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Fukushima: New Evidence of Nuclear Fuel Releases Found

Research team member monitoring for the presence of radioactive particles in the exclusion zone a few kms from the Fukushima site. July 2017 sampling trip. Credit: Dr. Gareth Law

Scientists have been looking at extremely small pieces of debris, known as micro-particles, which were released into the environment during the initial Fukushima Daiichi disaster in 2011.

The researchers discovered uranium from nuclear fuel embedded in or associated with cesium-rich micro particles that were emitted from the plant’s reactors during the meltdowns.

The particles found measure just five micrometers or less; approximately 20 times smaller than the width of a human hair. The size of the particles means humans could inhale them.

The reactor debris fragments were found inside the nuclear exclusion zone, in paddy soils and at an abandoned aquaculture center, located several kilometers from the nuclear plant.

It was previously thought that only volatile, gaseous radionuclides such as cesium and iodine were released from the damaged reactors. Now it is becoming clear that small, solid particles were also emitted, and that some of these particles contain very long-lived radionuclides; for example, uranium has a half-life of billions of years.

This study could mean the environmental impact from the fallout may last much longer than previously expected.

Credit: Dr. Gareth Law, University of Manchester

“Our research strongly suggests there is a need for further detailed investigation on Fukushima fuel debris, inside, and potentially outside the nuclear exclusion zone,” Dr. Gareth Law, Senior Lecturer in Analytical Radiochemistry at the University of Manchester and an author on the paper. “Whilst it is extremely difficult to get samples from such an inhospitable environment, further work will enhance our understanding of the long-term behavior of the fuel debris nano-particles and their impact.”

The Tokyo Electric Power Company (TEPCO) is currently responsible for the clean-up and decommissioning process at the Fukushima Daiichi site and in the surrounding exclusion zone. Dr. Satoshi Utsunomiya, Associate Professor at Kyushu University (Japan) led the study.

At present, chemical data on the fuel debris located within the damaged nuclear reactors is impossible to get due to the high levels of radiation. The microparticles found by the international team of researchers will provide vital clues on the decommissioning challenges that lie ahead.

Read more: Uranium Dioxides and Debris Fragments Released to the Environment with Cesium-Rich Microparticles from the Fukushima Daiichi Nuclear Power Plant, Environ Sci Technol. 2018 Feb 13. doi: 10.1021/acs.est.7b06309.

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