Detecting And Mitigating Rod Drive Control System Degradation In Westinghouse PWR's

A study of the effects of aging on the Westinghouse Control Rod Drive (CRD) System was performed as part of the U.S. NRC's Nuclear Plant Aging Research (NPAR) Program [l], [2]. For the study, the CRD system boundary includes the power and logic cabinets associated with the manual control rod movement, and the control rod mechanism itself. The aging-related degradation of the interconnecting cables and connectors and the rod-position-indicating system also were considered. This paper presents the results of that study pertaining to the electrical and instrumentation portions of the CRD system, including ways to detect and mitigate system degradation.