The document discusses the Chernobyl and Fukushima nuclear disasters. It begins by providing background on the 1986 Chernobyl disaster, where a reactor crashed in Ukraine, contaminating areas of Belarus with radiation and causing illnesses like cancer. It then describes the 2011 earthquake and tsunami in Japan that triggered problems at the Fukushima Daiichi nuclear power plant, including explosions at some of its reactors due to failures in the cooling system after the diesel generators were flooded. The aftermath of both disasters included widespread radiation contamination and immense economic and social costs.