Tritium desorption behavior from soil exposed to tritiated water

In this study, tritiated water was poured in a packed bed of natural soil and subsequently distilled water was poured in the bed to recover tritium retained in the soil at room temperature. From tritium balance, 22.5 % (7.1 MBq) of input tritium (31.5 MBq) was retained in the soil bed. By distilled water purge, 70 % (5 MBq) of retained tritium was recovered but 30% (2.1MBq) was left. To recover residual tritium, the soil was immersed in distilled water for 531 days but the amount of tritium released to distilled water was slight (0.04 MBq). A part of the soil immersed in the water was taken out and heated up to 300°C under humid oxygen atmosphere. Tritium release terminated at about 50 hours. 11 % (0.23 MBq) of retained tritium was released. By heating to 1000°C, the release amount of tritium increased proportionally to the time and additional 4% (0.09 MBq) was released at 5 hours. The desorption rates of tritium in each process was quantified. Tritium is quite slowly released from the natural soil exposed to tritiated water in water at room temperature. However, a long time heating by 1000°C would be required to try to recover all tritium from the contaminated soil positively, although tritium recovery was not completed in this work.