Research on the capacitance control rod position measurement sensor in NHR-200

Abstract

The accurate and reliable measurement of the control rod position concerns the operation and safety of the 200 MW nuclear heating reactor (NHR-200). In this paper, the static mathematical model of the capacitance control rod position measurement sensor (CCRMS) were established. The experimental research, finite element method (FEM) simulation, and model validation were carried out for the case of the ungrounded metal medium, grounded metal medium, dielectric medium control rod measured rod and eccentricity. The results show that the validity of the proposed model is verified and the CCRMS is basically realized the one-step display measurement requirement. Furthermore, the eccentricity inconsistency of the measured rod is solved. In addition, the end effect of the CCRMS can be reduced reasonably but the eccentricity of the measured rod still have some influences to a certain extent. Moreover, the static characteristics of the double-helix structure CCRMS were obtained based on the proposed model.