Analysis of the accuracy of primary coolant temperature measurement using the SVRK system

The causes are sought of differences in the data from resistance temperature sensors and thermoelectric sensors used in measuring the coolant temperature in primary circuits. A model experiment performed in Unit 4 of the Dukovany nuclear power plant gave evidence that the thermoelectric sensors were inaccurate. The differences were due to a false data correction resulting from the neglect of the effect of temperature conditions of the connection boxes. The errors might be corrected by achieving a quasi-isothermal state of the primary circuit following temperature stabilization of the connection boxes, which would be after about 200 to 3000 hours of reactor operation. (M.D.). 3 figs