Occupational Radiation Protection Aspects of Alkaline Leach Uranium in Situ Recovery (ISR) Facilities in the United States

In situ recovery or in situ leach (ISR/ISL) uranium facilities, also referred to in the past as "uranium solution mining" have operated since the late 1960s in the US and in recent years have accounted for over 70% of US production and, internationally, approximately half of worldwide uranium supplies. Note that throughout this paper, the uranium in situ recovery process, also known as in situ leach, will be abbreviated as "ISR." This paper presents a summary of the occupational radiation protection aspects of typical ISR processes being employed in the United States today that have traditionally used alkaline-based uranium recovery solutions known as lixiviants. The paper describes the health physics and associated monitoring programs necessary to adequately measure and control radiological doses to workers based on the radiological character of these processes. Although many radiological characteristics are similar to that of conventional mills, conventional-type tailings as such are not generated. However, liquid and solid by-product materials may be generated and impounded, which can result in sources of occupational exposure. Some special monitoring considerations are required due to the manner in which (222) Rn gas is involved in the process. The major aspects of the health physics and radiation protection programs that have been developed at these facilities over many years are discussed and listed in the Conclusion section of the paper.