Design of radon cup with solid state nuclear track detector for radon concentration measurement

A solid state nuclear tract detector(SSNTD) has been widely used for passive measurement of radon concentration because of its durability, simplicity and stability. Geometries and characteristics of conventional SSNTD samplers were reviewed, and the optimal SSNTD sampler so-called KEPRI-Radon Cup was developed to maximize the detection efficiency for radon by means of modification of their non-effective problems. The KEPRI-Radon Cup is made of polycarbonate, which has a hemispheric chamber of 80 mm in diameter. The size of diameter was determined to enhance the detection efficiency for radon based on the Monte Carlo simulation results and the ranges of radon and its daughters. Air inlets are provided on the polycarbonate disk which are covered with membrane filters to prevent radioactive aerosols or particles from entering the detector housing and the diffusion from fluctuating by local flow perturbation. The detector is placed on the holder which intersects the air inlets. The detector or membrane filter in the KEPRI-Radon Cup is rarely damaged and fouled because air inlets are placed at the bottom of the diffusion chamber. The six-legged stand supports the sampler to maintain its stability during the long-term exposure period