Tritium Producing Burnable Absorber Rods (TPBARs) use nickel plated, zirconium tubing for gettering tritium. However, during the development phase of the getter design only protium gas was used to determine getter rate. The verification phase of getter performance (product acceptance testing) also used only protium gas. Thus, isotope mass effects on getter rate were not evaluated. A modified getter rate test using both protium and deuterium gas was performed to determine isotope mass effects. Test procedures were developed to measure isotope effect on getter rate versus temperature while minimizing experimental uncertainties with respect to surface cleanliness and variability of test results between different specimens.