Conditions at the Fukushima Daiichi nuclear power plant site have improved since a review in 2018, the International Atomic Energy Agency (IAEA) has concluded following its fifth review of Japan's plans and activities to decommission the plant. The IAEA team of experts reviewed the current situation at the site and future plans in areas such as the removal of used fuel and the retrieval of fuel debris, radioactive waste, water and site management.
The leader of the review team, Christophe Xerri, visited the Fukushima Daiichi site under strict COVID-19 protective measures to obtain first-hand information about the conditions there and progress towards decommissioning of the site (Image: Tepco)
The 12-member team - comprising nine from the IAEA and one each from Indonesia, the UK and the USA - conducted a two-month review mission from 30 June to 27 August. The mission, which followed two previous reviews in 2013, one in 2015 and one in 2018, was conducted at the request of the Japanese government. The review comprised a combination of online discussions, face-to-face meetings in Vienna and Tokyo and a visit to the Fukushima Daiichi site.
The team said Japan had made significant progress since the accident in moving from an emergency to a stable situation, managing daily activities at the site, reducing risks to the workforce and the environment, and planning for decommissioning with a systematic industrial approach.
Site conditions have improved further since the previous IAEA review in 2018, with a decline in the generation of contaminated water, the safe emptying of a used fuel pool, better understanding of the reactor fuel debris, new waste management facilities, and measures against extreme tsunamis and earthquakes. However, the decommissioning environment remains complex and challenging, the team added.
The latest review took place just a few months after Japan decided in April how to dispose of large amounts of treated water that has accumulated at the site since the accident. The 2018 mission had advised Japan to urgently decide on the issue, and this year's mission welcomed that a decision had now been taken, saying it will facilitate the whole decommissioning plan.
To help address future challenges for a decommissioning project expected to last several decades, the review team encouraged Japan to start allocating sufficient resources to plan and prepare for activities beyond the next 10 years until the end of the work.
In its report delivered to Japanese authorities today, the team acknowledged a number of accomplishments since the 2018 mission, including: strengthening of project management; risk reduction measures, such as completing the emptying of the used fuel pool of reactor unit 3 in February; and, better understanding of the presence of fuel debris in units 1-3 and the development, with UK support, of a one-of-a-kind robotic arm for a trial fuel debris retrieval from unit 2 in 2022.
The review team encouraged Japan to continue carrying out and enhancing its strategy for safe and effective decommissioning. Further development of human resources in areas such as project management will be vital in this respect, it said. The team of experts also suggested the application of circular economy principles to maximise efficiency and reduce waste.
The team noted that information currently being gathered on the fuel debris, as well as the experience that will be gained from its retrieval from unit 2, will be used in the development of options for the next steps, in particular regarding units 1 and 3.
In addition, the team provided advice on more specific organisational and technical areas, including: the development of planning scenarios for the entire decommissioning programme, including all reactor units and ageing management for recently built supporting facilities at the site; comprehensive characterisation of the fuel debris to identify key parameters that will enable the design of future strategies, including potential treatment and conditioning, to manage this material from initial storage to disposition; further management development to optimise utilisation of site space and workforce logistics; conducting surveys to assess how the public outreach programme contributes to enhancing public confidence in the decommissioning activities; and, strengthening of international cooperation to ensure both that Japan benefits from external solutions and experience for safe and effective decommissioning and that it makes the knowledge and expertise it gained as a result of the accident available internationally.
"The decommissioning of Fukushima Daiichi is a uniquely complex and demanding undertaking that requires substantial technical skills and expertise as well as large scale management and project experience," said leader of the team Christophe Xerri, Director of the IAEA’s Division of Nuclear Fuel Cycle and Waste Technology. "Japan has continued to make impressive progress since our previous review mission three years ago.
"A successful decommissioning of Fukushima Daiichi in the coming two or three decades will require disciplined programme and project management to deal with significant risks and uncertainties, a continued focus on safety culture and further scientific and technological developments."