By Jonny Lupsha, News Writer

The miniseries Chernobyl is breaking streaming and ratings records for HBO, Forbes reported. Chernobyl tells the tale of the nuclear reactor meltdown and explosion in Pripyat in 1986. But how did the real-life incident happen?

According to the Forbes piece, the Chernobyl miniseries is currently the highest fan-rated TV show of all time on IMDb. The show is an in-depth look at the worst nuclear reactor accident in history—one which has shocked and fascinated the world for over 30 years. Moving past the dramatic storytelling of the HBO program, the real-life events that caused the Chernobyl explosion defy belief.

A Safety Test Turned Fatal

The Chernobyl explosion was mostly the result of a grossly mishandled safety test. “They wanted to test the function of the pumps during loss of power, so they reduced the power,” Dr. Lawrence Weinstein, Professor of Physics at Old Dominion University, said. “But the problem is, they overshot. Xenon built up and that caused the radioactivity to drop way down, so the operators removed control rods to compensate for that, and they removed just about every single one of the control rods.”

The Merriam-Webster dictionary defines a control rod as “a rod of neutron-absorbing material used to regulate the rate of nuclear fission in a reactor.” Removing all of these to induce radioactivity in the Chernobyl reactor put the reactor in an unexpected condition for the safety test, yet the operators continued the test anyway, further stressing the reactor.

Dr. Weinstein explained that the test was originally intended to reduce steam flow to the turbines in the reactor, which reduced the water flow as well, making the reactor more reactive. However, those numbers started to look troublesome, so the Chernobyl operators hurried to replace the control rods to regulate the fission rate. Unfortunately, that made things worse because of a design flaw that had caused water to accumulate in the control rod channel. When the rods were reinserted, they made contact with the water and an unstable reaction occurred.

Soon, the water tanks under the reactor turned to steam and exploded. “Steam explosions have a lot of force, and it blew the 500-ton reactor cap right off,” Dr. Weinstein said. “Then there was a hydrogen explosion and fire, and the core and the radioactive debris—and, worse than that, the fission products in the core—were widely dispersed.” They made no announcements regarding the explosion; the public only learned of it two days later when radiation alarms in Finland and Sweden sounded.

The Fallout

Once the Chernobyl incident was public, officials discovered an atmospheric plume of nuclear fallout. The 50 tons of vaporized uranium that fell from the sky weren’t the problem. “There were some noble gases like krypton-85 and xenon-133,” Dr. Weinstein said. “There were about 48 megacuries of iodine-131 with a half-life of eight days, so it’s pretty radioactive, and that concentrates in the thyroid and can damage the thyroid gland.” He also listed cesium-134, cesium-137, and strontium-90. “Strontium, like radon, seeks the bone.”

Then, 130 plant workers and firefighters were diagnosed with acute radiation syndrome, 30 of whom died. “There was population exposure from ingestion and from ground exposure,” Dr. Weinstein said. “People were warned not to drink milk because of cows grazing, taking in some of the fallout, and having radioactive fallout in their milk. There were several thousand measurable extra thyroid cancers due to that iodine-131.”

Today, a dome encloses the Chernobyl reactor site, but the silent and weed-choked town of Pripyat serves as a grim reminder of the dangers of unsafe nuclear power facilities.

Dr. Lawrence Weinstein contributed to this article. Lawrence Weinstein is a Professor of Physics at Old Dominion University and a researcher at the Thomas Jefferson National Accelerator Facility. He received his undergraduate degree from Yale University and his doctorate in Physics from the Massachusetts Institute of Technology.