Three Mile Island | TMI 2 |Three Mile Island Accident. (March 2001, minor update Jan 2012) In 1979 at Three Mile Island nuclear power plant in USA a cooling malfunction caused part of the core to melt in the # 2 reactor. The TMI-2 reactor was destroyed.Some radioactive gas was released a couple of days after the accident, but not enough to cause any dose above background levels to local residents.There were no injuries or adverse health effects from the Three Mile Island accident. The Three Mile Island power station is near Harrisburg, Pennsylvania in USA. It had two pressurized water reactors. The accident to unit 2 happened at 4 am on 28 March 1979 when the reactor was operating at 97% power. The operators were unable to diagnose or respond properly to the unplanned automatic shutdown of the reactor.
The chain of events during the Three Mile Island Accident Within seconds of the shutdown, the pilot-operated relief valve (PORV) on the reactor cooling system opened, as it was supposed to. Cooling Restored, radioactive releases to air Summary. List of Carnage. The Three Mile Island Population Registry. Backgrounder on the Three Mile Island Accident. Printable Version (does not include Animated Diagram of the Sequence of Events)Three Mile Island History (Video) On this page: The Three Mile Island Unit 2 (TMI-2) reactor, near Middletown, Pa., partially melted down on March 28, 1979. This was the most serious accident in U.S. commercial nuclear power plant operating history, although its small radioactive releases had no detectable health effects on plant workers or the public. Its aftermath brought about sweeping changes involving emergency response planning, reactor operator training, human factors engineering, radiation protection, and many other areas of nuclear power plant operations.
It also caused the NRC to tighten and heighten its regulatory oversight. All of these changes significantly enhanced U.S. reactor safety. A combination of equipment malfunctions, design-related problems and worker errors led to TMI-2's partial meltdown and very small off-site releases of radioactivity. Summary of Events Health Effects Current Status.
Three mile island.