IN-SITU RESPONSE TIME TESTING OF NUCLEAR PLANT PRESSURE SENSORS

THE DEVELOPMENT OF NOISE ANALYSIS FOR IN-SITU RESPONSE TIME TESTING OF SAFETY SYSTEM PRESSURE SENSORS IN NUCLEAR POWERPLANTS IS UNDER WAY. THE TECHNIQUE IS BASED ON RECORDING THE NATURALLY OCCURRING FLUCTUATIONS THAT EXIST AT THE OUTPUT OF PRESSURE SENSORS AS THE PLANT IS OPERATING. THESE FLUCTUATIONS CAN BE ANALYZED TO GIVE THE SENSOR TRANSFER FUNCTION FROM WHICH THE SENSOR RESPONSE CAN BE DETERMINED. WITHOUT ADDITIONAL EFFORT, NOISE ANALYSIS PROVIDES INFORMATION ABOUT THE STATUS OF SENSING PRESSURE LINES THAT EXTEND FROM THE PROCESS TO THE SENSOR. ANY SENSING LINE BLOCKAGE WILL MANIFEST ITSELF IN THE RESULTS OF NOISE ANALYSIS FOR PRESSURE SENSOR RESPONSE TIME TESTING. PRESENTLY, PRESSURE SENSORS ARE TESTED USING A PRESSURE SIGNAL GENERATOR TO APPLY A PRESSURE WAVEFORM TO THE SENSOR AND MEASURE ITS DELAY. EXPERIENCE HAS SHOWN THAT THIS METHOD PRODUCES ERRONEOUS RESULTS BECAUSE OF INHERENT DIFFICULTIES WITH THE TEST. IN ADDITION, THE CURRENT METHOD REQUIRES ACCESS TO EACH SENSOR, WHICH USUALLYRESULTS IN RADIATION EXPOSURE TO TEST PERSONNEL. ANOTHER DISADVANTAGE OF THE PRESENT METHOD IS THAT IT DOES NOT ACCOUNT FOR THE EFFECT OF VOIDS OR BLOCKAGES THAT MAY EXIST IN THE SENSING LINES. THIS PROJECT TAKES ADVANTAGE OF RECENT ADVANCES IN SIGNAL PROCESSING TECHNIQUES AND INTERPRETATION METHODS. THE PHASE I EFFORT IS CONCENTRATINGON RESEARCH ON VALIDATION OF NOISE ANALYSIS FOR RESPONSE TIME TESTING OF PRESSURE, LEVEL, AND FLOW SENSORS IN NUCLEAR POWERPLANTS.