A discussion of health risks associated with conversion of depleted UF6 to another chemical form.
General Health Risks of Conversion
The potential environmental impacts, including potential health risks, associated with conversion activities will be evaluated in detail as part of the Depleted Uranium Hexafluoride management program after a contract is awarded for conversion services. This section discusses in general the types of health risks associated with the conversion process.
The conversion of depleted UF6 to another chemical form will be done in an industrial facility dedicated to the conversion process. Conversion will involve the handling of depleted UF6 cylinders. Hazardous chemicals, such as ammonia, may be required for the operation of the conversion plant, and hazardous chemicals, such as hydrofluoric acid, may be produced in the conversion plant. Handling such material potentially poses a risk from exposure to radiation and from chemicals released if an accident were to occur.
During normal operations, the risks from conversion would be limited to exposure to low levels of penetrating radiation in the vicinity of uranium compounds. The PEIS (Appendix F) analysis showed that such exposures would be expected to be quite low. In addition, exposures to hazardous chemicals during normal operations would be expected to be nonexistent or very low.
The PEIS evaluated a number of hypothetical accidents that could occur at a conversion facility for several different types of conversion processes. The potential accidents included cylinder spills, process pipe leaks, earthquakes, tornadoes, storage tank ruptures, as well as many others. In the PEIS, the conversion accidents estimated to have the largest potential consequences were accidents involving the rupture of tanks containing either anhydrous HF or ammonia. Such accidents could be caused by a large earthquake.
The probability of large earthquakes depends on the location of the facility, and the probability of damage depends on the structural characteristics of the buildings. In the PEIS, the estimated frequency of this type of accident was less than once in one million years. However, if such an extremely low frequency accident did occur, it was estimated that up to 41,000 members of the general public around the conversion facility might experience adverse effects from chemical exposures (mostly mild and temporary effects, such as respiratory irritation or temporary decrease in kidney function). Of these, up to 1,700 individuals might experience irreversible adverse effects (such as lung damage or kidney damage), with the potential for about 30 fatalities. In addition, irreversible or fatal effects among workers very near the accident scene would be possible. (Note: The actual numbers of injuries among the general public would depend on the size and proximity of the population around the conversion facility).
It should be noted that the PEIS analysis of accidents was based on representative plant designs and representative sites. Conservative assumptions were used so as not to underestimate potential impacts. The types of accidents and probabilities of their occurrence will depend on the specific designs and locations of the actual conversion facilities and will be evaluated thoroughly during the design and licensing process.
(For more details on risks from conversion, see also Appendix F of the PEIS.)