The Truth About the Three Mile Island Disaster


The disaster at Unit 2 of the Three Mile Island (TMI) nuclear power plant near Harrisburg, Pennsylvania, began on March 28, 1979. Now, 40 years later, the reality, not only of what happened, but also the long-term aftermath and effects, remain cloaked in mystery and misinformation. Ironically, despite today’s popular “too much information” shorthand, TMI is a story of too little information. Beyond Nuclear has endeavored to dig into the lies and myths and uncover the truth about TMI. Starting with the disaster narrative we take a look at: the “no one died at TMI” myth; how much radiation really got out; the lack of adequate emergency planning and protective measures; the people’s experience downwind of the disaster; and the impacts on plants and animals. We hear from engineer, Arnie Gundersen, and longtime campaigner, Dr. Judith Johnsrud. Finally, we compare the mistakes of TMI with those at the Chernobyl and Fukushima disasters. If the lessons of TMI, Chernobyl and now Fukushima are unlearned, we are destined to repeat, rather than prevent them the next time. And until all nuclear power plants are closed, that "next time" is a tragic inevitability. For a synopsis of the Truth about TMI, see the Spring 2014 edition of The Thunderbird.

The Disaster: What Happened?

At 4 A.M. on Wednesday, March 28, 1979, the Three Mile Island Unit 2 reactor was at full power and had been commercially operational for only 88 days. Within minutes, a series of equipment failures and operator errors led to a runaway meltdown of a significant portion of the radioactive reactor core.  The ensuing nuclear accident resulted in the deliberate venting of extreme pressure, high temperatures and significant radioactive releases from containment to the atmosphere over the next several days. All the while, Metropolitan Edison officials repeatedly lied to state emergency officials and neighboring communities that “conditions are stable.”  Full backgrounder here.

No One Died at TMI: The biggest lie

The nuclear industry is fond of claiming that no one died at Three Mile Island. This is contradicted not only by medical science but by medical evidence found in the only independent epidemiological study conducted since the disaster. Claims of no - or minimal - harm due to a nuclear "accident" recurred after the Chernobyl reactor disaster in 1986 and today as the Fukushima nuclear catastrophe continues. Given the medical consequences of prolonged radiation exposure even to low doses, the claim that "no one died" is not supportable. Furthermore, the nuclear industry uses a focus on deaths to obfuscate many radiation impacts, not all of which manifest immediately and which are not necessarily fatal. Full backgrounder.

The Radiation Meters Went Off Scale

A nuclear disaster was considered “unthinkable.” So there was no reliable radiation monitoring equipment on hand when TMI started melting down and venting radioactivity. Today, the official line persists that the maximum radiation releases originally reported by Metropolitan Edison were orders of magnitude less than any dose required to produce the physiological symptoms of radiation exposure, reported domestic and wild animal deaths and the documented destruction and mutation of plant life actually observed around TMI. However, hundreds of local residents reported experiencing many of the symptoms of acute radiation exposure including nausea and vomiting, severe fatigue, diarrhea, hair loss and graying and a radiation-induced abnormal reddening of the skin medically known as erythema. In fact, the people became the radiation meters for the TMI accident. Full backgrounder.

No Emergency Plan

The Three Mile Island accident demonstrated that managing human behavior during a nuclear catastrophe is not realistic. Nuclear catastrophe provokes a unique human behavior and public perception dramatically different from any other technological and natural disaster. “Too little information too late” persisted throughout the TMI accident so that emergency officials had no precise data on time, direction and amount of radioactivity releases. The nuclear power industry and emergency officials continue to downplay emergency planning as a public relations problem that will never be tested. In the event of a nuclear catastrophe in the U.S., current emergency planning is unrealistic and not based on real human behavior. Full backgrounder.

Plants and Animals Show Damage After Nuclear Disasters

From serious deformities to subtle color changes to death, plants and animals experience damage after a nuclear disaster. Some damage shows up immediately and some slowly, over time, including increased sensitivity to radiation damage in successive generations that are chronically exposed. Full backgrounder.

TMI Myths: Arnie Gundersen, nuclear engineer

Once the TMI disaster had begun, evacuation of everyone in the surrounding population should have been ordered, but never was. Arnie Gundersen, a nuclear engineer, concludes that a portion of TMI Unit 2’s containment wall clearly failed after a hydrogen detonation, and that a thorough analysis of the TMI disaster indicates releases were 100 to 1,000 times higher than the NRC's low 2009 estimate of only 10 million Curies released. Full backgrounder.

Blood Reveals True Exposures from TMI

Residents around TMI were exposed to much more radiation from the accident than was claimed by industry. A study conducted by Dr. Steven Wing et al., used outside research (Shevshenko et al.) which examined blood of individuals exposed at the time of the TMI disaster. They found far higher chromosome malformations from  TMI accident radiation than releases “measured” by industry would have caused. Full backgrounder.

The X and Why of Radiation Damage

An explanation (with pictures) of how ionizing radiation creates specific chromosome malformations. These malformations were found in people at Three Mile Island who suffered radiation exposure symptoms, indicating that they were exposed to higher radiation levels than admitted to by officials. Testing for these malformations could help determine radiation exposure levels subsequent to nuclear catastrophes like Fukushima and Chernobyl, or even smaller radiation releases. Full backgrounder.

Three Mile Island: The People's Testament

From 1979 to 1988, Professor Katagiri Mitsuru and journalist Aileen Mioko Smith, took testimonials from approximately 250 TMI eyewitnesses who were residents in the area at the time of the nuclear meltdown. Together, they compiled, Three Mile Island: The People's Testament. These stories bring home the reality of the TMI experience. The consistency of their symptoms, the harm caused to their animals at the time, and the later manifestation of diseases support what we know about the health impacts of exposure to ionizing radiation. Today, Aileen directs Green Action, in Kyoto, Japan. Read their report.