ID :
183401
Fri, 05/20/2011 - 18:57
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https://oananews.org//node/183401
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Gov't briefly stopped TEPCO's seawater injection a day after quake
TOKYO, May 20 Kyodo -
Tokyo Electric Power Co. started to inject seawater into the troubled No. 1 reactor at the Fukushima Daiichi nuclear power plant a day after the March 11 earthquake and tsunami, but suspended the operation for 55 minutes at the direction of Prime Minister Naoto Kan, government sources said Friday.
With criticism growing that a delay in the seawater injection may have caused a meltdown at the No. 1 reactor, magnifying the nuclear disaster, analysts said the plant operator, known as TEPCO, should have continued to pump the seawater into the reactor vessel to cool it down.
The government had previously said TEPCO started to inject seawater into the No. 1 reactor at 8:20 p.m. on March 12, but a document released by the utility on Monday revealed it began the work at 7:04 p.m. that day, stopped it at 7:25 p.m. and resumed it at 8:20 p.m.
According to the sources, the government's Nuclear Safety Commission advised Kan that seawater injection into the reactor vessel could rekindle a nuclear chain reaction in a state called ''recriticality,'' prompting him to require TEPCO to suspend the operation.
But the commission later confirmed that the injection would not cause any problem, and TEPCO, which initially began pumping seawater at the discretion of on-site workers, restarted the work by also putting in boric acid, which works to suppress a criticality, the sources said.
On Friday, workers at the plant entered the troubled No. 1 reactor building to measure the level of water that has leaked into its basement, TEPCO said Friday.
The water, which may be leaking from the reactor vessel damaged by the devastating earthquake and ensuing tsunami and so could be highly radioactive, was visually confirmed to be around 4.2 meters deep when it was found last Saturday, the plant operator said.
Four other workers also entered the reactor building the same day to check radiation levels there using a special camera, called a ''gamma camera,'' which can image points of high-level radiation, said the utility.
It is believed that a nuclear fuel meltdown occurred at the No. 1 reactor on March 12, creating holes to its pressure vessel.
At a spent fuel pool for the No. 4 reactor, TEPCO has set up a water-level gauge so that it can monitor the temperature and the level of the water in the pool on a steady basis via wireless network, the firm said.
Meanwhile, a large artificial floating island with a capacity of about 10,000 tons, which will be used to store the contaminated water accumulated at the nuclear plant, is scheduled to berth along the quay near the plant Saturday, company officials said.
TEPCO expects the so-called ''megafloat,'' provided by the Shizuoka city government, to store water with relatively low contamination that has gone through a decontamination process, the officials said.
==Kyodo
Tokyo Electric Power Co. started to inject seawater into the troubled No. 1 reactor at the Fukushima Daiichi nuclear power plant a day after the March 11 earthquake and tsunami, but suspended the operation for 55 minutes at the direction of Prime Minister Naoto Kan, government sources said Friday.
With criticism growing that a delay in the seawater injection may have caused a meltdown at the No. 1 reactor, magnifying the nuclear disaster, analysts said the plant operator, known as TEPCO, should have continued to pump the seawater into the reactor vessel to cool it down.
The government had previously said TEPCO started to inject seawater into the No. 1 reactor at 8:20 p.m. on March 12, but a document released by the utility on Monday revealed it began the work at 7:04 p.m. that day, stopped it at 7:25 p.m. and resumed it at 8:20 p.m.
According to the sources, the government's Nuclear Safety Commission advised Kan that seawater injection into the reactor vessel could rekindle a nuclear chain reaction in a state called ''recriticality,'' prompting him to require TEPCO to suspend the operation.
But the commission later confirmed that the injection would not cause any problem, and TEPCO, which initially began pumping seawater at the discretion of on-site workers, restarted the work by also putting in boric acid, which works to suppress a criticality, the sources said.
On Friday, workers at the plant entered the troubled No. 1 reactor building to measure the level of water that has leaked into its basement, TEPCO said Friday.
The water, which may be leaking from the reactor vessel damaged by the devastating earthquake and ensuing tsunami and so could be highly radioactive, was visually confirmed to be around 4.2 meters deep when it was found last Saturday, the plant operator said.
Four other workers also entered the reactor building the same day to check radiation levels there using a special camera, called a ''gamma camera,'' which can image points of high-level radiation, said the utility.
It is believed that a nuclear fuel meltdown occurred at the No. 1 reactor on March 12, creating holes to its pressure vessel.
At a spent fuel pool for the No. 4 reactor, TEPCO has set up a water-level gauge so that it can monitor the temperature and the level of the water in the pool on a steady basis via wireless network, the firm said.
Meanwhile, a large artificial floating island with a capacity of about 10,000 tons, which will be used to store the contaminated water accumulated at the nuclear plant, is scheduled to berth along the quay near the plant Saturday, company officials said.
TEPCO expects the so-called ''megafloat,'' provided by the Shizuoka city government, to store water with relatively low contamination that has gone through a decontamination process, the officials said.
==Kyodo
