Nuclear Safety and Security Commission

The NSSC Approved Accident Management Program for Kori Unit 2

The Nuclear Safety and Security Commission (Chairperson Choi Won-ho, hereinafter referred to as the ‘NSSC’) approved the accident management program for Kori NPP Unit 2 during its 223rd meeting on October 23rd (Thursday).

* (Accident Management Program) A document that outlines measures such as strategies, implementation frameworks, and equipment essential for preventing the expansion of an accident, mitigating its impact, and turns it back to normal when nuclear accidents, including severe accidents, happen.

The AMP was newly added to the operation license documents following the revision of the Nuclear Safety Act in June 2016. Kori NPP Unit 2, which had already been in operation after receiving its OL, submitted the AMP in June 2019, in accordance with Article 3* of the addendum to the revised NSA.

* Nuclear power plants either in operation or under review for the OLs should submit the AMPs within three years, starting from the enforcement date of the revised NSA (from June 2016).

Regarding the AMP for Kori Unit 2, the Korea Institute of Nuclear Safety (hereinafter, KINS) focused on measurements to mitigate severe accidents using portable installations and to strengthen severe accident management capacity through probabilistic safety assessments during the review. It turned out that Kori Unit 2’s AMP, with its accident management strategies and implementation framework, meets the criteria for permission.

Moreover, the Nuclear Safety Committee* confirmed that KINS’ review result is appropriate based on a preliminary inspection conducted over approximately six months.

* Comprise a team of 15 specialists in reactor, severe accident, and radiation.

The NSSC held its 222nd meeting on September 25, 2025, and the 223rd meeting of the Commission to discuss the accident management program of Kori Unit 2. Ultimately, it was confirmed that the AMP met the requirements for permission under Article 21-1-6 of the Nuclear Safety Act and was granted approval.

Kori NPP Unit 2 has newly added severe accident mitigation equipment to its design, including an external injection channel for alternative containment spray. This is because Kori Unit 2 has different design characteristics from the advanced-type NPP, APR 1400 (NSSC approved its AMP at the 206th meeting of the Commission on January 9th, 2025), which has significantly incorporated severe accident response installations from the design stage.

As the AMP for Kori Unit 2 received approval, KHNP must complete on-site measures, such as modifying the design for mobile installations, and conduct biennial training to maintain the effectiveness of the accident response plan. The NSSC plans to meticulously evaluate whether the AMP for Kori Unit 2 is properly implemented on-site as approved.

Chairperson Choi Won-ho stated, “Approving the AMP will enable Kori Unit 2 to secure the same level of accident management capacity as new NPPs. Even for NPPs that have not yet received approval for the AMPs, safety should be the top priority during deliberation, and their AMPs will be promptly implemented at the site.”

Allow Criticality of Shinkori Unit 1 During Periodic Inspection


- Will confirm the final safety through follow-up tests, such as a power ascension test

- On October 10th, the Nuclear Safety and Security Commission (Chairperson Choi Won-ho, hereinafter referred to as the ‘NSSC’) allowed the criticality* of Shinkori Unit 1, following a periodic inspection that began on August 27th, 2025.

* A state in a reactor where nuclear fission chain reactions happen continuously, reaching an equilibrium where the number of neutrons generated equals to the number of neutrons extinct.

The NSSC tested 86 out of 97 required items, which must be completed before reaching criticality, and confirmed that the reactor could safely reach that state.

During the periodic inspection, the cause of the damage to the generator excitation equipment, which led to the power suspension on August 21st, and countermeasures for recurrence were reviewed.

The damage was caused by poor contact between the inner brushes and the collector ring* within the exciter, creating an arc. Therefore, brush quality management and current measurement during operation will be intensified to prevent this from happening again. Meanwhile, the damaged component was replaced with a new one, and the detailed inspection results showed that it meets the relevant standards.

* A device that supplies direct current to the inner coil to generate the electromagnetic force of the exciter

During the periodic inspection, 11 pieces of debris, including wires from the steam generator, were removed, and there were no issues with the tube inspection.

Based on the results of these periodic inspections, the NSSC approved Shinkori Unit 1 to reach criticality. Safety will be finally confirmed through follow-up tests (11), including a power ascension test.

3.1 Scale of Earthquake at Okcheon, Chungbuk Did Not Affect Nuclear Facilities’ Safety


The Nuclear Safety and Security Commission (Chairperson Choi Won-ho, hereinafter referred to as the ‘NSSC’) confirmed that there was no impact on the safety of all domestic nuclear facilities related to the 3.1 magnitude earthquake that occurred 17 km east of Okcheon-gun, Chungbuk, at 11:49 AM on October 8th.

The closest facility to the epicenter is Hanaro* (research reactor), located about 39km away, with a measured seismic instrumentation value of 0.0119g. This value is below the seismic design value (0.2g), indicating it would not affect the facilities. Additionally, the emergency site safety inspection** showed no significant issues.

* Hanaro’s reactor has been halted since August 25th for periodic inspection.

** NSSC Daejeon Regional Office conducted the site safety inspection for Hanaro (started at 12:28 PM).

However, this seismic instrumentation value was higher than the Hanaro earthquake alarm set point (0.0067g), but the alarm did not activate. Therefore, the Korea Institute of Nuclear Safety (KINS) will dispatch experts for further investigation.

Regarding the nuclear power plant, the seismic instrumentation value at the Hanbit NPP turned out to be 0.0043g to the fullest, and the value is below the seismic design value (0.2g), indicating no significant issue.

※ Seismic instrumentation values: Hanbit 0.0043g, Kori 0.0007g, Saeul 0.0004g, Wolsong 0.0004g, and Hanul 0.0005g

Responding to complex disasters as if in real life! The NSSC Conducted 2025 Unified National Radiation Emergency Drill


- A large group of 18 central government and municipalities near Hanul NPP, and local residents, participated in the Drill.

- Relocate from the Uljin Emergency Management Center to the Hanul Regional Emergency Response Center, and concentrate on reviewing the regional radiological emergency system.

The Nuclear Safety and Security Commission (Chairperson Choi Won-ho, hereinafter referred to as the NSSC) conducted the 2025 Unified National Radiation Emergency Drill (hereinafter the ‘Unified Drill’) on September 30th in Uljin-gun, Gyeongsangbuk-do, with 2,400 participants. These included personnel from the central government, local authorities, specialized agencies, licensees, and regional institutions, who participated in a scenario involving a radiation leak from Hanul NPP.

*(Central Administration) 18 authorities, including the Nuclear Safety and Security Commission and the Ministry of the Interior and Safety; (Local Government) five municipalities, including Gyeongsangbuk-do, Gangwon-do, Uljin-gun, Bonghwa-gun, and Samcheok-si; (Specialized Institution) Korea Institute of Nuclear Safety and Korea Institute of Radiological Medical Sciences; (Licensee) Korea Hydro and Nuclear Power; (Regional Institution) nearby military units, police offices, maritime police, fire stations, etc.

This year's unified exercise was linked to the “Safe Korea Exercise,” led by the Ministry of the Interior and Safety, and focused on complex disasters, assuming a radiation leak had occurred due to a severe accident and earthquake at Hanul Nuclear Power Plant Unit 5.

During the Drill, emergency response organizations such as the national emergency management committee, local emergency management centers, and the off-site emergency management center were formed and operated. At the same time, a comprehensive radiological emergency response system, including local resident evacuation, shelter, and field medical centers, and environmental radiation monitoring, was reviewed.

In particular, this training created a scenario where personnel in charge could not remain at the Uljin Off-Site Emergency Management Center due to NPP safety function failures, radiation leaks, and an additional earthquake.

The exercise involved approximately 150 field response personnel working at the Uljin Off-Site Emergency Management Center, who quickly relocated to the Hanul Regional Off-Site Emergency Response Center* to respond. The NSSC reviewed the ceaseless off-site radiological emergency command system.

* When the Uljin Off-Site Emergency Management Center cannot handle a large-scale NPP accident, such as earthquakes, tsunamis, and simultaneous events on multiple units, the Hanul Regional Off-Site Emergency Response Center takes over the field response. It opened this June and is located 43 km from Hanul NPP (Uljin Off-Site Emergency Management Center is 14 km away).

Details of the Drill for each institution:

1 NSSC Headquarter
It took a thorough response to radiation emergencies by creating the National Emergency Management Committee, which includes 18 central governments, and by conducting major decision-making training. This enabled the announcement of radioactive disasters and the declaration of special disaster areas.

2 Off-site Emergency Management Center

It conducted the drill, which comprehensively commands decision-making to protect residents (evacuation, escape, distribution of iodine thyroid blocking agents, instructions for taking such medicines, etc.) by operating the Off-Site Emergency Management Center Advisory Committee, which includes the central administration, local governments, and related institutions.

3 Local Governments

Five Metropolitan Cities near Hanul NPP, along with their local governments, installed local emergency management centers and reviewed the compliance of resident protection measures.

Nuclear power plants are located in Gyeongsangbuk-do (Uljin-gun and Bonghwa-gun). Therefore, the region installed two medical centers, including one at the South Uljin Public Sports Center, and conducted a resident evacuation drill involving a total of 250 people, such as local residents and students. The neighboring local government, Gangwon-do (Samcheok-si), prepared an additional medical center for a resident evacuation drill with 200 residents and students.

4 Specialized Institution

Korea Institute of Nuclear Safety (KINS) conducted drills to convey information necessary for major decision-making on resident protection measures to Off-Site Management Centers, aiming to protect against radioactive disasters. This was achieved by collecting data on land/sea/air radiation using radiation-detecting equipment and compiling the results into a comprehensive report.

The Korea Institute of Radiological & Medical Sciences held drills on medical services for persons who have suffered from exposure to radiation, including decontamination and transportation, by setting up an on-site clinic at Uljin Stadium. They collaborated with radiological emergency medical institutions such as Uljin-gun Medical Center, Gangneung Dong-in Hospital, and Wonju Severance Christian Hospital.

5 Nuclear Licensees

Korea Hydro and Nuclear Power conducted hands-on training for nuclear accident response, focusing on issuing and communicating radiological emergencies, externally injecting emergency cooling water with a movable pump, and providing emergency medical aid to the injured.

Chairperson Choi Won-ho said, “This drill became an important opportunity to assess the regional emergency response system through the Hanul regional center, which was newly opened last June. This joint drill will help improve the emergency response system so it can protect local residents quickly and effectively in any complex disaster situation.”

NSSC Is Operating Response System Due to the Fire At the National Information Resources Service


- NPP real-time monitoring system 'AtomCARE' is operating normally

- Nuclear and radiation safety information is released without any issue through Nuclear Safety Information Center (nsic.nssc.go.kr)

- Will put the best effort to restore NSSC website

The Nuclear Safety and Security Commission (Chairperson Choi Won-ho, hereinafter referred to as the ‘NSSC’) confirmed that it is actively monitoring the safety and operational status of nuclear power plants, considering the fire at the National Information Resources Service that occurred on September 26th. So far, there have been no significant issues concerning the safe operation of NPPs.

AtomCARE, which manages and monitors NPPs’ detailed conditions and multiple operational variables in real time, is unrelated to the incident, and NSSC checked through AtomCARE that all domestic NPPs are safe.

Additionally, the Nuclear Safety Information Center (nsic.nssc.go.kr) is operating normally, providing a variety of nuclear and radiation safety information. This includes the operating status of each nuclear facility, national environmental radiation monitoring data, and marine environmental radiation monitoring data, all delivered seamlessly through the Nuclear Safety Information Center's website.

The NSSC plans to quickly address the issues with the NSSC website and internal administrative system caused by the fire by working with the National Information Resources Service, ensuring minimal inconvenience to the public.

NSSC Checked Defense Readiness Condition of Wolsong NPP Preparing for APEC Summit 2025


- Field inspection of the physical protection system, including Wolsong NPP-military-police joint operations

- Chairperson Choi said, “Please put in the effort for a safe APEC by maintaining a seamless defense readiness condition.”

The Nuclear Safety and Security Commission (Chairperson Choi Won-ho, hereafter referred to as ‘NSSC’) inspected the physical protection system* at Wolsong nuclear power plant near Gyeongju, where the APEC summit will take place on October 26th.

* All measures to counter external and internal threats to nuclear materials and facilities in advance, respond appropriately by detecting threats promptly, and minimize damage caused by accidents.

The review was conducted to assess the preparedness and response systems at nuclear power plants against unexpected terror threats during APEC, with preparations underway for APEC 2025, scheduled for late October in Gyeongju.

According to the ‘Act on Physical Protection and Radiological Emergency’, NSSC assesses threats to nuclear facilities every three years and updates threat levels, which serve as criteria for designing and evaluating the physical protection system.

Korea Hydro and Nuclear Power secures and operates protection-related facilities and installations based on threats defined by NSSC, and conducts physical protection drills* periodically. NSSC evaluates KHNP’s physical protection drills, identifying weak points and backup measures.

* Nuclear licensees perform a full physical protection drill and conduct two partial drills annually at each site.

Chairperson Choi Won-ho received reports from KHNP on the response system for various threat scenarios, such as fence invasions by disruptive forces (land), illegal drones (air), and approaching unidentified ships (sea). He also reviewed the plan for protective measures, which will be strengthened during APEC.

Additionally, the NPP outer fences, guard posts, responsive installations, coastal surveillance equipment, and air defense equipment were inspected beforehand to ensure that alliance actions, combined with regional military and police, are well-coordinated in case of a threat.

Chairperson Choi said, “Since terrors targeting NPPs could directly lead to severe radiation accidents, preparedness is essential. Please make sure to maintain a thorough protective system between the relevant institutions, such as KHNP, the military, and the police.”