The use of nuclear devices in weapons is the primary cause of radioactive fallout, although the nuclear accident at Chernobyl and various volcanic eruptions have also contributed. Tritium (3H) and several isotopes of iodine, cesium and strontium are found in the environment largely because of nuclear testing. In the United States, most radioactive waste is a by-product of nuclear weapons production. It is estimated that 70% of U.S. radioactive waste results from defense department activities (Eisenbud 1987). The DOE is currently trying to remedy many defense sites due to past poor waste management practices.
■>. Represents discontinued or future activities Represents current activities
NRC for release to the environment. Processing rare-earth containing ores produces concentrated waste high enough in radioactivity to be disposed of as low-level radioactive waste. If monazite ore is the rare-earth source, nearly one ton in ten must be disposed of in this manner. Disposal costs have dramatically reduced imports of monazite (Table 11.22.1).
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