Requester: Prof. Massimo SALVATORES at CADARACHE, FR
Email:

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).

The request for the improved cross section and uncertainties for ²³⁸Pu(n,f) emerges for five of the eight cases studied. The most stringent requirements for this case arise from the SFR, LFR and ADMAB.
Improvements of the nuclear data for ²³⁸Pu(n,f) are important for estimates of k_eff for the SFR, LFR, ADMAB and GFR (in order of significance), the peak power of ADMAB and the void coefficient of an SFR.

Requested accuracy is required to meet target accuracy for burnup for an Accelerator-Driven Minor Actinides Burner (ADMAB). Details are provided in the SG-26 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.

Energy Range	Initial versus target uncertainties (%)
	Initial	SFR	EFR	GFR	LFR	ADMAB
2.23 - 6.07 MeV	21	6		7	8	7
1.35 - 2.23 MeV	34	6	24	8	7	6
0.498 - 1.35 MeV	17	3	10	5	3	3
183 - 498 keV	17	4	12	6	3	4
67.4 - 183 keV	9	5			5
24.8 - 67.4 keV	12	6		7	6
9.12 - 24.8 keV	11	7		7	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:

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