One of the storage tanks leaked more than 300 tons of highly radioactive water in August. The water is likely to have seeped into the soil.
Tokyo Electric Power Company has since increased the number of monitors to check radioactive materials in groundwater near the tank.The company says the level of radioactive tritium at one of the wells rose to 64,000 becquerels per liter on Tuesday, more than twice the reading the previous day.The well is located 20 meters north of the leaking tank.
Engineers checked soil taken when the well was dug and found beta radiation of 0.1 millisieverts an hour.Beta rays are kind of radiation emitted from tritium and other substances.The operator suspects the leak is spreading but says it doesn't know why as the well is not located near to the groundwater flows.
It says most of the contaminated soil around the tank has been removed.The company initially planned to pump up clean groundwater and release it into the ocean before it passes through heavily contaminated reactors buildings.
The finding that the groundwater is already tainted before its reaches the buildings may hamper that plan. Sep. 11, 2013 - Updated 22:18
A nuclear expert says radioactive groundwater at the crippled plant in Fukushima is likely still flowing into the sea.Attempts by Operator Tokyo Electric Power Company to stop the water appear to have had little effect.
The utility admitted the leak in May after detecting high radioactivity at some of the wells between reactor facilities and the sea, as well as the plant port's water.Head researcher at the Japan Atomic Energy Agency, Seiji Takeda, says levels of radioactive tritium in water samples from the wells and the nearby sea suggests the groundwater is to blame.Takeda says tritium, which resembles hydrogen in character, moves with water and can be used to track water flow.He noted that water samples taken in these wells at the sea side of the No. 2 reactor are showing higher levels of tritium compared to wells in surrounding areas.
The wells are close to an underground tunnel also between the reactor facility and the sea.From these reasons, he suggests the tunnel is one of the main sources of the contaminated water. He says the water is most likely flowing fairly quickly into the sea through pebbles inside the tunnel.The operator has been solidifying the embankment to plug the leak. But it admitted on Wednesday that the measure is not working so far. Sep. 11, 2013 - Updated 22:18