Abstract: By analyzing the production, transfer and release mechanism of noble gas from the Third Qinshan Nuclear Power Plant (TQNPP) CANDU6 reactors, derived the origin of calculation errors for noble gas emissions in the radioactive source term report, and further set forth the quantitative relationship of major noble gas including¹³³Xe, ⁸⁵Kr and ¹³¹mXe in the effluent of CANDU6 reactors. Therefore, the estimation of ¹³¹mXe and ⁸⁵Kr, which have much higher lower limit of detection, can beachieved by measuring the activity of ¹³³Xeinstead, and thus greatly reduce nuclear statistics of noble gas emissions. This method is also applicable to PWR reactors.

Key words: ⁸⁵Kr, radioactive noble gas, gaseous effluent, defective fuel, source term