2 Septembre 2013
September 2, 2013
TOKYO (AP) -- Japan's top nuclear regulator has raised safety concerns about hastily built storage tanks and their foundations amid reports of new leaks of radiation-contaminated water.
Nuclear Regulation Authority Chairman Shunichi Tanaka said Monday that a small leak and signs of possible leaks have been spotted at several other Fukushima Dai-ichi storage tanks. Officials say part of the leak has escaped into the sea.
He said the discoveries were the result of closer inspections after a 300-ton leak two weeks ago. Tanaka raised concerns about the tanks' foundations and urged careful monitoring.
The plant's operator says it suspects other possible leaks because radioactivity has been detected near the tanks, although it is not considered deadly.
The latest leaks have triggered further concerns about the plant's ability to manage the contaminated water.
September 02, 2013(Mainichi Japan)
TOKYO (Kyodo) -- Very high radiation levels were observed Saturday at three tanks and one of the pipes connecting them at the crippled Fukushima Daiichi nuclear plant, pointing to the possibility that radioactive water may have newly leaked, Tokyo Electric Power Co. said.
The radiation readings were from 70 to 1,800 millisieverts per hour, although none of the tanks showed any visible drop in their water levels, the plant operator said, adding it is investigating the cause.
The tanks are built of steel plates held together by bolts, the same structure as the tank that was found last week to have leaked 300 tons of highly toxic water.
Traces of water leakage were found below the pipe where 230 millisieverts per hour was measured, it said.
The utility also said that 900 becquerels per liter of tritium had been detected at a water well to pump groundwater before it reaches a reactor building, compared with 450 becquerels per liter recorded in February.
As the well is located near the "H4" area where the tank confirmed to have leaked stands, TEPCO is investigating if the rise in the tritium level is related to the leakage of toxic water.
On Sunday, the utility said it had detected 920 becquerels per liter of radioactive substances emitting beta rays, such as strontium-90, in a drainage ditch located south of the H4 area, compared with 580 becquerels recorded on Aug. 22. The drainage ditch leads to the Pacific
High levels of radiation have been detected in water leaking from pipes connecting tanks holding contaminated water at the crippled Fukushima No. 1 Nuclear Power Plant, it has been announced.
Tokyo Electric Power Co. (TEPCO), the operator of the plant, said on Sept. 1 that 300 million becquerels of radiation per liter was detected in water leaking from the tank-connecting pipes in the plant's "H5" area.
The announcement came following the detection of up to 230 millisieverts per hour of radiation underneath those pipes. TEPCO said on Sept. 1 that the radioactive water drops "are believed to be leaks of contaminated water."
TEPCO says it found on Aug. 31 that one drop of water every 90 seconds was leaking from the connections between the tanks and pipes, leading the utility to close the tanks' valves.
Tokyo Electric Power Co., manager of the stricken Fukushima nuclear plant, said Sunday it halted a slow leak from a pipe connecting two water storage tanks by patching it with tape just hours after stumbling upon a potentially lethal radioactive hot spot.
Tepco has been unable to safely contain the growing volume of water used to cool the three reactors hit by meltdowns triggered by the March 2011 earthquake and tsunami, and the government is in the process of taking over the cleanup.
The discovery of the dripping pipe came just after Tepco said late Saturday it had found hot spots at four sites near the water tanks, with one giving off 1.8 sieverts per hour — enough to kill a human being in four hours.
The other three hot spots were not detailed.
The pipe, which was leaking a drop about every 90 seconds, was sealed using absorption material and plastic tape. A puddle of giving off 230 millisieverts per hour was found below it, Tepco said.
“We have to suspect that the high radiation levels were caused by the toxic water oozing from the flange connections,” a Tepco spokesman said, adding that no conclusions had been reached.
The beleaguered utility also said it recorded 900 becquerels of tritium per liter in a groundwater interdiction well, compared with 450 becquerels per liter in February.
Since the well is near the H4 area, where a tank lost 300 tons of radioactive water last month without anyone noticing, Tepco is looking into whether the rise in tritium is related to that incident. Tritium is one of the elements Tepco’s makeshift filtering system, which is partially offline, can’t remove.
On Sunday, the utility said it logged 920 becquerels of strontium-90 per liter of liquid emitting beta rays in the drainage ditch south of H4 that leads from the tanks to the Pacific. Tepco logged 580 becquerels in the ditch on Aug. 22.
Last week, Tepco revealed that 300 tons of toxic water had disappeared from a huge tank — one of 930 on site — before anyone noticed. The spill sparked fears that the toxic water may have escaped into the ocean or seeped into the ground, and was categorized — by Japan’s Nuclear Regulatory Agency — as a Level 3 event on the International Nuclear Radiological Event Scale (INES), the most serious incident since the meltdown itself, which was rated Level 7.
The hot spots were discovered during daily inspections Saturday near three tanks and a pipe connecting them to the crippled plant.
Although it was unclear whether the hot spots indicated that a fresh spill had taken place, traces of water reading 230 millisieverts per hour were found below the pipe.
In response to growing domestic and international pressure on Tepco to stop tainting the ocean and to seek outside help, Prime Minister Shinzo Abe on Thursday promised the world that his government will play a greater role in solving the water crisis.
“The accident in Fukushima cannot be left entirely to Tokyo Electric Power. There is a need for the government to play a role with a sense of urgency, including taking measures to deal with the waste water,” he said.
Abe’s pledge came as the world’s nuclear watchdog urged Japan to explain more clearly what is happening at Fukushima and avoid sending “confusing messages” about the disaster, including the Level 3 rating.
The International Atomic Energy Agency recently questioned why last week’s 300-ton leak of radioactive water prompted the NRA to rate the event on its INES scale, when no other incident since the meltdowns had.