Japan nuclear operator admits years of seismic data manipulation

The operator of a nuclear power plant in central Japan has admitted that its engineering division has been manipulating seismic resistance data since 2012.

The Nuclear Regulation Authority said that Chubu Electric Power had identified more than 100 such cases, according to Japanese media reports.

In a report submitted to the regulator, the company acknowledged that it had received whistleblower warnings about possible data falsification as early as 2018 but failed to act on them. It had also previously admitted to selectively using “convenient” data when assessing the safety of the Hamaoka Nuclear Power Plant.

According to the findings, instead of calculating averages for seismic indicators as required, the company created multiple data combinations and selected those that best suited its assessments. At least 105 such instances were recorded between the 2012 and 2021 fiscal years. In some cases, the data were adjusted to align with a pre-determined “average” value.

The company said it has been unable to determine the full scope of those involved, noting that documentation was insufficient. It admitted that it had not established clear standards for generating seismic motion data or criteria for selecting representative samples.

Chubu Electric President Kingo Hayashi pledged to introduce reforms to prevent a recurrence, saying the issue would be "tackled with unwavering determination and total commitment."

The Hamaoka plant has remained offline since the 2011 disaster at the Fukushima Daiichi Nuclear Power Plant, which occurred under the government of Naoto Kan. The regulator has now suspended its safety review for a potential restart of the facility.

By Nazrin Sadigova