Kalsi Engineering, Inc. (KEI), initiated an independent test program that includes a number of actuator manufacturers, models, and sizes based on a survey of United States (U.S.) nuclear power plants. The test matrix includes evaluation of the effect of the key parameters on the effective diaphragm area (EDA) throughout the stroke. These parameters include stroke position, pressure, materials, measurement uncertainty, and manufacturing tolerances. Because of differences in the test data obtained by different sources for the same actuator type and size, systematic test procedures have been developed by KEI to address differences in the testing methods and test configurations, including testing of a balanced actuator (no spring in the actuator) vs. a spring-return actuator of the same diaphragm size. The effect of elevated temperature and aging may also be included later by testing a selected number of actuators based on industry input. The benefit of this program is to provide reliable data for air-operated valve (AOV) design-basis evaluations as required by U.S. Nuclear Regulatory Commission (NRC) Regulatory Issue Summary (RIS) 2000–03. This paper presents the results for the Masoneilan Model 38 Size 18 diaphragm actuator, which show that EDA is both position- and pressure-dependent.
Paper published with permission.