PNNL

Abstract

A methodology to non-invasively characterize the Tc-99 inside the equipment at the Portsmouth Gaseous Diffusion Plant was developed. The sensitivity of the approach was examined through critical benchmarking measurements and computer simulations. From comparison of the measurements and computer simulations, uncertainties in the computer simulations of these processes were established. The study results have shown that, given simplified geometries of pipe wall and deposit materials, that the Tc-99 bremsstrahlung can be used to characterize the level of contamination of Tc-99 in a uranium deposit assuming uniform distribution of Tc-99 in the deposit. In addition, the sensitivity of the approach is adequate to address worker safety limits based on calculations from the derived air concentrations. It is anticipated that the technique will be most successful in thin-walled containers, such as aluminum bellows or copper tubing. The reliability of the approach needs to be tested by conducting in situ measurements of known quantities of Tc-99 contamination.