ML18153D191
| ML18153D191 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 12/09/1992 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 92-014B, 92-14B, IEB-88-004, IEB-88-4, NUDOCS 9212140141 | |
| Download: ML18153D191 (3) | |
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. VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA, 23261 December 9, 1992 United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY.
SURRY POWERSTATION UNITS 1 AND 2 NORTH ANNA POWER STATION UNITS 1 AND 2 NRC BULLETIN 88-04 POTENTIAL SAFETY RELATED PUMP LOSS Serial No.
SPS/ETS Docket Nos.
- License Nos.
. 91-014B 50-280 50-281 50-338 50-339 DPR-32 DPR-37.
NPF-4 NPF-7 In our responses to NRC Bulletin 88-04, Potential Safety Related Pump Loss, Completed Actions, dated August 3 and 8, 1988 (Serial Nos. 88-275A and B)for Surry and North Anna respectively, we provided our plans for auxiliary feedwater pump disassembly and inspection. In the case of Surry, we initially committed to inspect one pump during the 1990 and 1991 refueling outages.
For North Anna, we initially committed to inspect one pump per outage so the three auxiliary feedwater pumps would be inspected at least once every three years. In addition, we committed to install full flow test lines at Surry.
- We also committed to_ consider modifications to the minimum flow recirculation lines at North Anna based on the inspection results. Both Surry and North Anna subsequently installed full flow test lines. For both stations, the results of these pump inspections were to determine the future inspection frequency and number of pumps to be inspected.. Based on the results of the auxiliary feedwater pump inspections at both stations, we have concluded that no additional inspections are necessary at either station. Future inspections will be based on pump performance and predictive analysis.
During outages in 1988 and 1989 both stations disassembled and inspected the three auxiliary feedwater pumps on each unit. These initial inspections revealed some pump degradation which was attributed primarily to the many years of pump testing using the minimum flow recirculation, lines. Appropriate repairs were made to restore each pump to design condition.
Since the initial inspection, we have completed additional inspections at both stations and reported those inspection results in letters dated January 18, 1991 and July 8, 1991 for Surry (Serial Nos.91-014 and 91--014A, 1 *i n r, h :*~
9212140141 921209 PDR ADOCK 05000280 1 '1 )*
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e respectively) and January 17, 1992 for North Anna (Serial No.92-017). Three pumps at
- Surry and two pumps at North Anna were inspected with representatives from the pump manufacturer present. The auxiliary feedwater pumps at both stations were supplied by the same manufacturer and are of similar design. No evidence of pump performance degradation was found at either station.
Prior to installation of the full flow test lines, surveillance testing was performed using.
the minimum flow recirculation lines which provided approximately 5%-10% of design flow. This flow was only adequate for thermal protection. These low flows were found to have contributed significantly to hydraulic instability and the consequent pump damage found during earlier inspections.. Providing full flow tesUng capability for these pumps has eliminated the primary contributor to pump degradation due to hydraulic instability.
At both stations, the auxiliary feedwater pumps are monitored in accordance with ASME Section XI requirements to provide early detection of pump performance problems.
Pump differential pressure and vibration are monitored for adverse trends which would be indicative of performance degradation. Our Predictive Analysis Group performs a
. detailed spectrum analysis of the pump vibration d~ta to identify potential problems which may be occurring before any pump damage could occur. In addition, at both stations, pump lubrication sampling and analysis are performed quarterly with parameters such as wear metals, contaminants, additives, particulate count and viscosity data reviewed and trended.
Through the Licensed Operator Retraining Program, our operations personnel have
.* beeri instructed on how to monitor operating auxiliary feedwater pumps and to minimize periods of extended operation at minimum flow conditions. Operating procedures have also been revised to include a cautionary note to avoid extended periods of pump operation at minimum flow conditions.
Based on the results of the auxiliary feedwater pump inspections to date, the system.
modifications which allow full flow testing, and the compre_hensive pump performance monitoring at both stations, we have concluded that routine auxiliary feedwater pump inspections are no longer necessary at either station. Accordingly, we are modifying our previous commitments for scheduled inspections of the-auxiliary feedwater pumps at both stations.
Future auxiliary feedwater pump inspections will be based on performance and predictive analysis.
- If you have questions regarding this information, please contact us.
Very truly yours,
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W. L. Stewart Senior Vice President - Nuclear
cc:
U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, N. W.
Suite 2900 Atlanta, Georgia 30323 Mr. M. W. Branch NRC Senior Resident Inspector Surry Power Station Mr. M. S. Lesser NRC Senior Resident Inspector North Anna Power Station
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