Photo/Illutration The government begins releasing treated radioactive water from the crippled Fukushima No. 1 nuclear power plant into the Pacific Ocean on Aug. 24. (Asahi Shimbun file photo)

The first round of release of treated radioactive water from the crippled Fukushima No. 1 nuclear power plant into the ocean has been completed without problem, the plant operator announced on Sept. 11.

Around 7,800 tons of treated water have been discharged, after being diluted with seawater, since the release started on Aug. 24, according to Tokyo Electric Power Co.

Starting in late September, at the earliest, the same amount of water will be released following a three-week checkup of the plant facilities.

By the end of March 2024, a total of 31,200 tons of treated water, which contains 5 trillion becquerel of tritium, will be discharged on four occasions.

However, this is only a fraction of the more than 1.3 million tons of treated water currently stored in rows of tanks at the plant, which will be discharged over the next few decades.

In addition, the plant generates some 90 tons of radioactive water each day as it continues pumping water to cool melted nuclear fuel in reactors damaged by the devastating Great East Japan Earthquake and tsunami in 2011.

Most radioactive elements in the water can be removed by treatment processes, but tritium will remain.

The concentration of tritium in nearby waters has remained far below prohibited levels, according to TEPCO and the Environment Ministry.

TEPCO sampled seawater within three kilometers of the plant everyday during the water release this summer.

The highest level of tritium, 10 becquerel per liter, was detected on Aug. 31 some 200 meters from the underwater discharging point, which is located one kilometer offshore from the plant.

The World Health Organization's guidelines state that the concentration of tritium in drinking water must be below 10,000 becquerel per liter.

The International Atomic Energy Agency also said on Sept. 8 that its own monitoring confirmed that the tritium concentration in the waters was within international standards.

The concentration of tritium in fish caught near the plant was also below 10 becquerel per kilogram, according to the fisheries agency.

The agency sampled flatfish, sea bream and tiger puffer fish several kilometers north and south of the discharging point on an almost daily basis.

(This article was written by Ryo Sasaki and Keitaro Fukuchi.)

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