Analyzing and Processing the Malfunction of Control Valve Dithering in PWR Nuclear Power Plant

Abstract

As digital technology is more and more used in nuclear power plants, the electromagnetic compatibility issues between new digital device and the plant environment are increasingly prominent. This paper is aiming at the dither of control valve in pressurized water reactor project, which is causing by the electromagnetic compatibility issues. And this paper mainly describes the experience of working process and the solving program of failure eliminating. First it introduces the installation condition and operating principle of the valve, then it analyzes the possible causes by using fault tree and find the root cause by site investigation. The root cause of the malfunction is that the feedback signal of valve position is disturbed by an interferential signal about 32 kHz. At last, this paper provides two kinds of program to solve the problem, one is grounding directly and another is grounding with capacitance.