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Ulsan boiler tower collapses, seven workers remain trapped under debris

Published: 06 Nov. 2025, 18:49

A boiler tower at the Ulsan Thermal Power Plant in Ulsan is seen collapsed on Nov. 6. The accident trapped nine subcontracted workers under the debris. Two were rescued as of Nov. 6, at 5 p.m. [YONHAP]

A boiler tower at the Ulsan Thermal Power Plant in Ulsan collapsed Thursday afternoon, trapping nine subcontracted workers under the debris.

According to Ulsan Fire Headquarters, the tower collapsed at 2:06 p.m. during preparation for a demolition. As of 5 p.m., two of the nine workers had been rescued. The two men, each in their 60s and 40s, were immediately transported to the hospital. Their injuries were not life-threatening, according to officials. Two others were located and were in the process of being rescued. About 50 firefighters were working intensively to search for the remaining trapped workers.

“We have not been able to confirm whether the located individuals are conscious,” said Kim Jeong-sik, head of the preventive safety department at Ulsan Nambu Fire Station. “We are attempting to reach them by digging and navigating the structural gaps.”

President Lee Jae Myung ordered the mobilization of “all available resources,” emphasizing the importance of preventing secondary accidents during rescue operations.

The collapsed structure was boiler tower No. 5, situated between towers No. 4 and No. 6 — each about 60 meters (197 feet) tall. The scene resembled the aftermath of a bombing, with mangled metal and debris piled high.

Fire officials said the collapse occurred while weakening the structure, a process in which structural supports are deliberately cut to facilitate demolition by explosion. The accident happened during oxy-fuel cutting operations — using heat to cut through metal — on the sixth and seventh floors of the 12-story-high, 70-meter-tall structure. The facility had been offline since 2021 and was being demolished in phases, with full teardown initially scheduled for completion by June next year.

Officials work to rescue workers trapped under a collapsed boiler tower at the Ulsan Thermal Power Plant in Ulsan on Nov. 6. The accident trapped nine subcontracted workers under the debris. Two were rescued as of Nov. 6, at 5 p.m. [NEWS1]

Rescue operations were ongoing with three cranes and technical specialists deployed to access gaps in the collapsed structure. In total, 13 vehicles, including three pump trucks, and over 50 personnel have been deployed.

The nine workers were employed by Korea Kacoh, a subcontractor of Hanjin Heavy Industries & Construction. One was a full-time employee, while the other eight were contract workers. All had been working on the site since October as part of a demolition team.

Experts believe the collapse may have been triggered by a shift in the tower’s center of gravity during the cutting process. “Before explosive demolition, the boiler’s four main support pillars must be prepared with oxy-cutting to facilitate a clean collapse,” said Lee Song-gyu, head of the Safety Professionals Association of Korea (SPAK). “It appears the center of gravity shifted slightly during cutting, leading to a structural failure.”

Lee also raised concerns about the possibility that the demolition was not carried out according to the official deconstruction plan. “Demolition must follow a detailed plan, and it remains unclear whether proper procedures were followed. If they were, the validity of the demolition plan itself needs to be reviewed,” he said, emphasizing the importance of calculating load distribution carefully to avoid secondary collapses during rescue operations.

Prime Minister Kim Min-seok ordered that life-saving efforts be made the top priority. “The Ministry of the Interior and Safety, the National Fire Agency, the National Police Agency, the North Gyeongsang provincial government and the Ulsan Metropolitan City Government must deploy all available equipment and personnel for rescue operations,” he said. He also called on the Climate Ministry and Ulsan Thermal Power Plant to promptly share information and work with relevant agencies to manage the aftermath.

“Safety measures must be fully enforced, including on-site firefighter protection and public evacuation guidance for the nearby residents,” Kim said.

Minister of Interior and Safety Yun Ho-jung also issued an emergency directive for all related agencies to mobilize their resources for rescue efforts.

“We will conduct a thorough investigation, including search and seizure, to identify the cause of the collapse,” said Kim Young-hoon, Minister of Employment and Labor. Authorities will examine possible violations of the Serious Accidents Punishment Act and the Occupational Safety and Health Act. The Labor Ministry also plans to establish a central disaster response unit alongside the Ministry of Interior and Safety and the Ministry of Climate, Energy and Environment to assist in the recovery effort.

This article was originally written in Korean and translated by a bilingual reporter with the help of generative AI tools. It was then edited by a native English-speaking editor. All AI-assisted translations are reviewed and refined by our newsroom.
BY SPECIAL REPORTING TEAM [[email protected]]