Hydrogen isotope biogeochemistry assumed that helium-3 was the radioactive component. The work of Luis Walter Alvarez and Robert Cornog first isolated tritium and reversed Rutherford's incorrect notion. Alvarez reasoned that tritium was radioactive, but did not measure the half-life, although calculations at the time suggested over ten years. At the end of World War II, the physical chemist Willard Libby detected the residual radioactivity of a tritium sample with a Geiger counter, providing a more accurate understanding of the half-life, now accepted at 12.3 years. The discovery of hydrogen isotopes also impacted the field of physics in the 1940s, as Nuclear Magnetic Resonance
Radioactive contamination from the Rocky Flats Plant caused by normal operations rather than accidental releases. From September 1947 to April 1969 there were 5 or more accidental surface water releases of tritium. Tritium, a radioactive element which was found in scrap material from Rocky Flats, was therefore directed in to the Great Western Reservoir. This was uncovered in 1973 and following this, urine samples were taken from people living or working near Broomfield who could have drunk water from the reservoir. The findings of the samples showed that those who were exposed to contaminated water had tritium concentrations near seven times higher than normal (4,300 picocuries per