Japan’s nuclear watchdog declared Wednesday the radioactive water leak at the crippled Fukushima plant a level-three “serious incident,” its highest warning in two years, as operators keep trying to seal a tank that has seeped 300 tonnes of toxic water.
Highly contaminated water still leaks from the plant, destroyed by an earthquake and tsunami in 2011. According to Reuters, the level of toxicity is such that a person standing close to it for an hour would receive five times the annual recommended limit for nuclear workers in a year.
At its height, the Fukushima crisis was classified as level seven—one of only two events ever rated in that category along with the Chernobyl disaster a quarter of a century ago.
Experts warn the plant will stay susceptible to failures for years, while the work of dismantling and cleaning up the damaged reactors is expected to take decades.
The news comes a day after plant operator Tokyo Electric Power Company (TEPCO) acknowledged that about 300 tonnes of radioactive water had leaked from one of the tanks that hold water used to cool the reactors.
Last month the company admitted for the first time that radioactive groundwater had been leaking outside the plant. In August it started pumping it out to reduce leakage into the Pacific.
TEPCO said the leak was thought to be continuing on Wednesday and it had not yet pinpointed the source.