Fukushima off-site clean-up success

Radioactive decontamination has been completed to target in one municipality affected by Fukushima accident, and operations to decontaminate other areas are making good progress, Japan's Ministry of Environment has reported.

Radioactive decontamination has been completed to target in one municipality affected by Fukushima accident, and operations to decontaminate other areas are making good progress, Japan's Ministry of Environment has reported.

Decontaminating residential property in Tamura (Image: MOE)

The International Atomic Energy Agency's (IAEA's) General Conference in Vienna was given a full briefing from the Japanese authorities on the current status of the stricken power plant as well as actions being undertaken in the surrounding areas. Eleven municipalities in the former restricted zone or planned evacuation area, within 20 km of the plant or where annual cumulative radiation dose is greater than 20 mSv, are designated Special Decontamination Areas, where decontamination work is being implemented by the government. A further 100 municipalities in eight prefectures, where air dose rates are over 0.23 µSv per hour (equivalent to over 1 mSv per year) are classed as Intensive Decontamination Areas, where decontamination is being implemented by each municipality with funding and technical support from the national government.

Work has been completed to target levels in one municipality in the Special Decontamination Areas: Tamura, where decontamination of living areas, farmland, forest and roads was declared to be 100% complete in June 2013. Over a period of just under a year, workers spent a total of 120,000 man days decontaminating nearly 230,000 square metres of buildings including 121 homes, 96 km of roads, 1.2 million square metres of farmland and nearly 2 million square metres of forests using a variety of techniques including pressure washing and topsoil removal.

Significant progress has also been made relative to targets in Naraha, with completion levels for living areas, farmland and forest ranging from 51% to 68%, and Kawauchi, where living areas and roads are 100% complete and forest is 69% complete. Naraha, Kawauchi and Okuma are on schedule to finish decontamination work within the current financial year which ends on 31 March 2014.

In the Intensive Contamination Areas, decontamination work is being implemented based on plans developed at the municipal level, with some municipalities setting targets of five years to complete the work and others choosing a timescale of two to three years. According to the update, decontamination work on spaces related to children, such as schools and nurseries, and public facilities, such as parks, is nearing completion, although it could take some time for all of the planned actions to be completed.

Municipalities are sharing their experiences of decontamination work through a so-called Good Practice Collection, compiled by the MoE's Fukushima Office for Environmental Restoration. The ministry said this can help to streamline decontamination work as accumulated knowledge and innovation are passed on from one municipality to another.

New follow-ups

The MoE has now announced new policies for follow-up work in areas where decontamination has been completed. These include ongoing monitoring for newly found contamination - for example, areas where dose rates may rise because of the re-accumulation of fallen leaves - followed, where necessary, further decontamination.

The ministry is also working to secure an interim storage facility for materials such as soil removed during the decontamination process, and is in the process of site selection. The facility is expected to enter service early in 2015.

Researched and written
by World Nuclear News