Japan's n-regulator clears Fukushima's underground ice wall

Japan's Nuclear Regulation Authority (NRA) on Wednesday approved the use of an underground "wall of ice" at the destroyed Fukushima nuclear plant to help contain spills of contaminated water into the Pacific Ocean.

After several delays, the plant's operator, Tokyo Electric Power Company (Tepco), on Thursday will be able to begin the process of freezing the ground around the buildings that housed the four reactors that were most affected by the earthquake and tsunami of March 11, 2011.

"This operation is a challenge, and it is necessary to carry it out with extreme care, and with all necessary details (for follow-up)," said the regulator's president Shunichi Tanaka at the end of a meeting held on Wednesday, NHK reported.

NRA had wanted to carefully analyse this project, originally raised in 2013, to certify that Tepco, which has a long history of negligence, can properly manage the system without causing additional leaks of radioactive water in the facilities.

Meanwhile, more than 1,500 pipes have been inserted into the earth at a depth of 30 metres (98 feet) around the four units, for the procedure.

Through these pipes a saline solution at a temperature of minus 30 degrees Celsius will be injected to freeze the ground in contact with the pipes and create a frozen barrier to prevent groundwater from seeping into the buildings and mix with polluted refrigerant.

The goal is to reduce the amount of radioactive water that accumulates in the basements of the buildings and prevent its leakage into the Pacific Ocean.

Currently between 150 and 200 tonnes of water penetrate into the structures daily and this system is expected to reduce the amount to only 50 tonnes at full capacity.

The process of creating the wall will be completed in three phases, the first of which will take three months, and its effects will be felt within 40 days approximately.