Improvement of data processing of the tritium monitor installed at the HANARO stack

Two real time tritium monitors are installed at the stack of HANARO, 30 MW research reactor, to measure the tritium concentrations in the discharged air from the reactor hall and reactor concrete island region. The tritium monitor adopts the coincidence and anticoincidence coupling to detect the very low energy beta particle from tritium. Since the tritium level in the air released from the reactor hall is very low in the normal operation of HANARO, the measured tritium concentration by the monitor is easily affected by the noble gas contribution and the background. So, the method to remove the noble gas contribution and to subtract the tritium background is established. At first, the noble gas contribution is verified and removed by using reliable noble gas measurements by other detector. The tritium background is deduced using the bubbling method. The tritium concentration is determined by the newly established method, and compared with bubbling data. The two data are fairly consistent with each other. Thus, it can be concluded that the above evaluation is very useful for the data processing of the HANARO tritium monitor used in the extremely low level of tritium.