ML19296D800
| ML19296D800 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 02/08/1980 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19296D796 | List: |
| References | |
| TAC-7837, TAC-7838, NUDOCS 8003130234 | |
| Download: ML19296D800 (2) | |
Text
COMMONWEALTH EDISON COMPANY CHARGING PUMP VIBRATIONS SAFETY EVALUATION ENGINEERING BRANCH DIVISION OF OPERATING REACTORS Introduction Vibrations induced by the operation of positive displacement pumps have been identified as one source that will cause fatigue failure in CVCS system piping.
On August 31, 1978 NRC requested information of pipe cracks in chemical volume control system due to excessive charging pump vibrations from Commonwealth Edison Company with respect to the Zion Unit No.1 and 2 operating experience.
The requested information was provided in letters dated October 4, 1978 and January 23, 1980.
Description and Evaluation Zion Unit Nos.1 end 2 have the identical arrangement of charging pumps.
Each plant has two centrifugal charging pumps and one positive displacement pump.
Each of the two centrifugal pumps is capable of handling the maximum rated letdown or purification flow by itself.
Therefore only one centrifugal pump is used to provide the full charging flow and the reactor coolant pump seal water supply during normal plant operations as well as the maximum letdown or purifica-tion flow. A second pump is used as a standby. The positive displacement pump is a backup and is only capable of providing the charging flow and the reactor coolant pump seal water supply during normal plant operations.
It is normally used to hydrotest the reactor coolant system. The safety injection functions to the Emergency Core Cooling System is accomplished by centrifugal pumps.
Early plant operations indicated the existence of excessive vibrations in the positive displacement pump discharge lines.
Field study made by Southwest Research Institute showed that the peak to peak pressure pulsations ranged from a maximum of 920 psi, at 49 Hz to a minimum of 200 psi at 54 Hz for Unit No.
1; and a maximum of 370 psi at 39 Hz to a minimum of 180 psi at 14 Hz for Unit No. 2.
The suction line pulsations were not severe. The peak to peak value ranged from 16 psi at 3 Hz to 1 psi at 40 Hz for Unit No.1 and 8 psi at 1 Hz to 6 psi at 3 Hz.
Two pulsation dampeners, one for each plant, were installed in the discharge lines as a result of tne study.
The dampeners were of the Greer Hydraulic, Inc.
Pulse-Tone 21/2-gallon bladder type design, with a maximum work pressure of 2800 psi to provide a 2% attenuation (or about 100 psi peak to peak). The dampeners were installed in 1978 for both Units.
A second field study by Southwest Research Institute was made in October 1979 to verify the performance of the dampeners.
The maximtal discharge pulsation in Unit No. I was found to be 40 psi instead of the 920 psi in the previous study.
This is about 1.8% of the normal operating pressure of 2250 psi.
Suction pulsations were also reduced due to smaller discharge pulsations.
80031so2 3 G
_2 Conclusion The Zion Unit Nos. I and 2 have installed dampeners to reduce the excessive pressure fluctuation in their charging lines.
Field study has verified that they are effective. Their performance is acceptable and will not likely cause fatigue failures in the positive displacement pump lines.
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FEB 0 81950 MEMORANDUM FOR:
A. Schwencer, Chief, Operating Reactors Branch #1 Division of Operating Reactors FROM:
V. Noonan, Chief. Engineering Branch Division of Operating Reactors
SUBJECT:
COMf10NWEALTH EDIS0N COMPAflY -
CHARGING PUMP VIBRATIONS (TACS 7837 AND 7838)
Plant Name: Zion Unit Nos.1 and 2 License No.: DPR-39 and DPR-48
_ Doc ke t No. : 50-295 and 50-304 Branch and Project Manager: ORB-1, E. Reeves Description of Task: TACS 7837 and 7838 l
Review Status: Complete i
The Engineering Branch, Division of Operating Reactors, has reviewed the infonnation supplied by Connonwealth Edison Company in letters dated October 4,1978 and January 23, 1980 on CVCS pump vibrations for the reference plantI. The evaluation and conclusion are attached.
Please make appropriate input to RAMS for the completion of the licensing action.
Vincent S. Noonan, Chief f'
Engineering Branch i
Division of Operating Reactors i
Enclosure:
As stated l
Contact:
H. Shaw l'
X27364 I
cc:
D. Eisenbut R. Tedesco L. C. Shao W. Gamill A. Schwencer I
V. Noonan K. Wichman i
E. Reeves i
H. Shaw D. 011 anni
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