Leonid Toptunov
The young engineer at the reactor control panel that night.
Last updated
Leonid Toptunov was the senior reactor control engineer at the controls of Reactor Unit 4 of the Chernobyl Nuclear Power Plant on the night of the disaster, 26 April 1986. Born on 16 August 1960, he had only two months of experience operating the reactor, and that night was his first shutdown as operator. He pressed the AZ-5 button on the order of his shift supervisor. He died of acute radiation poisoning on 14 May 1986.
Last updated 2026-09-29 from the source article.
Lore & Background
Toptunov was born in Mykolaivka in Sumy Oblast. His father worked in the Soviet space program, and he grew up among scientists and engineers.
He graduated from the Obninsk Institute for Nuclear Power Engineering in 1983 and started at the Chernobyl plant in March of that year. While studying the reactor documentation he remarked to a friend that the control rods might, in certain circumstances, speed up the reaction instead of slowing it. At the plant he became a close friend of Akimov.
During preparations for the rundown test the reactor stalled, dropping to 30 MW. Aware of his inexperience, Toptunov asked a colleague to help him raise the control rods. The operators withdrew a dangerous number of rods to reach 200 MW. When the AZ-5 button was pressed, a design flaw meant the descending rods briefly accelerated the reaction, and the reactor exploded.
Reader's Guide
After the explosion Toptunov was dismissed from the control room with other non-essential staff, but he chose to go back out of a sense of responsibility. He helped open water valves by hand, was found suffering from radiation sickness and was taken to the infirmary. He had been exposed to 1300 rem.
He was treated in Pripyat and then in Moscow, where he received a bone marrow transplant. He was buried at Mitinskoe Cemetery in Moscow. His family was told that his death was the only reason he was not prosecuted.
The first Soviet investigation blamed the operators and management almost entirely. Later findings by the IAEA gave more weight to the reactor design and to how safety information reached the operators.
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Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: Leonid Toptunov (CC BY-SA 4.0).
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