South Korean officials said on Wednesday they had uncovered new instances of fake certificates being supplied for parts operating in nuclear power plants, but a source indicated that the revelations would cause no further reactor shutdowns.
Authorities shut two of the country's 23 reactors last month after a nuclear safety commission found fake certificates supplied by eight firms. With nuclear power providing a third of electricity, that raised the prospect of winter shortages.
A third reactor was subjected to extended maintenance after microscopic cracks were found in tunnels that control fuel rods. The commission subsequently found nearly 1,000 more parts had been supplied with fake certificates by two other firms, but said remaining reactors would stay in operation.
In the latest revelations, the Board of Audit and Inspection said two unidentified firms had forged a combined 87 documents affecting parts.
It gave no further details, but a source at Korea Hydro and Nuclear Power said the documents related to parts not directly linked to the nuclear process, including pumps and cylinder heads for diesel engines. The documents served as guarantees for the quality of raw materials used to make the parts.
"This case is different from last month's as it is related to raw materials for parts," said the source, who declined to be identified. "We have no plans for (further) shutdowns as the parts are tiny."
The source said the affected parts were worth a total of 1.6 billion won ($1.48 million), while officials said all parts supplied by the companies were worth a total 11.4 billion won.
Authorities also said the parts affected in last month's revelations, including fuses, switches and heat sensors, had no connection to the nuclear process and ruled out any safety risk.
Officials in Asia's fourth-largest economy have said they may have to resort to rolling blackouts as the grid will have less than a third of normal reserve capacity.
The government has been criticised for a lack of transparency over safety in its nuclear programme and for the dual supervisory and promotion roles of regulators.
But the scandals have caused no backlash with the public, which remains fundamentally pro-nuclear. An opposition lawmaker has pressed the government to resume publishing polls on nuclear safety after a loss of confidence in the sector after last year's Fukushima disaster in Japan.