Self-Decomposition Behavior of High Concentration Tritiated Water

In order to handle high-level tritiated water (HTO) safely, the self-decomposition behavior has been investigated as functions of tritium concentration (from 16 GBq/cm³ to 2 TBq/cm³) and storage temperature (269K ~ 303K). The representative decomposition products such as H₂ in the gas phase and H₂O₂ in the liquid phase were measured periodically, storing HTO in a leak-tight vessel. The effective production rate of H₂ increased with tritium concentration, however, the normalized production rate by tritium decay, like effective G-value, decreased with tritium concentration. The effective production rate of H₂O₂ also increased with tritium concentration and the normalized one also decreased under consideration of its natural decomposition rate, though it thought that the almost H₂O₂ calculated by the reported G-value decomposed by extra stimulus in tritiated water. The effective production rates of H₂ and H₂O₂ increased with temperature.