The measurements of compensation factors of the KNK 50 power range detectors for the RSG-GAS'S core

It has been implemented the measurement of compensation factors on the KNK 50 power range neutron detectors installed around the RSG-GAS core. The measurements are needed to check performance of the compensating part of the detectors after they are used for more than a year. While the reactor are in operation, the core produce neutrons and also gamma rays other which will contribute to current signal of the detectors. The compensation factor indicate capability of the detectors to neutralize of effect of gamma radiations affect so as its design, that it only measures neutrons. The measurements were performed on two installed KNK 50 power range detector one day after reactor shutdown. The constant positive voltage is applied to the positive electrodes of the neutron and gamma sensitive chambers. While varied negative voltages were applied to the negative electrodes of compensation chamber. For each variation of negative voltage applied, the resulting current at the signal electrode was measured and noted. Eventually, the minimum resulting currents are measured and noted. The compensation factor of the detector is the percentage of the minimum resulting current at the signal electrode to the resulting current when the negative electrode was grounded. The results of measurements of the detector JKT 03 CX 831 has a compensation factor of 0.45 % and a detector JKT 03 CX 841 has a compensation factor of 0.41 %. Both of these detectors is within the specification limits 2 %^[3*] so that the ability of the gamma compensation detector is functioning properly. (author)