IAEA assistance has contributed to safer environment in Fukushima Prefecture, local officials said

Ten years after the nuclear accident at the Fukushima Daiichi Nuclear Power Plant, radiation levels in most of Fukushima Prefecture no longer restrict everyday activities, local officials said at the release of two reports on the outcomes of a cooperation project with the IAEA over the last eight years. They thanked the IAEA for the advice it provided – based on international expertise, experience and best practices – in radiation monitoring, decontamination and the management of radioactive waste arising from decontamination activities as well as in information dissemination related to the three technical areas.

Large quantities of radioactive particles were released into the environment as a result of the explosion at the plant, and an 1150 square kilometer area around and to the northwest of the plant was declared an evacuation zone. While the decrease in radioactivity levels since the accident is primarily the result of natural processes, the efforts by the Prefecture government with the assistance of the IAEA have contributed significantly to the fall in radiation levels in inhabited areas, said Haruo Uemuro, Director General of the Fukushima Prefectural Centre for Environmental Creation.

Area-wide decontamination has been completed for most residential buildings, public facilities and agricultural land and radiation levels, allowing for everyday activities to continue as before the accident. This is in a large part thanks to our joint efforts with the IAEA.

The accident at Fukushima Daiichi was the worst emergency at a nuclear power plant since the Chornobyl explosion in 1986. It was triggered by a tsunami that followed a massive earthquake. While the national government has the primary responsibility for the management of the plant itself and of the evacuation zones, prefecture and municipal authorities are in charge of decontamination, the management of radioactive waste, remediation and radiation monitoring in the wider area.

Since 2012, the IAEA has provided extensive assistance to the authorities of Fukushima Prefecture in areas related to radiation monitoring and remediation, in order to ensure on-going protection of people and the environment from ionizing radiation. The assistance is an example of IAEA support to authorities in dealing with the consequences of the accidental release of radioactive substances into the environment. 

“With the exception of the Difficult-to-Return Zone, area-wide decontamination has been completed for most residential buildings, public facilities and agricultural land and radiation levels, allowing for everyday activities to continue as before the accident,” Uemuro said. “This is in a large part thanks to our joint efforts with the IAEA.”

Since the establishment of the initial evacuation zones, restrictions have been either fully or partially lifted in many areas. Currently, evacuation designated zones occupy 337 square kilometers – just 2.4% of the prefecture.

Safety assessment of temporary storage sites

The IAEA’s assistance included the development of technical guidelines and advice on systematic assessment of safety for the over 800 temporary storage sites of radioactive waste located outside the plant throughout the prefecture. The sites, which hold tens of thousands of sealed bags of soil and other material containing radioactive caesium, were initially designed for three years. Their lifetime has since been extended, and this has necessitated new safety assessments to address, in particular, the ageing of different storage components, said Miroslav Pinak, Section Head at the IAEA Division of Radiation, Transport and Waste Safety.

IAEA experts advised the authorities – based on international experience – on safety assessment to demonstrate the safety of the temporary storage sites under various scenarios such as fires and flooding, as well as on the safety aspects of the retrieval of bags and the remediation of the storage sites following the removal of the waste, much of which has now been moved to an Interim Storage Facility, operated by the national government, next to the Fukushima Daiichi plant. “Releasing these sites back to their landowners is another example of life returning to normal,” Pinak said.

Rivers and lakes

While radioactive particles on land are stationary, rivers and lakes represent a greater challenge, because the movement of river water can displace radioactive substances, both away from and towards inhabited areas. IAEA experts have advised Prefecture authorities on the behaviour of radioactive caesium in the environment, the application of existing, international environmental models for the natural transport of caesium in rivers, as well as the analysis of the results of radiation monitoring in rivers and lakes. It provided recommendations on the feasibility of various remediation techniques in freshwater systems, which formed the basis of decisions by authorities.

Activities of dissolved caesium in rivers and lakes are very low, and there is a continuous decline of radiation rates as a result of natural processes and decontamination measures, the report stated. Natural processes include the decay of caesium isotopes over time, which leads to a loss of their radioactivity, as well as their transport into the ocean as a result of normal water flow in rivers.

Support by IAEA experts also focused on studying the effects of decontamination at riverbanks and the review of the impact of the distribution of radionuclides after flooding caused by typhoons.

Forest and wildlife

Most of the land area affected by the accident is forest, some of it used for recreational activities and hunting. IAEA experts have provided advice on the monitoring of radionuclides in forests and in wildlife. This has included advice on the study and estimate of the long-term behaviour of radioactive caesium in forests and the establishment of monitoring programmes to identify and track trends.

“We look forward to fully restoring the forests as recreational areas in the near future,” Uemuro said. “The advice of the IAEA has been instrumental to our analysis.”

Informing the public

The IAEA has also provided assistance to the Prefecture on the use of radiation monitoring data to develop maps for the public, as well as on effective ways to provide information to the public in a timely and understandable manner, based on global experience in dealing with accidental releases of radiation to the environment.

“Using pictures, infographics, clear explanations and language free of scientific jargon is key to achieving public understanding of the data and addressing perceived risks,” said Pinak.