Search Results

Cause Identified for Automatic Shutdown of Unit 3 at Shin-Kori Nuclear Power Plant in South Korea

The Nuclear Safety and Security Commission (NSSC) of South Korea reported on the 4th that it has completed its investigation into the automatic shutdown of Unit 3 at the Shin-Kori nuclear power plant during commissioning tests on the 11th of last month, and has approved the resumption of commissioning tests for the unit. The investigation confirmed that the direct cause of the incident was an operator error in inputting parameters during the process of restoring reactor power after the tests. According to the investigation findings, at the time of the incident, while setting the parameters for the turbine control valve position limiter, the operator mistakenly entered a value intended to limit the upper opening limit of the valve as a value in the valve closing direction. This limiter is used to prevent a rapid increase in the amount of steam entering the turbine for power generation within a short period. After the parameter error, the unit experienced an interruption in power output at approximately 80% power level, followed by an automatic shutdown.

2026-09-04

Investigation into Automatic Shutdown of Unit 3 at Japan's Ohi Nuclear Power Plant: Damage Found in Exciter Rotating Rectifier

Kansai Electric Power reported on August 19 that Unit 3 of the Ohi Nuclear Power Plant experienced an automatic generator trip triggered by a generator loss-of-field alarm at 23:56 on August 8, followed by an automatic reactor shutdown. At the time of the event, the unit was operating stably at rated thermal power. The company stated that the event caused no radiological impact on the environment. The loss-of-field alarm is used to indicate an abnormal state in the magnetic field generated inside the generator. Following the incident, Kansai Electric conducted on-site inspections of equipment related to generator magnetic field establishment, including the generator, exciter, and automatic voltage regulator (AVR). Among these, the exciter is used to establish the magnetic field for the generator...

2026-08-19

Automatic Shutdown of Unit 4 at South Korea's Hanul Nuclear Power Plant, Regulator Launches Investigation

The Nuclear Safety and Security Commission (NSSC) of South Korea reported on August 19 that Korea Hydro & Nuclear Power Co., Ltd. (KHNP) had reported the same day that Unit 4 of the Hanul Nuclear Power Plant, located in Uljin County, North Gyeongsang Province, automatically shut down at approximately 8:50 a.m. The NSSC stated that Unit 4 of the Hanul Nuclear Power Plant is currently in a stable condition. No abnormal alarms were triggered by on-site radiation monitors, and no leakage of radioactive materials to the outside environment has been detected. According to the notification, the NSSC's regional office for the Hanul Nuclear Power Plant is conducting inspections of on-site safety conditions. The regulatory body also plans to dispatch an investigation team comprising experts from the Korea Institute of Nuclear Safety (KINS) to the site to further confirm the cause of the automatic shutdown and related safety conditions.

2026-08-19

Automatic Shutdown of Unit 3 at Oi Nuclear Power Plant During Operation; Kansai Electric Power to Investigate Cause from the 12th

Unit 3 of the Oi Nuclear Power Plant in Fukui Prefecture, Japan, experienced an automatic shutdown during operation in the early hours of the 9th. Operator Kansai Electric Power stated that the fault is related to an internal abnormality in the generator and plans to formally begin a cause investigation from the 12th. Currently, there is no clear timeline for when the unit can resume operation. According to reports, an alarm related to loss of magnetic field occurred inside the generator used for power generation at the time of the incident, after which the generator stopped, and the reactor in operation also automatically shut down. On the 10th, Kansai Electric Power visited the Fukui Prefectural Government to apologize for the fault and report on subsequent response measures. Yuichiro Sakamoto, head of the Fukui Prefecture Disaster Prevention and Safety Division, pointed out that following a steam leak fault at Mihama Nuclear Power Plant Unit 3 in May this year, an unexpected emergency shutdown of a reactor in operation occurring within a short period may undermine public trust in nuclear safety. Local government authorities have demanded that the operator promptly identify the cause and implement measures to prevent similar issues from recurring.

2026-08-11

Unit 3 of Japan's Ohi Nuclear Power Plant Automatically Shuts Down

Kansai Electric Power Co. announced in the early hours of the 9th that Unit 3 of the Ohi Nuclear Power Plant, located in Ohi Town, Fukui Prefecture, Japan, automatically shut down during operation. The unit has a generating capacity of 1.18 million kilowatts. According to Kansai Electric Power, at around 23:56 on the 8th, an alarm was triggered at the unit, indicating that the generator had lost the conditions required to produce a magnetic field. Subsequently, the generator automatically stopped operating, and the reactor also automatically shut down. Preliminary information suggests that the anomaly may involve the exciter, a device used to establish the magnetic field for the generator. Kansai Electric Power stated that no radioactive material leakage occurred as a result of this incident, and there was no radiological impact on nearby personnel or the environment. The cause of the malfunction...

2026-08-10