ML20150F138
| ML20150F138 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 07/08/1988 |
| From: | Bradham O SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| IEB-88-004, IEB-88-4, NUDOCS 8807180146 | |
| Download: ML20150F138 (3) | |
Text
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July 8,1988 Document Control Desk U. S. Nuclear Regulatory Commission Washington, D.C. 20555
Subject:
Virgil C. Summer Nuclear Station Docket No. 50/395 Oparating License No. NPS 12 NRC Bulletin No.88 04 Potential Safety-Related Pump Loss Gentlemen:
This letter is provided in response to NRC Bulletin No. 88-04 which requested South Carolina Electric & Gas (SCE&G) to perform an investigation and correct as applicable two miniflow design concerns. The first concern involves the potential i
l for dead heading of one or more pumps in safety-related systems that have a miniflow line common to two or more pumps or other piping configurations that do not preclude pum 3 to pump interaction during miniflow operation. A second concern was whetler or not the installed miniflow capacity is adequate for even a single pump in operation.
The analysis performed by SCE&G focused on active safety related centrifugal pumps which perform safety functions required to avoid or mitigate the consequences of abnormal operational transients or accidents. A summary of the components are as follows:
Component Tao Number Centrifugal Charging Pumps XPP-43 A, B, C-CS Residual Heat Removal Pumps XPP 31 A, B-RH Reactor Building Spray Pumps XPP-38 A, B-SP Spent Fuel Cooling Pumps XPP-32A, B SF Component Cooling Pumps XPP-01 A, B, C-CC Service Water Pumps XPP 39A, B, C-SW Service Water Booster Pumps XPP-45A, B SW Emergency Feedwater Pumps (Motor)
XPP 21 A, B EF Emergency Feedwater Pump (Turbine)
XPP-08-EF HVAC Chilled Water Pumps XPP-48 A, B, C-VU Diesel Generator Intercooler Pumps XPP-1 A/B PP9 DG Diesel Generator Jacket Water Pumps XPP-1 A/B-PP8 DG h
8807180146 880700 1 \\
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- q Document Control Desk July 8,1988 Page 2 of 3 Upon completion of the analysis on all components, except the emergency feedwater pumps,it was concluded that there was no active safety related centrifugal pump with miniflow piping system configuration that has a pump to-pump interaction that could result in the dead heading of one or more pumps. The analysis results to date indicate that in each case the required thermal minimum flow is well below the actual minimum aump flow (i.e., the actual pump minimum flow is adequate to prevent pump over 1 eating, cavitation and potential short4erm failure) and the actual pump minimum flows are sufficient to preclude long term wear and eventual failure due to mechanical (vibration from internal recirculation) mechanisms.
SCE&G has requested information on the minimum flow required to prevent degradation from hydraulic instability from the manufacturer of the emergency feedwater pumps. This vendor information is expected to be received by July 29l
.1988. The emergency feedwater pumps meet the original vendor's design mmimum 4
flow rate during standby recirculation. Furthermore, during testing these pumps are observed and measured for elements such as flow rate, discharge head, bearing temperature and pum a vibration to identify any pump operational problems.
Therefore,it is concluc ed that the current operation of the motor driven pumps is acceptable untilthe vendor can verify the adequacy of the minimum flow. An additional response will be provided within 30 days following completion of the analysis for the emergency feedwater pumps.
At the present time, SCE&G considers the system design for the active safety related centrifugal pumps at VCSNS to be adequate to preclude pump degradation as
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identified in the Bulletin. This conclusion is based on the current analysis and the operating and maintenance history of the components since plant startuo.
Evaluations completed during this analysis of NRC concerns will be maintained for a minimum of two (2) years in accordance with the requirements of the Bulletin. The information contained in this letter is true and correct to the best of my knowledge, information and belief.
if you have any questions, please advise.
Very Truly Yours, k
O. S. B rad ham Vice President, Nuclear Operations CJM:DGC:OSB/hw I
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Document Control Desk July 8,1988 Page 3 of 3 c:
J. G. Con nelly, J rJO.W. Dixon, J r./T.C. Nichols, J r.
D. A. Nauman E. C. Roberts J. L. Skolds W. A. Williams, Jr.
J. N. Grace J. J. Hayes, Jr.
General Managers C. A. Price R.B.Clary W. R. Higgins R. M. Ca m pbell, J r.
K. E. Nodland J. C. Snelson G. O. Percival R. L. Prevatte J. B. Knotts, Jr.
File (815.02) l i
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