The paper introduced a technique

which is based on the adsorption of 85Kr function on activated carbon

to check-up the decommissioned reactor fuel element cladding. The measuring principle and the constitution of the measuring system are described. The opinion method of safety check-up the decommissioned reactor fuel element cladding is the detection quantity of beta count-rate of adsorption 85Kr by activated carbon. The beta detection efficiency is higher than 40% and background beta count-rate is 0.84 Counts?min–1 of the measuring system. A comparison between the method and chemical analysis to water sample showed that the two conclusions were agreement.