Highly radioactive water leaking into sea stops: TEPCO
TOKYO (Kyodo) -- Tokyo Electric Power Co. succeeded in stopping highly radioactive water from leaking into the Pacific Ocean from the crippled Fukushima Daiichi nuclear power plant early Wednesday, while saying it is considering injecting nitrogen to prevent a possible hydrogen explosion from occurring at the No. 1 reactor.
The highly toxic water, confirmed to have been flowing from around a seaside pit located near the No. 2 reactor water intake on Saturday, stopped at 5:38 a.m. after the plant operator injected some 6,000 liters of chemical agents, including what is called water glass.
The government's nuclear agency said it ordered the utility known as TEPCO to keep monitoring the pit to check whether the water leakage has completely stopped, and noted there is the possibility that the water, which has lost an outlet, may show up from other areas inside the plant's premises.
The highly radioactive water is believed to have come from the No. 2 reactor core, where fuel rods have partially melted, and ended up in the pit. The pit is connected to the No. 2 reactor turbine building and an underground trench connected to the building, both of which were found to be filled with high levels of contaminated water.
To make room to store the highly radioactive water that is hampering the plant's restoration work, TEPCO continued the work to dump massive amounts of low-level contaminated water from inside a nuclear waste disposal facility at the site, as well as that found from around the No. 5-6 unit buildings.
TEPCO aims to dispose a total of 11,500 tons of the low-level tainted water into the sea by this weekend from the plant on the coast, a move which has sparked concerns from neighboring countries.
Opening up the nuclear waste disposal facility may end as early as Wednesday, the nuclear agency said. The move would be followed by some repair work to make sure the facility can keep highly radioactive water safely without fear of the stored liquid leaking outside.
Meanwhile, TEPCO said it may inject nitrogen into the No. 1 reactor's containment vessel possibly later Wednesday.
Hidehiko Nishiyama, a spokesman for the Nuclear and Industrial Safety Agency, said the move is considered with the aim to stop a possible hydrogen explosion "in advance" and that it does not mean there is an "immediate danger."
The nitrogen injection process is expected to take several days, and may lead to the release of radioactive substances in the air.
Due to the magnitude-9.0 quake and ensuing tsunami, the plant's power grid and most of the emergency diesel generators were knocked out, resulting in the loss of many of the reactors' key cooling functions, partial melting of reactors cores and hydrogen explosions.
The utility has been pouring massive amounts of water into the reactors and their spent nuclear fuel pools as a stopgap measure to cool them down. But the measure is apparently connected to the massive amount of contaminated water found in various places at its premises, which TEPCO is now struggling to remove.
A seawater sample taken near the No. 2 reactor water intake Saturday showed a radioactive iodine-131 concentration of 7.5 million times the maximum level permitted under law, or about 300,000 becquerels per cubic centimeter.
As the first case of contamination levels in seafood have exceeded the limit, radioactive cesium over the limit was detected in young launce in the sea near the northern part of Ibaraki Prefecture.
(Mainichi Japan) April 6, 2011
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