What are the sources of tritium?
Less than 1% of tritium occurs naturally (e.g. through the interaction of cosmic rays with molecules of certain elements in the upper atmosphere). Most of tritium is man made; fallout from thermonuclear weapons testing, begun in the 1940s, is a source of tritium in the global environment; nuclear power reactors are also a large source of tritium. Canadian Deuterium Uranium (CANDU) nuclear reactors are the largest Canadian point source of tritium; CANDU reactors use deuterium oxide or “heavy water” as both a moderator and a coolant, and effectively “breed” tritium as the nuclear fission process releases free neutrons (i.e. tritium atoms are created when a deuterium atom absorbs an additional neutron). How is tritium released to the environment? At the Bruce nuclear complex, tritium is released to the station cooling water effluent stream (Condenser Cooling Water) which discharges into Lake Huron. There are two potential operational sources of tritium into this discharge stream: 1. Radio
