Natural radioactive material under the ocean floor scarcely has moved upward in a half-million years, a study showed Wednesday, lending support to advocates of deep-sea disposal of nuclear waste.
British researchers said their study of the radioactive decay of naturally occurring uranium deposits about 75 feet to 80 feet deep in the North Atlantic Ocean bed found most of the radioactive material was "remarkably immobile" over the past 500,000 years. The only exception was radium 226, and even that had not moved beyond the uranium-bearing layers into upper sediments where it could come in contact with marine organisms.Some experts have suggested that instead of burying high-level radioactive waste in steel canisters deep below the ground, it might be better to bury such wastes in similar canisters about 90 feet below the ocean floor. They contend this would provide an extra layer of protection from the food chain and prevent humans from encountering releases of harmful radiation.
However, concern has been raised about how effective barrier ocean sediments would be against the possible upward migration of radioactive material, which can take hundreds of thousands of years to decay.
In a study published in the journal Nature, Sarah Colley and J. Thomason of the Institute of Oceanographic Sciences in Godalming, England, said it appears to be the geochemical conditions of the ocean floor sediments, rather than how natural radioactive material is incorporated into rocks, that immobilizes the uranium and its radioactive byproducts.