ONLINE MONITORING TECHNOLOGY TO EXTEND CALIBRATION INTERVALS OF NUCLEAR PLANT PRESSURE TRANSMITTERS

摘要

Online monitoring (OLM) technology can be used in nuclear power plants as an analytical tool to measure sensor drift during plant operation and thereby identify the sensors whose calibration must be checked physically during an outage. The technology involves a procedure to (1) retrieve redundant sensor measurements from the process computer or through a separate data acquisition system, (2) calculate the average of these measurements and the deviation of each sensor from the average, and (3) identify any sensor that has deviated beyond its predetermined monitoring limit. OLM technology for transmitter drift monitoring involves a simple procedure that is passive and benign to plant operation and does not require any modification to the plant.1-8 All that is needed to implement OLM is a means to retrieve the readings of r edundant transmitters, which can be accomplished using the plant computer or a separate data acquisition system, and a software package to validate and analyze the data. OLM is not a substitute for conventional calibrations. Rather, it is an analytical tool equivalent to using measuring and test equipment to check for drift of transmitters during plant operation to determine whether they must be scheduled for a physical calibration by plant personnel during an upcoming plant outage.