February 15, 2016

TEPCO revises plan on contaminated groundwater

http://www3.nhk.or.jp/nhkworld/english/news/nuclear.html

Feb. 15, 2016 - Updated 10:24 UTC+1

The operator of the Fukushima Daiichi nuclear power plant has drafted a new plan to deal with contaminated groundwater, in an effort intended to prevent leaks into the sea.

Tokyo Electric Power Company presented the revised plan on an underground ice wall to the country's Nuclear Regulation Authority on Monday.

A large volume of groundwater is continuing to flow into the site and the damaged reactor buildings, where it becomes contaminated with radioactive particles.

Earlier this month, TEPCO completed construction of a wall made up of pipes that will carry refrigerant liquid. The wall stretches about 1.5 kilometers around 4 reactor buildings.
It is intended to act as a barrier to prevent groundwater from seeping into the buildings, where it becomes contaminated and could eventually leak into the sea.

But work to inject freezing agent into the pipes has been delayed because the operator and the regulators disagreed on where to start.

TEPCO wanted to start freezing the wall from the upstream side. But regulators argued the downstream side should be frozen first to cut the risk of water levels dropping suddenly, potentially triggering a release of tainted water.

Under the revised plan, TEPCO will freeze the downstream side wall first as the regulators suggest. It will also take steps to prevent water levels from falling too low.

The regulators did not oppose the revised plan, although they said there are several points to be clarified.

It will take 8 months to completely freeze the wall. TEPCO initially aimed to end the work by March.

TEPCO's senior official in charge of decommissioning the plant, Naohiro Masuda, says local residents have high interest in the ice wall and the company will implement the plan steadily to keep the public reassured.