Top > Releases ・ Announcements > Fukushima Daiichi NPS Prompt Report > 2015 > Recent topics:REMOVAL OF CONTAMINATED 'TRENCH' WATER COMPLETE AT UNIT 2, WITH UNIT 3 EXPECTED TO FOLLOW WITH GOVERNMENT'S APPROVAL

Fukushima Daiichi NPS Prompt Report 2015


Removal of highly contaminated water is a milestone in making site safer

FUKUSHIMA, Japan, June 30—Removal of the highly contaminated water that had drained into the trench outside the Unit 2 turbine building has been completed, TEPCO announced today.

The removal marks a major step toward the removal of all "trench*" water at Fukushima Daiichi. Removal of the remaining water at Unit 3 is pending government approval. TEPCO expects to complete the removal of all trenches soon after approval is obtained. This would mark the culmination of a long and difficult process, and achieves a significant risk reduction against the possibility of highly contaminated water leakage.

Stopping the Flow

The main challenge facing the workers had been to block the flow of contaminated water to and from the turbine buildings into the trenches. Until that flow could be blocked, any water removed from the trenches would simply be replaced by more water flowing out of the buildings.

Initially, efforts were made to freeze some of the water sitting in between the trenches and turbine buildings to create a barrier. Through trial and error, an alternative strategy was adopted to fill the trenches with special concrete and by doing so block the flow of contaminated water to and from the turbine buildings. This effort has been successful.

With the trenches being filled with concrete, engineers proceeded using pumps to remove the standing water. As a result, all water was removed from the Unit 2 trench at 10:50 a.m. JST on June 30.

Removal of the water from the Unit 3 trenches is awaiting regulatory approval of the plan to temporarily transfer the water to Unit 1.

The removed water that will be transferred to turbine buildings will be treated by Multi-nuclide Removal Facility (ALPS) just like any other contaminated waters.

*A trench is an underground tunnel housing pipes and cables.
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Tokyo Electric Power Company, Inc. (TEPCO) is Japan's largest power company, supplying energy to the greater Kanto area, including Japan's two most populous cities, Tokyo and Yokohama. Its 34,000 employees are committed to providing safe, reliable power to its 29.0 million customers, diversifying energy resources to ensure sustainability, and contributing to economic growth while fully meeting its responsibilities after the Fukushima Daiichi accident.
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