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 Range	Initial versus target uncertainties (%)
	Initial	ABTR			SFR			EFR		GFR		LFR		ADMAB		VHTR
		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.

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