NRC Information No. 91-61: Preliminary results of validation testing of motor-operated valve diagnostic equipment

In 1990, the MUG (Mov User's Group) initiated a program to conduct tests of MOV diagnostic equipment to validate the accuracy of the equipment asserted by the diagnostic equipment vendors. The MUG requested the Idaho National Engineering Laboratory (INEL) to provide a test stand for the program and to collect test data. The NRC Office of Nuclear Regulatory Research (RES) provided funds for INEL to participate, with the stipulation that the results of the testing would be made available to the NRC and the public. The INEL test stand included a Limitorque motor operator which drives a valve stem into a water reservoir with a compressed air overcharge. INEL obtained accurate measurements of actuator torque and thrust using a torque arm and a stem-mounted load cell, respectively. Each diagnostic equipment vendor installed and operated its own equipment to obtain measurements of torque, thrust, and various other parameters. Several diagnostic system vendors did not meet all of their stated claims of accuracy. Differences in the time response of the INEL test stand equipment and the diagnostic systems being tested may have contributed to deviations in the observed thrust measurements. Further, some of the diagnostic equipment exhibited problems and anomalies, such as failed sensors or difficulties in calibration, during the testing program. Of particular concern to the NRC is that these time inaccuracies, problems, and anomalies may not have been detected during normal use of the diagnostic equipment at a nuclear facility. The MUG is comparing the data collected by INEL with the data collected by each of the diagnostic equipment vendors