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

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wastes (Deese 1976). This treaty is currently being revised to deal more specifically and
completely with the problem of dumping low-level and some TRU wastes. This treaty arguably
does not preclude the controlled emplacement of high-level wastes or spent fuel into
geologic formations beneath the ocean floor. However, the intended prohibition of the
treaty would require clarification.
Subseabed disposal might offer the important political advantage of not directly
impacting any nation, state, or locality. Likewise, the alternative might have the
disadvantage of incurring risk to nations that do not realize the benefits of nuclear power
generation.
Assuming that the real impact uncertainties associated with the subseabed concept were
resolved, the primary political disadvantage of subseabed disposal would be its possible
perception as an ecological threat to the oceans. If publics, governments, and
international agencies were to view such disposal as merely an extension of past ocean
dumping practices, implementation would be difficult if not impossible. However, if this
option were understood as involving disposal in submarine geolgoic formations that have
protective capacities comparable to or greater than similar formations on land, opposition
might be less.
6.1.4.5 Potential Impacts Over the Long Term (Postemplacement)
Potential Events
Earthquakes, volcanic action, major climatological and circulational changes, and
meteorite impacts are examples of natural processes that might affect subseabed containment
stability. Careful selection of the ocean area would minimize the probability of the first
three events occurring. There is no known method of minimizing the probability of
meteorite impact other than concentrating emplacement, which, while reducing the random
target area, would correspondingly increase the potential consequences if a meteorite did
strike. On the other hand, other damage caused by any meteorite that could penetrate 5 km
(3 mi) of water would make the release of emplaced radioactive waste insignificant.
For HLW disposed of in a subseabed repository, a very low probability for criticality
is assumed because of the great distances between canisters at the bottom of the sea. For
spent fuel, the probability of criticality might be somewhat greater because of the higher
fissle content of a single canister.
Since the site would be located in a part of the ocean with no known materials of
value, future human penetration would be highly unlikely.
Potential Impacts
Two models have been developed by Grimwood and Webb (1976) to characterize the
physical transport and mixing processes in the ocean, as well as incorporation in marine