The leak involved a substantial amount of Tritium contaminated water that leaked from a Nuclear Power Plant in Minnesota. Tritium also known as hydrogen-3 is a rare and radioactive isotope of hydrogen with a half-life of about 12 years. Tritium is naturally occurring in the environment but is also produced by nuclear power plants. Tritium is one of the least dangerous radio nuclides because it emits very weak radiation and leaves the body relatively quick. From the article, it sound like the leaks were contained on site with no contamination of ground water. This is nothing compared to the Fukushima nuclear disaster in Japan. Sounds scary because it involves a Nuclear Power Plant.