The Research of Insufficient Output in TQNPC Unit 2

The revised electric power of TQNPC unit 2 was insufficient at the assessment test. The Hitachi supplier considered that the insufficient output was caused by the too large flow area of high pressure cylinder. After the nozzle modification the unit output had not been improved significantly. In this paper, the characteristic flow area (CFA) was used to evaluate the turbine flow capacity. The results showed that the CFA values of high pressure cylinder and low pressure cylinder were both too large, but also within the design margin (3-5%). The reason of insufficient output was not the mismatch with flow capacity. According to the nuclear power plant diagnosis and analysis models, the thermal performance of the hot side, the cold side and the thermal system was researched respectively. The performance of hot side and cold side were better than the design values, which was favor for the unit output. So the insufficient output was focus on the thermal system. Then the technical staffs took corresponding measures to transform the thermal system and then the unit output was improved finally.