Highly radioactive water leaks from Japan’s Fukushima plant

It is thought the toxic water overflowed after a valve was left open by mistake, Fukushima operator Tokyo Electric (Tepco) said.

Spokesman Masayuki Ono told reporters: “We apologise for worrying the public with such a leak. Water is unlikely to have reached the ocean as there is no drainage in that tank area. We are now in the process of recovering the leaked water and the earth it has contaminated.”

Early indications suggest the leak occurred when contaminated water was accidentally pumped into an overfilled storage tank.

We are deeply embarrassed that this sort of unacceptable event would occur. Zengo Aizawa

It is the latest setback for the stricken Fukushima Dai-ichi power plant, north of Tokyo, which was devastated by a tsunami in March 2011 which led to meltdowns at three reactors, the radioactive contamination of land, air and sea and the evacuation of 160,000 people.

The plant has faced multiple problems including leaks and power cuts since the disaster, although until the leak it seemed that Tepco – and the Japanese government – were getting things more under control.

Read more: What is happening at Fukushima?

However, this latest leak is the most serious since last August, when the plant leaked 300 tonnes of water, prompting Japan’s nuclear agency to raise the incident’s alert level.

Zengo Aizawa, executive vice-president of Tepco, added: “We are deeply embarrassed that this sort of unacceptable event would occur after the many steps we have taken to improve the management of stored water.

“We will therefore conduct a thorough investigation into what occurred and determine what additional steps must be taken to prevent any similar occurrence in the future, and will further strengthen field management of stored water. It also demonstrates the need for a permanent solution to the contaminated water issue.”