NHK — Feb 21

The operator of the Fukushima Daiichi nuclear plant says 100 tons of water containing record high levels of radioactive substances overflowed from a storage tank.

Tokyo Electric Power Company officials on Thursday said workers on patrol found the leak in one of the tanks located on the mountain side of the Number 4 reactor building late Wednesday night.They said the leaked water contained an extraordinarily high 230-million becquerels per liter of beta-ray emitting substances, consisting mainly of strontium 90.

The level is about 7.6 million times the government’s permissible standard for the nuclide level of water allowed to be released into the sea.

It is also the highest level of radioactive substances detected so far in the series of tank leaks at the site.

They say they also detected 9,300 becquerels per liter of cesium 137 in the water. That is more than 100 times the government’s limit.

They say the water was leaking from a seam near the top of the tank. It traveled along a rainwater pipe that extends to outside the barrier surrounding the tank.

Officials say they managed to stop the leak by transferring water from the overflowing tank to a neighboring one, 6 hours after the problem was first discovered.

The utility estimates that about 100 tons of water had flowed outside the barrier. But they say the water should not have flowed into the ocean because there are no spillways near the tank that lead to the sea.

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