Fukushima still a hazard due to melting ice plug, operator admits

A plug of ice has failed to completely block the flow of groundwater into the basement of Japan's crippled Fukushima nuclear plant, leading to the continued risk of radioactive contamination, officials at Tokyo Electric Power (Tepco) have admitted.

Since early June, engineers from Tepco have been pouring hundreds of tonnes of ice into a tunnel, which was originally used to run cable into the reactor's turbine building, in an effort to freeze a section of the passage.

As well as stopping more water seeping into the basement, the scheme would have permitted the removal and treatment, either frozen or in liquid form, of water already contaminated.

But an official at the company said the project was not working as anticipated.

"We estimate that 92 per cent of the water in the trench is frozen, but that's not enough and water is still flowing," the official said.

"We are going to have to use additional technologies to halt the flow of water and we are holding discussions with the government about what to do."

A decision on a course of action would be announced early next month, he added. One proposal was to use more chemicals in the process, or even cement.