FUKUSHIMA, June 3, 2014 - Construction began yesterday on the "ice wall," a key measure to prevent groundwater from being contaminated at the Fukushima Daiichi Nuclear Power station, TEPCO announced today.
Though often referred to as an "ice wall," it is actually a system that freezes the ground below and around the four crippled reactor units, intended to block the flow of groundwater and prevent its mixing with contaminated water, but without the problems associated with construction of a physical underground wall. Construction began after tests earlier this year demonstrated the effectiveness of the design.
TEPCO President Naomi Hirose noted the event's significance: "Beginning construction of the 'ice wall'represents another milestone in our overall effort to move forward in decontamination and decommissioning at Fukushima Daiichi,he said. "We appreciate the government's cooperation, and the innovative work being performed by Kajima Corporation to make this important progress happen.
<Installation of Freezing Pipes>
Yesterday, workers began installing equipment to freeze the soil around the four reactor units. Pipes for freezing the soil are being implanted, starting at the site's northwest corner. The start of construction followed approval from the Nuclear Regulatory Authority on May 30. Construction is expected to be completed in early 2015.
The barrier is being funded by the government, with construction being undertaken by Kajima Corporation, one of the few entities that has developed the necessary technology, which it has used at numerous construction sites, especially tunnels, to block water penetration. The refrigerant is an environmentally safe and the chilled brine will flow through the pipes to a depth of 30 meters, freezing the surrounding soil and forming a barrier around the reactor facilities. The circumference of the wall is approximately 1500 meters.
The principal benefit of the frozen barrier compared with a physical barrier is that it avoids the challenges of building a wall around such underground obstacles as pipes, and creates a seamless barrier. Its effectiveness was demonstrated in tests held in March through April of this year, when it maintained the ground temperature below 0 degrees Celsius.
The wall is also designed to withstand even long-term interruptions of electricity, maintaining its effectiveness for approximately two months after the loss of power. It is one of several measures TEPCO is undertaking to reduce the amount of water that becomes contaminated on the site, thereby reducing storage needs and protecting the environment.
TEPCO will continue the decommissioning operation safely and diligently with a support and the knowledge gain from our domestic and other international partners.
To see a video demonstrating the construction and planned operation of the "ice wall" go to:
Tokyo Electric Power Co., 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 35,000 employees are committed to providing safe, reliable power to its 28.8 million customers, diversifying energy resources to ensure sustainability, and contributing to economic growth while fully meeting its responsibilities after the Fukushima Daiichi accident.