ML18153D112
| ML18153D112 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 09/03/1992 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 91-134H, NUDOCS 9209150008 | |
| Download: ML18153D112 (3) | |
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VIRGINIA ELECTRIC AND PowER COMPANY RICHMOND, VIRGINIA 23261 September 3, 1992 United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 AND 2 REMOVAL OF INTERIM MEASURES
- DIESEL DRIVEN SUMP PUMPS AND DEDICATED CRANE OPERATORS Serial No.
NL&P/CGL Docket Nos.
License Nos.
91-134H RB 50-280 50-281 DPR-32 DPR-37 During the November 21, 1991 meeting providing a status update on the Surry
!PE/Internal Flooding, interim measures related to internal flooding were discussed.
Subsequently, our Individual Plant Examination - Internal Flooding Reanalysis (Serial No. 91-134D) quantified the conservatism in the original analysis and resulted in a more realistic, conservative estimate of core damage frequency due to internal flooding. The NRC has examined both the original and revised analyses and issued a Safety Assessment on April 21, 1992. Based on these evaluations and the completion of various mitigating measures, we have determined that certain interim measures are no longer necessary.
One interim measure was maintaining the availability of diesel driven sump pumps in the turbine building for backup sump pump capacity.
The following activities associated with the sump pumps have been completed:
Improved administrative controls governing turbine building sump pump operability have been established. Specifically, a seven day administrative clock is entered when a sump pump is declared inoperable.
A turbine building sump pump test procedure (including level switches, check valves, and pump flow testing) was developed. The initial performance of the turbine building sump pump test procedure to establish a baseline for each sump pump was completed. Each sump pump tested satisfactorily.
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A turbine building sump pump reliability program (including operability requirements and surveillance/preventive maintenance programs) was developed. This program has been implemented to ensure that at least seven of nine sump pumps are operable, consistent with the Surry Individual Plant Examination - Internal Flood Reanalysis.
Based on completion of these activities, the diesel driven sump pumps are no longer required as a backup means of pump capacity. Future utilization of diesel driven pumps as backup capacity will only be necessary if we determine that the seven day administrative clock discussed above will be exceeded. Termination of this interim measure was discusssed during a telephone conversation between Mr. M. L. Bowling of Virginia Electric and Power Company and Mr. H. N. Berkow of the NRC on August 10, 1992. This letter serves as our formal notification to the NRC of removal of these diesel driven sump pumps.
The second interim measure related to internal flooding was the dedication of resources (both material and personnel) for the installation of stop logs (discussed in our October 28, 1991 letter (Serial No. 91-1348)). Relative to material dedication, staging of the equipment and material required to insert the stop logs will continue.
Relative to personnel resources, a dedicated crane operator and riggers have been maintained available onsite on a continuous basis since this commitment was made.
We have determined that the dedication of a crane operator and riggers on a continuous basis is not necessary. This conclusion is also implicitly reached in the NRC Safety Assessment in the statement "The staff does not consider the existing stop log system to be a viable means for mitigating the identified turbine building flooding vulnerability." For flood scenarios where stop log insertion is considered, the Surry Individual Plant Examination - Internal Flood Reanalysis assumes the time to install the stop logs for long term isolable floods is 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Consistent with this assumption, a stop log installation time of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> for those flood scenarios can be accomplished with the continued prestaging of equipment and material required to insert the stop logs and the use of administrative controls for personnel availability.
The administrative controls will use personnel available onsite and, if required, personnel on call.
Replacement of the interim measure of continuously available dedicated crane operators and riggers by administrative controls for personnel availability was discussed with the NRC Project Manager, Mr. 8. C. Buckley, on August 31 and September 2, 1992. This letter serves as our formal notification to the NRC of replacement of the interim measure by administrative controls.
As previously indicated, we will advise you of the conclusions of the conceptual design report for the proposed long term modifications and our intended actions during October 1992.
If you have questions regarding this information, please contact us.
Very truly yours, (l<J?D;?/J~
fo-r 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