On 26 April 1986, Reactor No. 4 at the Chernobyl power plant suffered a severe accident during an electrical systems test. The RBMK reactor’s power rose rapidly, followed by explosions and a fire. “Explosion” here refers to the destruction of the reactor and steam explosions, not a nuclear-weapons detonation. The report IAEA’s INSAG-7 explains that design flaws and operating conditions both contributed, so the cause should not be reduced to the mistake of one person.
This article uses the 9arm video to establish its topic and discusses key facts alongside primary IAEA and UNSCEAR reports. It distinguishes the speaker’s explanations from findings in those reports; details in the video have not been independently verified here.
What the video discusses
Video: How did the nuclear power plant explode? The 9arm video was published on 1 April 2023 and runs for 45 minutes 30 seconds. The speaker approaches the subject from an engineering perspective, covering nuclear fission and power generation, RBMK characteristics, the electrical systems test, xenon, control rods and the AZ-5 emergency shutdown button.
The speaker uses an “accelerator and brake” analogy to explain how water, graphite and the reaction interact, then describes events from reducing reactor power and xenon buildup to pressing AZ-5. The speaker also cautions that some scenes in the television series are more dramatic than the evidence supports and acknowledges uncertainty about parts of the sequence. This article presents that as the speaker’s explanation, not as a definitive historical account of every figure or illustration.
The RBMK and the positive void coefficient
An RBMK reactor uses water as a coolant and graphite as a neutron moderator. Under some operating conditions, a higher proportion of steam in the core can increase the reaction; this is called a positive void coefficient. INSAG-7 says this response depends on core composition and operating mode, and that the void and power coefficients were positive during the accident. It is therefore inaccurate to conclude that every RBMK condition, or every kind of nuclear reactor, automatically accelerates into an explosion.
Another issue was the design of the control rods and emergency shutdown rods. In the RBMK design then in use, the graphite displacers could initially increase reactivity in local areas as the rods entered the core, under abnormal power distribution and operating conditions. The IAEA describes this as the positive scram effect. The actual mechanism is more complex than the video’s “graphite is the accelerator, water is the brake” analogy.
The test and AZ-5: do not reduce the cause to one factor
The test examined whether the generator’s remaining rotational energy could power the pumps during a switch to backup electricity. The video discusses power reduction and xenon, which absorbs neutrons, but saying xenon alone caused the reactor to lose control oversimplifies the event.
INSAG-7 discusses unstable operation, limitations in information and procedures, and the control rods’ response characteristics. When AZ-5 was pressed, inserting the rods under the core conditions at that moment could initially raise reactivity in localized areas instead of immediately reducing power as operators expected. A simple account that “the operators pulled all the rods out, then pressed AZ-5, causing the accident” is not an adequate substitute for the investigation report.
The IAEA revisited earlier conclusions that mainly blamed staff for violating procedures and highlighted how reactor and control-rod design flaws interacted with operating conditions. The lessons concern safe design, procedures suited to real conditions, oversight and risk communication—not finding a single person to blame.
Was it a nuclear explosion like an atomic bomb?
No. A reactor power surge and steam-pressure explosions are different from a nuclear-weapons detonation. IAEA technical reports describe destruction of the core and structures, followed by radioactive releases and fire. Comparing it to an atomic bomb may help tell the story but is misleading if read literally.
Health effects: figures need a population and time period
UNSCEAR reports that, among 600 workers present at the site in the early hours of the accident, 134 received high radiation doses and developed radiation sickness. Of these, 28 died within the first three months. Another 19 died between 1987 and 2004 from various causes that were not necessarily directly related to radiation. Among children and adolescents exposed to radioactive material at the time, more than 6,000 thyroid cancer cases had been diagnosed by 2005; UNSCEAR assessed that a substantial share was likely related to radioactive iodine.
Contamination and radiation doses differed by location, food, evacuation and exposure level. It is inaccurate to say that every area or person was affected equally, or that all genetic disorders and cancers resulted from this accident. See the UNSCEAR’s assessment of the Chernobyl accident
Closing reference: Thailand’s cobalt-60 source accident
The speaker’s closing reference is unclear; one phrase sounds like “Global 60.” The speaker appears to mention an event in 2000 and scrap metal from medical equipment. This article cannot identify the radiation-source accident intended by that statement, even though the report The Radiological Accident in Samut Prakarn by the IAEA documents a Co-60 accident in Thailand. This article does not assume that it is the event mentioned in the video.
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Frequently asked questions
Did Chernobyl explode like an atomic bomb?
No. It was a reactor accident involving a power surge, pressure explosions and fire, not a nuclear-weapons detonation.
What caused the loss of control at the RBMK reactor?
IAEA reports point to an interaction between the RBMK’s response characteristics, control-rod design and the operating conditions at the time. The cause should not be reduced to one factor.
Did everyone near Chernobyl experience the same health effects?
No. Radiation doses and effects varied with location and exposure. UNSCEAR distinguishes emergency workers, more highly exposed residents and the general population.