Design process and optimization method of an ⁸⁵Kr detector

Abstract With the rapid advancement of nuclear power industry, 85 Kr, a fission product of 235 U, is considered a potential nuclear pollutant. Consequently, developing 85 Kr detectors to monitor 85 Kr gas in the atmospheric environment is crucial. This paper establishes a design process and optimization method for 85 Kr detectors based on two critical indicators: Measurement Efficiency (ME) and Minimum Detectable Activity (MDA). Utilizing Monte Carlo simulation, the study investigates the combined effects of crystal geometry, chamber geometry, and lead shield thickness in classical 85 Kr detector structures on the measurement of β -rays produced by the decay of 85 Kr. Ultimately, the article presents five geometric design schemes for high ME and low MDA 85 Kr detectors of different sizes, achieving a maximum ME of 54.2% for 85 Kr in sample vial, and the MDA for the samples is less than 30 Bq/m 3 within one hour. Finally, based on one of the design schemes, this paper developed a set of 85 Kr detectors, and further validated the scientific rigor and reliability of the entire design process through experiments on ME and MDA. The design process and methods proposed in this paper fill the gaps in the geometric parameter constraint process for 85 Kr detectors.