On April 26, 1986, the worst nuclear disaster to date occurred at the Chernobyl Nuclear Power Plant in Pripyat, Ukraine. In 1970, construction began on the town of Pripyat near the Belarus border where workers would live. At the time of the accident, almost 50,000 people lived in Pripyat alone. The power plant first became operational in 1977 and construction was still occurring on reactors at the time of the accident. Energy produced at the plant accounted for 10% of Ukraine’s energy in 1986.
The reactors used at the Chernobyl plant were called RBMK, or High Power Channel-type Reactors. These reactors were popular in the USSR because they were relatively cheap to build, used natural uranium instead of enriched uranium, and could easily be operated. However, there were problems with the design, particularly that in the instance of a power failure, it would take a minute for backup power to be restored using generators. In this amount of time, decay heat from nuclear reactions could result in core damage and without energy to power the cooling pumps there could be catastrophic consequences.
On April 26, tests were being done on the reactors to find a way to provide energy to cooling pumps in case of a power failure using steam turbines. After some delays, the tests began at 1:23 in the morning. During these tests, there was a large spike in power, but when workers tried to regain control, a series of power surges in Reactor No. 4 led to a steam explosion and a fire. Since there was no containment building around the reactors, the explosion and fire resulted in radioactive materials being ejected into the atmosphere, producing radioactive fallout. Radioactive contamination fell throughout Europe, with most of it landing in neighboring Belarus.
Evacuations of the surrounding area did not begin once the resulting fires had been put out. It took two days for the government to announce the disaster and more than 24 hours for scientists to agree on evacuations. Over 350,000 people were evacuated from the area around Pripyat and a 19 mile exclusion zone around the disaster area still exists today. During the disaster 31 people died, but with many people exposed to high levels of radiation, the actual number of causalities has yet to be determined.
Items in Our Collection
Chernobyl: catastrophe and consequences by Jim T Smith; Nicholas A Beresford
Chernobyl record: the definitive history of the Chernobyl catastrophe by Richard F Mould
Chernobyl: the long shadow by Chris C Park