A concept for quantitative NDA measurements of advanced reprocessing product materials

As new reprocessing methods for spent nuclear fuel are developed, such as the uranium extraction (UREX) process, methods using nondestructive assay (NDA) techniques must also be developed to allow for quantitative measurements of product materials. Currently developed NDA techniques cannot directly quantify materials containing U, Np, Pu, and Am. This research investigates the ability to quantify these actinides in an oxide form using neutron multiplicity measurements. This technique assumes that the isotopic composition of the sample is known, either through gamma spectroscopy or other means. This measurement technique is based on performing three different neutron measurements and analyzing their neutron multiplicity response. The first is a passive measurement of the product material to determine the effective plutonium-240 (240Pueff) content, self multiplication (M), and alpha-neutron reaction rate (α). The second is an active, AmLi (α, n) source, measurement of the product material to determine the effective 235U content. The third is an active, AmB (α, n) source, measurement of the product material to determine the effective 237Np content. The quantity of Am in the sample can be determined from α. Simulated results using Monte Carlo N-Particle eXtended (MCNPX) version 2.6 will illustrate the viability of this technique and its practical limitations. (author)