Disposing of nuclear wastes under the sea

Press, 28 November 1980, Page 12

Disposing of nuclear wastes under the sea

The American Department of Energy has quietly changed its priorities on the burial of atomic wastes. Most experts agree that the best burial sites for highly radioactive wastes are on land, deep underground within stable geological formations. The trouble is the public strongly disagrees: nobody wants the waste beneath his own back garden. Unless there is a dramatic — and unlikely — change in public opinion, each candidate site for a land-based, nuclear-waste repository will face a long slog through a judicial jungle.

From the “Economist,’’ London.

So the American authorities have now promoted the alternative option of burial at sea into its major and “preferred” long-term solution. Suddenly, the results of technical studies into the seabed option, set in train some years ago, have acquired unexpected significance. Hashed over at a recent conference in Washington. D.C., these results suggest that a lot more work will have to be done — and awkward international political hurdles cleared — if. as the Americans hope, the oceans are to be used as the main repo-

sitory for high-level waste from the late 1990 s onward. The idea of oceanic disposal has attractions. Particularly during the early years of storage, radioactive decay of nuclear waste generates a lot of heat. iMarine sediments could absorb this reasonably well. More important, if, eventually, radioactive material escaped from the protective canisters housing the waste, the sediments might trap most of it in their own crystal structures. Red clay looks promising as a natural trap. (Clays also have the attraction of “healing” themselves if cracked by minor earth tremors). Finally, if some radioactive material did

escape, it would be dilluted and dispersed in the vastness of the oceans’ waters. However, there are problems to be solved. One is how best to bury the waste canisters: ideally. they should be sunk at" least 50100 metres below the level of the ocean floor. Do you dredge and refill burial sites? Can you shape your canisters like darts so that they burrow deep into sediments when dropped from a ship? Both approaches are being explored. Then there is the problem of finding suitable sites: ones well away from any areas with a record of seismic or volcanic activity, fre-* from erosion by cur-

rents and (so far as Wat can be foretold) devoid of significant economic potential. Results from the small number of sites investigated so far in the Atlantic and Pacific suggest that the best bet lies in the red clays of the so-called abyssal plains, nt the floor of the deep ocean. The slopes where the American continental shelf dips down to the plains are clayey but subject to erosion and" other instabilities. Awkwardly, under the present international rules (the London Dumping Convention which came into force in 1975), burial of high-level wastes at sea is ruled out even in territorial

waters —- let alone in the international waters in which the abyssal plains lie. Only (restricted) dumping of low-level wastes is permitted. If further research confirms the initial indications that burial of highlevel wastes in the deep ocean is feasible, the Americans and others with loom* ing disposal problems (e.g., the British) will have to try to change the rules. That will not be easy. Environmentalist pressures are not confined to domestic politics. Already, the Scandinavians have come out against any dumping at sea. The future looks full for international lawyers and diplomats.