The radiation level of underground water sampled at the six nuclear reactors of the Fukushima power plant in Japan has surged as much as 38 times from a week ago.

The Tokyo Electric Power Company (TEPCO) ran a survey Thursday and found 38 times more of radioactive material content in the water sampled near the Unit One and Two reactors compared to the previous week.

Groundwater near Reactor One contained 400 becquerels of iodine-131 per cubic centimeter, which is a six-fold rise from last week. The content of cesium-134 grew 38-fold to 53 becquerels per cubic centimeter.

The level of iodine-131 contained in the water near Reactor Two also grew 17 times and that of cesium-134 eight times.

Water gathered in a pit outside the reactors is seriously contaminated with radioactive materials of over 1000 millisieverts per hour. This water is believed to have seeped into the ground.