An Open-Walled Ionization Chamber Appropriate to Tritium Monitoring for Glovebox

An open-walled ionization chamber is developed to monitor the tritium concentration in glovebox in the tritium processing systems. Two open walls are used to replace the sealed wall in common ionization chambers, through which the tritium gas can diffuse into the chamber without the aid of pumps and pipelines. Some basic properties of the chamber are examined to evaluate its performance. Results turn out that an open-walled chamber of 1 L in volume shows considerably flat plateaus over 700 V. The chamber also gives a good linear response to the gamma field over five degrees under condition of 1 atm. The pressure dependence characters show that the ionization current is only sensitive to low pressure. The pressure influence becomes weaker as pressure increases mainly due to the decrease of the mean free path of β ray decayed by tritium. The minimum detection limit of the chamber is 3.7×10⁵ Bq/m³.