Fukushima’s giant ice wall fails to stop water leaking into radioactive area

The failure to contain the water is preventing clean-up teams from removing the last of the dangerous radioactive fuel, seven years after a tsunami hit the plant and triggered a catastrophic meltdown.

The refrigeration structure, which resembles giant ice lollies, was completed in 2016 and was an attempt to limit the amount of radioactive water created by the incident. 

The aim is to freeze the soil into a solid mass that blocks groundwater flowing from the hills west of the plant to the coast.

At the time of the ice wall construction, nearly 800,000 tonnes of contaminated water was being stored in 1,000 huge industrial tanks at the site.

Data released from operator Tokyo Electric Power Co (TEPCO) showed that water leakage has actually got worse since the structure was turned on.

An average of 141 metric tonnes of water per day seeped into the reactor and turbine areas, compared to an average of 132 metric tonnes a day during the prior nine months.

The structures cost around 34.5 billion yen (£233m) in public funds and consist of approximately 1,500 tubes filled with brine, cooled to minus 30°C, and buried 30 metres underground.

“I believe the ice wall was ‘oversold’ in that it would solve all the release and storage concerns,” said Dale Klein, the former chairman of the US Nuclear Regulatory Commission and the head of an external committee advising Tepco on safety issues.

“The hydrology of the Fukushima site is very complicated and thus the exact water flow is hard to predict,” he said, “especially during heavy rains.”

Overall, Tepco says a combination of drains, pumps and the ice wall has cut water flows by three-quarters, from 490 tons a day during the December 2015 to February 2016 period to an average of 110 tons a day for December 2017 to February 2018.

It is hard to measure exactly how much the ice wall is contributing, Tepco officials say, but based on computer analysis the utility estimates the barrier is reducing water flows by about 95 tonnes a day compared to two years ago, before the barrier was operating.

However, it expects to run out of space to store the water by 2021, so the decommissioning process needs to be completed as quickly as possible.

In 2016, the estimate for the total cost of the clean-up operation increased to 22.6tr yen (£151bn), more than double the previous estimate. 

According to a Greenpeace report on Fukushima, published last week, the people, towns and villages in the surrounding area are still being exposed to excessive levels of radiation. A ground-level study conducted by an international research team also found that uranium and other radioactive materials, such as caesium and technetium, were present in tiny particles released from the damaged nuclear reactors.