ML18081A625
| ML18081A625 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 11/09/1979 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18081A623 | List: |
| References | |
| NUDOCS 7911280488 | |
| Download: ML18081A625 (1) | |
Text
Introduction SALEM UN IT NO.* 1 eves PUMP VIBRATIONS SAFETY EVALUATION REPORT Vibrations induced by the operation of positive displacement pumps have been identified as one source that will cause fatigue failure in system piping.
On August 31,.1978, NRC requested inforamtion of pipe cracks in chemical volume control system.due to excessive charging pump vibrations from Public Service Electric and Gas Company with respect to the. Salem Unit No. 1 operating exper-ience. The requested information was provided in letters dated October 27, 1978 and October 5, 1979.
Description and Evaluation Salem Unit No. 1 has applied mechanical type vibration dampeners to its positive displacement charge pump on both the suction and the discharge sides of the pump.
The dampener design employs two carbon steel plates loaded by a coil spring. The dampening can be adjusted by the spring tension. Vibrations cannot be visually detected after the addition of these dampeners. In order to verify that vibrations have been arrested to an acceptable level, a test has been conducted on Salem Unit No. 2 positive displacement charging pump.
Since both units have similar designs on their chemical volume control systems, test results should be repre-sentative for both plants.
Test results gathered during the period of November 13, 1978 to November 30, 1978 indicated the following:
- 1. Without dampeners, maximum peak to peak displacement in the system for the normal operating pressure of 2400 psi was 85 Mils.
Maximum strain was 85 µin/in.
- 2.
With da~peners, maximum peak to peak displacement in the system was 20 Mils.
Maximum strain was 75 µin/in for the operating pressure range of 540 psi to 2400 psi.*.Maximums existed at 900 psi operating pressure.
Maximum stress fluctuation was 2200 psi.
- 3. At normal operating pressure of 2400.psi, maximum peak to peak displacemnt was 8 Mils, maximum strain was 10 µin/in.
Maximum stress fluctuation was 300 psi.
Conclusion Mechanical dampeners have been employed by Salem Unit No. 1 on the suction side and the discharge side of the positive displacement discharge pump.
Test data indicated that vibrations have been arrested to an acceptable range. With maximum stress fluctuation of 300 psi in the normal operating mode, fatigue failure in the system piping is not anticipated. The operation of Salem Unit No. 1 should be allowed to continue.
79112so'-/~'l