Three Mile Island accident



Three Mile Island nuclear facility, c. 1979

The Three Mile Island accident was a partial meltdown of reactor number 2 of Three Mile Island Nuclear Generating Station (TMI-2) in Dauphin County, Pennsylvania, near Harrisburg, and subsequent radiation leak that occurred on March 28, 1979. It is the most significant accident in U.S. commercial nuclear power plant history. On the seven-point International Nuclear Event Scale, the incident was rated a five as 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 in the primary system. This allowed large amounts of nuclear reactor coolant to escape. The mechanical failures were compounded by the initial failure of plant operators to recognize the situation as a loss-of-coolant accident due to inadequate training and human factors, such as human-computer interaction design oversights relating to ambiguous control room indicators in the power plant's user interface. In particular, a hidden indicator light led to an operator manually overriding the automatic emergency cooling system of the reactor because the operator mistakenly believed that there was too much coolant water present in the reactor and causing the steam pressure release.

The accident crystallized anti-nuclear safety concerns among activists and the general public and resulted in new regulations for the nuclear industry. It has been cited as a contributor to the decline of a new reactor construction program, a slowdown that was already underway in the 1970s. The partial meltdown resulted in the release of radioactive gases and radioactive iodine into the environment.

Anti-nuclear movement activists expressed worries about regional health effects from the accident. However, epidemiological studies analyzing the rate of cancer in and around the area since the accident determined there was not a statistically significant increase in the rate and thus no causal connection linking the accident with these cancers has been substantiated. Cleanup started in August 1979, and officially ended in December 1993, with a total cleanup cost of about $1 billion.

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In popular culture

The China Syndrome

On March 16, 1979, twelve days before the accident, the movie The China Syndrome premiered, and was initially met with backlash from the nuclear power industry, claiming it to be "sheer fiction" and a "character assassination of an entire industry."

In the film, television reporter Kimberly Wells (Jane Fonda) and her cameraman Richard Adams (Michael Douglas) secretly film a major accident at a nuclear power plant while taping a series on nuclear power. The operating crew notices a high-pressure measurement on a gauge and begins to reduce coolant flow to lower the pressure. This does not appear to work, and they continue reducing the flow until an emergency indicator lamp warns of extremely low pressure. Confused by the conflicting indications, an operator taps the gauge, at which point the needle becomes unstuck and swings over to indicate extremely low pressure. (This is based on a 1970 incident at Dresden Generating Station.) The reactor is SCRAMed. In the aftermath, the plant supervisor, Jack Godell (Jack Lemmon) discovers potentially catastrophic safety violations at the plant and with Wells' assistance attempts to raise public awareness of these violations. At one point in the film, an official tells Jane Fonda's character that an explosion at the plant "could render an area the size of the state of Pennsylvania permanently uninhabitable."

After the release of the film, Fonda began lobbying against nuclear power. In an attempt to counter her efforts, Edward Teller, a nuclear physicist and long-time government science adviser best known for contributing to the Teller–Ulam design breakthrough that made hydrogen bombs possible, personally lobbied in favor of nuclear power. Teller suffered a heart attack shortly after the incident and joked that he was the only person whose health was affected.

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