Radioactive Waste Management After Fukushima Daiichi Accident

Shinya Nagasaki

Abstract The categories of radioactive wastes have markedly changed due to the Fukushima Daiichi Nuclear Power Station accident. In addition to the conventional radioactive wastes such as high-level radioactive waste, the designated wastes, the wastes generated by decontamination work such as contaminated soil, the wastes contaminated with radionuclides or nuclear fuel which were generated within the on-site area of the nuclear power station, the spent nuclear fuel and debris, and the contaminated water are now critically required to be taken into account. The technological and legal schemes, by which these radioactive wastes will be appropriately processed and disposed of, must be established as soon as possible. These schemes also have to be widely supported by the public and society. This chapter gives an overview of the concept of radioactive waste management and discusses the problems and challenges to be solved for the management of all types of radioactive wastes and for the sustainable use of nuclear energy in the 21st century.

Keywords Radioactive waste management Temporary storage Intermediate storage Disposal Contaminated water Debris Spent fuel

Introduction

The Fukushima Daiichi Nuclear Power Station accident of Tokyo Electric Power Company (hereafter, “Fukushima accident”) brought about a significant impact and change on the policy of nuclear energy development and use in Japan. Simultaneously, a challenge which has not been assumed scientifically, technologically, and legally before March 11, 2011, namely the processing and disposal of radioactive wastes generated by the Fukushima accident, is now becoming evident. All members of the nuclear community in Japan have a responsibility to clearly and concretely illustrate a roadmap of how the processing and disposal of the wastes contaminated with radioactive materials and nuclear fuels, generated by the Fukushima accident, can proceed as a function of time. This is the most critical subject that cannot be bypassed for the restoration and revival of communities and residents who were obliged to evacuate due to the Fukushima accident. Furthermore, this is a primal premise for advancing the safe and steady decommissioning of Units 1–4 of Fukushima Daiichi. Consequently, what we learnt, what we are learning, and what we will learn from the Fukushima accident will be able to be made to be the common property of all human beings in the world.

From now on, it is considered that the concrete plans for processing and disposal will be proposed by the relevant ministries and agencies, and these will be put into action. The purpose of this chapter is to summarize the current legal system for radioactive waste management in Japan after the Fukushima accident and to discuss the practical challenges to be overcome for safe and secure radioactive waste management in the future.

Legislation for Radioactive Waste Management after Fukushima Daiichi Accident

The waste produced by the use of nuclear fuels such as uranium and plutonium in nuclear reactors is regulated by the Law for the Regulations of Nuclear Source Material, Nuclear Fuel Material and Reactors, and the waste generated by the use of radioisotopes, radiation rays, accelerators, and so on are controlled by the Law Concerning Prevention of Radiation Injury due to Radioisotopes, etc. This is the established legal structure, and the competent authorities have been designated. These laws presume that radioactive waste is generated in a controlled area, and is managed and stored there appropriately.

After the Fukushima accident, in addition to such conventional wastes, waste has been generated that is contaminated with radioactive materials and nuclear fuels produced outside of a controlled area, i.e., nuclear reactors or the nuclear power station of Tokyo Electric Power Company. Consequently, in order to manage the waste generated outside the nuclear power station, the Law on Special Measures Concerning the Handling of Environmental Pollution by Radioactive Materials by the NPS Accident Associated with the Tohoku District—Off the Pacific Ocean Earthquake that occurred on March 11, 2011 (hereafter, “the Law on Special Measures”) came into force, over which the Ministry of Environment has jurisdiction. Decontamination and processing and disposal of wastes are being conducted under this legal system.

Figure 15.1 shows the flow of processing of waste generated in Fukushima Prefecture by the Fukushima accident, determined by Cabinet decision, based on the Law on Special Measures. Disaster waste is treated by the Law on Special

Fig. 15.1 Flow of processing of wastes generated in Fukushima Prefecture by Fukushima accident. Radioactivity level is sum of 134Cs and 137Cs

Measures Concerning Disaster Waste Management after the Great East Japan Earthquake, but the waste of radiation levels higher than 8,000 Bq/kg (sum of 134Cs and 137Cs; hereinafter the same meaning shall apply) is treated in the Law of Special Measures, and hence, it will enter the flow of Fig. 15.1.

The criteria of 8,000 and 100,000 Bq/kg, illustrated in Fig. 15.1, were decided for the following three reasons [1]. First, when waste of 100,000 Bq/kg or less is disposed of in the landfill site which will not be used for residence and will be managed appropriately for a long period, the annual radiation dose rate of the residents around the site after the completion of landfill is estimated to be less than 10 μSv/y. Second, during the operation of controlled landfill sites for waste of 100,000 Bq/kg or less, the annual radiation dose rate of the residents around the site is evaluated to be less than 1 mSv/y, if their residence area is sufficiently far from the boundary of the site. Third, when waste of 8,000 Bq/kg or less is directly transferred to the landfill site, the annual radiation dose rate of workers is expected to be less than 1 mSv/y and the safety of workers is assured.

The waste generated in the countermeasure areas (areas where evacuation orders are ready to be lifted, areas where residents are not permitted to live, and areas where it is expected that the residents will have difficulties in returning for a long time) [2] is classified into two classes: waste of 8,000 Bq/kg or less and waste of over 8,000 Bq/kg. The former will be processed by local municipalities or waste disposers in accordance with the Waste Management and Public Cleansing Law. The latter will be treated as waste equivalent to the designated waste. The waste which is generated outside the countermeasure areas and for which radiation level exceeds 8,000 Bq/kg is labelled as designated waste by the Minister of Environment.

In Fukushima Prefecture, not only a large amount of waste accompanied with decontamination but also highly contaminated waste of over 100,000 Bq/kg is expected to be generated. The contaminated soil and other waste generated from decontamination will be stored in the temporary storage site, and then be transferred to the intermediate storage facility where those will be stored together with waste of over 100,000 Bq/kg. The waste generated outside Fukushima Prefecture is not transferred to the intermediate storage facility. Because waste of over 100,000 Bq/kg is not considered to be generated in prefectures other than Fukushima, the flows which go to the intermediate storage facility in Fig. 15.1 are not assumed for the waste outside Fukushima Prefecture.

Irrespective of location, waste of over 8,000–100,000 Bq/kg or less will be disposed of in a controlled repository/disposal site located in each prefecture. The existing landfill site is considered to be a candidate for this site. When a new controlled repository/disposal site needs to be built, the Japanese Government will select two or more proposed sites within the national lands in each prefecture, and will decide on a site. In addition, the volume of waste will be reduced through incineration, dryness, fusion, and so on, until a controlled repository/disposal site starts operation. A temporary facility will also be built for incinerating the byproducts (straw from rice and pastures, etc.) from agriculture or forestry which cannot be incinerated in the existing incineration facility.

The flow through the intermediate storage facility is particular to the waste generated in Fukushima Prefecture. The roadmap of the flow is planned as follows. The waste will be stored in the temporary storage site for approximately 3 years. Each city, town, or village is required to secure its own site within its boundary. In countermeasure areas, the Ministry of Environment will secure the sites in cooperation with local municipalities. By approximately 3 years after starting the formal temporary storage process, transport to the intermediate storage facility will be scheduled to start. The waste stored in the intermediate storage facility will be disposed of in a final repository, which will be constructed and operated outside Fukushima Prefecture. The transport from the intermediate storage facility to the final repository will be scheduled to start within 30 years after the intermediate storage starts.

However, under the current situation, many problems about specific processing and disposal still remain, as mentioned below, and the challenge of site selection for the intermediate storage facility and for controlled landfill has yet to be overcome. As can be seen in opposition movements and protests by the residents of Yaita City, Tochigi Prefecture, and Takahagi City, Ibaraki Prefecture, which were selected as the final landfill site by the Japanese Government, issues such as transparency of the selection procedure, communication with stakeholders, and equity in liability and onus are quite important. Furthermore, the Law on Special Measures decides only the framework on processing, decontamination, and budget. Most procedures and schedules are planned according to the basic policy by Cabinet decision, and specific methodology of landfill is illustrated in the notification from the Ministry of Environment. For the management of waste of over 100,000 Bq/kg, only the abstract requirements for safety of disposal are decided in Enforcement Regulations for the Law on Special Measures.

Management of radioactive waste generated within the Fukushima Daiichi nuclear power station by the accident must be performed primarily by Tokyo Electric Power Company in accordance with the Law for the Regulations of Nuclear Source Material, Nuclear Fuel Material and Reactors, but in actuality nothing is decided about processing, reprocessing, storage, and disposal of the waste. Damaged fuel, such as melted fuel, the debris and waste contaminated with radioactive materials, and nuclear fuel generated by the Fukushima accident, are not assumed in the Law for the Regulations of Nuclear Source Material, Nuclear Fuel Material and Reactors. Thus, revision of the law and/or the preparation of new legal system for the management of these radioactive wastes are critical and essential, and regulation for safety of radioactive waste management is inevitable. At present, solid wastes, such as debris and rubble, are planned to be stored in storage facilities in which the radiation shield and prevention of waste scattering are appropriately implemented. Furthermore, the volume of waste will be reduced and the materials with low radioactivity will be recycled within the Fukushima Daiichi Nuclear Power Station.

In the following three sections, the kinds of waste generated within Fukushima Daiichi Nuclear Power Station and the problems to be solved for safety and security of radioactive waste management are discussed.

 
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