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Research and Development Relating to the Accident at the TEPCO’s Fukushima Daiichi NPS

Environmental Remediation and Plant Decommissioning
1.Radiation monitoring ofenvironment

2.Environmental restoration
activities

Environmental
Remediation

3.Human resource
development

4.Communications
and public relations

5.Measurement andestimation of exposed dose

Fig.1-1 JAEA’s post-accident efforts at environmental remediation for recovery of Fukushima
These activities are discussed on the web page of the Headquarters of Fukushima Partnership
Operations of the JAEA. (https://fukushima.jaea.go.jp/en/)

Environmental RemediationAs a designated public institution established under theBasic Law on Natural Disasters, we started taking actions
immediately following the Great East Japan Earthquake onMarch 11, 2011. We have undertaken diversified actions
such as dispatching technical experts. As countermeasures tothe problems that are still continuing now, we are taking thefollowing actions (Fig.1-1) for the recovery of Fukushima.
Radiation Monitoring of Environment
It is necessary to grasp the precise contamination status
and radiation dose rate of the radioactive material in order
to assess the health effects and develop a decontaminationplan. Therefore, a continuous investigation of the radioactive
cesium (Cs) density in the seabed sediment (Topic 1-1) is being
performed. In addition, under a contract with MEXT, air dose
rate maps were obtained by a car-borne survey in East Japan(Topic 1-2) and by airborne monitoring around the Tokyo
Electric Power Company, Incorporated (TEPCO) Fukushima
Daiichi Nuclear Power Station (NPS) (Topic 1-3). In addition,measurement of the soil radioactivity distribution, aerial
monitoring throughout Japan, and measurement of purified
water in the Japan Atomic Energy Agency (JAEA) branchareas are being performed.
Environmental Restoration Activities
Quick decontamination is necessary for the recovery of theenvironment. Under a trust from the Cabinet Office, guideline
formulation, decontamination catalog development, anddecontamination technology verification projects are beingperformed. Waste reduction by decontamination of gravel(Topic 1-4) is being studied. By evaluating the changes in the
topographical characteristics and vegetation distribution, along-term environment change research project in Fukushima
has begun. Clarification of the soil contamination mechanism(Topics 1-5, 1-6, 1-7) and a study of the mobile Cs maintenancemechanism in forests (Topic 1-8) are being performed. In10

JAEA R&D Review 2013

addition, the development of a drinking water purifier (Topic 1-9)
and the study of Cs behavior inside and outside of theincinerator are under way. On the basis of the above studies,
investigations toward the optimization and increased efficiency
of decontamination for environmental recovery will becontinued in the future.
Human Resources Development
Upon request from Fukushima prefecture, we responded bydispatching lecturers for a decontamination work lecture class
led by the Nuclear Human Resource Development Center.
We held the class 15 times, and 7819 persons completed
it by March, 2013. In addition, under the support systemdeveloped upon request from the Cabinet Office, Ministryof the Environment, we acted to spread knowledge about
decontamination by dispatching experts to municipalities andcooperating in decontamination plan development, performing
decontamination technology consultation and instruction, andproviding inhabitant briefing session support.
Communications and Public Relations
We dispatched experts who explained radiation data anda scientific interpretation method and conducted meetings toanswer typical questions about radiation for about 1700 groups,for example, all the nursery schools, kindergartens, elementaryschools, and junior high schools in Fukushima prefecture. We held
these meetings in 210 places for 17286 persons by March, 2013.
Measurement and Estimation of Exposed Dose
We measured the internal radiation exposure using the wholebody counter (WBC) at the Tokai Research and Development
Center and a mobile WBC car for inhabitants upon requestfrom Fukushima prefecture. By the end of March, 2013, wehad measured 41043 people. In addition, the radiation exposure
doses for inhabitants under different conditions (Topic 1-10)
and for people who treated sludge including radioactive Cs(Topic 1-11) were evaluated.

Council for the Decommissioning of TEPCO s Fukushima Daiichi NPS
Chairman :Vice-chairman :Commissioner :Minister of Economy, Trade and Industry
Vice Minister of Economy, Trade and Industry
Senior Vice Minister of Education, Culture, Sports, Science and Technology, Japan Atomic
Energy Agency (JAEA) Chief Director, Executive President of TEPCO, President and CEOof Toshiba Corporation, Representative Executive Officer and President of Hitachi, Ltd.
Regulatory authority : Nuclear Regulation Authority, Chairman
Observer :Vice Governor of Fukushima prefecture※ The organization of the conventional “Government of Japan and TEPCO Council on
Mid-to-Long-Term Response for Decommissioning” has been
Committee on countermeasures forenhanced by the participation of concerned agencies involved in R&D.

contaminated water treatment

Notice and reporting on theconcept of facilities

Research base facility(JAEA)
Radioactive material
analysis and researchfacility
Remote-controlled
equipment and device
development facility

Notice and reporting on theresearch and development plan

Organization to manage R&D
Candidate members: JAEA, National Institute of Advanced Industrial
Science and Technology, Toshiba, Hitachi GE,
Mitsubishi Heavy Industries, TEPCO, and otherpower companies (with a total of 17companies)<Advice of both domestic and overseas experts>
Collaboration−Review of the system for gathering wisdom in Japan and from abroad
andutilization−Technical advice for R&D(2 to 3 international advisors will be employed)(International Decommissioning Experts Group (with 6 experts) will be organized)

Fig.1-2 Organizational chart of research and development promotion
We are studying the establishment of research base facilities and conducting research and development based on the national
R&D plan. [Council for the Decommissioning of TEPCO’s Fukushima Daiichi Nuclear Power Station (June 27,2013)]

Plant Decommissioning
Immediately after the accident, we began providing technicaladvice to the government and TEPCO, and conducting researchfor decommissioning and radioactive waste management into
the mid- and long-term.

Diet of Japan, and the Rebuild Japan Initiative Foundation, as
well as TEPCO, to investigate the accident and published theirrespective reports. We reviewed these reports to gain insights
useful for near-term regulatory activities, including accident
investigation (Topic 1-18).

Removal of Spent Fuel and Fuel Debris
In the accident, as sea water was injected into the spent
fuel pool for emergency cooling, the possibility of corrosion
problems with various materials was considered. Therefore,hydrazine was added to salt-containing water in order to reducethe dissolved oxygen. We evaluated the effect of irradiation on
deoxidation by hydrazine (Topic 1-12).
It is important to grasp the characteristics of the molten corematerials (the fuel debris) before defueling for safe handling,storage, processing, and disposal of the fuel debris. We areconducting R&D to investigate the characteristics using
simulated debris (Topic 1-13), examine the reactions between
the sea water used for emergency cooling and the fuel debris(Topic 1-14), study criticality control in order to prevent
re-criticality even if the form of the fuel debris or the water
volume changes during defueling (Topic 1-15), and determinematerial accountancy and control measures for the fuel debris
when it is removed from the core (Topic 1-16).

Radioactive Waste Management
A massive volume of contaminated water has been generated
as a result of the tsunami and the inflow of ground water into
the reactor buildings; this contaminated water is temporarily
stored at the plant site.
Some water treatment systems are being applied to remove
radioactive nuclides, e.g., cesium and strontium, from thecontaminated water. We are addressing the long-term storage,processing, and disposal of secondary waste produced bytreatment of the contaminated water, which presents important
challenges; making computational analyses of the cesium
absorption mechanism in zeolites (Topic 1-19); and examining
ways to simplify the water treatment process (Topic 1-20).

Estimation of Status inside Vessel and Investigationof Cause of Accident
The fuel in the reactors reached a high temperature andbecame molten when the core cooling system ceased operationin the station blackout due to the tsunami. To elucidate theprogress of the melting phenomena in the reactor core, weevaluated the nuclide inventory at the time of the nuclear
accident (Topic 1-17).
Several committees were established by the Government, theRemote Decontamination TechnologyDecontamination technology that uses remote accessdevices has to be developed to reduce the radiation dose ofworkers in the reactor buildings. It is necessary for effective
decontamination to comprehend the component nuclides, theirpenetration into the floors or walls, and the distribution of theradioactive contaminants. We conducted a radioanalysis of theconcrete core boring samples taken from the reactor buildings(Topic 1-21).
Future Plan
We will study the establishment of research base facilities
and conduct research and development based on the nationalR&D plan (Fig.1-2).

JAEA R&D Review 201311