An underground ice wall being built to keep groundwater from entering the crippled nuclear reactor buildings in Fukushima is expected to be completed soon.
Workers at the Fukushima Daiichi nuclear power plant are circulating coolant in pipes buried around the buildings to make the 1.5 kilometer-long barrier.
The operator, Tokyo Electric Power Company, hopes to keep groundwater from being contaminated with radioactive substances.
The utility has so far left part of the wall unfrozen, due to fears that freezing the entire area could lead to a sharp drop in groundwater levels outside the reactor buildings, which could cause the tainted water to leak out.
On Wednesday, the Nuclear Regulation Authority gave basic approval for the utility’s plan to freeze a 7 meter-wide section that remains on the mountain side.
Utility officials have explained to authority members that the groundwater level won’t plunge and that they are prepared for such an emergency.
TEPCO says that as soon as it gets official approval it will start freezing the remaining section of the wall. It has been functioning for about 15 months.
The daily amount of groundwater flowing into the buildings is now about 100 tons, compared with some 400 tons per day at the start of the operation.
The utility says the completion of the ice wall will further reduce the amount. The regulators plan to monitor the effects of the barrier after it is completed.