140 free Chernobyl trivia questions with answers — history quiz, new questions added Aug 2026.
Chernobyl trivia for history buffs, science readers and everyone who binge-watched the HBO miniseries and then fell down the Wikipedia rabbit hole. This quiz walks through the night of 26 April 1986: the botched turbine test at reactor 4, xenon poisoning, the AZ-5 button and the graphite-tipped control rods, and the design flaws that turned an emergency shutdown into a steam explosion. It then covers the response and the aftermath: the firefighters and the 600,000 liquidators, the helicopters dropping sand and boron, the three men who drained the bubbler pools, the miners under the reactor, Valery Legasov's report in Vienna and his death two years later, the evacuation of Pripyat and its never-opened Ferris wheel, the Red Forest, the Elephant's Foot, the sarcophagus and the arch that now covers it. It closes with the exclusion zone's wildlife and tourists, the 2022 Russian occupation and the making of the 2019 miniseries. Questions range from easy to expert, and every answer was checked against a reference page and carries its source. If you enjoy this quiz, try our Cold War, Soviet Union and nuclear science quizzes next.
30 of 140 questions with answers and explanations. Play the quiz
Q 01On what date did reactor 4 at Chernobyl explode?
26 April 1986
The explosion came at 1:23 in the morning during a test that was supposed to simulate a blackout.
Q 02Which numbered unit at the Chernobyl plant blew up in 1986?
4
Reactor 3, next door, kept running until 15 December 2000, when President Kuchma switched it off in a ceremony.
Q 03Besides Chernobyl, what is the only other accident rated at the maximum level of the International Nuclear Event Scale?
Fukushima
The Japanese accident followed the 2011 earthquake and tsunami; both are Level 7 events.
Q 04What was the reactor crew attempting when the accident happened?
A test simulating cooling in a blackout
The idea was to see whether the coasting turbine could power the coolant pumps until the diesel generators kicked in.
Q 05What type of Soviet reactor was used at Chernobyl?
RBMK
The graphite-moderated, water-cooled design had a positive void coefficient, so steam bubbles increased rather than reduced reactivity.
Q 06The RBMK design flaw known as a positive void coefficient meant that steam voids in the coolant did what?
Increased core reactivity
This positive feedback loop had little to restrain it, leaving the reactor at risk of an uncontrolled surge.
Q 07Which fission by-product 'poisoned' the reactor, dragging power far below the test plan?
Xenon-135
The neutron-absorbing isotope builds up when power drops and is normally burned off during steady operation.
Q 08What was the designation of the emergency shutdown button pressed at 01:23:40?
AZ-5
Inserting the control rods pushed graphite tips into the core first, briefly boosting reactivity instead of killing it.
Q 09What was on the tip of each RBMK control rod, displacing water and briefly boosting power?
A graphite extension
INSAG-7 later noted a widespread view that the conditions for this 'positive scram effect' would never occur.
Q 10Which deputy chief engineer was on hand to direct the fatal test?
Anatoly Dyatlov
Shift supervisor Akimov and 25-year-old engineer Leonid Toptunov, at the controls that night, both died within weeks.
Q 11How long after the accident did the Soviet government establish the initial 10-kilometre exclusion zone?
36 hours
About 49,000 people were moved at first; widening the zone to 30 km evacuated roughly 68,000 more.
Q 12Radiation from Chernobyl was first detected outside the USSR at a nuclear plant in which country?
Sweden
Alarms went off at Forsmark on 28 April, forcing Moscow to admit the accident in a 20-second bulletin that evening.
Q 13The Soviet Union first acknowledged the accident on which TV news programme?
Vremya
The announcement came at 21:02 on 28 April, two days after the explosion.
Q 21What happened to the scientist who led the Chernobyl commission on 27 April 1988, a day after the second anniversary?
He took his own life
He had recorded audio tapes, The Legasov Testament, describing the liquidation and the reactor's flaws.
Q 22Which deputy chairman of the Council of Ministers headed the government commission sent to Chernobyl?
Boris Shcherbina
Stellan Skarsgard played him in the HBO series.
Q 23What was the population of Pripyat when it was evacuated the day after the explosion?
About 49,000
Founded in 1970 for plant workers, it had officially become a city only in 1979.
Q 14What was dropped from helicopters onto the burning reactor in the days after the explosion?
Sand, lead, clay and boron
More than 5,000 tonnes went down, though later analysis found almost none of it reached the core.
Q 15Until what date did the fire inside reactor 4 keep burning?
10 May 1986
Possibly more than half of the reactor's graphite burned away in those two weeks.
Q 16Engineer Oleksiy Ananenko volunteered to open the sluice gates and drain what beneath the reactor?
The bubbler pools
Officials feared molten corium hitting the water would cause a steam explosion; in fact it dripped in harmlessly.
Q 17Coal miners were brought in to dig a tunnel under the reactor to install what?
A cooling system
The graphite-and-concrete 'sandwich' was abandoned when the melt stopped, but the idea prefigured modern core catchers.
Q 18Roughly what share of the debris on the reactor roof was cleared by robots before humans took over?
10%
Some 3,828 men did the rest by hand, averaging an estimated 250 mSv each; Legasov admitted robots were 'not the great remedy for everything'.
Q 19What name was given to the roughly 600,000 clean-up workers?
Liquidators
They received a special medal and certificate, but worked uninformed and with little protection.
Q 20Which Soviet scientist led the commission and presented its findings to the IAEA in 1986?
Valery Legasov
He later said 'I did not lie in Vienna, but I did not tell the full truth', having omitted the reactor's design flaws.
Q 24Pripyat's famous abandoned Ferris wheel had been due to open officially for which holiday?
May Day
The amusement park was scheduled to open five days after the disaster.
Q 25Which purpose-built city replaced Pripyat as home for the plant's workers?
Slavutych
It was built across the Dnieper marshes with a direct rail link to the plant.
Q 26The pine woodland downwind of the plant, killed outright by radiation, became known as what?
The Red Forest
The name comes from the ginger-brown colour of the dead trees; most were bulldozed and buried in trenches.
Q 27What is the 'Elephant's Foot'?
A mass of solidified corium under the reactor
It was once so hard that an armour-piercing AK-47 round was needed to chip a sample; it has since softened to a sand-like texture.
Q 28Which of Chernobyl's neighbouring Soviet republics got about 60% of the fallout on the USSR?
Belarus
Winds carried the plume north from the plant, which sits close to the Belarusian border.
Q 29Which two isotopes were most responsible for radiation doses to the general population?
Iodine-131 and caesium-137
Iodine-131 has an eight-day half-life and drove the surge in childhood thyroid cancers; caesium-137 still keeps the zone closed.
Q 30Movement restrictions on sheep from contaminated British uplands were lifted in which year?
2012
In 2009 some 369 farms in Wales, Cumbria and northern Scotland were still under controls.