01 Overview
On September 29, 1957, a cooling system failure at the Mayak nuclear waste storage facility caused an explosion of liquid high-level radioactive waste. The explosion had a force equivalent to 70โ100 tonnes of TNT and ejected approximately 20 million curies of radioactivity. The Soviet government kept the accident secret for decades.
02 Cause
A failure in the cooling system of one tank, combined with evaporation of the liquid, led to a buildup of dried sodium acetate and ammonium nitrate. The compounds reached a critical temperature and exploded, breaching the concrete cap and launching a plume of radioactive aerosols 1โ2 km into the atmosphere.
03 Impact
An estimated 10,000โ15,000 kmยฒ was contaminated. About 270,000 people received significant radiation doses. Around 10,000 people were evacuated, many not until weeks after the event. Villages and towns were simply erased from Soviet maps.
04 Response
The Soviet government maintained strict secrecy. Evacuations were conducted under the guise of military exercises. The first Western knowledge came from a 1976 book by dissident scientist Zhores Medvedev, initially dismissed as fabrication. The full extent was not acknowledged until the late 1980s.
05 Legacy
Kyshtym stands as a chilling example of state secrecy overriding public safety. The Mayak complex continued to dump radioactive waste into the Techa River for years. The area remains among the most radioactively contaminated places on Earth.