Procedure for Determining of Tritium Concentration in the Hanoi Atmosphere

Nguyen Thi Thu Ha, Vo Thi Anh, Ha Lan Anh, Vuong Thu Bac

Abstract: Environmental radiation monitoring around nuclear power plants is a mandatory task, an indispensable content of any nuclear power plants yet. The radiation measurement techniques using for environmental radioactivity monitoring are continuously being improved. One of the radioisotopes that should be regularly monitored is tritium (H-3), especially in the atmosphere. Tritium presents in the atmosphere mainly in the vapor (HTO) and gaseous (HT) forms. In this study the HTO and HT in the Hanoi atmosphere are collected simultaneously by the MARC-7000 Tritium sampler. The sampler was specifically designed for capturing Tritium by using a series of four bubbling bottles, a cooling system and an oven packed with Palladium-Alumina catalyst to oxydize HT. Sampling was carried out a flow rate of 30 L/h continuously for 10 to 14 days which depends on the atmosphere humidity. The trapping yields of HTO and HT were higher than 99% and 96%, respectively. The collected atmospheric moisture samples have been enriched by electrolysis then were measured for tritium activity on a Liquid Scintillation Analyzer Tri-carb 3170 TR/SL. Counting time was 100min x 10 cycles to achieve an accounting precision of less than 10%. The detection limit of the procedure was estimated as low as 0.46 TU. Average tritium radioactivity in the Hanoi atmosphere was found to be 16.94 (mBq/m³).

Keywords: HTO and HT in the atmosphere, MARC-7000 Tritium sampler, TRI CARB 3170 TR/SL LSA.

Pages: 191 – 199 | Full PDF Paper