Q: What is the status of the nuclear reactors?
A: There are nine units under states of emergency — three at Fukushima Daiichi, three at Fukushima Daini and three at Onagawa. All are north-northeast of Tokyo, along the eastern coast, and all are boiling-water reactors. Most concern has been directed at Daiichi units 1, 2 and 3.
Q: What are the worries?
A: An explosion today at Unit 2 may have damaged a reactor’s containment vessel, leading to a radiation leak. Emergency personnel were evacuated. At Unit 1, which began operating in 1971, workers were trying to prevent a meltdown, complicated by the fact that a need to release a pressure buildup in the reactor vessel led to a hydrogen explosion that blew off the roof and walls of the containment building. On Monday, a hydrogen explosion also hit Unit 3. Officials were using seawater to cool the units.
Q: What is the significance of using seawater?
A: Using it is a desperation move. It assures that these very expensive reactors will never be used again to generate power. The salty seawater, accompanied by a boron mix, is very corrosive.
Q: What is the situation at the nearby Fukushima Daini and Onagawa facilities?
A: Officials say units 1, 2 and 4 at Fukushima Daini were experiencing increased pressure inside their containment vessels and equipment failures. As of late Sunday, there are states of emergency at each of the three reactors at the Onagawa site. Officials have said only that they’ve detected higher-than- permitted radiation levels there.
Q: Any indications of radiation exposure to humans yet?
A: Of the more than 180,000 people evacuated from around the two Fukushima complexes, up to 160 may have been exposed. Thyroid cancer is the most immediate risk, and the Japanese government is handing out pills to help prevent it. Officials have told people still in the area to wear masks, which can keep radioactive particles from being inhaled. Of greater concern is the possibility that some cesium may have been released — a sign that the reactor rods may be damaged or melting. Cesium is absorbed throughout the body — not just by the thyroid — and stays in organs, tissue and the environment much longer. Cesium particles are relatively large and heavy, so they probably would not travel far in a plume. Most would drop near the reactor site.
Q: What is the worst-case scenario?
A: The attempts to cool the reactors fail, resulting in meltdowns and widespread radioactive contamination. If that occurs, everyone will be hoping the wind blows east, into the Pacific, as it usually does.
Q: The best-case scenario?
A: Officials gain complete control of the temperature and pressure at the troubled reactors; then conditions will need to improve enough so it will be safe for workers to get close to assess the damage and restore normalcy.
