Three Mile Island

Apropos of my earlier post, in which I asserted that nuclear power is extremely safe, I uncovered a short report from the Nuclear Regulatory Commission on the Three Mile Island accident. The TMI accident is important because it and Chernobyl are the most frequent arguments against the safety of nuclear power. Chernobyl was a Soviet design far below any standards ever employed in the West, so it isn’t actually relevant. On the other hand, TMI was an American design.

One counter to the TMI example is that designs and procedures have changed completely since the TMI accident. Moreover, modern pebble bed reactors are based on an entirely different technology that is self-limiting, and therefore incapable of melting down.

The preceding is by far the more important argument, but there is another to be made: If by “serious” one means “affecting the health of at least one person,” then there has never been a serious nuclear accident in the United States, TMI notwithstanding. In the words of the NRC report:

Detailed studies of the radiological consequences of the accident have been conducted by the NRC, the Environmental Protection Agency, the Department of Health, Education and Welfare (now Health and Human Services), the Department of Energy, and the State of Pennsylvania. Several independent studies have also been conducted. Estimates are that the average dose to about 2 million people in the area was only about 1 millirem. To put this into context, exposure from a full set of chest x-rays is about 6 millirem. Compared to the natural radioactive background dose of about 100-125 millirem per year for the area, the collective dose to the community from the accident was very small. The maximum dose to a person at the site boundary would have been less than 100 millirem.

In the months following the accident, although questions were raised about possible adverse effects from radiation on human, animal, and plant life in the TMI area, none could be directly correlated to the accident. Thousands of environmental samples of air, water, milk, vegetation, soil, and foodstuffs were collected by various groups monitoring the area. Very low levels of radionuclides could be attributed to releases from the accident. However, comprehensive investigations and assessments by several well-respected organizations have concluded that in spite of serious damage to the reactor, most of the radiation was contained and that the actual release had negligible effects on the physical health of individuals or the environment.

Of the two million affected, the average person got one-sixth of a chest x-ray. The maximum effect to anyone was equivalent to one year of natural background radiation.

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