Construction and application of a multivariable comparison model for steam generator level transmitters

Abstract

The steam generators (SG) of nuclear power units are equipped with wide and narrow range level transmitters. Due to the different design conditions, the process values indicated by the level transmitters often appear deviations, thereby, resulting in inconsistent test results of cross comparison projects for wide and narrow range level transmitters. In order to improve the accuracy and validity of the cross-comparison judgment, a multivariable comparison model for the steam generators level transmitters based on the hot shutdown working condition was proposed with the help of the analysis on the corrected working condition of the steam generators level transmitters. Based on the physical conditions of steam generators operation under different working conditions, multivariable corrections of actually measured water level and operating conditions were introduced. Meanwhile, the simplified correcting algorithm of cubic curve fitting over the 0% and 100% water level corrected discrete points was used to achieve the validation accuracy of the wide range level transmitters under different pressure platforms. Such cross-comparison model and method have been applied in a number of nuclear power units, and the results from comparison and analysis on statistical data before and after the correction of the level transmitters have been proved to be effective, therefore, its feasibility and effectiveness have been demonstrated.