A Study Of Calculation Method For Thermal Performance Correction Curves Of Steam Turbine Unit In PWR Nuclear Power Plant

Thermal performance test of nuclear power steam turbine unit is considered to be a vital tool for evaluating the design and manufacturing capability of equipments. System running status or operating parameters would not completely identical with the design condition when testing the thermal performance of a turbine unit. Therefore, it is necessary to employ the correction curves to update the test results. A series of thermal performance correction curves are obtained utilizing stage-by-stage calculation under off-design condition in design phase and provided by turbine manufacturer. Any mistake of these curves could have severe implication for test results. Due to lack of detailed turbine technological specification, power plant and testing agency have no capacity to implement the off-design and stage-by-stage analysis for turbine and its system. For this reason, it is of great significance for site test and power plant operation to find an unsophisticated method of correction curves checking.Given this, after systematic summarized and analyzed the characteristics of secondary circuit thermal system of PWR nuclear power plant, a calculation method based on thermal equilibrium theory was proposed for thermal performance correction curves of steam turbine unit in PWR nuclear power plant. This method could be used to reckon and provide correction curves of turbine unit output variation versus heaters terminal temperature difference, heaters drain cooler approach, feed water pumps enthalpy increment, water loss ratio, cooling water temperature, cooling water flow, thermal load variation of reactor, admission steam pressure variation and admission steam wetness. Furthermore, based on this methodology, one software for output power variation correcting calculation was developed which had a parameter input interface and could print out correction curves directly. Taking a certain home improved second generation PWR nuclear power plant steam turbine unit as an example, the calculated thermal performance correction curves from the program are fairly close to the ones provided by the turbine manufacturer, which demonstrates the latter’s authenticity and trustworthy. Also, the correction curves calculated by the software can provide reference for the site test and power plant operation and meet the requirements of engineering applications.