October 2000[NUMUG] Comparison of Wind Sensors1 of 14 Comparison of Wind Sensors - Ultrasonic versus Wind Vane/Anemometer Kenneth G. Wastrack Doyle E. Pittman John E. Hatmaker L. Wayne Hamberger Tennessee Valley Authority

October 2000[NUMUG] Comparison of Wind Sensors2 of 14 Background n Problem - Obsolete Wind Sensors –Difficulty obtaining spare parts (sensor, switch controller, etc) –Routine bearing replacement –Occasional history of mechanical failures n Requirements - Sensor Specifications –Comply with RG 1.23 requirements. »Wind direction +/-5 degrees. »Wind speed +/-0.5 mph. –Less maintenance than existing sensors.

October 2000[NUMUG] Comparison of Wind Sensors3 of 14 Vaisala 425AH Ultrasonic Wind Sensor n Sonic Wind Sensors –All-electronic –Minimal maintenance n Vaisala* (formerly Handar) 425AH ultrasonic wind sensor most suitable –Manufacturer specifications –Capabilities for integration –System meets RG 1.23

October 2000[NUMUG] Comparison of Wind Sensors4 of 14 System Performance

October 2000[NUMUG] Comparison of Wind Sensors5 of 14 Principle of Operation n Transmit signal along axis n Send in reverse direction n Calculate time differences n Convert to WS along axis n Repeat for other axes n Compute WD and WS

October 2000[NUMUG] Comparison of Wind Sensors6 of 14 Wind Tunnel Tests

October 2000[NUMUG] Comparison of Wind Sensors7 of 14 Field Tests n Establish that sensor works as expected. n Document that data are comparable to wind vane/anemometer data. n Verify software and hardware changes. n Provide maintenance experience.

October 2000[NUMUG] Comparison of Wind Sensors8 of 14 Field Sampling Configuration Anemometer mounted due North of wind vane.

October 2000[NUMUG] Comparison of Wind Sensors9 of 14 Comparison of Wind Roses ClimetVaisala

October 2000[NUMUG] Comparison of Wind Sensors10 of 14 Statistical Results Note:N, d, s, C, M, K are specified in ASTM D , Standard Practice for Determining Operational Comparability of Meteorological Measurements.

October 2000[NUMUG] Comparison of Wind Sensors11 of 14 Problems Encountered n Wind Tunnel Tests –Tunnel Configuration –Echo Effect n Software Changes n Alignment Error n Error Handling n Tower Shadow Effect

October 2000[NUMUG] Comparison of Wind Sensors12 of 14 Results Additional Benefits n Lower starting threshold n Continued functioning during icing conditions Vaisala Ultrasonic Wind Sensor is equivalent to the existing Climet wind vane/anemometer system.

October 2000[NUMUG] Comparison of Wind Sensors13 of 14 Pre-Operational Issues n EMI/RFI potential n Uniformity of sensors n Changes to operational practices and revision of procedures System Changes n Removal of wind translators n Connection of ultrasonic sensors directly to data logger computer n Software changes n Discontinue strip-charts

October 2000[NUMUG] Comparison of Wind Sensors14 of 14 Conclusion The Vaisala ultrasonic wind sensor meets the accuracy requirements of RG 1.23 and can be used as a replacement for the Climet wind speed/anemometer system. TVA plans to install the ultrasonic wind sensors at its nuclear plants as soon as EMI/RFI testing is completed and applicable documentation (procedures, FSARs, etc.) are updated.