Thermodynamic Calculation And Performance Analysis Of The Second Loop System In A Nuclear Power Plant

In Energy planning for the 13th five-year plan,the aim of safe development of nuclear power will be mounted on the stage of our country electric power applications.In this paper,we focused on the thermodynamic calculation and thermal performance analysis of the second loop in an AP1000 nuclear unit.Based on ASME PTC6 and other related standards,and the methodology based on heat balance,we implemented the high-precision thermal calculation and varible condition calculation of the main equipments and sencond loop.We also analysed the thermal performance factors and established accurate thermal performance.At the same time,when the unit operating,we collected some operation parameters and simulated the thermal system.When the unit is unhealthy,the thermal performance characteristic values of operating conditions will be calculated,such as CFA,stage efficiency,internal power,terminal temperature difference of regenerative water heaters,pipe losses,etc.,which would be compared with the reference values to diagnose the thermal performance of the unit by observing the deviation rates.As for the case unit,the deviation rates of CFA in stage 8 and stage 9 reach 6.38%and 17.07%,and the others are within a reasonalbe range,and thus,we judge stage 8 and stage 9 are faulty.Besides,the temperature deviations of the low pressure regenerative heaters are far from the design value,so the tube bundles might be blocked in the hydrophobic cooling section of regenerative heater 6 and regenerative heater 7.After completing the characterization algorithms and varible condition calculation method for the thermal system of nuclear poewer power plant,the offline performance calculation and analysis software for the major equipment in second loop system and thermal system were developed based on Eclipse development platform and Java language.The offline software mainly includes three modules:the design condition calculation module,the varible condition calculation module and the main parameter sensitivity analysis module.The programmed calculation of thermal performance of the secondary loop system of AP1000 nuclear power plant with high accuracy,and the historical unit performance record,and parameter changes figures,would provide a theoretical and technical fondation for further development of the on-line performance monitoring and diagnosiing software for PWR nuclear power plant.