Plutonium mining for cleanup.

Abstract

Cleanup is the act of making a contaminated site relatively free of Pu so it may be used without radiological safety restrictions. Contaminated ground is the focus of major cleanups. Cleanup traditionally involves determining Pu content of soil, digging up soil in which radioactivity exceeds guidelines, and relocating excised soil to a waste-disposal site. Alternative technologies have been tested at Johnston Atoll (JA), where there is as much as 100,000 m3 of Pu-contaminated soil. A mining pilot plant operated for the first 6 mo of 1986 and made 98% of soil tested "clean", from more than 40 kBq kg-1 (1000 pCi g-1) to less than about 500 Bq kg-1 (15 pCi g-1) by concentrating Pu in 2% of the soil. The pilot plant is now installed at the U.S. Department of Energy Nevada Test Site for evaluating cleanup of other contaminated soils and refining cleanup effectiveness. A full-scale cleanup plant has been programmed for JA in 1988. In this paper, previous cleanups are reviewed, and the mining endeavor at JA is detailed. "True soil cleanup" is contrasted with the classical "soil relocation cleanup." The mining technology used for Pu cleanup has been in use for more than a century. Mining for cleanup, however, is unique. It is envisioned as being prominent for radiological and other cleanups in the future.