Another environmental concern is radioactivity released during the 1979 Three Mile Island accident . However , extensive radionuclide studies over a 25 year period from 1979 through 2003 , confirm that the Three Mile Island accident has not resulted in any harmful radiation effects . The areas in and along a 262-km length of the Susquehanna River in Pennsylvania were monitored for the presence of radioactive materials . This study began two months after the 1979 Three Mile Island ( TMI ) partial reactor meltdown ; it spanned the next 25 years . Monitoring points included stations at the PPL Susquehanna and TMI nuclear power plants . Monthly gamma measurements documented concentrations of radionuclides from natural and anthropogenic sources . During this study , various series of gamma-emitting radionuclide concentration measurements were made in many general categories of animals , plants , and other inorganic matter , both within and near the river . Sampling began in 1979 before the first start-up of the PPL Susquehanna power plant . Although all species were not continuously monitored for the entire period , an extensive database was compiled . In 1986 , the ongoing measurements detected fallout from the Chernobyl nuclear accident . These data may be used in support of dose or environmental transport calculations
Three Mile Island accident
Three Mile Island accident
Susquehanna River