Abstract: The correlations between stable noble gas isotopic ratios and the burnup of spent fuel are calculated by Origen2.1 code. The production of stable Kr, Xe nuclides in reactor fuel and the subsequent dilution of these nuclides in the reprocessing plant stacks are estimated for PWR fuel with a burnup of 30 GWd/tU.~(82)Kr and~(129)Xe, at the natural background, are suggested being baseline for subtracting atmospheric parts of the other isotopes in the samples consisting of both fissiongenic and natural noble gas. The nuclide ratios of~(83)Kr/~(86)Kr,~(84)Kr/~(86)Kr,~(131)Xe/~(134)Xe and~(132)Xe/~(134)Xe near linearly correlated with the burnup of the spent fuel can be used for the nuclear safeguards.