Nuclear chain reaction between being slightly subcritical and slightly delayed-supercritical, but must always remain below prompt-critical. It is impossible for a nuclear power plant to undergo a nuclear chain reaction that results in an explosion of power comparable with a nuclear weapon, but even low-powered explosions due to uncontrolled chain reactions, that would be considered "fizzles" in a bomb, may still cause considerable damage and meltdown in a reactor. For example, the Chernobyl disaster involved a runaway chain reaction but the result was a low-powered steam explosion from the relatively small release of heat, as compared with a bomb. However, the reactor complex
Nuclear reactor accidents in the United States damage costs include destruction of property, emergency response, environmental remediation, evacuation, lost product, fines, and court claims. Because nuclear reactors are large and complex, accidents onsite tend to be relatively expensive. In the U.S., at least 56 nuclear reactor accidents have occurred. The most serious of these U.S. accidents was the Three Mile Island accident in 1979. According to the Nuclear Regulatory Commission, the Davis–Besse Nuclear Power Station has been the source of two of the top five most dangerous nuclear incidents in the United States since 1979. The United States Government Accountability Office reported more than 150 incidents from