May-June 2019 NPJ

44 NuclearPlantJournal.com Nuclear Plant Journal, May-June 2019 each section is accurate, readable, and consistent with other Quick Guides. “These guides support integration of wired and wireless sensors into plant equipment,” said Jim Heishman, EPRI Nuclear Maintenance Application Center program manager. “This provides plant staff with additional technical information on equipment’s health and informs decision-making on the extension or replacement of preventive maintenance tasks. It also allows staff to determine when maintenance needs to be performed based on sensor data and not a clock.” The Content Each Quick Guide takes the user through instrumentation layouts, detectability assessments, the PM’s task assessment, high value sensors, Advanced Pattern Recognition (APR) model configurations and recommendations. The instrumentation layout details every sensor selected for the ideal world sensor setup, including high value sensors, secondary sensors, and APR support sensors. A high value sensor is a sensor that provides direct detection of a degradation mechanism or failure mode. A secondary sensor is a sensor that does not provide direct detection of a degradation mechanism or failure mode, but may provide additional detection. An APR support sensor is a sensor required for an APR model to function correctly. The detectability assessment determines the probability that a sensor will detect a specific degradation mechanism. There may be several sensors that can possibly detect degradation, but some are better than others. Sensors are assigned either a high, medium, or low detectability. High detectability correlates to a 97% chance that the sensor will detect the degradation mechanism, medium detectability correlates to an 80% chance, and low detectability correlates to a 50% chance. A normalized sensor value chart also guides the user on which sensors provide the most value to their CBM program. This value is not in dollars and cents, but value relative to other sensors in the Quick Guide. The PM Task Assessment Table lists the current recommended PM task per the PMBD, monitoring methods, analysis methods, required sensors, monitoring result, and associated notes. This represents the most valuable information in the Quick Guide. It provides exactly which sensors and monitoring methods are needed to achieve the result listed for each PM task. One Example: A horizontal, single stage, double suction pump One of our Quick Guides evaluates a horizontal, single stage, double suction pump. The guide looks at 27 different failure locations with 45 degradation mechanisms and 142 corresponding degradation influences, and 10 PM tasks. For this pump, a total of 25 sensors were selected. In developing the Quick Guides, EPRI assumed that there were no issues gaining access to the equipment to install sensors, and the cost of each sensor is negligible. Sensors range from suction pressure, temperature and flow to triaxial vibration sensors and proximity probes, to lube oil supply temperature, pressure, and viscosity and particle count. Also included are APR support sensors such as unit megawatts and ambient temperature. In order for the Quick Guides to provide guidance for eliminating time- based PMs without increasing risk, some conservatism has been built in. Each of the degradation mechanisms and failure modes had to have a detectability EPRI Quick... ( Continued from page 43) The Cover of One of EPRI's Quick Guides.