Monday, December 19, 2011
New major issues related to radioactive contamination have emerged in the Tokyo area.
A few days ago, Prime Minister Yoshihiko Noda of Japan declared an end to the most critical phase of the accident at Fukushima Daiichi nuclear power plant. However, many members of the public, including myself, think that the situation is far from being stable. I think that anything could happen. If another strong aftershock hits the plant, it will surely bring us to an unimaginable situation. I'm wondering what ulterior motives the government have. Anyway, whether or not the landmark accomplishment rings true, I appreciate that a lot of workers at the crippled plant have been striving to regain control.
In this declaration, the term "state of cold shutdown" was used. However, since the term was defined in July as a milestone in the process of regaining control, what the term "state of cold shutdown" indicates is different from what the general term "cold shutdown" indicates. Because of this, it has been pointed out that the term "state of cold shutdown" may give an exaggerated impression of stability. As it's pointed out in a NY times article in the link below, it seems that the government is expected to use vague terminology in order to give itself some wiggle room.
Anyway, in the Tokyo area, new issues have emerged. Due to the hydrogen explosions at the Fukushima plant, bewildering quantities of radioactive substances were released from the crippled plant in March. Specifically, radioactive cesium 137 (30-year half life. In other words, it takes 30 years for cesium 137 to decay by half) and cesium 134 (2-year half life) are always on the table to discuss. These two kinds of cesium have been widely spread out. The cesium is washed away by rain, but won't disappear. It means that the cesium just travels from place to place.
In the Tokyo area, there are some areas where soil contamination levels of the cesium are relatively high. The contaminated areas have a large population. Almost all the roads are asphalted there. In the newly developed areas, urban drain systems are well designed. Unfortunately, these factors have created highly contaminated spots. Specifically, the cesium on asphalted roads is easily washed away by rain and the well designed drain systems effectively transfer the cesium to one specific spot, and as a result, the cesium ends up being concentrated there. Another major issue that has emerged is highly contaminated incinerator ash. In the Tokyo area, many incinerators are well designed to reduce the amount of incinerator ash. The high-tech incinerators have produced highly contaminated ash because they end up concentrating the cesium in the process. The ash is temporary stored in the incineration plants so far. However, it's predicted that the plants will be over capacity soon for the ash. The issue of how to deal with the ash remains unsolved.
