The Fukushima Daiichi Nuclear Power Plant accident has spread radioactive material throughout the Abukuma Mountains in the Hamadori region of Fukushima Prefecture, located west of the plant. Most radioactive material is contained within a depth of 5 cm from the surface of the forest soil. Cutting down and decontaminating the mountainous areas would generate a large amount of decontamination waste and be extremely costly. On the other hand, cutting and transporting only the trunks and branches of trees would prevent the spread of radioactive material. An organization has emerged that is challenging the effective use of radioactively contaminated forests. The Fukushima International Research and Education Organization (EFREI, Namie Town, Fukushima Prefecture) has developed a method using biofuel production technology that allows only tree cutting without disturbing the soil. If this experiment can be put into practical use, it is expected that forestry can be revived without the need for decontamination.
Decontamination following the nuclear accident has been limited to residential areas, leaving forests untouched. Vast areas of forest land remain unused. EFRAY has begun developing technology to produce biofuel from forests contaminated with radioactive materials. A demonstration experiment to produce biofuel from contaminated forests will begin in fiscal 2029. The experiment will be led by the leader of EFRAY’s Forest Bio-Utilization Organic Synthesis Research Unit. Participants include Hirosaki University, Tohoku University, Osaka University, and Deloitte Tohmatsu Consulting Inoda. The demonstration experiment will first involve pyrolysis of the cellulose and lignin contained in the wood. This pyrolysis extracts gasified hydrogen and carbon monoxide. The gas is then synthesized into biofuel and chemicals using a catalyst that promotes chemical reactions. Both technologies are established, and the key to practical application appears to be the development of new, highly efficient catalysts.
Finally, as a resident of Fukushima Prefecture, I’d like to say a few words. The 0.23 microsieverts per hour that has been used as a benchmark for decontamination will become an international safety standard. The 0.23 microsieverts standard means that 0.19 microsieverts, minus the natural effective dose of 0.04 microsieverts, would be 1 millisievert over a one-year period if exposed 365 days in a row. This standard has been overestimated, contributing to the negative public perception of the area. Immediately after the accident, some experts suggested that if the ambient radiation dose was 0.23 microsieverts, the human radiation dose would also be 0.23 microsieverts. In fact, ambient radiation doses do not directly enter the human body. Around the world, Ramsar sites, famous for the Ramsar Convention, experience annual radiation levels of over 6 millisieverts. Yet, no problems have been reported. The 0.23 microsievert target has created a situation in which decontamination continues indefinitely. The cost of decontamination work is estimated at 2 trillion yen for areas directly managed by the national government and 3 trillion yen for areas managed by municipalities. If this money had been allocated to other reconstruction projects, these areas might have become more prosperous.
