Imperial research to help in nuclear clean-up at Fukushima

In March 2011, an earthquake off the east coast of Japan triggered a tsunami, which smashed into the Fukushima Daiichi Nuclear Plant. This led to explosions and a partial meltdown of three boiling water reactors and the mass evacuation by authorities of citizens living in the surrounding area.

Since the accident, water has been used to cool the damaged cores and reactor buildings. As part of the cooling process more than 3,760 tonnes of radioactively contaminated water is collected per day. Engineers on the site are using several decontamination facilities containing waste filters to extract radionuclides from the water, but as yet, the authorities do not have an agreed solution for safely immobilising this hazardous leftover waste material.

Now, researchers at Imperial’s Centre for Nuclear Engineering are collaborating with partners in the UK and Japan to develop processes for capturing and disposing of these radionuclides. The team is developing a glass material to mix with the waste filters, which are melted to form a solid composite material that will be stable for thousands of years and suitable for disposal deep underground.

In the new project, the team aim to determine whether this material will be able to withstand the heat generated by the radionuclides as they decay. If it is sufficiently robust, this should mean the nuclear waste can be collected without the need for additional complicated processes for permanently sealing in the toxic material,  processes that would be time consuming and expensive.

Professor Lee, Director of the Centre from the Department of Materials at Imperial, said: “Multinational collaborations like this one are the key way for finding solutions to some of the world’s most pressing challenges. It is paramount that we find a safe and inexpensive approach to seal in and store this leftover radioactive material if the clean-up at Fukushima is to be a success. The results of this project may also have implications for the way we dispose of the UK’s legacy wastes, including those in the ponds and silos at the Sellafield storage and reprocessing site.”

During the clean-up process at the Plant, the contaminated cooling water is filtered through a material called High Dose Spent Absorbent (HDSA), which collects the radionuclides. The radionuclides generate heat as they decay in the HDSA and the Imperial team will develop computer models that quantify these heat levels.

The data generated by the models will enable the team to gauge whether the glass material they are currently experimenting with will be able encase the radioactive HDSA and withstand the heat generated.

The Imperial research will be carried out by the Professor Bill Lee and Dr Luc Vandeperre from the Centre for Nuclear Engineering at Imperial. Other related projects will be carried out by researchers from the University of Sheffield and teams at the Kyushu and Tohoku Universities in Japan.

The project is funded by the Engineering and Physical Sciences Research Council and is expected to run initially for two years.