Fallout monitoring. Hand-held detector measuring levels of radioactive fallout from the disaster at the Mayak nuclear fuel reprocessing plant in Russia. The detector's readout shows a high level of radiation. On 29 September 1957 a tank at Mayak holding 300 cubic metres of nuclear waste explod- ed. About 250,000 people were exposed to the 20 million curies of radiation released. This was about half as much radiation as was released from the Chernobyl disaster of 1986. The Mayak plant has since contaminated the environment by dumping radioactive waste directly into the River Techa. Radioactive chemicals remain dangerous for thous- ands of years, causing cancers & genetic defects.