Chernobyl: Details of the Worst Nuclear Disaster in History

Responding to the crisis required a monumental effort, involving over 500,000 personnel for emergency operations and subsequent environmental cleanup. This massive endeavor cost approximately 18 billion Soviet rubles, a figure equivalent to $68 billion in 2019 when adjusted for inflation. The scale of the response underscores the unprecedented challenges posed by the catastrophe, as well as the Soviet Union's desperate attempts to mitigate its consequences. 

The disaster itself unfolded during a scheduled safety test designed to assess the reactor's ability to maintain critical operations during a power outage. The test was carried out on an RBMK-type reactor, a design already known to have significant safety flaws. During the test, a sudden and unexpected drop in power output brought the reactor to near-zero levels. The operators, unaware of the reactor's increasing instability due to incomplete and misleading operating instructions, attempted to bring the power back up to the required level. However, these efforts placed the reactor in a precarious and highly unstable state.