• Kyodo


The Nuclear Regulation Authority has launched an investigation of the seafloor off the coast of Fukushima Prefecture to check current contamination levels from the Fukushima No. 1 nuclear power plant meltdowns.

A Geiger counter will be trailed from a ship over about 1,000 sq. km. of the seafloor to help determine the density of radioactive cesium there.

While past studies have focused on certain points in the Pacific around the radiation-leaking Fukushima plant, the NRA’s investigation aims to analyze more broadly how the contamination has spread on the seabed.

The results will be compiled by March and the data could be used to confirm the safety of marine products, although it is not clear whether the investigation will take up the effects that radioactive water leaks have on the plankton flowing through the area.

The NRA outsourced the project, which began Wednesday, to a team involving the University of Tokyo and the National Maritime Research Institute.

The team started with a sonic survey and other activities to check the geological formation of the seafloor. It will start measuring the cesium density between November and February, covering an area 20 km of the coast, 50 km north and 50 km south of the Fukushima No. 1 plant.

An official of the NRA secretariat said the study must continue for at least three years to properly gauge the changes in contamination.

The amount of highly radioactive water is increasing by the day at the plant because of the emergency cooling operations for the three crippled reactors. The water used is being stored in more than 1,000 huge tanks set up at the site, posing a risk of leaks.

Recently, 300 tons of contaminated water leaked from one of the tanks, some of which could have reached the ocean through drainage channels. In addition, an estimated 300 tons of tainted groundwater is thought to be entering the sea each day.

All trial fisheries operations off Fukushima were suspended in September.

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