ML17311B319

Responds to Request for Addl Info Re GL 92-08, Thermo-Lag 330-1 Fire Barriers

ML17311B319
Person / Time
Site:	Palo Verde
Issue date:	12/20/1995
From:	Stewart W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
102-03574-WLS-S, 102-3574-WLS-S, NUDOCS 9512270005
Download: ML17311B319 (9)

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ACCESSIOA NBR:9512270005 DOC.DATE: 95/12/20 NOTARIZED: NO FACIL:STN-50-528 Palo Verde Nuclear Station, Unit 1, Arizona Publi STN-50-529 Palo Verde Nuclear Station, Unit 2, Arizona Publi STN-50-530 Palo Verde Nuclear Station, Unit 3, Arizona Publi AUTH.NAME AUTHOR AFFILXATION STEWART,W.L.

Arizona Public Service Co.

(formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Responds to request for addi info re GL 92-08, "Thermo-Lag 330-1 Fire Barriers."

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A029D COPIES RECEIVED:LTR ENCL SIZE:

TITLE: Generic Letter 92-008 Thermo-Lag 330 Fire Barrier NOTES:STANDARDIZED PLANT Standardized plant.

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WILLIAML. STEWART EXECUTIVEVICE PRESIDENT NUCLEAR Arizona Public Service PALO VERDE NUCLEARGENERATING STATION 5801 S. WINTERSBURG ROAD TONOPAH, ARIZONA 85354-7529 102-03574-WLS/SAB/NLT December 20, 1995 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station P1-37 Washington, DC 20555

References:

1)

Letter dated November 3,

1995, from Charles R. Thomas, Project Manager-PVNGS, USNRC/NRR, to William L. Stewart, Executive Vice President, Nuclear, APS 2)

Letter No. 102-03297, dated March 28,

1995, from W.

L. Stewart, Executive Vice President, Nuclear, APS, to USNRC 3)

Letter dated September 23, 1994, from Roy P. Zimmerman, Associate Director for Projects, USNRC/NRR, to William L. Stewart, Executive Vice President, Nuclear, APS

Subject:

Palo Verde Nuclear Generating Station (PVNGS)

Units 1, 2, and 3 Docket Nos. STN 50-528/529/530

Response

to Request for Additional Information Regarding Generic Letter 92-08 By letter dated November 3, 1995 (Reference 1), the NRC requested that Arizona Public Service Company (APS) submit additional information regarding Generic Letter (GL) 92-08, "Thermo-Lag 330-1 Fire Barriers."

Specifically, the NRC requested that APS submit a description of the anticipated analytical methodology (including typical calculations) that willbe used to determine the ampacity derating parameters for the Thermo-Lag fire barriers installed at PVNGS.

It is APS'ntention to utilize test data as the basis for determining appropriate ampacity derating factors for PVNGS configurations.

Analysis may be used to account for PVNGS specific deviations from tested configurations.

APS has not developed the analytical approach that will be used if existing tests do not explicitly bound specific PVNGS configurations.

Therefore, ampacity derating evaluations, applicable test reports, and typical calculations are not available for submittal at this time.

As previously reported to the NRC, APS has performed extensive field inspections to,obtain as-built information on barrier configurations and attributes necessary for resolution of the fire endurance issue (Reference 2).

Additionally, as previously reported, the PVNGS Regulatory Guide 1.75 installations, though not field inspected, were installed similar to 1-hour Thermo-Lag fire barrier installations.

APS is in the process of evaluating industry information available to

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U. S. Nuclear Regulatory Commission ATTN: Document Control Desk

Response

to Request for Additional Information Regarding Generic Letter 92-08 Page 2 date to determine which design attributes must be considered when comparing tested configurations to the PVNGS configurations.

Upon determination of the required design attributes, APS will determine if additional field inspections are required.

Provided as an enclosure to this letter is an ampacity resolution strategy flowchart which depicts the approach APS willutilize forThermo-Lag-related ampacity concern resolution. APS expects to be able to submit a description of the analytical methodology, including typical calculations, should they be used to apply test results to PVNGS-specific configurations by June 30, 1996.

Other work to be accomplished by June 30, 1996, includes establishing a cable and load database to allow rapid application of cable derating factors when finalized (39% derating factors are currently being used for preliminary evaluation purposes) and completing evaluations of available industry tests and comparing them to PVNGS specific configurations.

Please note that although APS has no plans to perform ampacity testing at this time, the resolution strategy does not preclude testing.

APS will develop. firm ampacity derating test plans, as required, by June 30, 1996.

In the September 23, 1994 letter (Reference

3) the NRC stated that it is their view that the unresolved technical issues regarding ampacity derating can be resolved independently of the fire endurance issues.

APS has made significant progress towards resolving the fire endurance issue. APS has eliminated the need for approximately 80% ofthe Thermo-Lag installed to meet fire protection commitments and is resolving the fire endurance issues on the Thermo-Lag which willremain for 10 CFR 50 Appendix R compliance.

Field examinations have been performed for verification ofas-built parameters important to fire endurance issue resolution, and combustibility and seismic issues are being resolved.

APS acknowledges that the issues regarding ampacity derating can be resolved independently from the fire endurance issues and is pursuing s'uch resolution.

The current schedule for resolution of Thermo-Lag-related

issues, as identified at this time, is December 31, 1996.

Should plant modifications be necessary to resolve long-term derating

concerns, an updated schedule will be provided.

Should you have any questions, please contact Scott A. Bauer at (602) 393-5978.

Sincerely, WLS/SAB/NLT/rv Enclosure cc:

L. J. Callan K. E. Perkins B. E. Holian K. E. Johnston

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ENCLOSURE AMPACITYRESOLUTION FLOW CHART

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AMPACITYRESOLUTION FLOW CHART m

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Verifyattributes to be used in comparing tested configurations to as-built configurations.

Walkdown and document PVNGS's specific as-built configuration attributes required for ampacity resolution, as necessary.

Compare attributes of existing tests (TU, TVA, etc.) to as-built configurations Perform ampacity margin calculation for cable trays and conduits including diversity.

Forecast Completion by 6/96 H

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W Are existing tests applicable?

Apply derating factor determined by previous industry test or evaluation.

Is the actual amperage within the derated ampacity?

NO NRC Regulatory Compliance (by 12/96)

NO YES Analytical evaluations for PVNGS speciTic attributes.

Do the evaluations address the PVNGS speciTics?

NO m

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Evaluation of alternative approaches successful?

YES Obtain bounding tests for PVNGS configurations.

NO Apply derating factor determined by PVNGS speciTic testing Implement Mods or long term monitoring of cable conditions

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