Coupled CFD and Tritium Transport Modeling of a Permeator Probe for Tritium Concentration in Liquids

This work conducted multiphysics simulations of an α-Fe tritium permeator probe, a potential diagnostic for measuring tritium concentration in liquid breeders. The objective was to determine the relationships between the LiPb inlet tritium concentration and the flow rate on the tritium permeation rate through the probe. Two probe positions were tested, with the probe in or out of the direct line of fluid flow. Computational fluid dynamics simulations were performed with OpenFOAM, and results were fed into the tritium transport code Finite Elements Simulation of Tritium in Materials (FESTIM). Generally, less than 0.1% of the total tritium flux permeated into the probe, demonstrating that the probe is noninvasive. Behavior laws were derived to describe the impact of inlet concentrations (from 10−4 to 102 mol∙m−3) on the permeation rate. Varying only the inlet concentrations, two permeation regimes were identified. At an inlet concentration of 10 mol∙m−3, in the probe-in case, the permeation rate was ≈3 × 1018 T∙s−1, and in the probe-out case, the permeation rate was ≈5 × 1017 T ∙s−1. The impact of the flow rate (from 1 to 4 kg ∙s−1) on the permeation rate varied with the geometry: in the probe-in case having a negligible impact (<3%) and in the probe-out case demonstrating a peak in the permeation rate at 3 kg∙s−1. These results were assessed against detectability limits of typical pressure gauges.