NEA WPEC Subgroup 26
Impact:
Design phases of selected reactor and fuel cycle concepts require improved data and methods in order to reduce margins for both economical and safety reasons. A first indicative nuclear data target accuracy assessment was made within WPEC Subgroup 26 (SG-26). The assessment indicated a list of nuclear data priorities for each of the systems considered (ABTR, SFR, EPR, GFR, LFR, ADMAB, VHTR, EPR). These nuclear data priorities should all be addressed to meet target accuracy requirements for the integral parameters characterizing those systems (see the accompanying requests originating from SG-26).
Requested accuracy is required to meet target accuracies for keff and burnup for the Very High Temperature Reactor (VHTR). Details are provided in the OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).
Accuracy:
Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties. The weighting factor λ is explained in detail in the accompanying document. Changes from the reference value of λ=1 show the the possible allowance for other target uncertainties. Two cases (A and B) are distinguished for λ≠1 (see Table 24 of the report).
| Energy Range | Initial versus target uncertainties (%) |
| | Initial | SFR | ADMAB | VHTR | PWR |
| | | λ=1 | λ≠1,a | λ≠1,b | λ=1 | λ=1 | λ≠1,a | λ=1 | λ≠1,a |
|
| 0.498 - 1.35 MeV | 32 | 14 | 15 | 13 | 8 | | | | |
| 183 - 498 keV | 21 | 11 | 11 | 10 | 7 | | | | |
| 0.10 - 0.54 eV | 7 | | | | | 2 | 3 | 3 | 4 |
Justification document:
OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).
Comment from requester:
Given the present state of knowledge the above target accuracies are very tight. However, any attempt that significantly contributes to reducing the present accuracy for this quantity is strongly encouraged. Any such attempt will significantly enhance the accuracy with which reactor integral parameters may be estimated and will therefore impact economic and safety margins.
Review comment:
See appendix A of the attached report.
Entry Status:
Work in progress (as of SG-C review of May 2018)
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Theory/Evaluation
- H. Derrien et al., Reevaluation and Validation of the 241Pu Resonance Parameters in the Energy Range Thermal to 20 eV, NSE 150 (2005) 109
- Pu-241 evaluation was proposed to be part of INDEN (CIELO follow-up) initial program of work (as of Dec. 2017)
Validation
Additional file attached:SG26-report.html
Additional file attached:
| Request ID | 35 |
Type of the request | High Priority request |
| Target | Reaction and process | Incident Energy | Secondary energy or angle | Target uncertainty | Covariance |
| 94-PU-241 | (n,f) SIG | 0.5 eV-1.35 MeV | | See details | Y |
| Field | Subfield | Date Request created | Date Request accepted | Ongoing action |
| Fission | Fast and Thermal Reactors | 04-APR-08 | 12-SEP-08 | Y |
Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email: massimo.salvatores@cea.fr
Project (context): NEA WPEC Subgroup 26
Impact:
Distinct requests for this fission cross section are made at higher energies for fast reactor applications and also at lower energies for thermal reactor applications. Requested accuracy is required to meet target accuracy for k-eff for the GFR, SFR, LFR and ABTR and to meet k-eff and burnup for EFR. Requested accuracy is also required to meet target accuracy for k-eff for the VHTR and k-eff and burnup for the PWR. Details are provided in the OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (Final Draft attached).
Accuracy:
Target accuracies are specified per system and per energy group when they are not met by the BOLNA estimate of the current (initial) uncertainties. The weighting factor λ is explained in detail in the accompanying document. Changes from the reference value of λ=1 show the the possible allowance for other target uncertainties. Two cases (A and B) are distinguished for λ≠1 (see Table 24 of the report).
| Energy Range | Initial versus target uncertainties (%) |
| Initial | ABTR | SFR | EFR | GFR | LFR | ADMAB | VHTR | EPR |
| | λ=1 | λ≠1,b | λ=1 | λ≠1,b | λ=1 | λ≠1,a | λ=1 | λ=1 | λ=1 | λ=1 | λ≠1,a | λ=1 | λ≠1,a |
|
| 0.498 - 1.35 MeV | 17 | 12 | 9 | 3 | 3 | 8 | 7 | 4 | 4 | 2 | | | | |
| 183 - 498 keV | 14 | 9 | 7 | 3 | 2 | 7 | 6 | 3 | 3 | 2 | | | | |
| 67.4 - 183 keV | 20 | 9 | 7 | 3 | 2 | 6 | 5 | 3 | 3 | 2 | | | | |
| 24.8 - 67.4 keV | 9 | | | 3 | 3 | 6 | 6 | 3 | 3 | 2 | | | | |
| 9.12 - 24.8 keV | 11 | | | 4 | 3 | 7 | 6 | 3 | 4 | 2 | | | | |
| 2.03 - 9.12 keV | 10 | | | 5 | 5 | 8 | 7 | 2 | 5 | 2 | | | | |
| 0.454 - 2.03 keV | 13 | | | 4 | 4 | 7 | 6 | 3 | | 3 | | | | |
| 22.6 - 454 eV | 19 | | | 9 | 8 | | | 5 | | 7 | 6 | 8 | 5 | 6 |
| 0.54 - 4.00 eV | 27 | | | | | | | | | | 9 | 12 | 8 | 10 |
Justification document:
OECD/NEA WPEC Subgroup 26 Final Report: "Uncertainty and Target Accuracy Assessment for Innovative Systems Using Recent Covariance Data Evaluations" (link to WPEC Subgroup 26 Report in PDF format, 6 Mb).
Comment from requester:
Given the present state of knowledge the above target accuracies are very tight. However, any attempt that significantly contributes to reducing the present accuracy for this quantity is strongly encouraged. Any such attempt will significantly enhance the accuracy with which reactor integral parameters may be estimated and will therefore impact economic and safety margins.
Review comment:
See appendix A of the attached report.
Entry Status:
Work in progress (as of SG-C review of May 2018)
Main references:
Please report any missing information to hprlinfo@oecd-nea.org
Experiments
- F. Tovesson, T.S. Hill, Cross Sections for 239Pu(n,f) and 241Pu(n,f) in the Range En = 0.01 eV to 200 MeV, Nuclear Science and Engineering 165 (2010) 224, EXFOR 14271
- V.V. Desai, Determination of 241Pu(n,f) cross sections by the surrogate-ratio method, PRC 87 (2013) 034604, EXFOR 33053
Theory/Evaluation
- H. Derrien et al., Reevaluation and Validation of the 241Pu Resonance Parameters in the Energy Range Thermal to 20 eV, NSE 150 (2005) 109
- Pu-241 evaluation was proposed to be part of INDEN (CIELO follow-up) initial program of work (as of Dec. 2017)
Validation
Additional file attached:SG26-report.html
Additional file attached: