Three Mile Island nuclear plant is closing for good
September 30, 2019 - Forty years after the worst commercial nuclear power plant accident in U.S. history, the only reactor still operating at Three Mile Island (TMI) is to be shut down on September 30.
The nuclear accident caused the partial meltdown of TMI’s reactor number 2 and subsequent radiation leak that occurred on March 28, 1979. It was the most significant accident in U.S. nuclear power plant history.
It began with failures in the non-nuclear secondary system, followed by a stuck-open pilot-operated relief valve in the primary system, which allowed large amounts of nuclear reactor coolant to escape. Plant operators failed to recognise the situation as a loss-of-coolant accident, compounding the mechanical failures.
Radiation was then purposefully released into the air to relieve pressure within the system, triggering public panic.
The accident crystallised anti-nuclear safety concerns among activists and the general public and resulted in new regulations for the nuclear industry.
Although the partial meltdown was not as damaging as the nuclear crises at Chernobyl or Fukushima, people expressed worries about environmental health effects from the accident. Subsequent studies found a slight increase in cancer rates around the plant but concluded there was no causal connection linking the incident with these cancers.
The bill for making the site safe was $1 billion and took from 1979 to 1993. The plant’s owner, Exelon Corporation, estimates the cost of decommissioning the site costing a further $1.2 billion. Dismantling the structures will not begin until 2074 when radiation levels have fallen.
- Backgrounder on the Three Mile Island Accident (U.S. Nuclear Regulatory Commission)
- Nuclear plant accidents: Three Mile Island (Union of Concerned Scientists)
- Three Mile Island Accident (World Nuclear Association)
- Mar 28, 2019: Nuclear power industry still hurting 40 years after Three Mile Island accident (NewsAhead)