ML20058F534
| ML20058F534 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 12/01/1993 |
| From: | Dennis Morey SOUTHERN NUCLEAR OPERATING CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9312080168 | |
| Download: ML20058F534 (2) | |
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Southern Nuclear Operatng Company Post O%ce Box 1295 B.rmingham, A!abama 35201 Telephone (205) B68-5131 L
SOuthem Nudear Operating Company
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Dave Morey Vice President Faney Project the southem eleCfoC System December 1, 1993 Docket Nos. 50-348 50-364 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555 Joseph M. Farley Nuclear Plant hsponse to Inspection Report Nos. 50-348/93-13 and 50-364/93-13 Gentlemen:
During the recent Service Water System Operational Performance Inspection (SWSOPI) the NRC reviewed the results of Service Water pump testing for Farley Nuclear Plant and also reviewed the results ofinternal evaluations of the accuracy of the installed Annubar flow measuring devices. Inspection Report Nos. 50-348/93-13 and 50-364/93-13 expressed concerns regarding the accuracy of existing flow measurement techniques and requested a letter describing the SNC actions for resolution of this issue.
The installed Annubar flow measurement results are impaired by the physical configuration of the Service Water System piping. This is primarily attributable to the frequent bends in this large diameter piping in accessible areas. The areas of fully developed flow which would provide the most desirable location for flow measurement devices are not accessible.
In order to determine whether ultrasonic flow measurement techniques could enhance trending of pump performance, a state-of-the-art flow meter has been purchased and is under evaluation. The ultrasonic flowmeter is being used to gather data in parallel with the surveillance testing that is conducted using the Annubar flow elements. Rigid tracks to secure the transducers have been installed on each train of Senice Water in an effort to promote repeatability of Senice Water pump performance tests. Present plans are to collect the ultrasonic data for approximately six months, at which time a determination will be made as to whether the use of ultrasonic techniques would enhance the trending of pump performance at FNP. In addition, the present testing method is under evaluation to determine whether the Annubar performance can be enhanced through improved data collection techniques such as the use of a data recorder to establish the integrated pump flow over a given time interval rather than using the average of the instantaneous flows recorded at one minute intervals over a time interval.
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U. S. Nuclear Regulatory Commission Page 2 The existing means of trending flow with the installed Annubar flow meters has proven effective in trending degradation of pump flow. Overhaul of Service Water pumps on scheduled intervals provides added assurance that pump degradation is maintained within appropriate limits. Flow balance testing performed in 1989,1990,1992 and 1993 has also provided confirmation of Senice Water System capability. During this testing, the flow distribution within the Service Water System is determined by measuring the flow to individual components as well as measuring the flow from each operating Service Water pump. Although this testing was conducted for the purpose of determining flow distribution rather than confirming pump performance, review of the flow data for the operating pumps indicates they were found to be within 10% of the manufacturer's certified pump curve.
Further assurance of Senice Water System capability is provided by conservative design assumptions regarding Service Water pump flow. The flow balance model, which predicts the minimum flow available to safety related components under accident conditions, assumes that all Senice Water System pumps are performing at 10% below the manufacturer's certified pump curve. This is a significant conservatism since the pumps are replaced / rebuilt at different times and would actually be at varying stages of performance.
In summary, the present mechanisms for monitoring overall Senice Water System performance, in conjunction with conservative system design, provides adequate assurance that the Senice Water System will perform as required under normal and accident conditions.
SNC will continue its efforts to improve Senice Water pump performance trending capability.
If you desire additional information, please advise.
Respectfully submitted, SOUTHERN NUCLEAR OPERATING COMPANY hfw Dave Morey DPli/sar:SWPUM. DOC cc: Mr. S. D. Ebneter Mr. B. L. Siegel Mr. T. M. Ross}}