ML050060256

'B' Reactor Recirculation Pump Vibration Troubleshooting Summary

ML050060256
Person / Time
Site:	Hope Creek
Issue date:	12/30/2004
From:	Public Service Enterprise Group
To:	Office of Nuclear Reactor Regulation
References
TAC MC5111
Download: ML050060256 (2)

Text

'B' Reactor Recirculation Pump Vibration Troubleshooting Summary

'B' Reactor Recirculation Pump has had a history of high vibration. In any piece of rotating equipment high vibration can indicate a number of concerns. Below is a summary of these concerns and how they were evaluated on 'B' Recirc pump.

Indication Concern Evaluation Elevated 1/2X Internal rub in Pump This component is very small and frequency component or Motor the mechanical seal was replaced this outage to ensure satisfactory performance during next cycle.

Elevated IX Pump or Motor Balance weights were added on two frequency component Imbalance occasions, and the pump failed to fully respond as expected.

Elevated 2X Motor to Pump The alignment was corrected in frequency component misalignment RF09 and the resulted vibration data showed the alignment to be very accurate.

Elevated 5X The Recirc pump This component is very small.

frequency component impeller has 5 vanes and this indicates vane-passing concerns.

Elevated 20-25X Pump or Motor Vender discussions reported that the frequency bearing degradation first bearing to indicate wear is the components lower motor bearing. This bearing was replaced in RF09 and the old bearing found to be good. It was inspected again in RF10 and found good.

Various Instrumentation The vibration levels were measured problems with hand held instrumentation. The levels were consistent at all locations except the flange where the installed probe measures vibrations. The readings at that flange were consistent with the installed instrumentation.

The Control Room indication is an overall vibration level. The predominant component of that vibration level is the 1X frequency component. This component turned out to be not an imbalance but the 'egg" shaped condition of the outside of the flange face where the vibration probe was sensing vibration.

This was corrected by moving the probe to a "non-egg" shaped location, which gives a more representative sample of the vibration levels of the pump.

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