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information about Fukushima published in English in Japanese media info publiée en anglais dans la presse japonaise

Frozen wall not watertight

August 19, 2016

Panel: TEPCO’s ‘ice wall’ failing at Fukushima nuclear plant

http://www.asahi.com/ajw/articles/AJ201608190060.html

 

By KOHEI TOMITA/ Staff Writer

Frozen wall not watertight

Tokyo Electric Power Co.’s “frozen wall of earth” has failed to prevent groundwater from entering the crippled Fukushima No. 1 nuclear plant, and the utility needs a new plan to address the problem, experts said.

An expert panel with the Nuclear Regulation Authority received a report from TEPCO on the current state of the project on Aug. 18. The experts said the ice wall project, almost in its fifth month, has shown little or no success.

The plan to block groundwater with a frozen wall of earth is failing,” said panel member Yoshinori Kitsutaka, a professor of engineering at Tokyo Metropolitan University. “They need to come up with another solution, even if they keep going forward with the plan.”

One big problem hampering work at the nuclear plant, which was hit by the Great East Japan Earthquake and tsunami in 2011, has been the tons of groundwater entering the buildings housing the No. 1 through No. 4 reactors every day.

The water becomes contaminated with radioactive materials within the reactor buildings.

TEPCO’s plan was to create a frozen wall of earth around the reactor buildings to divert the groundwater away from the plant and into the ocean.

The company started freezing the ground on March 31, and the project's budget was 34.5 billion yen ($344 million) in taxpayer money as of the end of May.

But the amount of groundwater pumped from the ocean side of the frozen wall has shown little change from when there was no icy earth wall.

TEPCO’s report said 99 percent of thermometer readings on the 820-meter-long stretch showed temperatures of freezing or lower, suggesting the underground wall was frozen solid at those points.

However, the remaining 1 percent of the readings above freezing were in areas with high levels of groundwater concentration.

A 99-percent success rate may sound impressive, but much like dams, airlocks and Tupperware, TEPCO’s ice wall is failing if it is not 100-percent watertight.

The utility said the unfrozen sections could be reinforced with an injection of concrete.

The panel asked the utility submit calculations estimating the amount of groundwater that can be blocked if water is pumped before it reaches the frozen wall.

 

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