Year
1976
Abstract
A study to determine the feasibility of nondestructive assay (NDA) for residual fissile content in spent fuel\" assembly has been conducted. The conclusion of this study is that a direct NDA of LWR spent fuel assemblies is indeed feasible. The technique is based on inducing fissions in the material and the detection of the former by measurements of the prompt and possibly delayed neutrons. In order to achieve the latter the fission inducing source has to be removed. Two isotopic sources are readily available with the required intensities , ^52CF and 124Sb-Be. For the prompt neutron technique less than 100 yg of 252cf or 10 Ci of l24Sb-Be will be needed. For the delayed neutrons, because of the much poorer signal to background, sources' hundred times stronger are required. Typical measuring time for a LWR assembly would be a couple of hours and the estimated measurement error-mostly due to neutron self-whielding-could be less than 5%.