Modelling the Performance of Tritium Process Monitors from First Principles

TL;DR

This paper develops a first-principles computational model for ionization chamber-based tritium monitors, accurately describing their behavior across different regimes and aiding future detector design improvements.

Contribution

The paper introduces a novel first-principles model that captures the nonlinear and linear responses of tritium monitors, validated against experimental data.

Findings

Model accurately predicts monitor behavior across concentration ranges.

Nonlinear response observed at low voltage and pressure.

Model can be extended to other detector geometries.

Abstract

Ionization chamber-based, in-line tritium process monitors play an important part in determining the behavior of a tritium system. The one-liter detection volume monitor has been characterized well through experiment and to respond linearly to tritium concentrations for the range of $1 {\mu}Ci/m^3$ to $1 Ci/m^3$. Additionally, it has been shown to behave nonlinearly for low voltage on the central anode and low pressure of the carrier gas. A computational model was developed from first principles that successfully describes the behavior of the one-liter monitor for each of these regimes. Predictions from the model are compared to previously-collected experimental data in order to determine validity and tune the model. The model will be expanded to incorporate additional detector geometries and designs in the future.