Study of the concentrations of Kr and Ar in high-purity nitrogen of JUNO

Purpose In the JUNO, the LS serves as the medium for detecting neutrinos. When purifying the LS using HPN, it is essential to ensure low background levels of radioactive krypton and argon in the HPN Methods Using the low-temperature physical adsorption properties of activated carbon to adsorb and separate radioactive gases such as radon, krypton, and argon from nitrogen in a liquid nitrogen environment. Results Our results indicated that the 85 Kr concentration in the HPN purified by HP activated carbon is 6.84 μ Bq/m 3 , and the 39 Ar concentration is 3.6 μ Bq/m 3 for overground HPN, while the 85 Kr concentration is 31.4 μ Bq/m 3 for underground HPN. The 85 Kr concentration in the nitrogen purified by coconut shell activated carbon is 0.46 μ Bq/m 3 . Conclusions After adsorption with activated carbon, the content of 85 Kr and 39 Ar in HPN is lower than the 50 μ Bq/m 3 required by JUNO. This work validates that the 85 Kr and 39 Ar concentrations in HPN is fit the JUNO requirement.