ID :
174666
Mon, 04/11/2011 - 19:47
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https://oananews.org//node/174666
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Water injection to troubled reactors temporarily stops in Mon. quake
TOKYO (Kyodo) - The injection of coolant water into three troubled nuclear reactors at the Fukushima Daiichi power plant was stopped for about 50 minutes after the area was hit by a strong earthquake Monday evening, serving as the latest setback in efforts to contain the nuclear crisis that has continued for one month.
The water injection to the troubled Nos. 1-3 reactors, vital to keep the nuclear fuel inside cool, halted because electric supply was suspended after the quake, but power was restored and the government's nuclear safety agency said that no major safety problem is believed to have occurred.
The magnitude 7.0 quake that jolted eastern Japan at 5:16 p.m., however, led to a delay in the work to remove highly radioactive water that is hampering restoration efforts, and resulted in the suspension of an operation to inject nitrogen into the No. 1 reactor to reduce the potential risks of hydrogen explosion.
Plant operator Tokyo Electric Power Co. was expected to start from Monday pumping out some 700 tons of highly contaminated water from an underground trench to a nearby storage area it secured in the No. 2 reactor turbine building.
The start of the work was already delayed because a leak was found in a hose to be used to transfer the polluted water, but the latest quake made it certain that the pumping out of the water would be put off until Tuesday or later, the Nuclear and Industrial Safety Agency said.
As the plant located on the Pacific coast continues to be jolted by strong aftershocks of the March 11 deadly earthquake and tsunami that struck northeastern Japan, Hidehiko Nishiyama, a spokesman for the nuclear regulatory body, gave assurances that there are backup vehicle-mounted power sources and extra pumps to keep injecting water into the reactors even in the case external power source is lost.
But he admitted that no preparation has been made in the event the plant, already seriously damaged due to hydrogen explosions and other factors, was engulfed in giant tsunami waves again, and that it may be difficult to think of any efficient preventive measure.
While the six reactors appeared to be more stable than in the early days of the crisis, Nishiyama said in a press conference Monday morning that it is ''not yet a situation to be optimistic about'' and that it is ''extremely difficult to show a time schedule'' on the prospects of the restoration process.
''Now we are in a dilemma because we are seeing water which is pumped in to cool down the reactors showing up as pools of (contaminated) water in other places of the plant,'' Nishiyama said.
Water containing radioactive substances has been found in the basements of the Nos. 1-3 reactor turbine buildings, which contain key electrical equipment, as well as in tunnel-like trenches connected to them. The water, totaling some 60,000 tons, has to be removed and stored in nearby tanks and other places.
To make room to store some of the 60,000 tons of polluted water, Tokyo Electric, known as TEPCO, has dumped into the Pacific Ocean less-contaminated water from a facility for nuclear waste disposal in the plant.
The nuclear agency said Monday evening that the utility firm ''nearly ended'' the disposal of the liquid, which started from April 4. The water dumped from the facility was about 9,070 tons as of Sunday, in addition to about 1,300 tons of contaminated groundwater dumped from near the No. 5 and No. 6 reactors.
Once workers finish dumping the lower-level contaminated water, they can go on with the work to transfer the highly polluted water filling up the No. 2 reactor turbine building to the nuclear waste disposal facility, which can accommodate 30,000 tons of liquid.
The water inside the basement of the No. 2 reactor turbine building and the trench connected to it is highly contaminated, and is believed to originate from the No. 2 reactor core where fuel rods have partially melted.
Massive amounts of water have been poured into the reactors and their spent nuclear fuel pools as a stopgap measure to cool them down. But pools of contaminated water have been detected in various parts of the nuclear complex, with some leaking into the sea, as an apparent side effect of the emergency measure.
To prevent the highly radioactive water that had leaked from the plant from further spreading into the sea, the utility firm on Monday installed ''silt fence'' barriers in the sea area close to the plant. The leakage was plugged last week.
Meanwhile, TEPCO announced that it plans to check to what extent the spent nuclear fuel stored in the No. 4 unit is damaged, given the possibility that the fuel may have been temporarily exposed when the water level at the storage pool dropped following the March 11 disaster.
The firm has already estimated the damage to nuclear fuel rods in the Nos. 1-3 reactors, where, along with the No. 4 reactor, cooling functions were lost after the magnitude 9.0 quake and tsunami ravaged the plant a month ago.
In a sign that the slow progress in containing the country's worst nuclear crisis is frustrating the local community, Fukushima Gov. Yuhei Sato rejected a meeting with the utility firm President Masataka Shimizu on Monday.
TEPCO President Shimizu visited the Fukushima prefectural government office to apologize for the nuclear disaster, but the governor declined to meet him because he thought the president should place priority on settling the nuclear plant problems, according to officials from the utility and the prefectural government.
The water injection to the troubled Nos. 1-3 reactors, vital to keep the nuclear fuel inside cool, halted because electric supply was suspended after the quake, but power was restored and the government's nuclear safety agency said that no major safety problem is believed to have occurred.
The magnitude 7.0 quake that jolted eastern Japan at 5:16 p.m., however, led to a delay in the work to remove highly radioactive water that is hampering restoration efforts, and resulted in the suspension of an operation to inject nitrogen into the No. 1 reactor to reduce the potential risks of hydrogen explosion.
Plant operator Tokyo Electric Power Co. was expected to start from Monday pumping out some 700 tons of highly contaminated water from an underground trench to a nearby storage area it secured in the No. 2 reactor turbine building.
The start of the work was already delayed because a leak was found in a hose to be used to transfer the polluted water, but the latest quake made it certain that the pumping out of the water would be put off until Tuesday or later, the Nuclear and Industrial Safety Agency said.
As the plant located on the Pacific coast continues to be jolted by strong aftershocks of the March 11 deadly earthquake and tsunami that struck northeastern Japan, Hidehiko Nishiyama, a spokesman for the nuclear regulatory body, gave assurances that there are backup vehicle-mounted power sources and extra pumps to keep injecting water into the reactors even in the case external power source is lost.
But he admitted that no preparation has been made in the event the plant, already seriously damaged due to hydrogen explosions and other factors, was engulfed in giant tsunami waves again, and that it may be difficult to think of any efficient preventive measure.
While the six reactors appeared to be more stable than in the early days of the crisis, Nishiyama said in a press conference Monday morning that it is ''not yet a situation to be optimistic about'' and that it is ''extremely difficult to show a time schedule'' on the prospects of the restoration process.
''Now we are in a dilemma because we are seeing water which is pumped in to cool down the reactors showing up as pools of (contaminated) water in other places of the plant,'' Nishiyama said.
Water containing radioactive substances has been found in the basements of the Nos. 1-3 reactor turbine buildings, which contain key electrical equipment, as well as in tunnel-like trenches connected to them. The water, totaling some 60,000 tons, has to be removed and stored in nearby tanks and other places.
To make room to store some of the 60,000 tons of polluted water, Tokyo Electric, known as TEPCO, has dumped into the Pacific Ocean less-contaminated water from a facility for nuclear waste disposal in the plant.
The nuclear agency said Monday evening that the utility firm ''nearly ended'' the disposal of the liquid, which started from April 4. The water dumped from the facility was about 9,070 tons as of Sunday, in addition to about 1,300 tons of contaminated groundwater dumped from near the No. 5 and No. 6 reactors.
Once workers finish dumping the lower-level contaminated water, they can go on with the work to transfer the highly polluted water filling up the No. 2 reactor turbine building to the nuclear waste disposal facility, which can accommodate 30,000 tons of liquid.
The water inside the basement of the No. 2 reactor turbine building and the trench connected to it is highly contaminated, and is believed to originate from the No. 2 reactor core where fuel rods have partially melted.
Massive amounts of water have been poured into the reactors and their spent nuclear fuel pools as a stopgap measure to cool them down. But pools of contaminated water have been detected in various parts of the nuclear complex, with some leaking into the sea, as an apparent side effect of the emergency measure.
To prevent the highly radioactive water that had leaked from the plant from further spreading into the sea, the utility firm on Monday installed ''silt fence'' barriers in the sea area close to the plant. The leakage was plugged last week.
Meanwhile, TEPCO announced that it plans to check to what extent the spent nuclear fuel stored in the No. 4 unit is damaged, given the possibility that the fuel may have been temporarily exposed when the water level at the storage pool dropped following the March 11 disaster.
The firm has already estimated the damage to nuclear fuel rods in the Nos. 1-3 reactors, where, along with the No. 4 reactor, cooling functions were lost after the magnitude 9.0 quake and tsunami ravaged the plant a month ago.
In a sign that the slow progress in containing the country's worst nuclear crisis is frustrating the local community, Fukushima Gov. Yuhei Sato rejected a meeting with the utility firm President Masataka Shimizu on Monday.
TEPCO President Shimizu visited the Fukushima prefectural government office to apologize for the nuclear disaster, but the governor declined to meet him because he thought the president should place priority on settling the nuclear plant problems, according to officials from the utility and the prefectural government.
