Surface mediated isotope exchange reactions between water and gaseous deuterium

Maintaining isotopic purity of hydrogen is one of the major tasks in tritium processing systems. The work with multiple isotopes and isotopomers is accompanied by isotope exchanges which is often accelerated by catalysts e.g. surfaces of various materials. In this work, densities of D2O, HDO produced via isotope exchange reactions in the mixture of D2, H2, D2O, H2O, HD and HDO contained in a stainless steel (type SS304) vessel were measured as a function of time (40-36 000 s) and pressures near 3.5 × 102 Pa, using mass spectrometry. The derived rates of change of the isotopomers densities are described accurately by a postulated kinetic model.