Management of Commercially Generated Radioactive Waste - U.S. ...

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may be conveniently divided into surface and subsurface events. Surface operating accidents
would include pipe ruptures and spills, failure of transfer or injection pumps, and loss of
necessary cooling to the storage tanks. To minimize risk, normal nuclear engineering design
strategies would be required, with redundancies incorporated into all critical systems and
components (for example, pumps, power supply, and monitoring equipment). Subsurface acci-
dents, for which contingency plans would have to be prepared, would include well-pipe
rupture, equipment failures, uncontrolled fracture development (shale grout injection), and
penetration of waste through the containment formation due to highly permeable features,
abandoned or poorly sealed wells, or exploration or monitoring of drill holes. Site explora-
tion and analyses would be directed toward minimizing the probability and the effects of
subsurface failures.
Presently, there are no quantitative estimates of the radiological impacts of such acci-
dents to occupational personnel, nonoccupational personnel, or the ecosystem. Furthermore,
since the waste would be in a nonsolid form for well injection, the radiological impacts are
not expected to be similar to those resulting from accidents at a mined geologic repository.
Nonradiological Impacts. Little formal study has been completed on the nonradiological
health effects of the well injection disposal process. In general, predisposal activities,
such as fuel handling, storage, transportation, and reprocessing, for both reference concepts
would be the same as for a mined geologic repository. Pretreatment of the disposal formation
with acid, however, might be required. Although potential impacts have not been quantita-
tively assessed, it can be concluded that nonradiological health effects would result from
handling this hazardous material.
Because wastes injected into the wells would have to be in liquid or grout form, two
important differences are anticipated between well injection and mined geologic disposal.
First, the well injection disposal site would have to be at the same place as the reproces-
sing facility. Colocating these facilities would minimize the transportation requirements
and associated risks. It would also reduce some of the nonradiological impacts associated
with transportation activities.
Second, well injection would involve surface and subterranean activities with different
hazards than those associated with mined geologic disposal--formation drilling and fractur-
ing, compared to large-scale excavation, are the principal below-ground activities that could
lead to nonradiological health impacts. Preparing the wastes for disposal would involve
facilities designed to mix the wastes with clay, cement, and other additives for the shale-
grout method. For the liquid injection process, more limited mixing facilities would be
needed. In either case, studies completed to date have not identified significant nonradio-
logical impacts for these activities under routine operating conditions. Under abnormal
conditions, pipe ruptures and spills, failure of injection pumps, and other problems dis-
cussed under radiological impacts could lead to nonradiological impacts as well.