In preparation for an in-pile study of tritium release from lithium materials, a sweep gas and radioassay system was tested in Penn State's TRIGA reactor during both steady state and pulsed operation. Sweep gas helium, containing propane, carries tracer level tritium generated in a lithium oxalate powder to a flow-through ionization chamber for radioassay. High tritium sensitivity, the absence of tritium plateout and hysteresis, and good radiological control were demonstrated, encouraging adoption of this approach in our materials study.