DECONTAMINATION OF HEPA FILTERS.

Mound Facility, during many years of plutonium-238 experience, has recovered over 150 kg of plutonium-238. Much of this material was recovered from HEPA filters or from solid wastes such as sludge and slag. The objective of this task was to modify and improve the existing nitric acid leaching process used at Mound so that filters from the nuclear fuel cycle could be decontaminated effectively. Various leaching agents were tested to determine their capability for dissolving PuO//2, UO//2, U//3O//8, AmO//2, NpO//2, CmO//2, and ThO//2 in mixtures of the following: HNO//3-HF; HNO//3-HF-H//2SO//4; and HNO//3-(NH//4)//2Ce(NO//3)//6. Adsorption isotherms were obtained for two leaching systems. In some tests simulated contaminated HEPA filter material was used, while in others actual spent glovebox filters were used.