Discriminating Tritium Monitor For The Tritium Removal Facility At Darlington Nuclear Generating Station
In CANDU reactors, deuterium (heavy water) is used as a moderator and also as the primary heat transport from the nuclear fuel. In time, tritium is formed by neutron capture by the deuterium, producing a mixture of tritiated deuterium. If left to accumulate, the tritium oxide would become a hazard to operating staff, and to the public via emissions through the ventilation stacks, should any leak occurs from the heat transport system, or from the moderator system. The subsequent fluid evaporation from any spill or leak would give rise to airborne hazards due to the presence of tritium oxide in vapor form. The purpose of the Tritium Removal Facility (TRF), located at the Darlington Nuclear Generating Station, is to reduce the tritium concentration in the heavy water moderator. A low concentration of tritium is desirable, as it would significantly reduce the tritium occupational exposures and any environmental emissions during the life of the station. In the TRF building, there are large inventories of elemental tritium gas as well as in the tritium oxide form. Since the latter is the greater hazard from a health physics point of view, it is used for reporting purposes, hence higher levels are usually, but unnecessarily, reported if all tritium emissions were reported as Tritium Oxide. A Discriminating Tritium Monitor, described in this paper, was designed to discriminate between the two tritium species and would allow for a more accurate means of reporting exposures and doses.
This abstract was presented at the 35th Annual Midyear Meeting, "Decommissioning and Environmental Restoration", Instrumentation Session, 2/17/2002 - 2/20/2002, held in Orlando, FL.