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
Boiling water reactor safety systems or isolation signal. When an isolation signal is given to a group, both the inboard and outboard valves stroke closed. Tests of isolation logic must be performed regularly and is a part of each plant's technical specifications. The timing of these valves to stroke closed is a component of each plant's safety analysis and failure to close in the analyzed time is a reportable event. Examples of isolation groups include the main steamlines, the reactor water cleanup system, the reactor core isolation cooling (RCIC) system, shutdown cooling, and the residual heat removal system. For pipes which inject water into the