Comparison of the Classification of Radioactive Waste in Japan and the U.S.

Japan and the U.S. have established authorities that control the handling and clearance of radioactive waste. The disposal facilities in these two countries receive radioactive waste according to the categories of the waste. However, one distinct difference in the classification schemes is that the U.S. system has more categories than the Japanese system, which has only two categories. In addition, the basis of the formation of the classes differs between the two countries. In Japan, the first two categories are based on the amount of activity present in the wastes while the subdivisions of the second category are based on the source of the wastes.

In the U.S., conversely, there is no distinct basis for the formation of the classes. Some of the classes are formed according to the source of waste while others are formed based on methods of disposal, transportation, and worker hazards. Similarly, other classes are formed based on the extent of radioactive decay while others are founded on the half-lives of the materials. Instead of laying down a common basis for the classification system, the U.S. scheme has certain classes that share one base and others that share a different basis. Therefore, there exist ‘orphan wastes,’ which are wastes that fail to fit any given category due to inadequacies in the classification system.

Lowenthal comments that some of the problematic materials in nuclear management (wPu and depleted uranium) have not been classified as wastes thereby introducing flaws in the US classification system (12). According to the U.S. Department of Energy, these substances belong to a category named ‘materials not considered as waste’ (MNCAW). In contrast, the Japanese system is well organized and does not contain classes that overlap or omit certain substances from the classification system. Therefore, each waste type can be directed to a waste management facility that is equipped to manage it safely.