The Accident: A Timeline of the Chernobyl Reactor Explosion

A timeline that dives deep into the night of the Chernobyl reactor explosion and the causes associated with it. Starting with the decisions made leading up to the disaster and moving to a second-by-second description of the explosion, this project follows the status of the reactor with graphics that show the weight of what happened. This project hopes to make clear which underlying issues and decisions led to the disaster.

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When examining the Chernobyl disaster, a person could point to any number of different causes. There were social issues, political issues, technological issues, and others that all culminated in the worst nuclear disaster that the world has ever seen. The state of the Soviet Union at the time is important to understand because it put the operators of the reactor in a situation that only took a few missteps to cause a nuclear disaster. There was significant political pressure for industries (like the nuclear industry) to produce fast results no matter the way they did it. This led to corners being cut throughout the entire construction processes and officials disregarding safety precautions under the fear that they would lose their jobs if they didn’t produce the results the Communist Party was looking for.

While the factors that led to the early morning of April 26, 1986 were significant, the events that happened the night of the disaster and the day before were the physical causes of the reactor explosion. It is therefore important to understand what physically happened in the reactor and the decisions that were made by the operators that primed the reactor for disaster. Blame cannot be pinned on most of these operators because they were put in situations they were never prepared for, but their actions still caused the disaster.

The goal of my timeline is to help people better understand exactly what happened the night of the Chernobyl disaster. There are interactions of poor judgement, bad safety precautions, and flawed reactor design that can all be explored to show how the perfect storm came together and led to the explosion in reactor number 4.


  • Hjelmgaard, Kim. “Chernobyl: Timeline of a Nuclear Nightmare.” 10 News (17 April 2016).
  • INSAG-7, The Chernobyl Accident: Updating of INSAG-1, A report by the International Nuclear Safety Advisory Group, International Atomic Energy Agency, Safety Series No. 75-INSAG-7, 1992.
  • Mazin, Craig. Chernobyl. HBO, 2019.
  • Plokhy, Serhii. Chernobyl: The History of a Nuclear Catastrophe. New York: Basic Books, 2018.
  • U.S. Nuclear Regulatory Commission. “Report on the Accident at the Chernobyl Nuclear Power Station.” January 1987.

Elliot Kenaston ‘21 is an Astrophysics major from Fairbanks, Alaska.

RUSS043 Chernobyl: Nuclear Naratives and the Environment, Swarthmore College, Spring 2020