TEPCO plans for storing radioactive water dealt heavy blow

April 10, 2013

THE ASAHI SHIMBUN

Radioactive water continues to leak from tanks at the crippled Fukushima nuclear plant. Space is running out to store the hundreds of tons of contaminated water produced each day. And the initial plan to address the growing water problem now appears flawed.

That is the situation facing plant operator Tokyo Electric Power Co., which on April 9 admitted to another leak in an underground storage tank holding contaminated water.

The discovery at the No. 1 tank may force TEPCO to change its emergency plan to contain the water. Not only was the No. 1 tank receiving radioactive water from another faulty tank, but the latest leak indicates that TEPCO was wrong in its assessment of what was causing the spillages.

The company is throwing around ideas on where to keep the 400 tons of radioactive water created daily from the cooling of the damaged reactor cores at the Fukushima No. 1 plant.

But storage space at the plant is so limited that TEPCO will use the leaky tanks for the time being.

After the initial leaks were found in the No. 2 and No. 3 underground tanks, TEPCO began transferring 9,200 tons from the No. 2 tank to the No. 1 tank on April 6.

Company officials believed that radioactive water was flowing out from the upper part of the tank. That was based on an earlier assessment of the No. 3 tank, and TEPCO officials felt that leaks could be prevented if the tanks were not filled to capacity.

However, the No. 1 tank was only about half-full, meaning that the water was spilling out from a lower part of the tank where inner protective linings are connected.

Company officials will now have to determine if damage to the connected sections led to the leaks.

TEPCO officials have begun considering the option of transferring radioactive water to surface tanks. However, the maximum volume for such a measure is only about 7,000 tons.

Five of the seven underground tanks already hold about 27,000 tons of toxic water. TEPCO officials acknowledged it would be impossible to move all of that water to surface tanks.

For that reason, the company plans to continue using five underground tanks, including the No. 3 tank from where a small volume of water was confirmed to have leaked.

TEPCO officials initially believed the leakage from the No. 3 tank came from a pipe sloppily installed at the edge to detect leakage. They said that when the tank filled to about 95-percent capacity, the water likely reached the pipe hole and spilled out.

The officials decided to reduce the water level in all underground tanks to 80-percent capacity to prevent future leaks presumably from the upper parts.

At an April 9 news conference, Masayuki Ono, acting general manager of TEPCO's Nuclear Power and Plant Siting Division, would only say an investigation was continuing to determine the cause of the leak in the No. 1, No. 2 and No. 3 tanks.

Regarding the earlier measure taken by TEPCO, Ono said, "Reducing the volume of water stored was implemented because (leaking from the upper part of the tank) was one possible cause of the leaking."

TEPCO officials are now looking for other sites to store the toxic water that was transferred to the No. 1 tank from the No. 2 tank. Two possibilities being considered are condensate storage tanks located near the turbine buildings by the coast as well as one of the filtered water tanks. Those tanks have a total capacity of 7,300 tons.

That means TEPCO would still have to find room for the remaining 2,000 or so tons. The water may have to be moved to one of the other underground tanks, despite the possibility of leaks.

Contaminated water will continue to be transferred from the No. 2 tank to the No. 6 underground tank, which has shown no signs of problems. There are also plans to move water from the No. 3 tank to the No. 6 tank.

Although surface tanks at the Fukushima No. 1 plant still have room for about 21,900 tons of water, TEPCO officials are hesitant about using them because they need space for the 400 tons of radioactive water that is being produced every day.

(This article was compiled from reports by Ryuta Koike, Shunsuke Kimura and Keisuke Katori.)

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