Precision requirement of the photofission cross section for the nondestructive assay

Rei Kimura,Satoshi Chiba,Hiroshi Sagara,A Plompen,S Oberstedt,J Heyse,P Siegler,W Mondelaers,S Kopecky,F.-J Hambsch,P Schillebeeckx

doi:10.1051/epjconf/201714609041

Abstract

Principle of the new NDA technique based on the photofission reaction rate ratio (PFRR) has been developed by Kimura et al for measurement of uranium enrichment by using the only relative measured counts of neutron produced by photofission reactions of 235 U and 238 U at different specific incident photon energies. In the past analysis, no attentions have been paid for relatively large uncertainty of photonuclear cross section of special nuclear materials around 10%. In the present paper, quantitative analysis was performed to reveal the impact of photonuclear cross section uncertainty to predicted value of the uranium enrichment by the PFRR methodology. And also, the requirement of photofission cross section precision was evaluated as less than 3%, to satisfy the uncertainty of PFRR methodology to within 5%.

Highlights

The nondestructive assay (NDA) techniques for quantifying special nuclear materials (SNMs) have been developed by many organizations and some of which have been successfully applied to uranium enrichment measurement [1,2,3,4,5,6,7,8,9]
Cross sections of the photonuclear reaction of interested nuclides relating to PERR have, in general, around 10% uncertainty, which may lead the huge impact to the accuracy of uranium enrichment measurement by the photofission reaction rate ratio (PFRR) methodology
Quantitative analysis was performed to reveal the impact of photonuclear cross section uncertainty to predicted value of the uranium enrichment by the PFRR methodology

Summary

Introduction

The nondestructive assay (NDA) techniques for quantifying special nuclear materials (SNMs) have been developed by many organizations and some of which have been successfully applied to uranium enrichment measurement [1,2,3,4,5,6,7,8,9]. Cross sections of the photonuclear reaction of interested nuclides relating to PERR have, in general, around 10% uncertainty, which may lead the huge impact to the accuracy of uranium enrichment measurement by the PFRR methodology. Quantitative analysis was performed to reveal the impact of photonuclear cross section uncertainty to predicted value of the uranium enrichment by the PFRR methodology. The requirement of photonuclear cross section precision was evaluated (1) Few self-generated neutron or photon emissions because of shielding (2) Difficulty of measurement because of intensive gamma-ray backgrounds (3) Low measurement reliability due to impurities and unknown information. The development of the compact and quasimonochromatic photon (X-ray) source generator has proceeded, which is expected to be realized as portable photon generator device with higher energy than the photonuclear threshold energy [11,12,13,14]. Its application is expected to be one of the NDA techniques

Principle of the NDA technique based on the Photofission reaction rate ratio

Calculation model and methodology

Estimation of the 235U enrichment based on the PFRR method

Conclusion

Implication of the photofission cross section uncertainty