Soft-measuring method of the core exit temperature of coolant for the 200 MW nuclear heating reactor

Abstract

This paper reports a soft-measuring method of the core exit temperature of coolant for Chinese 200 MW nuclear heating reactor (NHR-200). The primary and vice sheath thermocouple are immersed in a space orthogonal slot that is located at one side of the support grid plate for fuel assemblies. The core exit temperature of the coolant is evaluated by using these two thermocouple's measurement temperatures. The experimental study gives the formula for evaluating the core exit temperature of the coolant. The space orthogonal slot is smooth to decrease the hydraulic resistance of the coolant, thus a part of coolant was steady flowing through the space orthogonal slot on the support grid plate. So the coolant temperature difference between the center region of fuel assembly and the measurement end of the primary sheath thermocouple is small. The flow of the coolant in the slot increases also the sensitive length of temperature of the sheath thermocouple. All of these ensure the measurement reliability and accuracy. The maximum measurement error of the core exit temperature of the coolant for the NHR-200 is 1.7 K.