Removal of 60,000 tons of radioactive water eyed at Fukushima plant
TOKYO (Kyodo) -- A total of 60,000 tons of radioactive water is believed to be flooding the basement of reactor buildings and underground trenches connected to them at the crisis-hit Fukushima nuclear plant, the industry minister said Tuesday, adding that its operator will later remove the liquid obstructing recovery work.
Tokyo Electric Power Co., which runs the Fukushima Daiichi power station, began dumping low-level radioactive water into the Pacific Ocean on Monday as an emergency step to secure room for the storage of more highly contaminated water. The utility known as TEPCO aims to dispose of a total of 11,500 tons of low-level tainted water into the sea by this weekend from the plant on the coast.
Economy, Trade and Industry Minister Banri Kaieda maintained that contamination of the sea to be caused by the disposal will pose no major health risk, while apologizing for raising concerns among the public, especially fishermen.
In another sign that contamination is affecting the marine environment, however, radioactive cesium exceeding the maximum allowable limit was detected in young launce taken Monday in the sea near the northern part of Ibaraki Prefecture, the prefecture's fishery cooperative said. It is the first time that contamination levels in seafood have exceeded the limit.
The Nuclear and Industrial Safety Agency said the 60,000 tons of water -- 20,000 tons each from the Nos. 1-3 reactor buildings and trenches -- will be stored in tanks at the units, a facility for nuclear waste disposal at the site, an artificial floating island called a "megafloat," U.S. Navy barges and provisional tanks.
The complex for nuclear waste disposal can accommodate 30,000 tons of such water but it will take a while before it can store the liquid because TEPCO will try to ensure that radioactive water will not leak from the facility by using coating agents, the agency said.
The provisional tanks will be shipped to the Fukushima plant by the end of this month, it added.
Meanwhile, TEPCO began work Tuesday afternoon to stop the leakage into the sea of highly radioactive water believed to be originating from the No. 2 reactor's core, where fuel rods have partially melted.
The water containing radioactive iodine-131 more than 10,000 times the legal concentration limit has been leaking from a cracked seaside pit connected to the No. 2 reactor turbine building.
In a new finding, TEPCO said Tuesday a seawater sample taken Saturday near the No. 2 reactor's water intake showed the iodine-131 concentration at 7.5 million times the maximum allowable level under law.
To halt the flow of radioactive water, the operator injected "water glass," or sodium silicate, shortly after 3 p.m. Tuesday into graveled areas beneath the pit's bottom, where radioactive water is believed to be seeping through.
The utility has tried to block the radioactive water leakage with concrete and water-absorbing polymeric materials, but its efforts have so far been unsuccessful.
TEPCO has also poured in white bath agents to trace the route of the leakage but colored water did not emerge from the seaside pit, leaving the path of contamination unknown.
Removal of tainted water is necessary to reduce the risk of workers being exposed to radioactive substances and facilitate efforts to restore vital cooling functions to cool down the reactors and spent nuclear fuel pools at the site, which was ravaged by the devastating March 11 quake and tsunami.
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, because serious damage to the fuel rods from overheating could lead to the release of enormous amounts of radioactive materials into the environment.
However, the measure is believed to be linked to the possible leak of highly contaminated water from the reactors.
(Mainichi Japan) April 5, 2011
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