[en] Spectral line emission from tritium in a plasma may be distinguished from deuterium emission by a small isotope shift. A diagnostic system to measure tritium Balmer-alpha emission from the plasma edge has been installed on TFTR. This system has been used in deuterium plasmas, and the deuterium alpha line profile used as a basis to predict the spectrum at differing tritium concentrations in future D-T runs. The tritium and deuterium lines are partially blended, however, analysis of the predicted D-T spectra by a line fitting program produced estimates of the tritium density that closely matched those input to the spectra, providing confidence that the tritium density can be reliably measured. The spectrum maps the tritium velocity distribution at the plasma edge and will be important for studies of tritium edge physics