ML18153D297
| ML18153D297 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 04/12/1993 |
| From: | Stewart S VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML18152A044 | List: |
| References | |
| 92-834, GL-92-08, GL-92-8, NUDOCS 9304190072 | |
| Download: ML18153D297 (7) | |
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e VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 April 12, 1993 United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITS 1 AND 2 SURRY POWER STATION UNITS 1 AND 2 RESPONSE TO NRC GENERIC LETTER 92-08 THERMO-LAG 330-1 FIRE BARRIERS Serial No.
NL&P/CGL Docket Nos.
License Nos.92-834 R1" 50-338 50-339 50-280 50-281 NPF-4 NPF-7 DPR-32 DPR-37 On December 17, 1992, the NRC issued Generic Letter 92-08, entitled "Thermo-Lag 330-1 Fire Barriers." The generic letter requests additional information from licensees to verify that Thermo-Lag 330-1 fire barriers manufactured by Thermal Science, Incorporated comply with the NRC's requirements. Specifically, the NRC has identified three areas of concern: the fire endurance capability of Thermo-Lag 330-1 barriers, the ampacity derating of cables enclosed in Thermo-Lag 330-1 barriers, and the evaluation and application of the results of tests conducted to determine the fire endurance ratings and the ampacity derating factors of Thermo-Lag 330-1 barriers.
The response to NRC Generic Letter 92-08 for North Anna and Surry Power Stations is provided in the attachment.
Should you have questions regarding this information or require additional information, please contact us.
Very truly yours,
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W. L. Stewart Senior Vice President - Nuclear Attachment - Response to NRC Generic Letter 92-08 for North Anna and Surry Power Stations
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U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, N. W.
Suite 2900 Atlanta, Georgia 30323 Mr. M. S. Lesser NRC Senior Resident Inspector North Anna Power Station Mr. M. W. Branch NRC Senior Resident Inspector Surry Power Station Mr. R. E. Bradley Nuclear Management and Resources Council 1776 Eye Street, NW Suite 300 Washington, DC 20006 e
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I, COMMONWEAL TH OF VIRGINIA )
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COUNTY OF HENRICO
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The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by W. L. Stewart who is Senior Vice President -
Nuclear, of Virginia Electric and Power Company. He is duly authorized to execute and file the foregoing document in behalf of that Company, and the statements in the document are true to the best of his knowledge and belief.
Acknowledged before me this /t,!fday of vf~f,
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My Commission Expires:
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fu- "6-1/utL, Notary Public (SEAL)
e ATTACHMENT RESPONSE TO NRC GENERIC LETTER 92-08 FOR NORTH ANNA AND SURRY POWER STATIONS The responses for the requested actions specified in Generic Letter 92-08 for North Anna and Surry Power Stations are as follows:
- 1.
State whether Thermo-Lag 330-1 barriers are relied upon (a} to meet 10 CFR 50.48, to achieve physical independence of electrical systems, (b} to meet a condition of a plant's operating license, or (c} to satisfy a licensing commitment.
RESPONSE
Thermo-Lag 330-1 material was installed at both stations to comply with the requirements in 10 CFR 50.48 for physical independence of electrical systems.
Identification of locations and descriptions of Thermo-Lag applications at North Anna and Surry were provided in letters dated July 29, 1992 (Serial No.92-436), September 30, 1992 (Serial No.92-583), and April 12, 1993 (Serial No. 92-436A/92-583A).
- 2.
If Thermo-Lag 330-1 barriers are used at the facility, (a}
State whether or not the licensee has qualified the Thermo-Lag 330-1 fire barriers by conducting fire endurance tests in accordance with the NRC's requirements and guidance or ficensing commitments.
RESPONSE
We have not conducted any fire endurance tests to qualify the Thermo-Lag 330-1 fire barrier systems installed at North Anna and Surry Power Stations.
(b}
State (1) whether or not the fire barrier configurations installed in the plant represent the materials, workmanship, methods of assembly, dimensions, and configurations of the qualification test assembly configurations; and (2) whether or not the licensee has evaluated any deviations from the tested configurations.
ATTACHMENT (continued)
RESPONSE
(1)
The Thermo-Lag 330-1 fire barrier systems installed at both stations are based on the manufacturer's design and installation guidance. It is our understanding that the designs tested by the manufacturer, TSI, represent our plant specific installations.
NRC Bulletin 92-01 and Supplement 1 to the Bulletin have made these tests invalid and the fire resistance rating of Thermo-Lag 330-1 material indeterminate.
(2)
We have not evaluated any deviations from the configurations tested by TSI.
However, we have developed an engineering evaluation for existing fire rated wrap in the Surry Unit 1 cable vault/tunnel, based on TSI test data to support a one hour fire rating (refer to the response to Item 3 (a)).
(c)
State (1) whether or not the as-built Thermo-Lag 330-1 barrier configurations are consistent with the barrier configurations used during the ampacity derating tests relied upon by the licensee for the ampacity derating factors used for all raceways protected by Thermo-Lag 330-1 (for fire protection of safe shutdown capability or to achieve physical independence of electrical systems) and (2) whether or not the ampacity derating test results relied upon by the licensee are correct and applicable to the plant design.
RESPONSE
(1)
The ampacity derating factors used for electrical raceways protected with Thermo-Lag 330-1 fire barrier systems were based on the recommendations of TSI for their as-built designs.
(2)
The original ampacity derating calculations for Thermo-Lag 330-1 fire barrier systems used a derating factor of eighteen percent (18%).
lnstrum~nt/signal cable derating was not considered due to negligible heat release from these cables. Derating is not an issue for Surry since only instrument/signal cables are protected by Thermo-Lag. However, we have performed an engineering calculation for the power cables at North Anna using thirty percent (30%) as the derating factor. Based on a worst case condition, 30% derating was calculated for the component cooling and charging pump power cables. The calculation concluded that the cables supplying power to the affected component cooling and charging pumps.will have adequate current carrying capacities for accident and non-accident loading conditions even with the more severe derating factor of 30%.
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ATTACHMENT (continued)
- 3.
With respect to any answer to items 2(a), 2(b), or 2(c) above in the negative, (a) describe all corrective actions needed and include a schedule by wh.ich such actions shall be completed and (b) describe all compensatory measures taken in accordance with the technical specifications or administrative controls.
When corrective actions have been completed, confirm in writing. their completion.
RESPONSE
(a)
The Thermo-Lag 330-1 fire barrier systems credited as either a one or three hour fire rated barrier system at North Anna and Surry are being evaluated to determine the basis and need for the barrier system.
One and three hour fire rated barrier systems evaluated as not meeting NRG regulatory requirements will be replaced.
Preliminary determinations regarding replacement have been made.
Upon finalization of these determinations, we will advise you of the specific planned replacements. Any new fire barrier systems installed will satisfy NRG regulatory requirements for one and three hour fire rated assemblies, as applicable.
Engineering evaluations of those one and three hour fire rated barrier systems not requiring replacement are being developed to verify compliance with NRC regulatory requirements. To date, two engineering evaluations have been developed for Surry. Specifically, engineering evaluations 22 and 23 have been developed for the evaluation of the fire rating for ventilation ducts coated with Thermo-Lag and for existing fire rated wrap in the Unit 1 cable vault/tunnel, respectively.
These engineering evaluations, which are enclosed for your information, demonstrate the adequacy of these particular applications.
Corrective actions at North Anna are scheduled to be completed by the end of 1993. At Surry, the corrective action schedule will be developed upon finalization of replacement determinations, discussed above.
(b)
Compensatory measures documented in our September 30, 1992 response to Bulletin 92-01, Supplement 1 (Serial No.92-583) will remain in place until the Thermo-Lag material is replaced or until an engineering evaluation has been developed to verify compliance with NRG regulatory requirements.
e ATTACHMENT (continued)
- 4.
List all the Thermo-Lag 330-1 barriers for which answers to item 2 cannot be provided in the response due within 120 days from the date of this generic letter, and include a schedule by which such answers shall be provided.
RESPONSE
The complete response to item 2 is contained herein.