Dr Stephanie Handley – Sidhu discusses the University of Birmingham’s involvement in the Fukushima nuclear power plant incident.
The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident is considered as one of the biggest environmental, social and economic disasters in recent years. Stabilisation of the FDNPP and decontamination of surrounding areas is likely to take over 100 years and is estimated to cost trillions of yen. Problems to contend with include the types and amounts of radionuclides released and the vast areas and complexity of the environmental media (e.g. soils, biomass and waters) contaminated.
Contamination from the FDNPP covers approximately 1700 km2; land use comprises of ~75% forests, ~15% agricultural lands and 10% urban and other areas. The radionuclides of immediate concern are 90Sr and 137,134 Cs because they are mobile, occur in larger quantities and are bioavailable. Image 1 [below] shows the ‘bagged’ waste from one decontamination operation. The top soil (10-20 cm) is mechanically removed and stored in temporary repositories onsite. Decontamination of the agricultural land alone by this method is likely to produce ~40-90 mega tonnes of waste. Public concern regarding radiation from the waste left on-site has led to the development of soil clean-up technologies, such as soil washing techniques that use organic acids to remove the radioisotopes and reduce waste volumes. Collaborative work between the University of Birmingham and the Japanese Atomic Energy Agency (JAEA) showed that the efficiency of these chemical washing techniques was dependent on the soil type and showed that the waste solutions produced were very complex and difficult to clean-up using traditional sorbent materials [Grant 1]. For soils collected from Iitate village, less than 40% of the Cs could be removed, confirming that the Cs is locked securely within the clay structure, these findings and other research suggest that the most resource efficient remediation plans would be to leave the soil in on-site waste repository and allow radioactivity levels to decay naturally over time.
The concluded in a December 2013 report that it was difficult to take effective measures using only existing general knowledge and the committee asked for technical information to be further gathered from both domestic and overseas experts in the following six topics: (1) Storage of contaminated water, (2) Treatment of contaminated water, (3) Removal of radioactive materials from the seawater in the harbour, (4) Control of contaminated water within buildings, (5) Site management to restrict groundwater flowing into the site, and (6) Understanding groundwater flow including the behaviour of radionuclides.
The University of Birmingham is taking the lead in collaborative research (Grant 2) by producing novel restoration materials (e.g. magnetic zeolite sorbents, metal phosphate sorbents and fluidised materials) for the clean-up of radioactive contaminated sites, focussing on topics 2 & 3. Dr Handley-Sidhu and collaborators recently presented preliminary research results to Tokyo Electrical Power Company (TEPCO) who are responsible for Fukushima clean-up). The technologies and materials presented were praised for their innovation; of particular interest were the saline tolerant bacteria which can precipitate large quantities of calcite in seawater and capture Sr; amorphous hydroxyapatite which shows superior Sr uptake in saline waters and magnetic zeolites which can remediate radionulclides (Cs and Sr) and can be deployed and recovered from difficult to reach areas.
Image 1: Farmland at Iitate Village located ~30km from the FDNPP. The decontamination methods used have produced large quantities of soil waste which is currently being stored in black sacks and temporary repositories on-site.
Image 2: Environmental monitoring and soils sampling at Iitate Village (~40 mSv/y with hotspots of 200 mSv/y). The Japanese Nuclear Decommissioning Authority aims to reduce radiation levels close to natural background (< 2 mSv/y).
Image 3: April 2015 outside the TEPCO office in Tokyo. Meeting arranged to discuss remediation of FDNPP and surrounding areas. From left to right Prof. Yamashita, Shibaura Institute of Technology; Prof. Ohnuki, JAEA and Dr Handley-Sidhu, University of Birmingham.
Grant 1 March 2014 – June 2015 NERC Technology Proof of Concept, ‘Biogenic metal phosphates: Low cost, high capacity, stable ‘lockups’ for the removal of radionuclides from groundwater and decontamination solutions’ £178,000. Principal Investigator Prof. Lynne Macaskie, email@example.com
Grant 2 November 2014 – March 2017 EPSRC, UK Japan Civil Nuclear Research Program, ‘Novel restoration materials for clean-up of radionuclides in the environment’, £325,000. Principal Investigator Dr Joe Hriljac, firstname.lastname@example.org. In collaboration with Prof. Ohnuki, JAEA; Prof. Yamashita, Shibaura Institute of Technology and Prof. Utsunomiya Kyushu University.