Cracks in control rod tunnels found at S.Korean nuclear plant

Microscopic cracks.

South Korean nuclear regulators have found those in tunnels that guide control rods at a nuclear plant under maintenance.

"There are cracks in six tunnels. The reactor has been halted since Oct. 18 for regular maintenance and now the process has been extended by a further 47 days for repair of the cracks," said a spokeswoman for the presidential Korea Nuclear Safety and Security Commission.

She said it was the first time cracks of this type had been found in South Korea's nuclear sector, but added the safety risk was not serious enough to require public disclosure.

The reactor affected by the cracks has a capacity of 1,000 megawatts, and a government official said the extended shutdown could complicate efforts to ensure steady supply of power through the peak winter season after the two other reactors had been stopped until the end of this year.

The discovery of the cracks at the reactor comes just days after two reactors at the same plant in Yeonggwang county, in the southwest of the country, were shut down to replace parts that had been provided with forged certificates.

South Korea is investigating how thousands of parts for its nuclear reactors were supplied using forged safety documents, with regulators set to inspect all 23 of the country's facilities - a move that could test public support for the industry and threaten billions of dollars worth of export Asia's fourth-largest economy generates 30 percent of its electricity from 23 nuclear reactors at state-owned plants, and the government has warned of the potential for unprecedented power shortages due to the shutdowns as demand peaks in winter.

South Korea's state-run nuclear power utility said it was investigating the cause of the cracks, but said they had not caused any leaks.

"There are no penetrating cracks or leaks," Korea Hydro & Nuclear Power, a subsidiary of state utility Korea Electric Power Corp (KEPCO), said in a statement.

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