The detection of rare cases requires a very low background, and radon and its daughters are one of the main background sources. In this paper, a set of liquid nitrogen radon removal system was designed according to the demand for radon removal of 1 725 m? liquid nitrogen in the underground laboratory, and the radon removal effect of KC-6 series activated carbon was preliminarily tested at -10~ -120 ℃. Experimental results show that the error function can well fit the penetration curve of activated carbon at different temperatures. The fitted data shows that the dynamic adsorption coefficients of radon on activated carbon at -10 and -30 ℃ are 23.01 ± 0.33 and 58.68 ± 0.63 L/g, respectively. Limited data indicate that there is no radon overflow at -120 ℃. However, it can be calculated that the dynamic adsorption coefficient is already greater than 432 L/g. The data obtained in this paper could lay a foundation for the study of radon removal from low emission background liquid nitrogen.
