Tokyo Electric Power Co. reported at 3:00 p.m. EDT that work had resumed to pump seawater into Fukushima Daiichi 2 to maintain safe cooling water levels after the utility was able to vent steam from the pressure vessel. The fuel had been exposed for 140 minutes Monday night due to a malfunctioning pressure relief valve. Water levels later went up to cover more than half of the rods.
The U.S. Nuclear Regulatory Commission reports that the Japanese government has formally asked for assistance from the United States on nuclear power plant cooling issues triggered by the March 11 tsunami.
The agency has already sent two experts on boiling water reactor issues to Japan as part of a U.S. Agency for International Development disaster relief team. The experts now are in Tokyo providing technical assistance. The U.S. NRC is also monitoring the Japanese reactor events around the clock from its headquarters operations center in Rockville, Md.
Prior to the second exposure of the rods around 11 p.m., March 14 local time in Japan, radiation at the plant site was detected at a level twice the maximum seen so far – 313 millirem per hour, according to TEPCO.
Chief Cabinet Secretary Yukio Edano said he believes the problem at the plant ''will not develop into a situation similar to Chernobyl,” even in the worst case.
The utility said a hydrogen explosion at the nearby No. 3 reactor that occurred Monday morning may have caused a glitch in the cooling system of the No. 2 reactor.
The hydrogen explosion at reactor 3 on March 14 injured 11 people: seven TEPCO workers at the site and four members of the country’s Self-Defense Forces. The reactor's containment vessel was not damaged and the reactor remains safely contained in its primary containment.
At the time of the quake, only three of the units (1, 2, and 3) were operating. They were immediately shut down. Fission stopped. BWRs don’t use borated water and there was no need to add boron to the coolant. The first unit (FD1) appears to have the most difficulties. These older BWRs need emergency power to cool down safely, and their backup generators were damaged by the tsunami. That seems to be the root of the problem.
TEPCO says the water-drenched equipment and machinery short-circuited after the power plants were submerged in sea water on Friday.
Based on the government's guidelines, the Fukushima No. 1 plant was designed to withstand tsunami waves of up to 5.7 meters and the No. 2 plant, up to 5.2 meters.
TEPCO says the tsunami waves that hit the plants were higher than 10 meters.
Fukushima I Nuclear Power Plant Reactor #3 explosion March 14, 2011
This apparent hydrogen blast involved the plant's troubled No. 3 reactor. A similar explosion happened at the No.1 reactor at the same plant on Saturday. Both blasts tore the roof off of the affected structure, but are believed not to have damaged the reactor core.
The Nuclear and Industrial Safety Agency says what it believes was a hydrogen blast occurred at 11:01 AM on Monday at the No.3 reactor of Tokyo Electric Power Company's Fukushima No.1 nuclear power plant.
The agency says it has so far observed no abnormal rise in radiation around the compound of the plant.
The company says the blast injured 11 people.
The Nuclear and Industrial Safety Agency has advised anyone remaining within 20 kilometers of the power plant to take shelter inside buildings as soon as possible. About 600 people are thought to be still in the area.
Authorities again urged residents in a 20-kilometer radius around the plant to evacuate.
The IAEA confirms that the explosion occurred at 11:01AM local Japan time, roughly two hours prior to the time of this blog post.
The Fukushima Daiichi unit 3 was built by Toshiba. Last year, the unit began using some reprocessed fuel known as “mox,” a mixture of plutonium oxide and uranium oxide, produced from recycled material from nuclear weapons as part of a program known as “from megatons to megawatts.”
Anti-nuclear activists have called mox more unsafe than enriched uranium. If it escapes the reactor, plutonium even in small quantities can have much graver consequences on human health and the local environment for countless years, much longer than other radioactive materials. -----------------------------------------------
March 12, 2011 Fukushima Japan Nuclear Power Station Reactor #1 Explosion
Explosions at Fukushima Nuclear Power ReactorsHere is a related overview/update from the IAEA about the status of Units 1, 2, 3 and 4 at Fukushima Daini nuclear power plant.
From Japan's Kyodo news agency:
Chief Cabinet Secretary Yukio Edano said the plant operator Tokyo Electric Power Co. confirmed that the 11:01 a.m. blast did not damage the container of the No. 3 reactor, allaying concerns that the explosion may have caused a massive release of radioactive substance. TEPCO said three workers, including its employees, were injured by the blast. All of them suffered bruises.
''According to the plant chief's assessment, the container's health has been maintained,'' Edano told a press conference. ''The possibility is low that massive radioactive materials have spattered.''
Please take some time to read this Q&A from Nuclear Technologist Kirk Sorensen to understand exactly what is happening.
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