* 1,000 MW Hanul No.5 reactor shut due to technical glitch -operator
* Operator says investigating cause
* Out of country’s 23 reactors, 4 now offline (Adds quotes and detail)
By Meeyoung Cho
SEOUL, Jan 29 (Reuters) - A South Korean nuclear power plant automatically shut down on Wednesday due to a technical glitch, taking the number of reactors closed to four out of 23 and increasing the risk of power shortages over winter.
A spokesman at the country’s nuclear operator, Korea Hydro & Nuclear Power, said the exact cause of the shutdown was under investigation and it was not yet clear when the 1,000-megawatt Hanul No.5 reactor would be restarted.
Asia’s fourth-largest economy is striving the avoid the risk of power blackouts during times of peak demand after a series of nuclear reactor closures linked to a safety scandal.
In May last year, a scandal broke over parts supplied using fake documents, resulting in closures of some reactors to replace these parts.
Last July, the Hanul No.5 reactor automatically shut and remained closed for a week to fix part of its steam-cooling system for a turbine, according to a second spokesman at the nuclear operator.
Nine non-core parts of the reactor had previously been replaced after being supplied using fake certificates and the new parts had been cleared by the regulator, he said.
Seoul has also faced public pressure to curb its use of nuclear power after Japan’s Fukushima disaster and plans to cut its reliance on nuclear power to 29 percent of total power supply by 2035, down from a planned 41 percent by 2030.
South Korea has 23 nuclear reactors, which generate about a third of its electricity. Alongside the latest closure, two are shut for scheduled maintenance and one is awaiting an extension of its licence after its 30-year lifespan expired in November 2012, according to the nuclear operator, which is owned by state-run Korea Electric Power Corp (KEPCO). (Reporting by Meeyoung Cho; Editing by Ed Davies)