Fukushima Daiichi NPS Prompt Report 2015

Multiple challenges overcome to reduce any risk of water leakage

FUKUSHIMA, July 30, 2015 — After overcoming numerous technical challenges, TEPCO has removed the last of the retained water from the trenches (underground tunnels housing pipes and cables) on the seaside of Units 2 and 3 of the stricken Fukushima Daiichi Nuclear Power Station.

Removal of this highly contaminated water is expected to reduce the risk against any possibility of water leakage.

Initially, TEPCO had attempted to block the water flow between the trenches and the turbine buildings by freezing some of the accumulated water. Through trial and error, a different strategy was adopted to fill the inside of the trenches directly with special liquid cement while removing the retained water.

Removal of the water from Unit 2 was completed on June 30. With the completion of water removal from Unit 3 on July 30, the entire project has been basically completed. What remains is filling of the vertical shafts up to where the turbine building meet. This is intended to prevent any further inflow of water from the turbine buildings.

"One of our most important goals this year is to reduce any risk of water leakage and to prevent the possibility of environment or ocean contamination," said Naohiro Masuda, TEPCO D&D Engineering Company leader. "Completion of the water removal from the trenches is an important milestone towards achieving that goal. It has been a challenging task and I congratulate our workers on their persistence and their success."

The removed water, which has a somewhat higher saline concentration than other water managed on the site, will be stored onsite and eventually treated by the treatment systems in place at Fukushima Daiichi to remove Cesium, Strontium, and other nuclides.

For detail, please go to the following pages;
http://www.tepco.co.jp/en/decommision/planaction/trench/index-e.html
http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2015/images/handouts_150730_01-e.pdf

About TEPCO

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.
TEPCO Website: http://www.tepco.co.jp/en/index-e.html
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