ML20081J516

Forwards Response to Followup Questions Re GL 92-08, Thermo-Lag 330-1 Fire Barriers

ML20081J516
Person / Time
Site:	Sequoyah
Issue date:	03/22/1995
From:	Burzynski M TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-92-08, GL-92-8, NUDOCS 9503280010
Download: ML20081J516 (21)

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Terinessee Valley Authonty. Post offrce Box 2000. Soddroatsy Teririenee 37379 March 22,1995 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Gentlemen:

In the Matter of

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Docket Nos. 50-327-Tennessee Valley Authority

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50-328 SEQUOYAH NUCLEAR PLANT (SON)- RESPONSE TO THE FOLLOW-UP REQUEST FOR ADDITIONAL INFORMATION (RAl) REGARDING GENERIC LETTER (GL) 92-08, "THERMO-LAG 330-1 FIRE BARRIERS"

References:

1. TVA letter to NRC dated April 15,1993, "Sequoyah Nuclear Plant (SON) - Generic Letter (GL) 92 Thermo-Lag 330-1 Fire Barriers"

2. TVA letter to NRC dated February 10,1994, "Sequoyah Nuclear Plant (SON) - Request for Additional Information Regarding Generic Letter 92-08,'Thermo-Lag 330-1 Fire Barriers,' Pursuant to 10 CFR 50.54(f)- Sequoyah Nuclear Plant, Units 1 and 2 (TAC Nos. M85604 and M85605)"

3. TVA letter to NRC dated July 9,1993," Watts Bar Nuclear Plant (WBN) - Results of Qualification Testing for Thermo-Lag 330 Fire Barriers (TAC M63648)"

4. TVA letter to NRC dated December 23,1994, " Watts Bar Nuclear Plant (WBN)- Response to NRC Questions Regarding the Use of Thermo-Lag Fire Barrier Systems at WBN (TAC M63648)"

5. TVA letter to NRC dated November 11,1994, " Watts Bar Nuclear Plant (WBN) - Response to NRC Request for Additional Information Related to Thermo-Lag Fire Barrier Assembly Seismic Capabilities (TAC M61648)"

The purpose of this letter is to provide TVA's response to the subject RAI (Enclosure 1) and the measures TVA is taking to ensure that Thermo-Lag 330-1 fire barrier material used at SON conforms to NRC regulations. Additionally, this letter provides an updated response to Reference 1.

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U.S. Nuclear Regulatory Commission Page 2 March 22,1995 TVA has performed extensive testing of Thermo-Lag 330-1 fire barrier material. The testing demonstrated that Thermo-Lag 330-1 can be relied upon to protect electrical raceways and associated cabling in the event of a fire. The testing qualified Thermo-Lag 330-1 for use as a rated one-hour raceway fire barrier material. The qualification was based on maintaining the temperature rise inside the fire barrier below the acceptance criteria provided in Supplement 1 to GL 86-10 (250 degrees Fahrenheit [ F] average temperature rise, 325 F maximum temperature rise, or performing cable compressive load testing based on fire test results).

TVA's Thermo-Lag 330-1 test results were submitted by References 3,4, and 5 by WBN. Based on discussions with NRC staff personnel who observed TVA's testing and have reviewed the test results, it is TVA's understanding that NRC conclusions about the testing are positive.

To ensure Thermo-Lag 330-1 used at SON is qualified, TVA is implementing measures to verify the material installed in the plant is representative of the tested materials and configurations. TVA's measures ensure that the important test configuration installation parameters bound the in-plant configurations. Implementation of SON's t

Thermo-Lag 330-1 program is contingent upon NRC acceptance of TVA's testing program. contains the commitment discussed in Enclosure 1 and supplements the previous commitment transmitted in Reference 2. Please direct questions concerning.

this issue to W. C. Ludwig at (615) 843-7460.

Sincerely, M.'J.

rzynski Acting SON Site Vice President Sworn t and subyscr' bed bpfore me

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Enclosures cc: See page 3

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U.S. Nuclear Regulatory Commission

- Page 3 March 22,1995 j

cc (Enclosures):

Mr. D. E. LaBarge, Project Manager Nuclear Regulatory Commission One White Flint, North

.11555 Rockville Pike Rockville, Maryland 20852-2739 NRC Resident inspector Sequoyah Nuclear Plant 2600 lgou Ferry Road Soddy-Daisy, Tennessee 37379-3624 Regional Administrator U.S. Nuclear Regulatory Commission Region 11 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323-2711 t

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ENCLOSURE 1

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SEQUOYAH NUCLEAR PLANT (SON) - RESPONSE TO THE -

l NRC FOLLOW UP REQUEST FOR ADDITIONAL INFORMATION (RAI)-

REGARDING GENERIC LETTER (GL) 92-08 DATED DECEMBER 22,1994

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4i From the time Reference 2 was subrnitted to NRC, TVA has completed qualification testing (i.e., fire, ampacity, and seismic) that addresses planned TVA Thermo-Lag 330-1 configurations.' This testing was performed and documented for Watts Bar Nuclear Plant (WBN). The scope of the testing was twofold: (1) To provide the design bases for the new Thermo-Lag 330-1 installations at WBN, and (2) to

- provide a qualification basis, or determine acceptable upgrades, for existing installations at other TVA nuclear plants (e.g., SON). The detailed test information has been incorporated into, and is controlled by, upper tier TVA nuclear documents (i.e., General Engineering Specification [G-Spec] and Design Standards [DS]), which all TVA nuclear sites are required to use.

Based on results from the TVA WBN test program, SON will upgrade Thermo-Lag 330-1 installation on conduits smaller than three inches, junction boxes, and other applicable unique configurations. Until upgrades are completed, appropriate compensatory measures will remain in place. SON will not upgrade conduits three inches and larger since testing demonstrated that current installations on these conduit sizes are qualified. (It should be noted that cable compressive load testing will be performed to complete qualification of existing 3-inch conduit designs. This is discussed in Response No. 25 to NRC Request 2a.)

The following response updatee 'oformation previously submitted in Reference 2 and follows the format established m the enclosure to the December 22,1994, RAl.

Thermo-Lag 330-1 MATERIALS 1

NRC Reauest la Describe the specific tests and analyses that will be performed to verify that Thermo-Lag 330-1 fire barrier materials that are currently installed at SON Units 1 and 2, or that will be installed in the future, are representative cf the materials that were used to address the technicalissues associated with Thermo-Lag 330-1 barriers and to construct the fire endurance and ampacity derating test specimens. The test and analyses shall address the material properties and attributes that were determined or controlled by Thermal Science incorporated (TSI) during the manufacturing process and the quality assurance program. The test and analyses shall also address the material' properties and attributes that contribute to conclusions that Thermo-Lag 330-1 materials and barriers conform to NRC regulations. These include:

1.

Chemical Composition 2.

Material Thickness 3.

Material Weight and Density 4.

Presence of Voids, Cracks, and Delaminations 5.

Fire Endurance Capabilities 6.

Combustibility 7.

Flame Spread Rating 8.

Ampacity Derating 9.

Mechanical Properties Such as Tensile Strength, Compressive Strength, Shear Strength, and Flexural Strength.

, TVA RESPONSE The following tests and analyses will be performed to provide assurance that Thermo-Lag 330-1 materials and barriers conform to NRC regulations:

1.

Chemical Composition Infrared (IR) Spectroscopy and Thermogravimetric Analysis (TGA) will be performed to verify that Thermo-Lag 330-1 fire berrier materials installed at SON Units 1 and 2 are representative of the materials used in the fire endurance, ampacity derating, and seismic tests. IR Spectroscopy will be conducted in accordance with TVA procedures derived from American Society for Testing and Materials (ASTM) E 1252-88," Standard Practice for General Techniques for Qualitative infrared Analysis." TGA will be performed in accordance with procedures derived from ASTM E 1131-93," Standard Test Method for Compositional Analysis by Thermogravimetry," to the extent practical for the equipment used by TVA.

IR and TGA testing will be performed on samples taken from the production lots used to upgrade existing Thermo-Lag 330-1 installations to comply with the TVA tested configurations. Additional samples will be obtained for analysis from Thermo-Lag 330-1 material that will be removed from the plant as part of the SON planned Thermo-Lag 330-1 reduction program.

Baseline testing (i.e., IR and TGA analysis) wi!! he performed for WBN on samples taken from production lots used for testing. Testing of three lots to verify homogeneity will also be conducted at WBN. Results of analysis on SON samples will be compared to results from these WBN tests.

Test specimens required for analysis will be obtained from an interior location of the solid sample. Where practical, the sample will be taken from a general area or several areas rather than removing a small, localized piece of material. This will provide a more representative sample for testing.

Trowel-grade material will ne thoroughly mixed prior to removing a sample for testing. Samples of trowel-grade materials will be cured to a solid form prior to testing.

2.

Material Thickness

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i TVA did not manufacture or fabricate any Thermo-Lag 330-1 panels or shapes at SON. Thermo-Lag 330-1 material originally procured for SON had a spersfied minimum thickness of 1/2 inch for a one-hour fire rating. The testing thn was performed to support the WBN Thermo-Lag 330-1 testing program had a specified thickness of 5/8 inch plus or minus 1/8 inch. The requirements for material thickness are identified in G-Spec G-98. SON will perform upgrades to conduits

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, less than 3 inches in diameter to comply with the upgrade requirements of G-Spec G-98. Thickness of upgrade materials will be verified during TVA quality control inspections. These upgrade activities will eliminate potential thickness concerns for installed conduits. For conduits with diameters greater than or equal to 3 inches, no upgrade is required or planned. SON will verify the material thickness from samples removed from Units 1 and 2 during the Thermo-Lag 330-1 reduction program. From this data, we will determine if other existing Thermo-Lag 330-1 installations require additionalinspection.

3.

Material Weight and Density Density acceptance criteria will be established based on the results of weighing and measuring samples from the lots used during TVA fire endurance, ampacity derating, and seismic testing. For installation of new Thermo-Lag 330-1 material, a sample from each lot being installed at SON will be measured to ensure that Thermo-Lag 330-1 conforms to the density acceptance criteria. For the existing Thermo-Lag 330-1 material that will remain in place, the material weight and density will be verified by sampling Thermo-Lag 330-1 installations, which will be removed from Units 1 and 2 during the Thermo-Lag 330-1 reduction program.

4.

Presence of Voids, Cracks, and Delaminations During the upgrade of Thermo-Lag 330-1 material for conduits less than 3 inches in diameter, G-Spec G-98 will be used as the governing document for acceptable configurations. G-Spec G-98, " Installation Modification, and Maintenance of Electrical Raceway Fire Barrier Systems," defines acceptance criteria for voids, cracks, and delaminations as follows:

1. Surface voids - Surface voids are unacceptable.

2. Cracks - Surface cracks that exceed 2 inches in length and 1/16 inch in depth are unacceptable.

3. Delaminations - No observable separation of materialis allowed.

All upgrades will be inspected to the acceptance criteria provided in G-Spec G-98.

For the existing conduits greater than or equal to 3 inches in diameter that do not require upgrades, the acceptance criteria of G-Spec G-98 will be verified by inspecting material removed from Units 1 and 2 during the Thermo-Lag 330-1 reduction program.

TVA will not inspect for internal voids. During qualifVtion testing for WBN, TVA used standard production Thermo-Lag 330-1 materiN manufacated and inspected to the TVA specifications and tolerances described above. While preparing the ritatorial for testing, internal voids were discovered during cutting operations for installation. The material containing voids was used during testing.

No problems resulting from the internal voids were discovered in any of the full i

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1 scale fire tests. This may be attributed to the fact that Thermo-Lag 330-1 swells during its sublimation process and clnses the internal voids. Therefore, the internal voids that are inherent in the manufacturing process of the Thermo-Lag 330-1 prefabricated boards and conduit sections are considered to be acceptable.

5.

Fire Endurance Capabilities TVA performed two phases of fire testing to demonstrate the fire endurance capabilities of Thermo-Lag 330-1. The first phase of testing consisted of six, full scale one-hour fire tests for Thermo-Lag 330-1. These tests were submitted to NRC by Reference 3. The second phase of fire testing consisted of seven, full scale one-hour fire tests for Thermo-Lag 330-1 and were submitted to NRC by Reference 4. These thirteen fire tests document the fire endurance capabilities of Thermo-Lag 330-1 when installed in accordance with TVA procedures.

The fire endurance capabilities of Thermo-Lag 330-1 fire barriers are dependant on the materials being used and the manner in which the Thermo-Lag 330-1 material is installed. The material verification measures described earlier ensure that consistent materialis used. The installation procedures governed by TVA's G-Specs and dss ensure that Thermo-Lag 330-1 will be installed in an acceptable manner similar to that used during the TVA testing program. Upgrades to conduits less than 3 inches will use the upgraded requirements of G-Spec G-98, while the conduits not to be upgraded will be evaluated by reviewing samples from the material that is removed during the Thermo-Lag 330-1 reduction program. The methods used for the preparation of the test samples were comparable to those used during SON's originaliristallation. Th.isa measures are adequate to ensuro that the fire endurance capabilities of Thermo-Lag 330-1 fire barrier assemblies installed at SON are consistent with those used in the fire endurance tests.

6.

Combustibility No combustibility tests or analyses are planned. TVA will define Thermo-Lag 330-1 as a " Limited Combustiblo." This is based upon the test results described in NRC Information Notice 92-82; Nuclear Utility Management and Resource Council (NUMARC), "Thermo-Lag 330-1 Combustibility Evaluation Methodology Plant Screening Guide"; ASTM E136, D1929, E1321, and E1354 test results; and Underwriters Laboratory Inc. (UL) 723 test report, File R6076 Project 81NK3238 dated June 16,1981. The definition will be included in the next revision of TVA DS-M17.2.2," Electrical Raceway Fire Barrier Systems."

SON does not use Thermo-Lag 330-1 as noncombustible radiant energy shields.

Additionally, SON does not use Thermo-Lag 330-1 to create combustible free zones.

5-7.

Flame Spread Rating No flame spread rating tests or analyses are planned. Thermo-Lag 330-1 was tested by UL in 1981 (UL test 723 File R6076 Project 81NK3238 dated June 16,1981).. UL indicates a Flame Spread value of 5, Fuel Contribution value of 0 and smoke developed value of 15. Additional tests were conducted by NUMARC ("Thermo-Lag 330-1 Combustibility Evaluation Methodology Plant Screening Guide") and ASTM (D1929, E1321, and E1354 test results). TVA will review the results of these tests to establish values for flame spread ratings and document them in the DS-M17.2.2.

8.

Ampacity Derating TVA performed two phases of ampacity derating tests that are applicable to SON.

The first phase ampacity derating test results (Thermo-Lag 330-1) were submitted to NRC by Reference 3. WBN will submit the second phase (Thermo-Lag 330-1) ampacity test reports to NRC when they become available.

Ampacity derating associated with a Thermo-Lag 330-1 fire barrier is dependant on the materials being used and the manner in which the Thermo-Lag 330-1 is installed. The material verification measures described herein (e.g., chemical testing, weight and density measurements) ensure that consistent materialis used. The installation procedures governed by the G-Specs and dss ensure that Thermo-Lag 330-1 used in the plant is installed in the same manner as the Thermo-Lag 330-1 used during testing. These measures are adequate to ensure that the ampacity derating factors used for the Thermo-Lag 330-1 fire barrier materials installed at SON are consistent with the derating factors developed during the ampacity derating tests.

9.

Mechanical Properties Such as Tensile Strength, Compressive Strength, Shear Strength, and Flexural Strength TVA has performed mechanical property (static) testing of the materials used to construct the TVA Thermo-Lag 330-1 fire barriers. Seismic (static and dynamic) test results were submitted to NRC by Reference 5.

To provide additional assurance of reliable mechanical properties for seismic qualification, board shear strength acceptance criteria will be determined in accordance with ASTM D 4255 using samples from the lots used in the TVA testing programs. For installation of new Thermo-Lag 330-1 material as part of -

the upgrades, a sample from each lot of board material being installed at SON will be tested to ensure that Thermo-Lag 330-1 conforms to the board shear strength acceptance criteria. For existing Thermo-Lag 330-1 materials that will remain in place, the shear strength will be verified by sampling Thermo-Lag 330-1 installations, which will be removed as part of the SON Thermo-Lag 330-1 1

reduction program.

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. Other mechanical properties such as tensile strength, compressive strength, and flexural strength do not need to be tested further. In TVA's designs, the stainless and carbon steel mesh (stress skin) bonded to the Thermo-Lag 330-1 board is the principal material used to ensure that Thermo-Lag 330-1 remains in place under postulated desis basis seismic events. Tensile strength, compressive strength, and flexural strength of Thei no-Lag 330-1 depend primarily on the physical properties of the steel mesh. Since steel properties are relatively consistent and not controlled by TSI, no confirmatory test prograrn is needed to establish the consistency of those properties.

NRC Reauest - 1b Describe the methodology that will be used to determine the sample size and demonstrate that sample size will be large enough to ensure that the information and data obtained will be sufficient to assess the total population of in-plant Thermo-Lag 330-1 barriers and the materials that will be installed in the future, in determining the sample size, consider the time of installation and manufacture of the various in-plant materials and barrier installations. Give the number and types (e.g.,

panels, conduit preshapes, trowel-grade material, stress skin) of samples that will be tested or analyzed.

TVA RESPONSE Sample sizes used for verifying that Thermo-Lag 330-1 conforms to regulatory requirements are described above. Pending the results of the testing described above for the presently installed material, TVA considers it sufficient to take a sample from each lot of the new Thermo-Lag 330-1 material that will be used to upgrade or replace Thermo-Lag 330-1 fire barriers at SON. Samples will be obtained from Thermo-Lag 330-1 material that is removed from Units 1 and 2 during the Thermo-Lag 330-1 reduction program. Samples will also be obtained and analyzed from material presently held at Hartsville, Tennessee. The materials obtained from the Hartsville warehouse were procured at approximately the same time as that installed at SON. This will enlarge the sample of older material tested. Results of these samples will be combined with those from the WBN program, which will give TVA a very comprehensive picture of Thermo-Lag 330-1 materials and their acceptability as a rated fire barrier.

NRC Reouest - 1c Submit the schedule for verifying the Thermo-Lag 330-1 materials.

TVA RESPONSE TVA's proposed schedule is as shown below:

1.

Complete Thermo-Lag 330-1 reduction review by May 31,1995.

2.

Complete cable compressive load testing for 3-inch conduits by September 29,1995.

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Complete sample analysis for material from Hartsville by September 29,1995.

4.

Complete inspection / evaluation of Thermo-Lag 330-1 removed from SON by October 1,1996.

NRC Reauest - 1d After the analyses and tests have been completed, submit a written supplemental report that confirms that this effort has been completed and provide the results of the tests and analyses. Describe any changes to previously submitted plans or schedules that result from the tests or analyses.

TVA RESPONSE TVA will submit a supplemental report providing the requested information. Any changes to the plans or schedules discussed above will be provided in this report.

IMPORTANT BARRIER PARAMETERS NRC Reauest - 2a Describe the examinations and inspections that will be performed to obtain the important barrier parameters given in Section 11 of the RAI of December 21,1993, for the Thermo-Lag 330-1 fire barrier configurations installed at SON Units 1 and 2.

TVA RESPONSE Thermo Lag Electrical Raceway Fire Barrier Systems (ERFBS) installations at SON will 1

be upgraded in accordance with G-Spec G-98 and site specific drawings and instructions. Existing installations will be verified by physical inspection, when practical, and by verification of originalinstallation methods. Originalinstallation methods have been determined by interviews with the members of the original installation crews and will be verified by destructive examination of selected Thermo Lag 330-1 ERFBS installations, which will be removed as part of the SON Thermo-Lag 330-1 reduction program.

The importance of variations of Thermo-Lag 330-1 ERFBS parameters has been determined from TVA's fire endurance, seismic, and ampacity test programs. The important design parameters are controlled in TVA's DS as follows:

1.

DS-M17.2.2, " Electrical Raceway Fire Barrier Systems."

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DS-C1.6.16," Structural Evaluation of Electrical Raceway Fire Barrier Systems."

3.

DS-E12.6.3, " Auxiliary and Control Power Cable Sizing Up To 15,000 Volts."

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These dss and the applicable SON design criteria will be the basis for the site specific drawings and design change documents, which will define the specific upgrades.

G-Spec G-98 describes the engineering requirements for installation, modification, and maintenance of ERFBS. It also reflects lessons learned from TVA's fire endurance, seismic, and ampacity test programs.

G-Spec G-98,in addition to the site specific drawings and design change documents, will provHe the complete design output for control of the SON Thermo-Lag 330-1 ERFBS upgrades.

The following 32 sections correspond to the specific parameters identified in the December 21,1993, NRC RAl. In each case, a brief description is given of the basis for the associated inspections and examinations to be performed for the SON upgrades, as justified by TVA's testing program and dss.

1.

Raceway Orientation (horizontal, vertical, radial bends)

TVA varied raceway orientation as a part of the fire endurance testing. Typically, fire test assemblies had the raceway running both horizontally and vertically in the same test. Items used to change direction such as radial bends and condulets (lateral bends) were included in the testing. TVA also tested assemblies running verticalin a wall furnace to ensure our designs were not position dependent.

important fire barrier parameters for different raceway orientations are documented in TVA DS-M17.2.2.

Additionally, TVA considered potential raceway orientations and locations when defining Required Response Spectra (RRS) for seismic qualification tests. TVA DS-C1.6.16 provides the associated methods for seismic qualification. Installation, examination, and inspection will be in accordance with corre.sponding installation and inspection documents (e.g., G-Spec G-98) and SON site specific drawings of typical enclosures.

2.

Conduit TVA varied the sizes of conduits to determine the number of layers and thick. ness of Thermo-Lag 330-1 required for each size during fire endurance testing.

Important fire barrier parameters for conduits are documented in DS-M17.2.2.

Installation, examination, and inspection for conduit parameters will be in accordance with corresponding installation and inspection documents.

3.

Junction Boxes and Lateral Bends TVA performed fire endurance testing on the smallest and largest anticipated junction boxes and lateral bends expected to be encountered at SON. Important fire barrier parameters are documented in DS-M17.2.2. DS C1.6.16 provides methods for seismic qualification. Installation, examination, and inspection for junction box and lateral bend parameters will be in accordance with corresponding installation and inspection documents.

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s' 4 4. ~ Ladder-back Cable Tray With Single Layer Cable Fill TVA performed'a fire endurance test on a ladder backed cable tray with a single

' layer of cable fill to compare the results with other amounts of cable fill. Important

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' barrier parameters for this attribute are documented in DS-M17.2.2. Installation,-

examination, and inspection for cable fill parameters will be in accordance with corresponding installation and inspection documents.

5.

Cable Tray With T-Section TVA performed a fire endurance test on the largest expected cable tray T-Section.

Important fire barrier parameters are documented in DS-M17.2.2. DS-C1.6.16 provides associated allowable stresses and analysis methods for seismic qualification. Installation, examination, and inspection for T-section parameters will be in accordance with corresponding installation and inspection documents.

6.

Raceway Material (Aluminum, Steel)

TVA tests used steel and aluminum conduits. The cable trays used in the fire endurance and seismic testing were steel, which is representative of the cable tray to be protected at SON. Important fire barrier parameters are documented in DS-M17.2.2. DS-C1.6.16 provides associated methods for seismic qualification.

Installation, examination, and inspection for raceway material parameters will be in accordance with corresponding installation and inspection documents.

7.

Support Protection, Thermal Shorts (Penetrating Elements)

Both phases of the TVA test program included tests using steel supports to determine support protection and thermal short parameters. The supports in the testing were steel, which is representative of the supports to be protected at SON.

Important barrier parameters are documented in DS-M17.2.2. SON raceway supports will be protected such that the supports will retain sufficient strength to ensure raceway functionality during the postulated fire event. Installation, examination, and inspection support protection parameters will be in accordance with corresponding installation and inspection documents.

8.

Air Drops TVA tests included air-drop cab!as to determine their protection parameters. As previously reported in Reference 1, SON has one cable air-drop fire barrier installed inside a pull box in the 480-volt shutdown transformer room on Elevation 749 of the auxiliary building. This configuration was installed because of support problems associated with the protection of the pull box. TVA now has a tested and qualified junction box fire barrier configuration that involves.a free-standing frame that will not add load to the box. This box protection upgrade will be incorporated

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at SON for the box containing the presently installed cable air-drop barrier

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' configuration. When this modification is completed, SON will have no cable

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9. Baseline Fire Barrier Panel Thickness Baseline fire. barrier panel thickness tolerances were_ determined prior to the ;

.i construction of the test assemblies. TVA has defined the thickness as nominal--

3/8 inch and nominal 5/8 inch. The tolerances for these nominal sizes of materials.

are plus or minus 1/8 inch. This requirement corresponds to the Thermo-Lag 330-1 material used in the TVA testing. This barrier parameter will be verified during inspections at SON. New materials will comply with G-Spec G-98.

10. Preformed Conduit Panels t

Baseline preformed conduit fire barrier panel thickness tolerances were determined prior to the construction of TVA's test assemblies. TVA has defined the thickness :

as: nominal 3/8 inch and nominal 5/8 inch. The tolerances for these nominal sizes of materials are plus or.minus 1/8 inch. This requirement corresponds to the Thermo-Lag 330-1 material used in the TVA testing program. This barrier parameter will be verified during sampling inspections at SON.

11. Panel Rib Orientation Panel rib orientation is not considered to be a critical attribute since seismic and fire endurance qualification did not rely on the presence of panel ribs.

12. Unsupported Spans I

TVA will evaluate and seismically qualify each SON Thermo-Lag 330-1 installation unsupported span in accordance with DS-C1.6.16. Typical qualified unsupported span configurations will be shown on SON site specific drawings.

13. Stress Skin Orientation (Inside or Outside)

Standard production Thermo-Lag 330-1 boards and preformed conduit sections -

are manufactured with intemal stress skin. In addition to the internal stress skin,-

a number of SON design upgrades will use external stress skin. External stress skin is an important parameter for fire endurance and seismic qualification. The designs specifying stress skin orientation will be documented in DS-M17.2.2 and SON site specific drawings. For installations that will be upgraded at SON, the -

installation, examination, and inspection for stress skin orientation parameters will be in accordance with corresponding installation and inspection documents.

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14. Stress Skin Over Joints or No Stress Skin Over Joints TVA fire tested a number of external applications of stress skin that could be used as upgrades at SON. The designs specifying stress skin orientation will be documented in DS-M17.2.2 and SON site.. pacific drawings. For installations that will be upgraded at SON, the installatior., examination, and inapection for stress skin over joints parametcrs will be in accordance with corresponding installation and inspection documents.

15. Stress Skin Ties or No Stress Skin Ties TVA tested a number of designs using stress skin ties (stitching) that could be used as upgrades at SON. The designs specifying stress skin tie placement are documented in DS-M17.2.2. Installation, examination, and inspection of stress skin ties will be in accordance with corresponding installation and inspection documents.

16. Dry-fit, Postbuttered Joints or Prebuttered Joints TVA design and testing uses complete prebuttered joints. This fire barrier parameter will be documented in DS-M17.2.2 and SON site specific drawings.

Installation, examination, and inspection for buttered joints will be in accordance with corresponding installation and inspection documents.

17. Joint Gap Width Joint gap width is specified in DS-M17.2.2. Installation, examination, and inspection for joint gap widths will be in accordance with corresponding installation and inspection documents.

18. Butt Joints or Grooved and Scored Joints TVA's fire endurance testing program tested a number of designs using both butt joints and grooved and scored (score and fold) joints. The designs specifying the type of joint will be documented in DS-M17.2.2 and site specific drawings.

Installation, examination, and inspection for joints will be in accordance with corresponding installation and inspection documents.

19. Steel Bands or Wire Ties One-hour fire barrier systems at SON will use tie wires and/or bands where qualified per DS-M17.2.2 and DS-C1.6.16. The designs specifying this barrier parameter will be documented in DS-M17.2.2 and SON site specific drawings.

The presence of tie wires or steel bands is an important parameter for seismic qualification of enclosures requiring them. Installation, examination, and inspection for tie wire / band parameters will be in accordance with corresponding installation and inspection documents.

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. 20. Band / Wire Spacing Band or tie wire spacing requirements were detamined by TVA fire endurance testing and seismic qualification evaluations. The designs specifying band or tie wire spacing will be documented in DS-M17.2.2 and SON site-specific drawings.

Approximate band or tie wire placement is a significant parameter for seismic qualification of the enclosures requiring them and is addressed in DS-C1.6.16.

Installation, examination, and inspection for tie wire / band parameters will be in accordance with corresponding installation and inspection documents.

21. Band / Wire Distance to Joints Band or tie wire distance from joint requirements were determined in the TVA testing. The designs specifying wire distance to joints will be documented in DS-M17.2.2 and SON site specific drawings. Band or tie wire placement from joints is a significant parameter for seismic qualification of the enclosures and is

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addressed in DS-C1.6.16. Installation, examination, and inspection for band or tie wire parameters will be in accordance with corresponding installation and inspection documents.

22. No Internal Bands in Trays Internal bands will not be used inside SON cable trays. The cable tray design will be evaluated in accordance with DS-M17.2.2. Installation, examination, and inspection for internal tie wires will be in accordance with corresponding installation and inspection documents.

23. No Additional Trowel Material Over Sections and Joints or Additional Trowel Material Applied TVA installations at SON used additional trowel grade in the finishing process over sections and joints. The designs specifying use of trowel grade material are acceptable as documented in DS-M17.2.2. Installation, examination, and inspection for added trowel grade material will be in accordance with corresponding installation and inspection documents.

24. No Edge Guards or Edge Guards Stainless steel edge guards will remain at SON where qualified per DS-M17.2.2 and DS-C1.6.16. Examination and inspection will be performed to ensure proper installation.

25. Cable Size and Type (Power, Control, or Instrumentation)

Cable size and type are not considered to be critical attributes because the TVA designs used at SON except as noted below will meet the 250 F average temperature rise /325oF maximum temperature rise acceptance criteria provided in

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Supplement 1 to GL 86-10. During the TVA fire test program conducted at Omega Point Laboratories, temperatures measured on the bare #8 AWG wire installed in 3-inch conduits barely exceeded the cold side temperature acceptance values. To address the performance of cables installed in the 3-inch conduit, TVA.

will perform compressive load testing in accordance with Supplement 1 to GL 86-10. In order to address the concern for size and type, SON will test representative samples of each type and manufacturer utilized in the subject 3-inch conduits, which are available in the TVA warehouse system. Where multiple constructions are available from a given manufacturer, SON will pick the construction most likely to fail as the representative specimen. Results from this testing will provide information for determining whether or not upgrading is required for each representative configuration.

Cable size and type is a consideration when determining the effects of ampacity qualification. Ampacity derating f actors are assigned depending on the type of Thermo-Lag 330-1 enclosure used. TVA design control measures ensure that the appropriate ampacity derating factor is used where a Thermo-Lag 330-1 enclosure is specified.

26. Cable Jacket Type (Thermoplastic, Thermoset) and Materials Except for the 3-inch conduit testing described above, cable jacket type is not considered to be a critical attribute since the TVA designs used at SON will meet the 250 F average temperature rise /325 F maximum temperature rise acceptance criteria provided in Supplement 1 to GL 86-10.

27. Cable Conductor insulation Type (Thermoplastic, Thermoset Plastic) and Materials With the exception of the 3-inch conduit testing described above, cable insulation type is not considered to be a critical attribute because the designs used at SON shall meet the 250 F average temperature rise /325 F maximum temperature rise acceptance criteria provided in Supplement 1 to GL 8610. Therefore, no examinations or inspections are needed to identify cable insulation type.

28. Cable Fill and Distribution of Cables Within the Protected Conduit or Cable Tray in conduits, cable fill and distribution are not considered to be critical attributes because the designs used at SON, except for 3-inch conduit barriers, will meet the 250 F average temperature rise /325 F maximum temperature rise acceptance i

criteria provided in Supplement 1 to GL 86-10. TVA testing to establish the -

acceptable designs was performed with no cables installed. Installed cable will increase the interior thermal mass and result in improved performance (i.e., inside temperatures will be lower than those which occurred during the tests).

Therefore, no examinations or inspections are needed to identify cable fill and distribution in conduits.

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In cable trays, TVA determined that a minimum mass of 1.33 pounds-per-linear:

s foot must be present in the cable tray to meet the 250oF average temperature-

-i rise /325 F maximum' temperature rise acceptance criteria provided in Supplement 1 to GL 86-10. Where insufficient mass exists, additional cable is installed to meet the mass requirements specified in TVA designs. Minimum mass I

requirements are specified in DS-M17.2.2.' Installation, examination, and inspection will be in accordance with corresponding installation and inspection 1

documents.

Seismic qualification is based on a predetermined cable weight. Cable fill and cable weight is tracked and maintained in the SON Consolidated Cable Routing System (CCRS) data base and is considered when evaluating the seismic adequacy by DS-C1.6.16.

29. Proximity of Cables to the Unexposed (Inside) Surfaces of the Fire Barrier Cable proximity to the surface of'the fire barrier is not considered to be a critical i

attribute at SON. Cables in cable trays and conduits do not come into contact with the fire barrier. Therefore, no examinations or inspections are needed to identify cable proximity to the fire barrier.

30. Presence of Materials Between the Cables and the Unexposed Side of the Fire Barrier Material (For Example, Seaftemp Cloth, Which is Used in the NUMARC Test Specimens)

Material presence is not considered to be a critical attribute because the TVA designs used at SON, except for 3-inch conduits, will meet the 250 F average temperature rise /325oF maximum temperature rise acceptance criteria provided in Supplement 1 to GL 86-10 without specifying additional material. Therefore, no examinations or inspections are needed to ensure the presence of additional materials. It should be noted that many cables at SON have been coated with the fire retardant "Flamemastic." This coating was applied before the Appendix R j

requirements were promulgated, and no credit is taken for its presence.

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31. Cable Operating Temperature l

Cable operating temperature is not considered to be a critical attribute because the 1

designs used at SON will meet the 250oF average temperature rise /325 F maximum temperature rise criteria provided in Supplement 1 to GL 86-10 or compressive load testing will have been performed as described above. Those.

latter tests assume that all power cables are operating at their rated temperature at the onset of the event. As a result of their insignificant loading, control and instrumentation cables are assumed to be operating at the maximum normal ambient temperature for their respective environments. ' Therefore, no examinations or inspections are needed to identify the cable operating temperature.

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.. 32. Temperatures at Which the Cables Can No Longer Perform Their Intended Function When Energized at Rated Voltage and Current Those temperatures are not considered to be a critical attribute because the designs used at SON will meet the 250 F average temperature rise /325 F maximum temperature rise criteria provided in Supplement 1 to GL 86-10 or compressive load testing will have been performed as described above.

Therefore, no exarrinations or inspections are needed to identify the temperatures L

at which cables can no longer perform their intended function when energized at rated voltage and current.

NRC Reauest - 2b Describe the methodology that will be applied to determine the number and type of t

representative in-plant fire barrier configurations that will be examined in detail and demonstrate that the sample size is adequate to ensure that the information and data that will be obtained are adequate to assess the total population of in-plant Thermo-Lag barriers. A large enough sample of the total population of configurations should be examined to provide reasonable assurance that the materials and important barrier parameters used to construct the in-plant barriers and any future barrier installations or modifications, are representative of the parameters used to construct the fire endurance test specimens.

TVA RESPONSE SON will be performing upgrades on conduit less than 3 inches in diameter and other unique configurations. These upgrades will be performed in accordance with G-Spec G-98; therefore, this RAI question is not applicable as the material and important barrier parameters will be addressed during the modification process.

SON will not be performing upgrades to conduits with 3 inch and greater diameters.

Based on previously performed reviews and walkdowns, the configurations of Thermo-Lag 330-1 installations at SON appear to be extremely uniform and consistent.

At this time, the methodology requested has not been determined since the Thermo-Lag 330-1 reduction program review is not completed. Based on the results of this review, the configurations and the sample size will be determined. A description of this methodology will be included in the Section 2d requested supplemental report.

NRC Reouest - 2c Submit the schedule for obtaining and verifying all of the important barrier parameters.

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, TVA RESPONSE TVA's proposed schedule for this section is contained in our response to Section 1c of this submittal.

NRC Reauest - 2d After the information has been obtained and verified, submit a written supplemental report that confirms that this effort has been completed and provides the results of the examinations and inspections. Verify that the parameters of the in-plant configurations are representative of the parameters of the fire endurance test specirnens. Describe any changes to previously submitted plans or schedules that result from the examinations.

TVA RESPONSE TVA will submit a supplemental report providing the requested information. This requested information will be included in the report committed to in the response to NRC Request 1d of this submittal. Any changes to the plans or schedules discussed above will be provided in this report.

References 1.

TVA letter to NRC dated April 15,1993, "Sequoyah Nuclear Plant (SON) - Generic Letter (GL) 92 Thermo-Lag 330-1 Fire Barriers" 2.

TVA letter to NRC dated February 10,1994, "Sequoyah Nuclear Plant (SON) -

Request for Additional information Regarding Generic Letter 92-08,'Thermo-Lag 330-1 Fire Barriers,' Pursuant to 10 CFR 50.54(f)- Sequoyah Nuclear Plant, Units 1 and 2 (TAC Nos. M85604 and M85605)"

3.

TVA letter to NRC dated July 9,1993," Watts Bar Nuclear Plant (WBN)- Results of Qualification Testing for Thermo-Lag 330 Fire Barriers (TAC M63648)"

4.

TVA letter to NRC dated December 23,1994, " Watts Bar Nuclear Plant (WBN)-

Response to NRC Questions Regarding the Use of Thermo-Lag Fire Barrier Systems at WBN (TAC M63648)"

5.

TVA letter to NRC dated November 11,1994, " Watts Bar Nuclear Plant (WBN)-

Response to NRC Request for AdditionalInformation Related to Thermo-Lag Fira Barrier Assembly Seismic Capabilities (TAC M61648)"

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ENCLOSURE 2.

Commitment TVA will submit the report required by Sections 1d and 2d of the enclosure to the December 22,1994, Request for Additional Information. This willinclude the discussion of methodology requested in Section 2b and any changes to the plans or -

schedules for Thermo-Lag resolution.

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