The Mainichi Daily News just reported:
The level of radioactive substances in seawater increased sharply overnight inside a containment fence installed near the Fukushima Daiichi nuclear power plant, the operator Tokyo Electric Power Co. said Saturday.
The utility said the rise suggested that the fence is helping to curb the spread of contaminated water, but the government’s Nuclear Industrial and Safety Agency remained cautious, citing the possibility that radioactive water could still be seeping from the complex.
The company said the level of radioactive iodine rose Saturday morning to 260 becquerels per cubic centimeter in seawater inside the fence near an intake leading to the No. 2 reactor.
The figure, 6,500 times the legal limit, was around six times the 42 becquerels detected the previous day, the company said, adding the reading of radioactive cesium had also jumped by four times.