Comparison of the major accidents
To effectively compare the major accidents with the fallout caused by nuclear testing, two factors have been considered: the activity of the most important radioisotopes released, and the surface area affected by the radiation (or the surface area evacuated as a result). In the case of Three Mile Island in 1979, for instance, while there was no permanent evacuation, some 100,000 people freely decided to temporarily vacate their own homes.