The fire at the National Information Resources Service (NIRS) in Daejeon on 26th last month began with a sudden spark from the battery pack in the data center, according to findings.
According to closed-circuit (CC)TV footage from inside the data center on the fifth floor of NIRS released by Democratic Party of Korea lawmaker Kim Seong-hoe, a member of the National Assembly's Public Administration and Security Committee, on the 14th, a spark is seen around 8:16 p.m. from the upper area of a battery pack shelf installed on the data center wall.
Another CCTV video installed on the right-hand wall of the battery pack shelf shows a worker using a tool that appears to be a power drill working from beneath the battery pack when a spark flies. At the time, workers were moving uninterruptible power supply (UPS) lithium-ion batteries to the basement.
A worker near the battery pack fell backward in surprise at the sudden spark and then got up, while other workers evacuated in a hurry. One worker sustained first-degree burns to the face and arm.
One minute and 30 seconds after the first spark, stronger sparks began to fly. A chain of explosions occurred, as if the sparks had spread to the adjacent battery pack, and 30 seconds after the second spark, the inside of the data center was filled with thick smoke.
Even after the workers fully evacuated, explosions continued and the flames intensified. Three minutes after the first spark, the interior of the data center was filled with black smoke to the point of making identification impossible.
The fire was completely extinguished around 6 p.m. on the 27th last month, the following day. All 384 battery packs in the fifth-floor data center where the fire broke out were destroyed. As of 6 p.m. that day, 297 of the 709 administrative information systems disrupted by the NIRS fire had been restored (41.9% recovery rate).