Nuclear reactor accidents in the United States the Joint Committee on Atomic Energy that: "the cumulative effect of all design defects and deficiencies in the design, construction and operations of nuclear power plants makes a nuclear power plant accident, in our opinion, a certain event. The only question is when, and where. On March 28, 1979, equipment failures and operator error contributed to loss of coolant and a partial core meltdown of Unit 2's pressurized water reactor at the Three Mile Island Nuclear Power Plant in Pennsylvania. The scope and complexity of this reactor accident became clear over the course of five days, as a number of
Nuclear chain reaction and intense it cannot be controlled after it has started. When properly designed, this uncontrolled reaction can lead to an explosive energy release. Nuclear weapons employ high quality, highly enriched fuel exceeding the critical size and geometry (critical mass) necessary in order to obtain an explosive chain reaction. The fuel for energy purposes, such as in a nuclear fission reactor, is very different, usually consisting of a low-enriched oxide material (e.g. UO). When a heavy atom undergoes nuclear fission, it breaks into two or more fission fragments. Also, several free neutrons, gamma rays, and neutrinos are emitted, and a large