The development of a rapid and highly sensitive monitoring system for radioxenon isotopes

The rapid monitoring of radioactive gas is one of the most direct and sensitive methods used to characterize the leakage of nuclear installations, and its technical difficulty lies in achieving the goals of rapid and high sensitivity as much as possible. Several techniques, including adsorption at ultralow temperatures, impurity removal with hollow fiber membranes, and on-site measurements with low background, were used to develop a rapid and highly sensitive monitoring system for radioxenon isotope. This system could simultaneously separate xenon from air and measure radioxenon isotopes in a rapid and efficient way. The technical specifications of this system are as follows: the recovery of stable xenon is greater than 70%; and the MDCs of ¹³³Xe and ¹³⁵Xe are 4.3 Bq/m³ and 0.4 Bq/m³ within a 30 min cycle of sampling and testing, respectively. It is worth noting that the MDC of ¹³³Xe here is only approximately 1/18000 to 1/800 of those obtained with other similar equipment, and the monitoring period of this system is one fortieth of that of noble gas equipment for OSI, for example, XESPM-III. As a result, the standard uncertainties are less than 16%. The system developed in this paper can be applied in leakage monitoring of nuclear facilities and can also provide instructive technical support for other tests, such as nuclear safety monitoring and evaluation.