The explosion at the Hanwha Aerospace Daejeon plant, which left five people dead and two injured, has been identified as a sudden event that occurred without any prior warning signs.

According to an investigation report on the Hanwha Aerospace Daejeon plant explosion submitted by the National Fire Agency to the office of Democratic Party lawmaker Park Jeong-hyun on June 24, the report includes CCTV screenshots taken from outside the plant, capturing the moment of the explosion at Building 56 (the cleaning room).

The footage shows a flash and flames erupting from the building. Based on this video, fire authorities believe the explosion occurred suddenly without any preceding signs, such as smoke or initial fires, and subsequently spread into a blaze.

The accident took place at 10:59 a.m. on June 1 at Building 56 of the Hanwha Aerospace Daejeon plant in Oesam-dong, Yuseong-gu, Daejeon, during a cleaning operation.

This facility is used to clean tools and equipment contaminated with propellant (explosives) used in missiles and rockets.

The investigation by fire authorities suggests the explosion originated in the "Separation and Cleaning Room 1," located in the center of Building 56.

The cleaning process in this area involves using spatula-like tools to remove residue, soaking equipment in water tanks, and performing additional cleaning with high-pressure machinery.

While the National Fire Agency concluded that the propellant caused the explosion, it stated that the specific ignition source has not yet been identified.

However, the cleaning agents, which were initially suspected of being flammable and hazardous, were tested by the Korea Fire Institute and the National Fire Research Institute. The results confirmed that all tested substances were "non-hazardous."

Explosives in mixture form are classified as military explosives under the Defense Acquisition Program Act and are not subject to the supervision of fire authorities under the Hazardous Chemicals Safety Control Act.

Furthermore, Building 56, which was classified as a simple cleaning facility within the Hanwha Aerospace Daejeon plant—a site that manufactures and stores military explosives—was excluded from the oversight of both fire authorities and the Defense Acquisition Program Administration (DAPA), which holds the authority to permit, manage, and supervise military explosive manufacturers.

Permits for facility installation and operation were only granted for explosive manufacturing and storage facilities, and safety inspections and supervision were conducted only within those authorized areas. Consequently, Building 56 was effectively operating without a permit, leaving it in a safety blind spot.

In response, a DAPA official stated, "We will pursue institutional improvements and strengthen safety management to ensure more thorough management and inspection systems, covering not only permitted facilities but also auxiliary facilities."

(Photo: Provided by the office of Democratic Party lawmaker Park Jeong-hyun, Yonhap News)