[Report] No Problem Even with 'Red Alert' for Nuclear Radiation Leak Due to Earthquake

Nuclear Power Plant Complex Disaster Response 'Ready Korea' Drill
Magnitude 8.6 Earthquake Scenario with Nuclear Fire and Radioactive Material Leak
48 Organizations and 2,200 Participants Involved
Advanced Firefighting Vehicles and Robots Deployed for Response

"Saewool Unit 2 declared a red emergency at 13:50 due to the loss of all power and emergency cooling water, raising concerns about reactor core meltdown."

At around 2 p.m. on the 25th, the area in front of Saewool Nuclear Power Headquarters in Ulsan, Gyeongbuk, bathed in sunlight, was bustling with advanced fire trucks, ambulances dispatched from various health centers and hospitals, and military vehicles. Following consecutive earthquakes measuring 5.0 and 8.6 on the Richter scale occurring 120 km away from Saewool Nuclear Power Headquarters, the reactor was shut down, and a simulated scenario involving a fire caused by a fuel leak from the 'auxiliary boiler' was enacted. For this drill, a total of 2,200 personnel, including about 1,200 local residents, were mobilized.

On the 25th, the Ministry of the Interior and Safety conducted the third READY Korea drill of the year in cooperation with 48 related organizations, including the Nuclear Safety and Security Commission, Ulsan Metropolitan City, Gyeongsangnam-do, and Korea Hydro & Nuclear Power. The READY Korea drill is designed to check the response system of both public and private sectors to large-scale and complex disasters caused by potential risks such as the climate crisis.

Firefighters are carrying an injured person during the Ready Korea 3rd drill held at Ulsan Saewool Nuclear Power Headquarters on the 25th. Photo by Ministry of the Interior and Safety

At 1 p.m., when the drill began and alarms sounded reporting earthquakes of magnitude 5.0 and 8.6, the scenario started with the automatic shutdown of the reactor in the Saewool Nuclear Power Plant's main control room. As damage to key safety functions of the nuclear facility was feared, the plant issued a 'Blue Emergency.' The Blue Emergency is a level within the four-stage radiation emergency classification, categorized as 'serious,' and is declared when there is a significant functional loss that could cause or escalate an accident.

In preparation for emergencies, the Saewool plant's own firefighting and medical personnel were the first to respond. Employees injured during earthquake evacuation were transported by the Radiation Emergency Medical Center (REMC) ambulance and received treatment according to the severity of their injuries. The REMC, composed of three nurses, one emergency medical technician, and one clinical pathologist, is responsible for initial response to both general patients and radiation-contaminated patients.

Fire in Boiler Room Caused by Earthquake

The scenario also included a fire caused by a crack in the piping of the auxiliary boiler and fuel oil leakage due to the earthquake. Some workers engaged in emergency repairs were injured or trapped inside the boiler room. The first responders were again the plant’s own firefighting team. The in-house firefighting team, consisting of 17 firefighters, deployed with a high-performance chemical fire truck, conducted initial fire suppression until the local fire department arrived.

Upon recognizing the fire, the 119 emergency control center dispatched the regional fire services, including the Emergency Rescue Control Team. The Emergency Rescue Control Team effectively suppressed the fire in the auxiliary boiler room using special vehicles such as high-performance chemical trucks and unmanned water cannon trucks. Unlike regular fire trucks that spray water from below to extinguish flames at the upper part of the boiler room building, the special vehicles extended their water nozzles to directly spray large amounts of water at the upper area to suppress the fire. Injured persons in the scenario were rescued by the rescue team arriving on-site via hotline and treated at the on-site emergency medical station. At this time, the Korea Institute of Radiological & Medical Sciences also dispatched personnel to assist radiation-exposed patients with fire protection and other measures.

Response up to 'Red Emergency' for Loss of Power and Cooling Water

This drill assumed a 'Red Emergency,' which is declared when damage to the nuclear facility’s last line of defense is feared, beyond the Blue Emergency. After the earthquake, the nuclear plant lost power and water supply due to transmission line failure, causing the coolant temperature and pressure to rise, leading to the leakage of radioactive materials. The Nuclear Safety and Security Commission established the Central Disaster and Safety Countermeasures Headquarters 1st Division to respond to radiation accidents, while the Ministry of the Interior and Safety set up the 2nd Division to handle earthquake, fire, and resident protection.

However, damage from a tsunami caused by the earthquake was assumed to be nonexistent. The scenario included a 6-meter-high tsunami reaching the Saewool Headquarters, but since the coastal barrier at Saewool is over 9.5 meters high, no damage occurred. A Korea Hydro & Nuclear Power official explained, "After the Fukushima nuclear accident, we made many reinforcements. We simulated the possibility of earthquake-induced tsunamis and their maximum wave heights for our region. As a result, the current site can sufficiently withstand such events."

On the 25th, advanced robots 'Hamster', 'Rapid', and 'Armstrong' were demonstrated during the Ready Korea 3rd training held at the Ulsan Saewool Nuclear Power Headquarters.
Photo by Ministry of the Interior and Safety

Special equipment such as robots was deployed for radiation detection and facility maintenance at the nuclear plant where radioactive materials leaked. The 'Hamster' robot, developed with quadrupedal movement like an animal, can climb stairs and navigate bends, while the 'Rapid' robot, shaped like a four-wheeled vehicle, freely moves inside the reactor building to detect radiation. The Korea Atomic Energy Research Institute’s 'Armstrong' robot enters the building to perform maintenance work instead of humans, considering worker safety.

During the Red Emergency stage, all residents living within 3 to 5 km of the nuclear facility must be evacuated, and residents within 20 to 30 km must be partially evacuated depending on wind direction. Trains and ships were mobilized to disperse 1,200 residents to Ulsan Sports Complex, Auto Valley Welfare Center, and Yangsan Sports Complex Indoor Gymnasium. The location of shelters may change depending on wind direction during an accident. A Korea Hydro & Nuclear Power official explained, "Typically, shelters are located outside the danger zone, as being downwind during an accident can be hazardous."

Lee Hangyung, Director of the Disaster and Safety Management Headquarters at the Ministry of the Interior and Safety, said on-site that "Although the maximum possible earthquake magnitude in Korea is considered to be 7.0, we assumed a magnitude of 8.6 because unimaginable disaster situations are occurring frequently. Since nuclear accidents can lead to large-scale casualties, drills involving cooperation among related agencies are essential, and in that sense, this drill was meaningful."