Temperature Measuring System of the In-core Components for Chinese 10 MW High Temperature Gas-cooled Reactor

Abstract

The 10 MW High Temperature Gas-cooled Reactor (HTR-10) constructed at the Institute of Nuclear Energy Technology (INET), Tsinghua University in China reached its first criticality by the end of 2000. The temperature measuring system of the in-core components is described in this paper. This system consists of the thermocouple penetration assembly of the reactor pressure vessel (TPARPV), the thermocouple penetration assembly of the reactor containment (TPARC) and the distributed computer-based data acquisition and processing system (DCS). Some new techniques were developed and applied, such as the thermocouple penetration technology under the high temperature and high-pressure environment and the laser welding technique. The TPARPV is the key measurement device and is described in detail. The general behavior of the TPARPV and TPARC was confirmed under HTR-10 operating conditions. The helium leakage rate of the TPARPV is 1×10-7Pa-m3/s while the helium leakage rate of the TPARC is less than 1×10-2 Pa-m3/s. The insulation resistance of the sheathed thermocouple is more then 109Ω. The temperature measurement error of the system is 2.3°C. The results of testing and field inspection and operation demonstrate that the design of the temperature measuring system is reasonable and reliable and that the performance of the system satisfies the design requirements of the HTR-10. These new techniques used in the temperature measuring system can be applied not only to other high temperature gas-cooled reactors but to various reactor types as well.