October 25, 2014
The Latest From Japan’s Nuclear Disaster
Posted on Mar 12, 2011
For the very latest, watch the live stream from Japanese television below.
Update, Tuesday, March 15: Wednesday (Japan time), multiple news services reported that Japanese officials had withdrawn all emergency workers from the Fukushima Daiichi nuclear power plant. Meanwhile, the Nikkei.com news service reported that officials now estimate that 70 percent of the fuel rods at the Unit 1 reactor core were damaged, with damage to approximately 33 percent of the fuel rods in the Unit 2 reactor core also reported.
According to the NHK TV News channel, around 10:30 a.m. Japan time on Wednesday, white smoke or steam poured from one of the damaged reactor buildings. At the same time, radiation levels within the plant went rose significantly, into the low millisievert-per-hour range. The plant’s operator could not confirm the origin or nature of the cloud, but said that supervisors had withdrawn their workers as a result of the radiation spike. Radiation levels began to drop after the initial spike. It was not immediately clear when workers would return to the plant. Commentators and officials speculated that the cloud could have come from either the Unit 4 waste pool or the Unit 2 reactor building.
Update, Tuesday, March 15: The fire is reported as no longer “visible” at Unit 4. That is significant because of the danger of an active fire at the fuel pool.
Update, Tuesday, March 15: At 5:45 a.m. Wednesday (Japan time) a new blast and fire were reported in the waste storage area in the Unit 4 reactor containment building at the Fukushima Daiichi reactor facility. The Unit 4 reactor had been offline for maintenance before the earthquake, but extremely radioactive nuclear waste was stored in the building above the reactor core. Like the cores, that waste requires constant water cooling, but unlike the cores it is not contained within a hardened metal pressure vessel. The blasts are believed to have been caused by hydrogen byproducts that are safely suppressed during normal plant operations.
Square, Site wide
The Japanese government immediately expanded the exclusion zone to 30 kilometers around the plant. Individuals in that zone were told to either evacuate or stay indoors with the windows closed and the air conditioning off.
Recap, Tuesday, March 15:
Update, Monday, March 14: The owner of the Fukushima plant reported that a blast was heard Tuesday (local time) at the building containing the stricken Unit 2 reactor. The blast, which followed explosions at Unit 1 and Unit 3, may have occurred near the suppression pool at the bottom of the reactor assembly. The atmospheric pressure in the pool dropped suddenly, indicating that the pool’s casing may have cracked or otherwise been damaged.
Japanese channel NHK reported that noncritical workers at the Unit 1 and Unit 3 reactors were being evacuated, at least temporarily. The plant operator said that water injection efforts would continue as efforts were made to cool the three damaged reactor cores.
There were no reports of visible damage to the Unit 2 building, but local radiation levels increased, leading to the staff evacuation.
Update, Monday, March 14: Clarification: British Nuclear Fuels Ltd. became defunct in 2010. Since then French nuclear firm AREVA has replaced it as a major foreign supplier of nuclear fuel.
Update, Sunday, March 13: A large explosion has occurred at the Unit 3 reactor at Japan’s Fukushima nuclear power plant. The explosion included a large orange flash, which indicates that it was probably the result of a hydrogen detonation. This explosion follows the partial destruction of the Unit 1 containment building in a previous hydrogen explosion. [See video of the explosion here]
The Washington Post reports that Japanese nuclear officials have resorted to using fire pumps to inject tens of thousands of gallons of seawater directly into the reactors at two Fukushima nuclear power complexes. This emergency action has been undertaken to control what is now being described as a “partial meltdown” of at least two reactor cores.
Reports said that Japanese nuclear officials believe the inner containment vessel of the Unit 3 reactor was still intact after the explosion. The danger posed by a containment breach at the Unit 3 reactor is especially serious because the reactor was recently fueled with a semi-experimental MOX nuclear fuel, which is a combination of plutonium oxide and the more common uranium oxide. Plutonium is considered a substantially more dangerous nuclear fuel, and the Japanese MOX program was delayed for more than a decade because of local opposition and the revelation that the British fuel manufacturer, British Nuclear Fuels Ltd., had falsified safety reports in the late 1990s.
Dramatic and conflicting reports emerged Saturday regarding the safety status of the Unit 1 reactor at Japan’s Fukushima Daiichi power plant.
The news aggregator Drudge Report linked to a story in the Japanese press that said the explosion that destroyed the reactor’s outer containment building “could only have been caused by a meltdown of the reactor core.” The Japanese article said the source of the report was the Japanese Nuclear and Industrial Safety Agency.
Some websites and blog posts criticized the article, saying it was either the result of “hysteria-driven journalism” or old information.
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