NDA MEASUREMENT FOR MATERIAL IN DRY-VACUUM TRAPS

A non-invasive method is needed to measure the uranium content in material caught in traps that are part of dry vacuum systems at the Y-12 National Security Complex. Given the size of the traps and the apparent density of the material in the traps, it appears that a radiation attenuation measurement can be used to estimate the amount of uranium in these traps. Early calculations indicate that a 22Na source can be used to estimate the amount of uranium in a trap if the matrix material is composed of low Z elements. Absorption rates for the 511-keV and 1275-keV gammas emitted from 22Na will be measured. Calculations indicate that the absorption of the 511-keV gammas will be more sensitive to changes in the matrix to uranium ratio than the absorption of the 1275-keV gammas. Calculations also indicate that changes of the matrix composition have little effect on the absorption of any of the 22Na gammas as long as the matrix material contains elements with a Z of less than 50. Results of the calculations and a proposed instrument design are presented.