In Situ Recovery Facilities
In situ recovery (ISR) is one of the two primary extraction methods that are currently used to obtain uranium from underground. ISR facilities recover uranium from low-grade ores where other mining and milling methods may be too expensive or environmentally disruptive. This method uses the following process, as illustrated in the figure to the right:
A solution called lixiviant (typically containing water mixed with oxygen and/or hydrogen peroxide, as well as sodium carbonate or carbon dioxide) is injected through a series of wells into the ore body to dissolve the uranium.
The lixiviant is then collected in a series of recovery wells, through which it is pumped to a processing plant, where the uranium is extracted from the solution through an ion-exchange process.
The uranium extract is then further purified, concentrated, and dried to produce a material, which is called "yellowcake" because of its yellowish color.
Finally, the yellowcake is packed in 55-gallon drums to be transported to a uranium conversion facility, where it is processed through the stages of the nuclear fuel cycle to produce fuel for use in nuclear power reactors.
About 12 such ISR facilities exist in the United States. (For details, see Locations of Uranium Recovery Facilities.) Of these, the U.S. Nuclear Regulatory Commission (NRC) regulates four facilities in the Western States, and conducts routine annual inspections to ensure that they are safely operated. (These relatively infrequent inspections reflect the fact that these sites have experienced few safety violations, all of which have been relatively minor.) The remaining ISR facilities are licensed by Agreement States, which have entered into strict agreements with the NRC to exercise regulatory authority over such facilities and the materials they produce.