COMPUTATIONAL SIMULATION OF HYDROGEN PERMEATION EXPERIMENT

Tritium control and mitigation is one of the most significant
issues in Fluoride Salt-cooled High-temperature Reactors
(FHRs). Tritium is primarily generated from neutron activation
of the primary coolant, FLiBe, a eutectic mixture of LiF and
BeF2 and has the tendency of permeating into the surrounding
environment especially under the high operating temperature of
the reactor system. To address this issue, a cross-flow tritium
removal facility has been proposed to collect and remove
molecular tritium, T2, from the primary coolant. Previous
simulations and calculations have shown the effectiveness of the
cross-flow design. To validate the simulation results, a lab-scale
experiment has been set up with a cross-flow tritium removal
facility fabricated. For the validation experiment, instead of
using a molten salt, a carrier gas is planned to be used and will
be premixed with hydrogen before entering the cross-flow
facility. A sweep gas will be flowing in the tubes and remove the
permeated hydrogen. Samples will be collected from the gas
inlets and outlets for component analysis using a gas
chromatography. By obtaining the hydrogen concentration
change with experiment time in the carrier and sweep gases, the
efficiency of the cross-flow tritium removal facility can be
derived.
Computational simulations have been carried out for the
experiment setup using COMSOL to inform the experiment
design. The COMSOL model is validated against a static
hydrogen permeation experiment. The tritium removal rate
under the planned experimental conditions is predicted. In the
experiment, the operation temperature, initial tritium
concentration, as well as the gas flow rates will be varied to
study their effects on tritium removal. The simulation results
will be compared to the experiment results once available.