Automatic continuous-action radionuclide analyzer of water coolants for NPPs

Structural scheme and basic parameters of automatic INVARIANT-2 analyzer designed for radiometric control for the content of radioactive additions in aqueous coolants, of NPP are considered. Analyzer is based on the method of the two-dimensional continuous chromatographical extraction of element groups on the system of unitized porous sorbents. Analyzer consists of four self-contained units: unit of chromatographic analysis, unit of additional solutions, detection unit, unit of electronics and automatics, γ radiation detection is carried out with the help of typical spectrometers including semiconducting Ge(Li)-detector, multichannel amplitude analyzer and computer. Analyzer can operate in automatic regime or in regime of remote controlled periodic analysis. Positioned directly at the sample-selecting reactor line, analyzer operating in the continuous automatic regime permits to identify the following isotopes: in the first fraction -132I, 133I, 134I, 135I, sup(99m)Tc, 101Tc, 104Tc, in the second fraction - 91Cr, 92Sr, 93Sr, 94Sr, 133Ba, 140Ba, 141Ba, 142Ba, in the third one - 137Cs, 138Cs, 139Cs, 88Rb, 89Rb, 90Rb. Time of sample transportation from core to measuring chambers does not exceed 10 min, that gives an opportunity for reliable control of short-lived isotopes with lifetime of 100 S order. Reproducibility of obtained data is within the ranges from 5 to 10%. A conclusion is made that operation stability of the analyzer described permits to follow the dynamics of fission fragments storage in the coolant at reactor operation under variable conditions