Chernobyl
24 Apr 1986, 21:06 – 29 Nov 201642 items
disasternuclearOne night by the minute, then the months after
At 01:23 on Saturday 26 April 1986 a safety test on Unit 4 of the Chernobyl nuclear power plant, in the north of Soviet Ukraine, ended in two explosions that blew the reactor open. This timeline follows the delayed test from the day before, the night second by second and minute by minute, the firefighters, the evacuation of Pripyat, the silence that Sweden's instruments broke, and the liquidation that ended with the reactor entombed in November. A short tail runs to the trial, the revised verdict and the steel arch slid over the ruin in 2016.
It is one of two accidents rated 7, the top of the International Nuclear Event Scale; the other is Fukushima Daiichi (2011).
By the numbers
2 plant workers dead on the night, and 28 of the 134 people diagnosed with acute radiation syndrome dead by the end of 1986 (UNSCEAR)
about 116,000 people evacuated in 1986, about 49,000 of them from Pripyat; some 230,000 more were resettled in later years (Chernobyl Forum)
up to about 4,000 eventual deaths among the 600,000 most exposed, projected by the Chernobyl Forum (WHO, IAEA and others, 2005); higher totals come from wider populations: about 16,000 across Europe by 2065 (IARC, 2006) and 30,000 to 60,000 (TORCH, 2006)
Reading it
Bands frame the delayed test, the fire, the ten days of release and the six months of liquidation. Filter by reactor for what happened to Unit 4, liquidators for the people sent to fight it, evacuation, news for who knew what and when, medicine and engineering.
All times are UTC. The plant kept Moscow summer time, four hours ahead, so AZ-5 at 01:23:40 on the station's clocks shows as 21:23:40 on 25 April; the notes give the local time. Minute-level times come from the IAEA's INSAG-7 report (1992); the 1986 Soviet account and INSAG-1 differ by seconds to minutes, and the notes say where.
Items
Power reduction begins
Emergency cooling off, and Kyiv asks for a delay
Power reduction resumes
The night shift takes over
Power collapses to almost nothing
AZ-5 pressed
Two explosions
Valery Khodemchuk is lost
Pravik's crew arrives
Telyatnikov takes command
Vladimir Shashenok dies
The Red Forest takes the fallout
The government commission reaches Pripyat
Pripyat is evacuated
The first patients reach Moscow
Forsmark's alarms
Moscow admits an accident
May Day parade in Kyiv
The bubbler pools are drained
Gorbachev speaks
Unit 1 back on line
A helicopter hits a crane
The sarcophagus is finished
Legasov dies
Slavutych's first residents
- ≈ 3 years, 8 months
INSAG-7 revises the verdict
- ≈ 7 years, 11 months
The last reactor shuts down
- ≈ 4 years, 8 months
The Chernobyl Forum's reckoning
- ≈ 11 years, 2 months