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CNN ..
Radiation in reactor's building tests 10 million times above normal
Tokyo (CNN) -- Radiation levels in pooled water tested in the No. 2 nuclear reactor's turbine building at the Fukushima Daiichi power plant are 10 million times normal, utility company and government officials said Sunday.
Hidehiko Nishiyama, an official with Japan's nuclear and industrial safety agency, said the surface water showed 1,000 millisieverts of radiation. By comparison, an individual in a developed country is naturally exposed to 3 millisieverts per year, though Japan's health ministry has set a 250 millisievert per year cumulative limit before workers must leave the plant.
"Certainly, we have to be concerned about the fact that the level of radiation is increasing," said Nishiyama. "But at this point, we do not ... envisage negative health impacts."
The 10-million-times normal reading applies to radioactive iodine-134 found in the No. 2 building's pooled water, according to the nuclear safety agency. This isotope loses half its radioactive atoms every 53 minutes, compared to a half-life of every eight days for radioactive iodine-131 that has also been detected in recent days.
Two people working in and around the No. 2 reactor when the test result became known, according to an official with the Tokyo Electric Power Company, which runs the plant. Those individuals subsequently left, and work there has stopped until the government signs off on the power company's plan to address the issue.
Work has similar ceased at the No. 3 reactor, where tests earlier indicated radiation 10,000 times normal in its own turbine building.
On Sunday, water was being pumped out of the No. 1 reactor's turbine building -- a process that authorities eventually want to repeat in the other two reactors' buildings with pooled, and contaminated, water.
Authorities are still trying to pinpoint the relationship, if any, between these alarming readings from inside these buildings to a continued spike in radiation detected in seawater just offshore.
A Japanese nuclear safety official said Sunday that levels of radiation were 1,850 times normal at a monitoring post situated 330 meters (361 yards) into the Pacific Ocean. This is near the discharge canal for the Nos. 1, 2, 3 and 4 reactors.
On Saturday, similar readings from the same monitoring posts showed readings were 1,250 times above normal. The previous day, they'd been lower -- at 104 times more than a typical level.
This substance is a biproduct during the nuclear energy process, and officials suspect the seawater contamination may be a direct result of problems at the plant.
Up until Sunday, the potential for contamination from the No. 3 reactor had been a primary concern. This unit, which has had a building severely damaged by a hydrogen explosion and that an official said last week might have leaked radiation from its reactor core, is the only one of the facility's six reactors to use a combination of uranium and plutonium fuel, called MOX. Experts say this mix is considered more dangerous than the pure uranium fuel used in other reactors.
Three men laying cable in the No. 3 unit turbine building's basement have been hospitalized after stepping in the highly radioactive water there on Thursday.
An official with Tokyo Electric Power Company, which runs the plant, apologized Saturday, saying the exposure might have been avoided with better communication.
Hideyuki Koyama, the company's associate director, said pooled water had been discovered in the basement of the No. 1 reactor six days earlier. But a sample was not taken for analysis until the 24th, after the three workers were exposed to between 173 to 181 millisieverts of radiation.
Such incidents threatened to undermine the public's trust in Tokyo Electric, Japanese Chief Cabinet Secretary Yukio Edano told reporters.
He added the Japanese government "would like to give stronger instructions" to the company that it fully disclose as much information as possible about conditions at the plant.
"Every piece of information must be provided accurately and swiftly" to Japan's nuclear and industrial safety agency, Edano said. "Without this communication, it's very difficult for the government to (establish) proper safety measures."
As important, the chief secretary said, was the need for Tokyo Electric to be upfront with the Japanese -- millions of whom get power from the company and millions more of whom have been affected by radioactive emissions stemming from the crisis.
"We need to be sure that (Tokyo Electric) isn't going to act in a way that will create distrust," Edano said.
Koyama told reporters that radiation alarms went off while the three men were working, but they continued with their mission for 40 to 50 minutes after assuming it was a false alarm.
This continued debate about the working conditions for the roughly 500 individuals -- among them utility workers, Japanese soldiers and firefighters from several cities -- comes as work continued Sunday to cool nuclear fuel at the plant and prevent the further emission of radioactive material into the air and sea.
These was no immediate indication Sunday that issues with radiation in the two turbine buildings' water had stopped the injection of fresh water into the Nos. 1, 2 and 3 reactor cores, a switch from the previous policy of pumping in seawater.
In addition, power and lighting were restored late Saturday afternoon to the No. 2 unit's control room, according to an online update from the nuclear safety agency.
Those units have largely been authorities chief focus, since they were the only ones operating (and, thus, with nuclear fuel rods in the reactor cores) when the March 11 earthquake and subsequent tsunami hit.
Nishiyama said that fresh water should be injected into the No. 2 unit's spent fuel pool on Monday and No. 1 unit's spent fuel pool on Tuesday. Some nuclear fuel rods, which may have been fully or partially exposed, remain in these pools -- meaning that, if they aren't sufficiently cooled, the fuel rods have the potential to heat up and emit radiation into the atmosphere.
Fresh water should also be pumped, starting Monday, into the No. 4 unit's nuclear fuel pool. This suffered possible damage and has been subject to frequent external spraying of seawater, given concerns that its water levels were low and fuel rods there may be fully or partially exposed.
Authorities have been trying to restart a steady supply of electricity to power the cooling systems, in order to control the temperatures of nuclear fuel and prevent further radioactive emissions, for that reactor and several other in the nuclear facility.
This has already occurred in the Nos. 5 and 6 units, which are considered stable. These units have fuel rods in spent fuel pools, but not in their reactor cores.
http://www.cnn.com/2011/WORLD/asiapcf/03/27/japan.nuclear.reactors/index.html?hpt=T1
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27 มี.ค. 54 14:41:44
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