Excessive cutting of support columns blamed for deadly Ulsan power plant collapse

The structure that collapsed was a boiler tower at Unit 5 of the Ulsan Thermal Power Plant. It fell while workers were preparing it for demolition, before explosives were used. The collapse was therefore a construction and demolition accident, not a planned blast.

The plant is in Ulsan, a city about 300 kilometers southeast of Seoul. The tower stood 63.4 meters tall. Its collapse killed seven workers and injured two others, making the location important not only as a plant site but also as the scene of a deadly workplace accident.

An investigation committee examined what happened. It concluded that excessive cutting of support columns weakened the tower. The Ministry of Land, Infrastructure and Transport released the findings and proposed stricter inspections, new demolition standards, and closer oversight of high-risk projects.

A boiler tower is a large industrial structure built around boiler equipment. In general power-plant use, boilers heat water until it becomes steam. That steam can drive turbines connected to generators, producing electricity. The article identifies the collapsed structure as a boiler tower but does not describe its internal equipment or exact operating role.

Its height and structural design matter because the tower must support its own weight and the weight of equipment, platforms, and other components. At Ulsan, the tower was 63.4 meters tall. It collapsed while workers prepared it for demolition, before explosives were used.

The investigation found that too many support columns had been cut after flawed structural assessments. Those columns could no longer support the upper structure. The finding shows why boiler towers require careful engineering review during both operation and dismantling.

The collapsed structure was 63.4 meters tall. That height made it a substantial industrial tower and increased the potential danger of an uncontrolled collapse. It was part of Unit 5 at the Ulsan Thermal Power Plant, where workers were preparing the structure for planned demolition with explosives.

The accident caused seven worker deaths. Two other workers were injured. These figures show the human cost of a structural failure during high-risk demolition work. The tower collapsed before the planned explosive demolition, so the casualties resulted from the premature failure rather than the scheduled blast.

Investigators linked the collapse to excessive cutting of support columns. Flawed structural assessments led workers to remove too many supports. The remaining columns could not carry the upper structure’s weight. The investigation therefore connected the tower’s scale, its weakened support system, and the severe outcome.

Support columns were cut because the tower was scheduled for demolition by explosives. Cutting structural members is commonly part of preparing a building or tower for controlled demolition. It helps create a planned failure path so the structure can come down when the explosives are activated. The article states that the cuts occurred ahead of the planned demolition.

The danger came from the amount of cutting. Investigators found that too many support columns had been removed because of flawed structural assessments. The remaining columns were unable to support the weight of the upper structure. The tower therefore lost stability before the explosive demolition began.

This distinction matters. Preparing a structure for demolition requires weakening it in a carefully calculated sequence, not simply removing supports. The committee’s recommendations for stricter inspections and new technical standards reflect the need to verify every cut before workers continue.

Tall structures stay upright by directing weight through load-bearing members, such as columns, into the foundation. Each support carries part of the total load. If enough supports are removed, the remaining ones must carry more weight. They may then bend, buckle, or fail, causing the upper structure to fall.

That is what investigators determined happened in Ulsan. Too many support columns were cut after flawed structural assessments. The remaining columns could not support the upper structure’s weight. The 63.4-meter boiler tower consequently collapsed during preparation, before its planned explosive demolition.

The key issue was loss of stability, not merely the presence of explosives. Demolition work must control how and when loads shift as supports are removed. The committee called for stricter on-site inspections and new technical standards, which could help confirm that each stage remains stable before more columns are cut.

The investigation committee recommended three main safeguards against similar demolition accidents. It called for stricter inspections at work sites, new technical standards for demolition work, and tighter oversight of high-risk demolition projects. Together, these measures would strengthen checks before and during dangerous structural dismantling.

The recommendations respond directly to the Ulsan failure. Investigators found that flawed structural assessments led workers to cut too many support columns. The remaining columns then could not carry the upper structure’s weight. More rigorous inspections and technical rules could help identify unsafe cutting plans before work advances.

Tighter oversight is also important because demolition can change a structure’s stability quickly. High-risk projects need closer review while work is underway, not only approval at the start. The Ministry of Land, Infrastructure and Transport released the committee’s findings, giving the proposed safeguards a national policy context.

A load-bearing structure works by sharing weight among its supports. Columns and other structural members carry forces from upper floors, equipment, and the structure itself downward toward the foundation. Safe design depends on each member carrying an appropriate share, with enough strength and stability across the whole system.

When workers remove supports, the load does not disappear. It shifts to the columns and connections that remain. If too many are cut, those members can become overloaded and fail. In Ulsan, investigators said flawed structural assessments led to excessive cutting, leaving the remaining columns unable to support the upper structure.

Accurate assessments are therefore essential during dismantling. Engineers must understand how the structure will behave at each stage, not just when it is complete. The committee’s proposed inspections, technical standards, and stronger oversight aim to reduce mistakes before a planned demolition becomes an uncontrolled collapse.