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Analysis of excursions at selected in situ uranium mines in Wyoming and Texas. [Case studies]

Technical Report ·
OSTI ID:5712867

Intensive research and development of in situ uranium mining took place in the United States during the 1970s. By the end of the decade, nearly 10% of all uranium production came from in situ mines. Recent poor market conditions, however, forced the closure of all domestic in situ uranium mines. When market conditions improve, domestic in situ mining is expected to make a modest recovery. Successful licensing of future in situ mines will depend to a large extent on the ability to contain the leach solutions (lixiviant) within the ore zone. Uncontrolled movement of lixiviant beyond the ore zone is called an excursion. The industry has demonstrated the capability to reduce, monitor, and control lateral excursions in an ore zone aquifer. On the other hand, vertical excursions of lixiviant migrating into an overlying aquifer through poorly plugged exploration holes continue to plague the industry. This paper summarizes the history of excursions at selected in situ mines in the United States and discusses methodologies for excursion identification and control. The incidence of vertical excursions can be significantly reduced by certifying well field units through field-wide testing of the ore zone aquifer prior to the injection of lixiviant. An overlying aquifer can be effectively monitored for excursions by periodically analyzing fluids in observation wells for nonreactive ionic species common to the lixiviant. These ions would necessarily have low probabilities of naturally exceeding a given concentration, referred to as an upper control limit. A mining unit would require recertification after each vertical excursion.

Research Organization:
Oak Ridge National Lab., TN (USA)
DOE Contract Number:
AC05-84OR21400
OSTI ID:
5712867
Report Number(s):
NUREG/CR-3967; ORNL/TM-9956; ON: TI86012486
Country of Publication:
United States
Language:
English