The Three Mile Island accident was an environmental disaster

The Three Mile Island accident had no detectable health or environmental consequences. Nevertheless, it participated in an in-depth reconsidering of how to train personnel responsible for controlling nuclear reactors.

A gross exaggeration

This statement grossly exaggerates the consequences of the accident. While the 1979 Three Mile Island accident in the United States was a serious event and raised concerns about the safety of nuclear reactors, it did not result in any major environmental or health consequences. The accident was classified (retroactively) at level 5 on the International Nuclear Event Scale (INES), meaning that it only led to limited radioactive releases [1].

Very low overexposure to radioactivity

No resident in the vicinity of the plant was exposed to a dose greater than 1 mSv, i.e. one third the average annual dose received by an American due to natural radioactivity [2]. Independent studies conducted in the aftermath of the accident tend to show that the accident had no detectable effect on the health of plant workers or the surrounding population [3]. 

Therefore, despite the partial melting of the reactor core and the resulting significant radioactivity in the containment vessel, the immediate radiological consequences were minimal. On the whole, the reactor enclosure effectively ensured containment. In summary, the Three Mile Island accident did not have a significant impact on health or the environment. It has, however, contributed to a slowdown in the expansion of nuclear power in the United States and some other countries. It has also led to an awareness of the importance of nuclear safety culture, putting safety even more at the forefront of design and operation of installations.