 100 keV. These measurements are strongly encouraged as complementary to TOF and feasible activation measurements.
Review comment:
Entry Status:
Work in progress (as of SG-C review of May 2018)
Main references: Experiments Theory/Evaluation Validation
Please report any missing information to hprlinfo@oecd-nea.org
Additional file attached:Trkov2018.pdf
Additional file attached:
| Request ID | 13 | Type of the request | General request | ||
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 24-CR-52 | (n,xd),(n,xt) SIG | Threshold-65 MeV | 20 | Y | |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action | |
| Fusion | IFMIF, First wall | 23-OCT-07 | 07-NOV-07 | ||
Requester: Dr Robin A. FORREST at UKAEA/CUL, UK
Email:
Project (context): JEFF, EFF
Impact:
Accuracy:
Justification document:
Comment from requester:
Review comment: 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. According to the attached report a single measurement at 14 MeV exists. Above that energy two recent evaluations divergence by nearly a factor 2. 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.
Entry Status:
Main references: Theory/Evaluation Additional file attached:effdoc-1015.pdf
Requester: Dr Stanislav SIMAKOV at KIT, GER
Project (context): IRDFF project
Impact:
Accuracy:
Justification document:
Comment from requester: References
Review comment:
Entry Status:
Main references: Theory/Evaluation Additional file attached:Simakov2017.pdf
Requester: Dr Roberto CAPOTE NOY at IAEA, AUT
Project (context):
Impact: Neutron absorption in the Cr isotopes of structural materials affects the criticality of fast reactor assemblies [Koscheev2017]. These cross sections are also of interest for stellar nucleosynthesis [Kadonis10].
Accuracy: 8-10% in average cross-sections and calculated MACS at 10, 30, 100 keV. Selected criticality benchmarks with large amounts of Cr (e.g., PU-MET-INTER-002, and HEU-COMP-INTER-005/4=KBR-15/Cr) show large criticality changes of the order of 1000 pcm due to 30% change in Cr-53 capture in the region from 1 keV up to 100 keV [Trkov2018]. On the other side different evaluations (e.g., BROND-3.1, ENDF/B-VII.1, ENDF/B-VIII.0 and JEFF-3.3) for Cr-53(n,g) are discrepant by 30% in the same energy region. For Cr-50, evaluated files show better agreement at those energies but they are lower than Mughabghab evaluation of the resonance integral by 35%. These discrepancies are not reflected in estimated uncertainty of the evaluated files (e.g., JEFF-3.3 uncertainty is around 10% which is inconsistent with the observed spread in evaluations). Due to these differences we request new capture data with 8-10% uncertainty to discriminate between different evaluations and improve the C/E for benchmarks containing Chromium and/or SS.
Justification document: Criticality benchmarks can test different components of stainless steel (SS), including Cr which is a large component of some SS. Currently, a large part of the uncertainty in SS capture seems to be driven by uncertainty in Cr capture [Koscheev2017]. Indeed, some benchmarks highly sensitive to Cr (as a component of SS) indicate a need for much higher capture in Cr for both Pu and U fueled critical assemblies (e.g., HEU-COMP-INTER-005/4=KBR-15/Cr and PU-MET-INTER-002=ZPR-6/10). Capture in natural Cr is driven by capture on Cr-50 and especially in odd Cr-53. For Cr-53(n,g) there is a very large spread in MACS(30) values in different libraries compared to recommended KADoNiS 1.0 [Kadonis10] value of 41 +/- 10 mb (the latter is 25% larger). Existing measurements from the 70s are even larger being close to 60 mb with 30% uncertainty. Note also discrepancies in resonance integrals (in barns) between evaluated libraries and ATLAS [Mughabghab2006] for both Cr-50(n,g) and Cr-53(n,g) Finally, the re-evaluation for ENDF/B-VIII.0 of the ORNL TOF measurement on enriched Cr-53 target [Guber2011] contradicts the increase suggested in Ref. [Koscheev2017] where preliminary data have been used. Such contradictions need to be resolved thanks to new measurements and evaluation. References
Comment from requester:
- Cr-50(n,g) may be measured by activation or TOF. An accurate activation measurement at 5 and 25 keV may help in solving the puzzle of Cr capture.
Review comment:
Entry Status:
Main references: Experiments Theory/Evaluation Validation Additional file attached:Trkov2018.pdf
See attached report EFF/DOC-1015, "Preparatory work for the evaluation of Cr-52 high energy neutron data for EFF", P. Pereslavtsev.
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.
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).
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.
Completed (as of SG-C review of May 2018) - This request didn't trigger any measurement and should its priority rise again it will have to be resubmitted. Nevertheless, it has been partially addressed by the JEFF-3.2 evaluation using state-of-the-art nuclear reaction codes [Pereslavtsev:2011].
Please report any missing information to hprlinfo@oecd-nea.org
Additional file attached:
Request ID 68
Type of the request Special Purpose Quantity
Target Reaction and process Incident Energy Secondary energy or angle Target uncertainty Covariance
24-CR-52 (n,2n) SIG/SPA 252Cf(sf)-235U(n,f) 2-5 Y
Field Subfield Date Request created Date Request accepted Ongoing action
Dosimetry D-T fusion 06-OCT-17 06-OCT-17
Email: intersurfen@gmail.com
The International Reactor Dosimetry and Fusion File (IRDFF) aims at providing evaluated neutron dosimetry reactions validated for all applications related to fission reactors and fusion technology development [IAEA2017].
2%-5%
Accurate cross sections as well as spectrum-averaged cross sections (SACS) in relevant and well-characterized neutron fields are essential for improvement and validation of the evaluated data [Simakov2017].
Following a recommendation from the IAEA Data Development Project on Neutron Standards [Pronyaev2013], the IRDFF project supports SACS measurements of high-threshold (above 10 MeV) dosimetry cross-sections in well-characterized 252Cf(sf) and 235U(nth,f) neutron fields in order to improve the cross sections and/or the high-energy part of the prompt fission neutron spectra.
Measurements of the spectrum-averaged cross section are missing for validation purposes and for improvement of the cross section and prompt fission neutron spectrum above 10 MeV. See Cf252U235_HighThreshold.pdf below.
http://www-nds.iaea.org/IRDFFtest/.
Work in progress (as of SG-C review of May 2018)
Please report any missing information to hprlinfo@oecd-nea.org
Additional file attached:Cf252U235_HighThreshold.pdf
Request ID 98
Type of the request High Priority request
Target Reaction and process Incident Energy Secondary energy or angle Target uncertainty Covariance
24-CR-53 (n,g) SIG 1 keV-100 keV 8-10 Y
Field Subfield Date Request created Date Request accepted Ongoing action
Fission 20-JAN-18 05-FEB-18 Y
Email: roberto.capotenoy@iaea.org
Reaction ENDF/B-VII.1 BROND-3.1 ATLAS 2006 Cr-50(n,g) 7.21 7.21 11.7 +/- 0.2 Cr-53(n,g) 8.42 11.2 12.3
- Cr-53(n,g) can only be measured by TOF. There is no publication of the final analysis of the ORNL TOF measurement using enriched Cr-53 sample.
- Lead Slowing Down Spectrometer (LSDS) measurements of Cr-50, Cr-53 and Cr-52 enriched samples and of Cr-nat sample could be extremely important to validate and select a proper evaluation of Cr capture cross section below 100 keV. These measurements are strongly encouraged as complementary to TOF and feasible activation measurements.
Work in progress (as of SG-C review of May 2018)
Please report any missing information to hprlinfo@oecd-nea.org
Additional file attached: