Kansai Electric (9503) confirmed completion of reactivation preparations for its Mihama No. 3 reactor following a September 18 shutdown. The utility plans to start the unit on October 10, with full commercial operations expected in November.
The path from shutdown to restart of the Mihama No. 3 reactor (rated output 826,000 kW) highlights rigorous equipment maintenance protocols. Kansai Electric triggered an emergency shutdown on September 17 at 4:03 a.m. after detecting water drops from insulation material in the feedwater heater during adjustment operations.
Investigations revealed that incorrect installation of exterior plates during 2010 construction allowed rainwater ingress, leading to external corrosion and pinhole leaks in the piping. To prevent recurrence, the utility replaced the affected piping with stainless steel, updated maintenance guides with clear installation instructions, and strengthened its repeat-prevention framework through physical and procedural upgrades.
This three-tiered approach of root cause analysis, hardware modification, and manual revision reinforces trust as a public utility.
The specific timetable for the restart is as follows:
| Category | Scheduled Date |
|---|---|
| Reactor Start / Adjustment Ops Begin | October 10, 2026 |
| Full Commercial Resumption (Post-Inspection) | November 4, 2026 |
The restoration of this large-scale 826,000 kW asset helps Kansai Electric secure supply amid tight regional demand. While nuclear restarts typically take years, the rapid resolution of causes and countermeasures here is notable.
Contributing to Power Assurance for Winter Peak Demand
For investors, this was a temporary stoppage due to equipment issues rather than planned outages, suggesting limited long-term impact on reliability.
This incident draws attention to the maintenance management of aging infrastructure. The root cause being a human error in plate installation underscores the need to review manual checks in inspection processes.
Thorough Prevention of Recurrence
Before full operations resume on November 4, a comprehensive load performance test will verify design specifications. Successful completion positions the reactor as a stable revenue source.
For job seekers, this case illustrates organizational resilience: rapid identification of human error, physical correction, and systemic prevention foster a high-compliance culture that supports long-term employment stability. For investors, it offers material to re-evaluate risk management standards at Kansai Electric, which has high nuclear dependency.
Analyst take
The speed of technical recovery is notable, but the pinhole leak caused by a simple installation error reveals potential blind spots in inspection processes. Assessing the true value of repeat-prevention measures is essential.
Investors should monitor the October restart and November full operation milestones while watching for changes in maintenance costs or additional regulatory requirements. While recovering power availability supports stable dividends, continuous confirmation that prevention measures are strictly enforced on-site is required.
