Development and Performance of a HTO-in-Air Monitor Using a Cold Trap and a Flow Cell Filled with Glass Scintillator Powder

Abstract

An improved type of HTO-in-air monitor was developed. The HTO contained in the air was condensed to liquid water using a cold trap. The tritium activity in the trapped water was measured using a flow cell filled with glass scintillator powder. This monitor made it possible to measure the airborne HTO concentration with a detection limit of 1.4×10^-4Bq/cm³ under a representative atmospheric condition, 22°C in temperature and 55% in relative humidity. This system is now in use to observe the HTO level of the exhaust gas released from the reactor containment building of the research reactor of Kyoto University.