ML20046A608
| ML20046A608 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 07/20/1993 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 93-433, NUDOCS 9307290107 | |
| Download: ML20046A608 (2) | |
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VinoINIA EI ncTRIC AND Powen CoMiny ItzennoxD,VIHOINIA 200G1 July 20, 1993 United States Nuclear Regulatory Commission Serial No.
93-433-Attention: Document Control Desk NL&P/AML RMN -R2 Washington, D. C. 20555 Docket Nos.
50-338 50-339 License Nos. NPF-4 NPF-7 i
Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY
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NORTH ANNA POWER STATION UNITS 1 AND 2 EMERGENCY DIESEL GENERATOR COMMITMENT' REVISION A report was made on January 31,1979 in accordance with '10 CFR 50.55(e) notifying the NRC that the exhaust muffiers for the Unit 2 Emergency Diesel Generators (EDGs)-
at North Anna Power Station were neither seismically qualified nor missile protected.
Furthermore, Licensee Event Report No. 79-005/01T-0 dated February 12,1979 was-submitted to the NRC which detailed the same concern on the Unit 1 EDGs. The mufflers were removed from the EDG exhaust manifolds and braces were installed to secure the exhaust piping until an engineering study could be completed.
In a letter dated March 2,1979 (Serial No. 061 A), Virginia Electric and Power.
Company notified the NRC of corrective actions to be taken to modify the. exhaust systems on the EDGs. These modifications included providing' a qualified' parallel, unmuffled exhaust path. Also, flexible tear away connectors were added to the muffled exhaust to prevent line movements induced from external' sources from being transmitted back to the corresponding EDG. Finally, the roof structures were. reworked to include the required seismic qualification and missile p'rotection for the unmuffled exhaust lines.
- The letter of March 2,1979 also stated that the EDGs would be periodically tested with the unmuffled exhaust lines isolated via manually operated high temperature valves to reduce the low pitch operating drone noise. The commitment to periodically test the EDG with the seismicially. qualified and missile protected unmuffled exhaust'line isolated has been reevaluated and determined to be unnecessary.
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. Sound level roadings were taken on June 30,1993 in locations surrounding the diesel l
- generator rooms while the Unit 1 H EDG was being tested with the unmuffled exhausti line unisolated. Sound level readings were again measured on July 7,1993 while the 5
Unit 2 H EDG was being tested using only the muffled exhaust line. These tests show.
only a small benefit from use of the muffler. Hearing protection is required whether or
'i not the muffler is bypassed. We therefore conclude that the unmuffled exhaust lines for each diesel can remain unisolated. The Station Nuclear l Safety and Operating Committee has reviewed and approved this change.
If you have any questions or require additionalinformation, please contact us.
Very truly yours, lf0Q QJ W. L Stewart Senior Vice President - Nuclear cc:
U. S. Nuclear Regulatory Commission Region 11 101 Marietta Street, N. W.
Suite 2900 Atlanta, Georgia 30323 NRC Senior Resident inspector North Anna Power Station r
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