The International Atomic Energy Agency’s (IAEA’s) first independent sampling and analysis of seawater near the Fukushima Daiichi NPP (FDNPP) since discharges of treated water started on 24 August confirms that the tritium levels are below Japan’s operational limit.

The water, used to cool the melted reactor cores in the aftermath of the 2011 nuclear disaster at Fukushima, is stored in around 1,000 huge tanks at the plant containing more than 1.3m tonnes and total storage capacity has been reached. The contaminated cooling water and groundwater is treated by the Advanced Liquid Processing System (ALPS), which removes most of the radioactive contamination, with the exception of tritium. The water is diluted so that tritium levels fall below national regulations before it is released, following multiple checks, through an undersea tunnel one kilometre offshore. The release, which is expected to take place over several decades, has sparked protests in China, South Korea and some Pacific islands as well as within Japan.

Agency staff present at the IAEA’s Office at the site sampled seawater from several locations within three kilometres from the site, at sea and from the coast. The Agency’s independent sampling and measurement of the seawater from the coast shows consistency with the values reported by FDNPP owner/operator Tokyo Electric Power Company (TEPCO) as well as with those of the Ministry of Environment of Japan. TEPCO reports daily public results on its website showing that the tritium activity concentration in the sea falls below its operational limit, that is, the limit set for operation of the ALPS discharge process that must not be exceeded. The Agency is continuing its analysis of all the seawater samples.

The IAEA’s safety review of Japan’s plan to release the treated water into the sea, carried out before the discharge started, concluded that Japan’s approach and activities to discharge ALPS-treated water are consistent with relevant international safety standards. The report noted that the controlled, gradual discharges of the treated water into the sea, as currently planned and assessed by TEPCO, would have a negligible radiological impact on people and the environment.

The IAEA has been collecting marine samples in the waters off Fukushima over the past decade since the accident in 2011. This came after a request by the Japanese Government to assist it in ensuring that its sea area monitoring maintains a high quality, and is credible and transparent. The project is a follow-up activity to recommendations made on marine monitoring in a report by the IAEA in 2013 related to the decommissioning of the Fukushima plant.

Meanwhile, a group of 150 people in Japan, including fishery workers in Fukushima Prefecture, filed a lawsuit on Friday to halt the release of the ALPS water into the sea. In a suit lodged against the Japanese government and TEPCO, the plaintiffs claimed that the ocean discharge violates their fishing rights and threatens the rights of consumers to live peacefully. In addition, they are seeking to reverse regulatory approval of facilities installed for the water discharge and to ban further releases. The plaintiffs filed the suit with Fukushima District Court.

A recent opinion poll conducted by the Social Survey Research Centre, 54% of respondents said that the discharging of treated water into the ocean by the Japanese government and TEPCO was "problematic but unavoidable," and 29% said it was "reasonable." On the other hand, 10% of respondents said that the release must be stopped. In South Korean polls indicate that more than 70% percent of respondents opposed or were concerned about the Fukushima water discharge.

Image (top left): IAEA staff sampling seawater within three kilometres from the Fukushima Daiichi Nuclear Power Station as part of the Agency’s safety review of the ALPS treated water discharge (courtesy of TEPCO)

Image (right): Protests against the release of the treated water continue across China and Japan, as well as South Korea and some Pacific islands