The determination of trace amounts of natural 133Xe in gas under high radon activity concentration levels

Radioxenon monitoring has become one of the major concerns in both international monitoring systems and on-site inspection. The most important technical specifications for radioxenon system are the radon removal coefficient and the minimum detectable activity concentration. We have developed one kind of on-site radioxenon sampling, separation and measurement system, and have tested it under high radon activity concentration levels. The result shows the natural 133Xe background activity concentration, the 133Xe/222Rn ratio and the radon removal coefficient to be in the ranges 0.73–1.6 mBq/m3, (1.5–3.5) × 10−8 and (2.3–57) × 10−8, respectively.

► 238U can decay to 222Rn and spontaneously fission to 133Xe simultaneously. ► Developed onsite inspection radioxenon sampling, separation and measurement system. ► System measured trace level of 133Xe concentration, under high radon concentration. ► The radon removal coefficient for the system was achieved. ► The 133Xe/222Rn ratio was calculated.