FLOW COASTDOWN TEST OF THE PWR MAIN COOLANT PUMP
A series of flow coastdowm tests were run on an AED loop at Cheswick. This loop had the PWR prototype pump installed for the tests. All tests were run uslng hot pressurized water ni 2000 psig and 5O5 to 510 deg F. The initial flow rates were varied from 2000 to 20,000 gpm, some of which were within the pump at half speed and some with the pump at full speed. Variable data collected consisted of pump head, loop flow, and pump motor voltage decay in continuously recorded form. The tests were run to obtaln further information about the flow coastdown mechanism and to evaluate the theoretical methods of calculation of flow coastdown. This report presents the raw and reduced data obtained and a brief analysis of the data. A further analysis of the data is contemplated and desirable. The experimental data confirmed the fact that fluid flow continues after the impeller stops. It was found that the ratio of the kinetic energy of the pump impeller to the kinetic energy of the water was not constant during coastdown as had been assumed in the theoretical method of calculation. This requires that the method be reviewed in light of the facts obtainable by analysis of the data. The exerimentally obtained curve was fitted mathematically more closely by a hyperbolic rather than exponential curve. The theoretical method of calculation employs an exponential curve. There is an energy transfer from the impeller to the water during coastdowm until the impeller bearing film fails. The comarison of an experimental coastdown curve with a corresponding curve calculated for the Cheswick loop was satisfactory to the point of bearing film failure even though the theoretical method is now known to be in error. An improved agreement between the calculated and experimental curve for longer times after coastdown should result from a correction of the method of calculation. A further analysis of the data should yield more details of the flow coastdown mechanism and allow the derivation of a more accurate method of calculation. (auth)
- Research Organization:
- Westinghouse Electric Corp. Atomic Power Div., Pittsburgh
- NSA Number:
- NSA-12-007483
- OSTI ID:
- 4353598
- Report Number(s):
- WAPD-PWR-PA-626
- Country of Publication:
- United States
- Language:
- English
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