**Inspection of the Demolition Plan Shows:**
– Inducing vulnerability by exploding the lower section
– Application of construction method with high risk of collapse noted
– Recovery of third deceased amid structural difficulties
– Decision made to dismantle adjacent boiler towers
On November 9, at the accident site of the Korea East-West Power Ulsan Thermal Power Plant in Nam-gu, Ulsan, the Central Accident Response Headquarters decided to proceed with the rescue operation after dismantling Units 4 and 6 of the collapsed boiler tower Unit 5.
In the boiler tower collapse accident at the Korea East-West Power Ulsan Thermal Power Plant, which resulted in three deaths and four individuals being buried, it was confirmed that the turbine room behind the tower had been demolished using a blasting method before the demolition. There is a possibility that the blasting impact affected the structure of the aging boiler tower. According to the ‘Safety Management Plan for the Demolition of Ulsan Thermal Power Units 4, 5, and 6’ by HJ Heavy Industries, the plant’s turbine hall, boiler hall, and chimney were all scheduled to be sequentially demolished using the blasting method.
The three boiler towers were demolished by toppling to the site where the turbine hall used to be after blasting. For this, a weakening operation was performed by cutting the lower steel structures of the tower, which led to its collapse.
According to the industry, thermal power boiler towers have a structure where the boiler drum is fixed to a steel structure about 10 meters high above ground. Because the tower is a unified structure, it is challenging to dismantle from top to bottom, so the method of toppling by blasting the lower section is predominantly used.
The issue is that such toppling methods bear a high risk of collapse during the weakening process, as seen in the Ulsan incident, and there are hardly any experts domestically. It is reported that all blasting operation workers at the ongoing demolition site of Yeosu Honam Thermal Power Plant using this method lack experience with toppling methods.
Professor Kim Sun-woong of the Department of Architecture at Youngsan University stated, “In our country, structural verification for special facilities such as power plants is lacking,” and emphasized the need to properly interpret structures and establish demolition methods and sequences in preparation for increased future power plant demolitions.
Meanwhile, on the fourth day of the accident, at around 11 a.m. on November 9, the fire authorities recovered one body. The recovered body was identified as 40-year-old male worker A, who became trapped in debris on the afternoon of November 6, the day of the accident, and passed away in the early hours of November 7 while awaiting rescue.
As of this day, three of the seven buried individuals have been found deceased, while four are still awaiting rescue. The Central Accident Response Headquarters, facing difficulties in the rescue operation, decided to demolish Units 4 and 6 standing on either side of the collapsed boiler tower Unit 5 through blasting after consulting with family members of the deceased and the buried individuals.