With the sudden suspension of another nuclear reactor, authorities issued a level-two warning on the nation’s electric power supply, for the fourth time this summer.

The Korea Power Exchange raised the “attention” warning at 1:37 p.m. on Thursday as the quick-start reserve fell below the 3.5-million-kilowatt level, officials said.

This caused tension in the power supply control towers as the alarm came some 20 minutes sooner than expected.

The Ministry of Trade, Industry and Energy claimed late last week that the worst of this summer’s electricity shortage crisis was over.

The situation, however, was aggravated this week with the prolonged heat wave and the sudden breakdown and suspension of the 1-million-kilowatt Hanbit Reactor 6 in Younggwang, South Jeolla Province, on Wednesday afternoon.

Concerns are rising further as Hanbit Reactor 1, which as a total capacity of 950,000 kilowatts, is scheduled to halt operation next week for regular maintenance.

“We have maximized the output of private generators and lowered the general voltage level, but still expect difficulties in fluid power supply for a while,” said a KPX official.

By Bae Hyun-jung (tellme@heraldcorp.com)