Early Restart and Safety Improvements at the Tomari Nuclear Power Station

「当社は，2026 年 7 月 30 日付で開示した「泊発電所における防潮堤設置工事の完了時期について」において，工事の完了時期を 2027 年 8 月とし，工事費の変更額については精査中としておりましたが，本日，工事の完了時期の決定に伴う工事費が 1,255 億円に決定いたしましたので，お知らせいたします。」

「For Unit 3 of the Tomari Nuclear Power Station, we will devote all available resources to the approval of the design and construction plan, the review of approval for changes to the operational safety program, pre-use operator inspections, and safety-related construction including the seawall, with a view to restarting the unit as early as possible in 2027.」

「With a view to restarting Unit 3 of the Tomari Nuclear Power Station as early as possible in 2027, we will devote our full efforts to the review of applications for approval of the design and construction plan and approval of changes to the operational safety program, pre-use operator inspections, and safety improvement construction, including the seawall.」

「We are responding to the review of compliance with the new regulatory standards toward the restart of the Tomari Nuclear Power Station, and in July 2025 received permission from the Nuclear Regulation Authority to change the installation of Unit 3 at the Tomari Nuclear Power Station.」

「We are responding to the review of compliance with the new regulatory standards toward the restart of the Tomari Nuclear Power Station. Explanations at review meetings have been completed for the assessment of the thickness of deposited pyroclastic material (volcanic ash), the assessment of the impact if the breakwater is damaged by a tsunami, measures to prevent drifting of vessels transporting fuel and other materials, and volcanic monitoring. We continue to address the remaining major review items, including the formulation of design-basis ground motion (Note 1) and the formulation of the design-basis tsunami (Note 2).」

「In June 2023, during the review of compliance with the new regulatory standards for the Tomari Nuclear Power Station, we received an assessment that the design-basis ground motion had been examined in a generally appropriate manner. We will continue to devote all available resources to the other review items toward achieving an early restart. We will also steadily carry out the construction to install a new seawall, which began in March 2024, while actively communicating information about the status of the review and our initiatives.」

「We have positioned safety assurance at the Tomari Nuclear Power Station as our top management priority and, under the president's leadership, are working to further improve safety based on the Safety Improvement Plan. Specifically, in addition to complying with the new regulatory standards for nuclear power stations, we are undertaking safety-related construction to further improve safety and reliability, conducting nuclear emergency preparedness drills assuming severe accidents and other scenarios, diversifying safety measures, and strengthening and enhancing systems for responding to severe accidents and other events. We are also responding to the review of compliance with the new regulatory standards toward the restart of the Tomari Nuclear Power Station. The assessment of the combination of tsunamis caused by earthquakes and tsunamis caused by landslides on land was deemed to have been examined in a generally appropriate manner. With respect to the seawall design policy, we completed the explanation of the assessment results regarding the structural feasibility of the seawall and the matters pointed out, and there were no matters requiring attention. We continue to address such matters as the formulation of the design-basis tsunami, the assessment of the possibility of volcanic activity, the assessment of the thickness of deposited pyroclastic material (volcanic ash), the assessment of the impact of drifting objects from vessels transporting fuel and other materials, and the assessment of the impact if the breakwater is damaged by a tsunami.」

「In October 2022, during the review of compliance with the new regulatory standards for the Tomari Nuclear Power Station, we received an assessment that the assessment of seismic motion developed without specifying an earthquake source had been examined in a generally appropriate manner.」

「We have positioned safety assurance at the Tomari Nuclear Power Station as our top management priority and, under the president's leadership, are working to further improve safety based on the Safety Improvement Plan.」

「Following the enforcement of the new regulatory standards, we submitted applications for permission to change the installation of nuclear reactors and other applications and have been responding to the compliance review. The re-evaluation of the tsunami caused by earthquakes assumed in the eastern margin of the Sea of Japan and the assessment of seismic motion developed without specifying an earthquake source were deemed to have been examined in a generally appropriate manner. We are continuing to address such matters as the assessment of design-basis ground motion, the combined assessment of tsunamis caused by earthquakes and tsunamis caused by landslides on land, the assessment of tsunamis caused by active faults assumed northwest offshore of the Shakotan Peninsula, the assessment of the possibility of volcanic activity, the assessment of the thickness of deposited pyroclastic material (volcanic ash), the assessment of the impact of soil liquefaction beneath the seawall caused by earthquakes, and the assessment of the impact if the breakwater is damaged by a tsunami.」

「Following the enforcement of the new regulatory standards, we submitted applications for permission to change the installation of nuclear reactors and other applications and have been responding to the compliance review. We received an assessment that the re-evaluation of the tsunami caused by earthquakes assumed in the eastern margin of the Sea of Japan had been generally appropriate.」

「In July 2021, during the review of compliance with the new regulatory standards for the Tomari Nuclear Power Station, the Nuclear Regulation Authority assessed the activity of faults within the power station site, which we had identified as the top-priority issue, as having been examined in a generally appropriate manner. We will continue to devote all available resources to the other major review items as well and proceed with measures toward the early restart of the Tomari Nuclear Power Station, with safety assurance as the overriding priority.」

「Following the enforcement of the new regulatory standards, we submitted applications for permission to change the installation of nuclear reactors and other applications and have been responding to the compliance review. In July of that year, we received an assessment that the examination of the activity of faults within the power station site had been generally appropriate, and in October that the assessment of seismic motion caused by faults northwest offshore of the Shakotan Peninsula had been generally appropriate.」

「Following the enforcement of the new regulatory standards, we submitted applications for permission to change the installation of nuclear reactors and other applications and have been responding to the compliance review. In July of that year, we received an assessment that the examination of the activity of faults within the power station site had been generally appropriate.」

「To achieve the early restart of the Tomari Nuclear Power Station, we will conduct additional investigations into the activity of faults within the site, the top-priority issue in the review of compliance with the new regulatory standards, compile the results of our examination as soon as possible based on the data obtained, and explain them at review meetings.」

「Alongside the early restart of the Tomari Nuclear Power Station, we will work to establish a highly competitive power generation mix for the future and seek to improve profitability by pursuing an integrated business strategy across the generation and retail businesses.」

「With a strong determination never to cause an accident like the one at the Fukushima Daiichi Nuclear Power Station, we have formulated the Tomari Nuclear Power Station Safety Improvement Plan to further reduce nuclear risks. In addition to complying with the new regulatory standards, we will make continuous efforts to achieve the world's highest level of safety, or excellence.」

「We are examining issues including the coastal landform on the west coast of the Shakotan Peninsula identified in the review of compliance with the new regulatory standards, the impact of a tsunami on the breakwater and earthquake-induced soil liquefaction beneath the seawall, and will devote all available resources to the restart of the Tomari Nuclear Power Station.」

「To achieve the earliest possible restart of the Tomari Nuclear Power Station, with safety assurance as the overriding priority, we will establish a company-wide support structure so that confirmation by the Nuclear Regulation Authority can be obtained as soon as possible, and shorten the schedule by making maximum use of precedents.」