Apart from the more exotic approaches to waste disposal that have been mentioned before, shallow burial and sea disposal are widely used. Disposing of liquids into isolated aquifers or exhausted oil lenses has been mentioned as a special technique for tritium waste.

Burial grounds have become quite common, mainly in those countries where nuclear activities have a long history and originated in weapons research. The safety of this disposal technique is largely dependent on the type of soil, particular groundwater occurrence, and on the type of land use. Presently, a volume of over 200,000 m3 containing approximately 2 X 106 Ci of radioactivity including 80 kg of plutonium are disposed of in commercial burial grounds in the United States and about the same order of magnitude in burial grounds established by the former U. S. Atomic Energy Commission. Although this technique cannot be considered unsafe when properly conducted, some incidents of radionuclide migration resulting in off-site contamination have occurred. It is fair to say that shallow burial of non-high-level, non-alpha waste may be safe in remote areas, but these usually do not exist in Europe. The overall policy of establishing burial ground needs reconsideration.

The term sea disposal includes two basically different techniques, namely, disposal into coastal waters and deep-sea disposal. Deep-sea disposal may be perfectly safe if handled

2000 4000

Distance from center of repository, ft. (1000 ft. = 304.8 m)

Vertical Cross Section of Repository

(2)b: surface of container

End View of Burial Zone Side View of Burial Zone

for High-level Waste for High-level Waste

Figure 11.27 Schematic cross sections of proposed HLW repository. (From Cheverton and Turner [C1J.) responsibly. For certain types of waste that are difficult to deal with on land, such as bulky parts from decommissioning, it may even be the most appropriate technique. Deep-sea disposal has been practiced mainly under the supervision of international agencies. Disposal into coastal waters as practiced with non-high-level liquids from European reprocessing plants, however, is highly debated.