Mystery surrounds explosion during water-washing process; experts urge thorough probe to reassure importing nations

The Hanwha Aerospace factory in Yuseong-gu, Daejeon, where an explosion occurred Monday. [Yonhap]
The Hanwha Aerospace factory in Yuseong-gu, Daejeon, where an explosion occurred Monday. [Yonhap]

An explosion at Hanwha Aerospace's Daejeon factory left seven workers dead or injured — the site's third major blast in seven years. Experts said the fire's unusual origin in a washing room warrants close scrutiny, and concerns have emerged that the investigation's findings could affect the safety record of South Korea's defense exports.

Eom Hyo-sik, security director at the Korea Defense and Security Forum and a former Hanwha communications official during the company's 2018 and 2019 accidents, said Monday that propellants are sensitive materials capable of igniting from static electricity alone. He added, however, that investigators should keep multiple possibilities open — including whether the blast actually occurred in the washing room itself or in an adjacent workspace.

A Hanwha official said at a briefing Sunday that the explosives used in that process are neutralized on contact with water, and that large amounts of water are used during washing, so the company had not considered the step particularly hazardous.

On safety equipment, the official said flame-retardant suits and blast barriers are installed in certain zones and some areas are partially isolated, but that the exact point of the explosion still requires further confirmation.

Shin Jong-woo, secretary-general of the Korea Defense and Security Forum, called for a thorough on-site investigation to determine whether safety protocols were strictly followed. "This is not a place that just started washing things yesterday," he said. "It is hard to understand how a fire could break out in the washing room."

Concerns were also raised that the investigation's outcome could affect future exports and deliveries. Eom said the stability of exported products could take a hit depending on what the propellant in question is loaded into. "We need to get to the bottom of the cause and put to rest any anxiety among the countries importing these items," he said.

The Daejeon factory produces the Korea Tactical Surface-to-Surface Missile (KTSSM), the Chunmoo multiple rocket launcher, the long-range surface-to-air missile L-SAM, and the air defense system Cheongung-II.

The site has previously seen two major explosions that claimed eight lives. In May 2018, two workers died at the scene and three others who suffered burns died while receiving treatment. In February 2019, an explosion and fire broke out in the propellant demolding room of Building 70 at the Daejeon factory, killing three people.

Both accidents were attributed to inadequate safety management. In the 2018 incident, investigators found that workers had struck the valve of a propellant container with a rubber mallet after the filling equipment malfunctioned. The 2019 blast occurred when residual static electricity inside a rocket propellant reacted with the explosive charge — the result of a failure to install a grounding device to discharge static electricity.

Defense Minister Ahn Gyu-baek said Sunday on Facebook that the ministry would spare no technical support needed for the accident investigation, working alongside the Defense Acquisition Program Administration.


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