Precision requirement of the photofission cross section for the nondestructive assay

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 235U and 238U 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%.