NDA MEASUREMENT FOR MATERIAL IN DRY-VACUUM TRAPS

摘要

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.