Site qualification plan for the Subseabed Disposal Program

In our evolving study to identify and examine sites in subseabed geological formations for use as repositories for high-level nuclear wastes, two primary criteria guide all phases of this work: the stability and barrier criteria of the site. The stability criterion defines areas of the seabed not likely to be disturbed by tectonic forces and oceanographic changes during the lifetime of a waste repository. The barrier criterion defines those subseabed geological formations most likely to form an effective barrier to the release of radionuclides. Because of the large area of the oceans, a phased approach has been adopted so that successively smaller areas of the seafloor can be studied in ever greater detail. The first phase, which is complete, has identified the abyssal clay deposits that are remote from tectonic boundaries and continental margins as being the regions (<10/sup 6/ km/sup 2/) on the seafloor within which acceptable sites might be most readily identified. The second phase involves downgrading less desirable areas within these regions using archived seismic reflection profiling, sediment cores, and oceanographic data. This winnowing process identifies locations about one degree square (≤10/sup 4/ km/sup 2/) for more detailed field studies during the first part of the third phase. From these locations candidate sites will be chosen, based on detailed geological and geophysical surveying. The second part of the third phase will involve detailed monitoring of the candidate sites to determine long-term baseline conditions. After monitoring is underway, a pilot repository will be established, using waste canisters