Acoustic and ultrasonic signals as diagnostic tools for check valves
- B and W Nuclear Technologies, Lynchburg, VA (United States)
A typical nuclear plant has between 60 and 115 safety-related check valves ranging from 2 to 30 in. The majority of these valves control water flow. Recent studies done by the Institute of Nuclear Power Operations (INPO), Electric Power Research Institute (EPRI) and the US Nuclear Regulatory Commission (NRC) found that many of these safety-related valves were not functioning properly. Typical problems found in these valves included disk flutter, backstop tapping, flow leakage, disk pin and hinge pin wear, or even missing disks. These findings led to INPO's Significant Operating Experience Report (SOER, 1986), and finally, NRC generic letter 8904, which requires that all safety-related check valves in a nuclear plant be regularly monitored. In response to this need, the industry has developed various diagnostic equipment to monitor and test check valves, using technologies ranging from acoustics and ultrasonics to magnetic - even radiography has been considered. Of these, systems that depend on a combination of acoustic and ultrasonic techniques are among the most promising for two reasons: these two technologies supplement each other, making diagnosis of the check valves much more certain than any single technology, and this approach can be made nonintrusive. The nonintrusive feature allows the check valves to be monitored and diagnosed without being disassembled or removed from the piping system. This paper shows that by carefully studying the acoustic and ultrasonic signatures acquired from a check value, either individually or in combination, an individual with the proper training and experience in acoustic and ultrasonic signature analyses can deduce the structural integrity of the check valve with good confidence. Most of the conclusions are derived from controlled experiments in the laboratory where the diagnosis can be verified. Other conclusions were based on test data obtained in the field.
- OSTI ID:
- 6357529
- Journal Information:
- Journal of Pressure Vessel Technology; (United States), Vol. 115:2; ISSN 0094-9930
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
VALVES
ACOUSTIC TESTING
ULTRASONIC TESTING
DIAGNOSTIC USES
EPRI
INSPECTION
MAINTENANCE
US NRC
CONTROL EQUIPMENT
EQUIPMENT
FLOW REGULATORS
MATERIALS TESTING
NATIONAL ORGANIZATIONS
NONDESTRUCTIVE TESTING
TESTING
US ORGANIZATIONS
USES
220200* - Nuclear Reactor Technology- Components & Accessories