Abstract: Increased Accuracy in Diagnosis of Nuclear Plant Valves

Water control motor operated vales (MOV’s) for nuclear power plant systems are critical to a plant’s safe operation and operating efficiency. Currently, the Nuclear Regulatory Commission (NRC) requires these valves to be periodically tested for operability.

During 1991, Duke Power Company, (Charlotte, N.C.), began investigating newer, more accurate measurement techniques for MOV’s. Their investigation led to the discovery and selection of Snap-Master. This software has the ability to perform phase angle and FFT calculations, which are extremely useful in this application. Snap-Master also provides support of simultaneous sampling an d display of all channels, as opposed to other systems that sample each channel in succession, thereby reducing calculation accuracy.

The data acquisition system was able to detect and display unique changes and shifts in the power waveform relative to each problem. This new measurement approach has demonstrated that it provides a far more accurate diagnosis of a valve condition than did previous methods.

Duke Power is currently refining the tools and techniques that will allow them to implement this approach in their own plants, as well as market it to other utilities.