Three Mile Island accident
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The Three Mile Island accident was a partial nuclear meltdown of the Unit 2 reactor (TMI-2) of the Three Mile Island Nuclear Generating Station on the Susquehanna River in Londonderry Township, near the capital city of Harrisburg, Pennsylvania. The reactor accident began at 4:00 a.m. on March 28, 1979, and released radioactive gases and radioactive iodine into the environment. It is the worst accident in U.S. commercial nuclear power plant history. On the seven-point logarithmic International Nuclear Event Scale, the TMI-2 reactor accident is rated Level 5, an "Accident with Wider Consequences".The accident began with failures in the non-nuclear secondary system followed by a stuck-open pilot-operated relief valve (PORV) in the primary system that allowed large amounts of water to escape from the pressurized isolated coolant loop. The mechanical failures were compounded by the initial failure of plant operators to recognize the situation as a loss-of-coolant accident (LOCA). TMI training and operating procedures left operators and management ill-prepared for the deteriorating situation caused by the LOCA. During the accident, those inadequacies were compounded by design flaws, such as poor control design, the use of multiple, similar alarms, and a failure of the equipment to clearly indicate either the coolant-inventory level or the position of the stuck-open PORV.The accident crystallized anti-nuclear safety concerns among activists and the general public, and led to new regulations for the nuclear industry. It accelerated the decline of efforts to build new reactors.Anti-nuclear movement activists expressed worries about regional health effects from the accident. Some epidemiological studies analyzing the rate of cancer in and around the area since the accident did determine that there was a statistically significant increase in the rate of cancer, while other studies did not. Due to the nature of such studies, a causal connection linking the accident with cancer is difficult to prove.Cleanup at TMI-2 started in August 1979 and officially ended in December 1993, with a total cost of about $1 billion (equivalent to $2 billion in 2022). TMI-1 was restarted in 1985, then retired in 2019 due to operating losses. Its decommissioning is expected to be complete in 2079 at an estimated cost of $1.2 billion.
Excerpt from the Wikipedia article Three Mile Island accident (License: CC BY-SA 3.0, Authors, Images).Three Mile Island accident
Independance Road, Londonderry Township
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| Latitude | Longitude |
|---|---|
| N 40.15329 ° | E -76.72534 ° |
Address
Independance Road
17057 Londonderry Township
Pennsylvania, United States
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