The prospects for using piezoelectrically-driven valves with elastomeric or thermoplastic poppets in tritium gas service have been investigated. A modeling study of a typical valve incorporating ethylene-propylene rubber (EPR) or high density polyethylene (HDPE) was performed. Equations were developed linking applied voltage; ceramic bimorph preloading force, elastic deflection modulus, and specific deflection force (per volt applied); polymer elastic modulus, thickness, seal surface area, and compression (to make seal); elastomer compression set; thermoplastic creep modulus; and flow gap between seat and polymer tip. It was determined that, while EPR should seal the valve orifice more easily, HDPE should produce a valve flow rate vs. voltage curve less variant with time and exposure. Both should, however, be sealable and allow flow curves perturbed by ≤10% of full scale after ∼100 days of exposure to 105 Pa (1 atm) T2 gas (equivalent to ∼7 × 107 rad = 7 × 105 Gy dosage). aMound is operated by Monsanto Research Corporation for the U. S. Department of Energy under Contract No. DE-AC04-76DP00053. bThe Princeton University Plasma Physics Laboratory is operated by the U. S. Department of Energy under Contract No. DE-AC02-76CH03073.