In addition to its potential for destruction, the energy released in nuclear fission was seen as a potential source of controlled power generation. By 1944, large-scale nuclear reactors were in operation for the production of plutonium, although the energy produced by these reactors was not used. Following World War II, increased efforts were turned toward the extensive use of nuclear power to produce electricity. Nuclear power plants use the radiant energy of a controlled nuclear reaction to heat water, converting it to steam to spin turbines that generate electricity. The major drawback to nuclear fission is the lack of a safe means of disposal for the waste produced by the reaction, which retains its lethal radioactivity for hundreds of years. Another hazard is the possibility of a malfunction in the reactor that could lead to a meltdown of the core. Despite massive safety precautions, human error and equipment failures can lead to devastating accidents such as the explosion at Chernobyl in 1986, in which at least 30 people were killed and thousands lost their homes and face possible long-term illness after exposure to near-lethal doses of radiation. Because of growing public concern, the development of new nuclear power plants has slowed as scientists search for viable solutions to these problems.