Mayak plant is associated with two other major nuclear accidents. The first occurred as a result of heavy rains causing Lake Karachay, a dried-up radioactively polluted lake (used as a dumping basin for Mayak's radioactive waste since 1951), to release radioactive material into surrounding waters. The second occurred in 1967 when wind spread dust from the bottom of Lake Karachay over parts of Ozersk; over 400,000 people were irradiated.. Major accidents at Mayak, 1953–1998 Source: 15 March 1953 – Criticality accident. Contamination of plant personnel occurred. 13 October 1955 – Rupture of process equipment and the destruction of a process building. 21 April 1957 – Criticality accident. One operator died from receiving over 3000 rad. Five others received doses of 300 to 1,000 rem and temporarily became sick with radiation poisoning. 29 September 1957 – Kyshtym disaster. 2 January 1958 – Criticality accident in SCR plant. Plant workers conducted experiments to determine the critical mass of enriched uranium in a cylindrical container with different concentrations of uranium in solution. Personnel received doses from 7600 to 13,000 rem, resulting in three deaths and one case of blindness caused by radiation sickness. 12 May 1960 – Criticality accident. Five people were contaminated. 26 February 1962 – Destruction of equipment. An explosion occurred in the absorption column. 9 July 1962 – Criticality accident. 16 December 1965 – Criticality accident. Seventeen individuals received exposure to small amounts of radiation over a period of 14 hours. 10 December 1968 – Criticality accident. Plutonium solution was poured into a cylindrical container with dangerous geometry. One person died, another took a high dose of radiation and radiation sickness, after which he had both legs and his right arm amputated. 11 February 1976 – Unsafe actions of staff development at the radiochemical plant caused an autocatalytic reaction of concentrated nitric acid and organic liquid complex composition. The device exploded, contaminating the repair zone and areas around the plant. The incident merited an International Nuclear Event Scale rating of 3. 10 February 1984 – Explosion. 16 November 1990 – Explosion. Two people received burns and one was killed. 17 July 1993 – Accident at radioisotope plant, resulting in the destruction of the absorption column and release into the environment of a small amount of α-aerosols. Radiation emission was localised at the manufacturing facility of the shop. 8 February 1993 – Depressurisation of a pipeline caused of radioactive slurry (about