This document discusses the Chernobyl nuclear disaster that occurred in 1986 at a nuclear power plant in Ukraine. It provides background details on the disaster, noting that it was caused by flawed Soviet reactor design, severe mistakes made by plant operators, and a lack of safety culture. The accident resulted in a steam explosion and fires that emitted radioactive reactor core material into the atmosphere. The Chernobyl disaster was unique as it is the only nuclear power accident that caused radiation-related deaths and illnesses.