Chubu Electric prepares to withdraw the Hamaoka restart after seismic data was falsified

Chubu Electric Power plans to withdraw the safety-review applications for Units 3 and 4 at the Hamaoka nuclear plant in Omaezaki, Shizuoka Prefecture, government sources said Friday, after investigators confirmed that earthquake-motion data used in the restart file had been manipulated.

The company said the same day that it had received the report of an external lawyers' committee. President Kingo Hayashi will take questions in Nagoya on Monday, 14 September. Chairman Tetsu Katsuno has told people around him that he intends to resign over the misconduct, Japanese newspapers reported.

Industry minister Ryosei Akazawa said he had not yet seen the report in detail. "Based on Chubu Electric's response to our reporting order, we will take as strict action as possible," he said in Tokyo.

Why a withdrawal is rare

Utilities almost never pull a restart application once the Nuclear Regulation Authority has opened a file. Doing so concedes that the numbers the regulator was asked to trust cannot be used. It also resets the clock. Hamaoka 3 and 4 have been in the screening queue for more than a decade. A fresh application would have to be built on a new seismic model, then survive a new review, then face a local politics that has not grown warmer.

The NRA had already paused the review earlier this year after Chubu disclosed possible misconduct in the earthquake-safety data. NHK reported Friday that the company was making final arrangements to abandon the restart. Shares fell as much as 4.2 percent on that report.

One estimate circulating in Japanese financial coverage put the lost annual earnings improvement from a working Hamaoka restart at about 250 billion yen. Chubu said on Friday that the earnings impact of the scandal has not been determined.

A plant on a fault coast

Hamaoka sits on the Enshu coast, above the Nankai Trough, the subduction zone that Japanese disaster planners treat as the country's most serious seismic risk. Then-prime minister Naoto Kan ordered the plant shut in 2011, after Fukushima, because a large trough earthquake was judged too plausible to ignore. Units 1 and 2 are already in decommissioning. Units 3, 4 and 5 have been idle. The restart case always turned on whether Chubu could prove the remaining reactors would ride out a trough shock at the ground motions the NRA now requires.

That is the file that was cooked. The suspected method, as described in Japanese reporting, was to understate possible earthquake vibrations in the screening documents. If the ground motion used in the model is too low, every calculation that follows, from pipe stress to building settlement, is too optimistic.

A wider governance problem

The seismic file is not the only recent failure. Chubu has also faced document tampering tied to decommissioning costs and overbilling by a group sales subsidiary. Those cases are why the lawyers' report, and Hayashi's Monday briefing, will be read for more than Hamaoka. Investors want to know whether the data problem was a closed team or a habit. The ministry wants to know the same thing before it decides how hard to strike.

Katsuno's expected resignation is the first personnel cost. It will not be the last if the report finds that managers above the engineering desk knew, or should have known, that the numbers were wrong.

What Monday must answer

Hayashi has to say whether the applications will in fact be withdrawn, what the lawyers found about motive and knowledge, and who else will leave. He also has to say what Chubu now believes about the real ground motion at Omaezaki. That last point is the one that decides whether Units 3 and 4 have a second life at all.

Japan's government still wants reactors back on the grid. Resource-poor utilities have treated restarts as the cheapest way to cut gas bills while Middle East oil and LNG stay expensive. A withdrawn Hamaoka file does not change that policy. It does show what happens when the safety numbers used to justify it cannot be defended in public.