METHOD TO DETERMINE CONTENT OF ADMIXTURES IN GAS UNDER SHELL OF FUEL ELEMENTS (FE) OF NUCLEAR REACTORS

FIELD: power engineering.SUBSTANCE: method to determine content of admixtures in gas under a shell of fuel elements (FE) of nuclear reactors consists in the fact that the FE shell integrity is damaged inside a vacuum chamber, from which air is pumped, to ensure that the gas, which filled the vacuum chamber and contains helium and admixtures, gets into a gas analyser. Then readings of the analyser are recorded, which characterise gases within the composition of the gas mixture in FE, and content of admixtures in the gas is determined by readings of the analyser. At the same time into the vacuum chamber, from which air is pumped, extra-pure (EP) helium is supplied under pressure, which is equal to pressure in the vacuum chamber after damage of the FE shell, and similarly readings of the analyser are recorded, and content of admixtures in the EP helium is identified. And when determining content of admixtures in gas under the FE shell, the content of these admixtures in EP helium is taken into account. It is preferable to use a chromatograph as a gas analyser, and its readings are gas peaks. At the same time determination of admixtures content in gas under the FE shell and in EP helium is carried out by measurement of areas of chromatographic peaks, subtracting from the value of area of the chromatographic peak of each admixture of gas under the FE shell the value of the similar area of the same admixture of EP helium and comparison of produced values with the available calibration characteristic of the chromatograph. It is preferable to use a chromatograph with two measurement channels with heat conductivity detectors. It is preferable to use a chromatograph with a thermochemical detector.EFFECT: improved accuracy of measurements.7 cl, 1 dwg Изобретение относится к атомной энергетике, а именно к тепловыделяющим элементам (ТВЭЛ) ядерных реакторов. Способ определения содержания примесей в газе под оболочкой тепловыделяющих элементов (твэл) ядерных реакторов, заключается в том, что нарушают целостность оболочки ТВЭЛ внутри вакуумной камеры, из которой откачан воздух, с обеспечением попадания газа, заполнившего вакуумную камеру и содержащего гелий и примеси, в газовый анализатор. Затем регистрируют показания анализатора, характеризующие газы, входящие в состав газовой смеси в ТВЭЛ, и по показаниям анализатора определяют содержание примесей в газе. При этом подают в вакуумную камеру, из которой откачан воздух, особо чистый (ОСЧ) гелий под давлением, равным давлен