Investigation of gasification rate for several radionuclides dissolved in HANARO pool water

The gasification rates of several radionuclides dissolved in HANARO pool water were investigated in order to produce the basic data related to the potential release of radioactivity from the reactor pool water to the atmospheric environment. The primary coolant water was collected during 30 MW operation of HANARO. The variation of activity concentrations of several radionuclides in the water with the cooling time were continually measured using the HPGe detection system. The nuclides of interest were Ar-41, Xe-133 and iodine nuclides. The effective half-life of Ar-41 in the water sample was measured to be 0.65±0.02 hours, and its elimination half-life due to the gasification and surface exchange coefficient were determined to be 1.01 hours and 6.89±10^-4 cm s^-1, respectively. For Xe-133, the elimination half-life due to the gasification and surface exchange coefficient were determined to be 1.44 days and 2.27±10^-5 cm s^-1, respectively. For iodine nuclides, the measured effective half-lives were similar to their radioactive half-lives. Therefore, it is confirmed that the gasification of the iodine nuclide from the pool water is negligible unless the evaporation of water occurs. Above data for the gasification of several nuclides will be very useful for the assessment of the research reactor safety. (author)