A Heavy-Water Vapour Loss Monitor Incorporating a Liquid Phase Isotopic Measurement

Abstract

A new heavy-water vapour loss monitor of the condensing type is described. The monitor incor- porates an infrared liquid isotopic analyzer. A field-engineered unit has been developed and built, and is being installed at Douglas Point NGS. Performance of this unit in the laboratory is described. During the design phase, emphasis was placed on the use of commercially-available components, and on the achievement of high sensi- tivity and reliability. A programmable controller with a mathematics capability has eliminated the need for a separate hygrometer, and has allowed the use of a mechanically simple condensing system. In addition, on-board self-diagnostics and calibration programs are expected to minimize maintenance time.