00:00
SHIFT CHANGE — The evening shift of Reactor No. 4 hands over to the night shift. The reactor is operating at 100% thermal power (3,200 MW). The scheduled turbine test is discussed.
00:28
POWER REDUCTION — Operators begin manually reducing reactor power for the turbine-generator rundown test. The automatic regulator is switched off — a violation of procedure.
01:00
POWER COLLAPSE — Due to xenon-135 poisoning, reactor power plunges to just 30 MW — far below the 700 MW target. The reactor enters an unstable regime.
01:19
RODS WITHDRAWN — In a desperate attempt to raise power, operators withdraw nearly all control rods. Only 6-8 rods remain in the core out of 211. The positive void coefficient becomes dominant.
01:23:04
☢ AZ-5 PRESSED — Reactor power surges to 530 MW. Chief Engineer Akimov orders the emergency shutdown. But the graphite-tipped control rods briefly INCREASE reactivity before the boron absorbers engage — a fatal design flaw.
01:23:40
☢ FIRST EXPLOSION — Steam explosion tears through the reactor. The 1,000-tonne upper biological shield (Scheme E) is blown off. The core is exposed to the atmosphere.
01:23:46
☢ SECOND EXPLOSION — Hydrogen/carbon monoxide explosion destroys the reactor building. Graphite blocks and fuel debris ejected. The graphite fire begins — it will burn for 10 days.