Helium-3 of the airway tree, locate unventilated defects, measure the alveolar oxygen partial pressure, and measure the ventilation/perfusion ratio. This technique may be critical for the diagnosis and treatment management of chronic respiratory diseases such as chronic obstructive pulmonary disease (COPD), emphysema, cystic fibrosis, and asthma. Production, sales and distribution of helium-3 in the United States are managed by the US Department of Energy (DOE) Isotope Program. Virtually all helium-3 used in industry today is produced from the radioactive decay of tritium. Tritium is a radioactive isotope of hydrogen and is typically produced by bombarding lithium-6 with neutrons in a nuclear
Tritium boron, cadmium, or hafnium), at the reactors of the commercial Watts Bar Nuclear Generating Station from 2003–2005 followed by extraction of tritium from the rods at the new Tritium Extraction Facility at the Savannah River Site beginning in November 2006. Tritium leakage from the rods during reactor operations limits the number that can be used in any reactor without exceeding the maximum allowed tritium levels in the coolant. Tritium has an atomic mass of 3.0160492 u. Diatomic tritium ( or ) is a gas at standard temperature and pressure. Combined with oxygen, it forms a liquid called tritiated water ().