A HIGH-PERFORMANCE, LOW-DENSITY WASTE ASSAY SYSTEM*

Year
1988
Author(s)
Norbert Ensslin - Los Alamos National Laboratory
S.C Bourret - Los Alamos National Laboratory
T.K. Li - Los Alamos National Laboratory
James K. Sprinkle - Los Alamos National Laboratory
S.M. Simmonds - Los Alamos National Laboratory
J.L. Parker - Los Alamos Scientific Laboratory
L.R. Cowder - Los Alamos Scientific Laboratory
M.N. Hykel - Los Alamos National Laboratory
Abstract
We have developed a high-performance, low- density waste assay (LDWA) system for determining uranium content in low-density, low-Z waste mate- rials within a short count time (typically, 120 s) and for detection of any uranium lumps that might exist in waste boxes. The LDWA system employs a far-field gamma-ray spectroscopy tech- nique. The amount of 235y ^s determined by ana- lyzing the 185.7-keV gamma ray from the waste box, which will be rotated during assay to smooth the spatial response. The detector is a high- resolution, high-purity germanium N-type coaxial unit. For a 120-s count time, the detection sensitivity of the LDWA is 0.03 g 235U and the precision (la) for a 1.7-g ^35jj sampie is 4.0%. The assay accuracy arising from the effect of the vertical position of uranium is