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4.1.5 RESONANCE SEARCH
At the completion of the radiation aging simulation, the test valves were mounted to a shaker table and subjected to resonance search tests. The valves were attached to the table in accordance with normal mounting procedures. The table input motion was controlled by an accelerometer mounted adjacent to the valve location. A triaxial output accelerometer was mounted on an extended part of the valve in a position suitable to record the response in each of the three orthogonal axes. The motion measured by this accelerometer was compared to the input level values, and a resonance was declared when the ratio of the output to the input motion exceeded 2.
The valves were subjected to continuous sinusoidal motion having an acceleration level of 0.75 'g'. The frequency was then swept in each axis, separately, from 1 to 100 to 1 Hz at a rate of 1 octave per minute. The valves were energized at 120 V AC, or 132 V dc, during the sweep from 1 to 100 Hz; they were de-energized during the 100 to 1 Hz sweep. The valve maximum operating pressure differential (MOPD) was applied during the entire test phase.
Any resonance values identified were subsequently incorporated into the SSE tests and operability was demonstrated at these values, as well as the SSE RIM requirements, out to 100 Hz.
4.1.6 VIBRATION AGING
Following the resonance search tests the valves were subjected to vibration aging by the continuous application of a single frequency sinusoid in each of the three orthogonal axes. This test was similar to the resonance search tests, except that the sweep frequency was from 5 to 100 to 5 Hz at a rate of two octaves per minute. This was continued for a total of 90 minutes, in each axis. The valves were alternately energized and de-energized every 15 minutes at either 120 V AC or 132 V dc, as applicable. MOPD was applied throughout the entire test.
4.1.7 SEISMIC OBE AGING
At the conclusion of the vibration-aging phase of the test, and with the valves still in their original mounting and connection configuration, they were subjected to OBE aging tests. This was accomplished by performing two sinusoidal sweeps at 2/3 the fragility RIM levels shown in Figure 4.3.
Each sweep was from 2 to 35 to 2 Hz, at a rate of 1 octave per minute, in each orthogonal axis, separately. One sweep was performed with the valves energized at either 120 Vac or 132 Vdc; one sweep was performed with the valves de- energized. MOPD was applied throughout the testing.
For convenience, the seismic SSE level tests were conducted at the conclusion of the OBE level tests.