System for preparation of standard tritium gas sample for calibration of monitoring system

Standard sample of low level tritium gas is necessary to examine the detailed performance of tritium monitoring system. We have designed a system based on the principle of the dilution to prepare tritium standard from commercially available tritiated methane gas with nitrogen gas. The system is capable of preparing 640 Nl_max of tritium standard with concentration in the range of 0.01∼1.0 pCi/cm³ at one time and is capable of supplying this gas at a constant flow rate of 5∼20 Nl/min. Following results are obtained by detailed examinations: (1) The concentration error of gas dilution is no more than ±5%, (2) The rate of gas leakage equals less than 632 ml/h, (3) The flow rate fluctuation of diluted gas is held to ±1%. (author)