Japanese Labs Reliable in Analysing Seawater, Sediment and Fish Samples Near Fukushima, IAEA Report Finds

Seawater samples collected for analysis near the Fukushima Daiichi Nuclear Power Plant in November 2015. (Photo: Paul Morris/IAEA)

Japanese laboratories working for the country’s government, and tested by the IAEA, have produced reliable data on the level of radionuclides in seawater, sediment and fish samples collected near Fukushima, according to a report released last month.

The IAEA collected the samples from the sea near Fukushima multiple times in 2014 and 2015, and has analysed them independently in its own laboratories in Monaco. Some of the samples were also analysed separately by laboratories in Ireland and New Zealand, associated with an IAEA network of laboratories measuring environmental radioactivity. The results were then compared to those obtained by five Japanese laboratories that have regularly monitored radionuclide levels in seawater, sediments and fish since the accident at the Fukushima Daiichi nuclear power plant in 2011.

“There were no statistically significant differences between the results reported by the various laboratories,” said Iolanda Osvath, Head of the IAEA’s Radiometrics Laboratory (see chart). This indicates that the participating Japanese laboratories have the capacity to analyse these samples accurately, the IAEA report concluded.

The next seawater and sediment sampling mission is scheduled to take place from 16-22 May.

Sample analysis results (example): good agreement is shown between activity concentrations of Cesium-137 isotope in five seawater samples reported by laboratories in Japan (Japan Chemical Analysis Center: JCAC), Ireland (Environmental Protection Agency: EPA), New Zealand (Institute of Environmental Science and Research: ESR) and the IAEA. The yellow bar represents the reference value based on the mean of the four results.

Two other exercises, called proficiency tests, confirmed that participating laboratories were performing well in measuring radioactivity in water samples. In these exercises, the IAEA prepared low radioactivity seawater test samples and had the Japanese laboratories measure their level of radioactivity. The amount of radioactivity in these so called spiked samples was not known to the participating laboratories, who reported their methods and results to the IAEA. Proficiency test results published so far are available on the IAEA website.

The analyses and the studies were part of the IAEA’s work to assist the Government of Japan in ensuring that its sea area monitoring around Fukushima Daiichi maintains a high quality, and is comprehensive, credible and transparent.

The work was 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 Daiichi Nuclear Power Station, which reviewed Japan's efforts to plan and implement the decommissioning of the plant.

Interlaboratory comparisons and proficiency test exercises are held to support high-quality gathering and analysis of marine samples and radioactivity data. The IAEA runs similar exercises for analytical laboratories worldwide so that they can improve and maintain high quality analytical capabilities.

Seawater samples for analysis collected near the Fukushima Daiichi Nuclear Power Plant in November 2015.

Fish samples collected from fishermen’s catches at the port of Onahama, Fukushima Prefecture.

Fish samples prepared for the interlaboratory comparison of radionuclide measurements.