2008 Volume 7 Issue 4 Pages 439-451
Tritium migration behavior in the next-generation nuclear plant (NGNP) employing a high-temperature electrolysis (HTE) process to produce hydrogen is estimated by numerical analysis. Estimated tritium concentrations in the hydrogen product and tertiary heat transport fluid in heat exchangers in the HTE process are higher than the limit in drinking water defined by the U.S. Environmental Protection Agency (EPA) and in the effluent at the boundary of an unrestricted area defined by the U.S. Nuclear Regulatory Commission (NRC), respectively. The effects of some countermeasures (i.e., reducing tritium release rate, increasing purification system capacity, removing tritium at high-temperature positions in the heat transport fluids, reducing the permeability of heat exchangers, and hydrogen or water injection in the heat transport fluids) to reduce tritium concentrations in the hydrogen product and tertiary heat transport fluid are proposed and evaluated. The alternative countermeasure proposed in this study to decrease the tritium permeation rate by water injection, which produces HTO from HT according to an isotope exchange reaction (HT+H2O=H2+HTO) in the heat transport fluids, is effective for decreasing the tritium concentrations.
