What about the health effects? How many people got cancer or mutations from the radiation that was released? The answer is possibly one cancer death over a lifetime and 1 or 2 hereditary mutations, according to an expert group, the Ad

Hoc Population Assessment Group (7). To put this in perspective, about 450,000 people would be expected to die from natural causes of cancer in this population of 2 million people living within a 50-mile radius of the plant (6). Again, it all comes down to dose. It is estimated that the average dose to the 2 million people in the area was about 1 mrem (0.01 mSv) and the maximum dose to a person at the boundary of the plant was about 100 mrem (1 mSv) (2). Recall that you would get a dose of about 0.05 mSv flying from New York to London, or about five times the dose for the average person around TMI. The average annual natu­ral background radiation is about 1 to 1.25 mSv in Pennsylvania, but remember that in Colorado the average natural background radiation is about 4.5 mSv and Coloradans have among the lowest cancer rates in the nation. Without even doing a study, you can predict that there would be no observable cancers resulting from the radiation released from TMI. The highest exposed person got a dose less than one-fourth of the annual dose to an average Coloradan!

But, of course, many studies were done—by the NRC, the DOE, the EPA, the Pennsylvania Health Department, and independent researchers. These studies show that there were no effects on pregnancy outcome, spontaneous abortions, fetal and infant mortalities, or cancer (6). Actually, there were fewer cancer deaths than expected in residents within 20 miles of the plant in the following five years. Given that thyroid cancer and leukemia would be the only cancers that are likely to crop up within five years, these are of special concern, but no excess in these cancers was found. In fact, the only cancer that would be likely to appear would be thyroid cancer, because the only radioisotope of biological significance in the release was 1 31I. Iodine, including radioactive iodine, is rapidly transported through grass to cows’ milk to children who drink milk and is concentrated in the thyroid. There was no measurable release of 137Cs or 90Sr (6, 7) (the next section has more details about these isotopes). The only health concern caused by the accident was a high level of stress in people in the surrounding area.

Nevertheless, TMI was a huge wake-up call to the Nuclear Regulatory Commission (NRC), the governmental agency that regulates nuclear power, and the nuclear industry. The NRC made major changes in its regulations and oversight of the nuclear industry—plant design and equipment requirements were upgraded and strengthened; human factors were taken into account in redesigning control panels and instrumentation to avoid confusion; training was greatly improved and increased; emergency preparedness was increased; the resident inspector program was expanded so that two NRC inspectors live nearby and work exclu­sively at each plant; and numerous other changes were made (2). Two of the most important changes were the creation of the Institute of Nuclear Power Operations (INPO) and the National Academy for Nuclear Training—industry-run organiza­tions that promote safety and excellence in the nuclear power industry—follow­ing the realization that major problems at a single nuclear reactor in the United States would affect public acceptance of every other plant (4).

Coming on the heels of the release of The China Syndrome, the TMI accident sparked a resurgence in the anti-nuclear environmental movement, with authors such as Helen Caldicott, Amory Lovins, and John Gofman transforming their anti-nuclear weapons stance to anti-nuclear power, claiming that it was too dangerous to be used and calling for a shutdown of the nuclear power indus­try (8-10). Protesters tried to block the completion of reactors undergoing con­struction. Public hearings extended plant licensing for years and made the cost of construction prohibitive. The public view of nuclear power was very negative, and people were scared of radiation. Demonstrations took place at nuclear power plant sites (my sister and brother-in-law demonstrated at the nuclear power plant in Kansas). And utilities became afraid of the liabilities they might face with a nuclear accident. Of the 129 nuclear power plants scheduled to be built at the time of the accident, only 53 were completed (1). Despite all of that, existing reac­tors and newly constructed reactors became safer and more efficient and nuclear power provided about 20% of the electricity in the United States over the coming decades.

When I visited the Wolf Creek Nuclear Plant in my birth state of Kansas, I had the opportunity to see firsthand the result of these changes. Every nuclear reactor in the United States has a training control room that is identical to that used in the actual reactor. Dials, gauges, and controls are grouped together so that operators can easily see and control reactor operations, unlike at TMI. Operators train 10 weeks every year in the training control room, and the con­trols work with feedback, so they function exactly like the real controls in the actual control room. Supervisors running the simulator can create all kinds of accident scenarios for training purposes. While I was there, the supervisor sim­ulated a loss of electrical power to the pumps, and it is pretty scary to see all of the lights flashing and horns blaring. But it gives the operators a chance to work through all kinds of scenarios before they need to deal with a real-life situation.

These changes in nuclear power plant design, operation, and training have obviously been effective because there have been no accidents in the United States since Three Mile Island. The United States has over 3,600 reactor-years of expe­rience with commercial nuclear power without the loss of a single life from a nuclear accident (11). And sailors have been living right next to pressurized water reactors on nuclear submarines for nearly 60 years, with nary a loss of life or expo­sure to harmful doses of radiation. Despite decades of warnings from anti-nuclear people who imagine that the worst will soon happen, it just doesn’t happen. Of course, that does not mean that it is impossible, but the risk is very small. There is always a risk from any energy source, but nuclear power has the best safety record of any major power industry in the United States.