Fukushima

UPDATE, 1 pm, Sunday, The International Atomic Energy Agency reports that a first-level (lowest-level) emergency has been declared at the three-unit Onagawa nuclear station north of Fukushima. Immediately after Friday’s earthquake a fire broke out at this facility, but it was said to have been extinguished fairly quickly. However, on Saturday, elevated radiation levels were measured at the Onagawa site (about 10 microSievert/hour or about 1 millirem/hour) for a few hours. The emergency was declared due to these elevated levels, but utility officials say the reactors there are under control.

Statement of Citizens’ Nuclear Information Center,

UPDATE, 3:25 pm, Saturday, The International Atomic Energy Agency reports that a total of 140,000 people have now been evacuated from zones 20 kilometers around Fukushima Daiichi and 10 kilometers around Fukushima Daini. The IAEA says that evacuation has not been completed.

UPDATE, 1:45 pm, Saturday, It is being reported that Japanese authorities are preparing to distribute potassium iodide to the public in the most affected zones. This helps protect against thyroid cancer caused by exposure to radioactive Iodine-131. The release of Iodine-131 to the environment indicates melting of reactor fuel.

UPDATE, 1 pm, Saturday, World Nuclear News is reporting that a worker who was apparently trapped in the exhaust stack of Unit 1 at Fukushima Daiichi has died. Tokyo Electric Power Co. (Tepco) has announced that it will begin venting the containments of three of the four reactors at the Fukushima Daini site in an effort to reduce pressure inside those containments. This will cause additional radiation releases to the air. Evacuation of a threekilometer zone around the Daini site has begun; people from 3 to 10 kilometers from the site are being told to take shelter indoors and have been notified that they may be asked to evacuate.

UPDATE 12:30 pm, Saturday, Japanese government officials state that radiation levels at the Fukushima Daiichi site have decreased from 1015 micro/Sieverts per hour to about 70 microSieverts/hour. There is no independent confirmation of these levels. Officials state that the primary containment remains intact.

UPDATE, 11:30 am, Saturday, Official reports are that radiation levels have decreased from those reported below; however radiation monitoring systems are either still down or not available to the public.

UPDATE, 9:30 am, Saturday, An explosion has occurred at Fukushima Daiichi Unit 1. Video of the aftermath of the explosion shows that the containment building has been destroyed. In a General Electric Mark I reactor, the containment building is fairly weak and is considered the secondary containment. The primary containment is a steel liner that surrounds the reactor core. So far, video and photos have not been clear enough for us to determine whether this steel liner is intact.

UPDATE, 8 pm, Friday, Venting of the containment began at Fukushima Daiichi Unit 1 around 9:00 am Tokyo time. This will release some radiation into the air. Because radiation monitors at the site are inoperable (see below), it will be impossible to know how much radiation is being released.