South Korea

Javascript is required to view this map.
INES-event
INES 2

Loss of shutdown cooling due to station blackout during refueling outage

On February 9, 2012, during a refueling outage, loss of off-site power (LOOP) occurred and emergency diesel generator (EDG) 'B' failed to start while EDG 'A' was out of service for scheduled maintenance, resulting in a station blackout (SBO). Off-site power was restored 12 minutes after the SBO condition began.
The LOOP was caused by a human error during a protective relay test of the main generator. The EDG 'B' failing to start was caused by the failure of the EDG air start system.

Category: Power Reactor South Korea »

South Korea pulls out of Lithuania nuclear project: gov't

Monday, December 6, 2010

A four-nation nuclear power plant project in Lithuania was thrown into doubt Friday, as the government said a South Korean bidder had pulled out and another was rejected.

Lithuania's deputy energy minister, Romas Svedas, told reporters that South Korea's state energy firm Korea Electric Power Corp (KEPCO) had withdrawn from the race to build and run the plant.

Posted in | »

INES-event
INES 2

Inadvertent Containment Spray of Reactor Coolant

On 17 September 2010, during the reactor coolant system (RCS) heat-up in hot shutdown condition under commissioning test, the containment spray isolation valve was opened inadvertently. The opened valve formed the flow path through the shutdown cooling system (SCS) from the RCS to the containment spray nozzles.

Category: Power Reactor South Korea »

INES-event
INES 1

Contamination of Demineralized Water System & Uncontrolled Minor Radioactivity Release

Event Description

1. Circumstances at the initial stage of the Event
On December 22, 2003, at 23:32, just prior to the plant start-up, an "Alert" alarm of the radiation monitor (RM, RE-054) monitoring the radiation level of intake air of Technical Support Center HVAC actuated. Plant start-up was proceeding in parallel with checking of the cause of RM alarm actuation. Full power was achieved on December 24, 2003.

Category: Power Reactor South Korea »

INES-event
INES 1

Steam Generator Tube Failure

Steam generator tube failure event occurred at Ulchin unit 4 on April 5, 2002. Ulchin unit 4 was in shutdown mode to initiate cooling down at 01:20 on April 5, 2002 for the 3rd refueling outage. At 18:33 (all times are KST) the operators observed notable decreases in the pressurizer level and pressure at the beginning stage of cooling down. In reponse, the letdown flow was isolated and a third charging pump started to compensate the loss of primary coolant inventory at 18:55. Even though a third charging pump was activated, it couldn't make up the loss.

Category: Power Reactor South Korea »

INES-event
INES 0

Reactor trip due to the malfunction of optical isolator

Yonggwang unit 4 was operated at the rated power. During normal operation, reactor was tripped due to the dropping of control rods. Investigation revealed that CEAC (Control Element Assembly Calculator) #1 caused the reactor trip because one of the optical isolator had failed and generated wrong control rod position signal.
There were no releases of radioactive materials outside the reactor building and no unplanned exposure to employees.

Category: Power Reactor South Korea »

INES-event
INES 0

Manual shutdown for repairing the fueling machine

Refueling machine of Wolsong unit 1 stuck to calandria during fuel loading in normal operation. Reactor was shut down manually in order to decouple the fueling machine.
Disengagement of locking ring and locking tang was the cause of fueling machine malfunction.
There were no releases of radioactive materials outside the reactor building and no unplanned exposure to employees.
Justification: As full safety functions were available, the event is rated at level "0" as per User's manual Part III, Table II, A1.

Category: Power Reactor South Korea »

INES-event
INES 0

Manual shutdown for repairing the steam generator tube leak

Yonggwang unit 2 was operated at the rated power. On July 19, 1996 radioactive material Xe-135 was detected when condenser off-gas was monitored. Continuing surveillance was carried out to detect the leakage rate from the primary side. Leakage rate from primary to secondary side increased gradually.
When the leakage rate reached around 9 l/hr, the plant started manual shutdown to repair the S/G tubes on August 7, 1996.

Category: Power Reactor South Korea »

INES-event
INES 0

Manual shutdown for repairing of main condenser tube

Ulchin unit 1 was operated at the rated power. On Aug. 11, 1996 conductivity and concentration of sodium ion were increased at #5 water-box of condenser. As the deterioration of S/G secondary side water chemistry was expected, condenser purification system was inserviced additionally and reactor power was decreased to 65%. Evaluation on the water chemistry of S/G secondary side was carried out and the results of it required the immediate shutdown. Ulchin unit 1 was manually shut down to hot shut down condition and maintained.

Category: Power Reactor South Korea »

INES-event
INES 0

Blockage of sea water screen by jellyfish

Ulchin unit 2 was operated at the rated power. On Sep. 14, 1996, a lot of jellyfish had moved to the seaside and blocked the sea water screen. As sea water did not flow sufficiently to the intake area, one of the circulating water pumps was tripped because of NPSII low signal.
Reactor power was reduced to 69% of full power. However, incoming of jellyfish was not stopped and the other circulating water pump was tripped also. Vacuum low signal from main condensers arose and it made turbine trip. Reactor was tripped by turbine trip signal finally.

Category: Power Reactor South Korea »