ML20196B705

Forwards Preliminary Fire Endurance Test Results,As Part of Action Plan for Closure of Remaining Open Items Associated with CPSES Unit 1 Thermo-Lag Fire Barriers & 980520 Confirmatory Order

ML20196B705
Person / Time
Site:	Comanche Peak
Issue date:	11/25/1998
From:	Terry C, Walker R TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
TAC-M85536, TXX-98256, NUDOCS 9812010164
Download: ML20196B705 (6)

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Log #TXX-98256 7UELECTRlC File # 10010 909.5 Ref. # 10CFR50.48 c.ta w ery 3,,,i,, vic, p,uu,,,, November 25,1998

& PrinacipalNuclear Officer U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)- Unit 1 DOCKET NO. 50-445 PRELIMINARY FIRE ENDURANCE TEST RESULTS (TAC NO. M85536)

AND CONFIRMATORY ORDER MODIFYING LICENSE FOR TU ELECTRIC CPSES UNIT 1 REF: 1) NRC Letter from Mr. T. J. Polich to Mr. C. L. Terry dated May 22,1996 .

2) NRC Letter from Elinor G. Adensam to C. L. Terry t dated May 20,1998 l

3) TU Electric Letter logged TXX-98098 from  ;

Mr. C. L. Terry to the NRC dated April 9,1998  !

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4) NRC Letter from Mr. T. J. Polich to Mr. C. L. Terry l

dated April 1,1998

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5) TU Electric Letter logged TXX-97252 from Mr. C. L. Terry to the NRC dated December 10,1997

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6) NRC Letter from Suzanne C. Black to Mr. William J. Cahill, Jr. dated October 29,1992 f

As part of the action plan for closure of the remaining open items associated with Comanche p)l3 Peak Steam Electric Station (CPSES) Unit 1 Thermo-Lag fire barriers (items 1 and 4) as described in the NRC Safety Evaluation Report (SER) dated May 22,1996 (Reference 1) and the Confirmatory Order sent via Reference 2, TU Electric performed a fire endurance test on October 27,1998. This test (Test Scheme 13-3) was conducted with the following three (3) objectives:

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1) to evaluate the performance of Thermo-Lag raceway fire barrier systems representative of as-installed CPSES Unit 1 configurations on 12 inch wide cable trays and 2 inch diameter conduits containing lower bound cable fill conditions (open item 1);

COMANCHE PEAK STEAM EL.ECTRIC STATION P O. Rox 1002 Glen Rose. Texas 76043-1002 PDR ADOCK 05000445#

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e TXX-98256 Page 2 of 6 2)in the event that unsatisfactory performance occurred for the as-installed Unit 1 barrier system configurations, this test evaluated the performance of barriers with an increased thickness of %"(+/- 1/8-) installed on a 12 inch wide cable tray and 2 inch diameter conduit. These raceway articles also contained lower bound cable fill conditions; and

3) to evaluate the performance of Dow Coming 3-6548 silicone RTV foam material as an acceptable means for sealing terminations of Thermo-Lag envelopes on cable trays (i.e., fire stops). For this purpose, TU Electric utilized a separate 12 inch wide cable tray test article.

It should be noted that, except at specific locations, such as cable tray tee sections, condulet fitting enclosures and conduit radial bends, the fire barrier systems installed on 12 inch cable trays ar;d 2 inch conduits for CPSES Unit i have not been upgraded, and therefore differ from the corresponding CPSES Unit 2 configurations. Specifically, all Thermo-Lag protective envelopes installed on cable trays in CPSES Unit 2, are reinforced in joint areas with either tie wire " stitching" techniques, or a layer of external stress skin and Thermo-Lag 330-1 trowel grade material. Additiona!!y, all Thermo-Lag barriers installed on 2 inch diameter and smaller conduits for CPSES Unit 2 have been upgraded via use of preformed " overlay" sections to increase the installed barrier thickness by a minimum of % inch. Therefore, the fire barrier configurations evaluated in Test Scheme 13-3 did not reflect as-installed CPSES Unit 2 configurations. On this basis, Test Scheme 13-3 had no affect on previous NRC staff acceptance of CPSES Unit 2 Thermo-Lag fire barrier installations as documented via NUREG 0797, Supplements 26 and 27.

The Thermo-Lag fire barriers used for the test were fabricated using TU Electric stock material. TU Electric utilized the test plan, acceptance criteria and test articles as described in TXX-97252 and TXX-98098 (Reference 5 and Reference 3). The methodology and criteria described above, when considered in its entirety, constitute a valid qualification process for resolution of issues raised by the NRC staff. In particular, concerns regarding measurement of temperature inside cable tray enclosures and cable functionality have been resolved by use of thermocouples installed along #8 AWG bare copper conductors at six (6) inch intervals and i use of a hot air test to demonstrate cable functionality, if required.

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TXX-98256 Page 3'of 6 PRELIMINARY TEST RESULTS A description of the preliminary test results for each of the raceway fire barrier test articles is provided below.

Conduit 1 Article B 2 inch diameter conduit test article clad with %" thick (nominal) preshaped Thermo-Lag sections representing the Unit 1 as-installed barrier configuration:

Excessive temperatures were experienced on the external raceway surface and on the single 5/C 12 AWG cable within the conduit.

Therefore, this test article will not be utilized as a basis for qualification of CPSES Unit 1 Thermo-Lag barriers installed on 2 inch conduits.

Approximately 700 linear feet of CPSES Unit 1 Thermo-Lag barriers installed on 2 inch conduits are impacted by this test result. However, since the 2 inch conduit test article with additional barrier thickness (Article A) demonstrated satisfactory test performance, a design change has been initiated to increase the thickness on the affected scope of CPSES Unit 1 barriers commensurate with the Article A configuration.

Article A 2 inch diameter conduit test article fabricated the same as Article B with addition of %" thick (+/- 1/8") (wet film thickness) layer of Thermo-Lag trowel grade material over %" thick (nominal) preshaped sections:

. Average and single maximum temperatures recorded on external raceway surfaces met test acceptance criteria.

. Barrier condition following the hose stream test met test acceptance criteria.

. Cable visual inspection met test acceptance criteria.

Cable insulation resistance (megger) values met test acceptance criteria.

The performance of this test article will be utilized as the basis for qualification of the scope of CPSES Unit 1 Thermo-Lag barriers installed on 2 inch conduits described above.

TXX-98256 Page 4'of 6 Cable Trzys Article D 12 inch wide x 4 inch high cable tray test article clad with %" thick (nominal) prefabricated Thermo-Lag panels representing the CPSES Unit 1 as-installed barrier configuration:

Average and single maximum temperatures recorded on cable tray side rail surfaces exceeded those allowed by the test acceptance criteria Average and single maximum temperatures recorded on the #8 AWG bare copper conductor exceeded those allowed by the test acceptance criteria. However the maximum temperature recorded on the bare copper conductor was significantly lower than that previously used by TU Electric to demonstrate cable functionality Barrier condition following the hose stream test met test acceptance criteria.

Cable visual inspection met test acceptance criteria.

Cable insulation resistance (megger) values met test acceptance criteria.

The performance of this test article will be utilized as part of the basis for qualification of CPSES Unit 1 Thermo-Lag barriers installed on 12 inch wide cable trays.

Additionally, the NRC staff has previously accepted a TU Electric evaluation demonstrating the functionality of CPSES electrical cables at temperatures that bound those recorded on the bare copper conductor during this test (Reference 1).

Article C 12 inch wide x 4 inch high cable tray test article fabricated the same as Article D with addition of %" thick (+/- va-) (wet film thickness) layer of Thermo-Lag trowel grade material over %" thick (nominal) prefabricated panels:

Average and single maximum temperatures recorded on cable tray side rail surfaces met test acceptance criteria.

Average and single maximum temperatures recorded on the #8 AWG bare copper conductor met test acceptance criteria.

Barrier condition following the hose stream test met test acceptance criteria.

TXX-98256 Page Sof 6 Cable visual inspection met test acceptance criteria.

Cable insulation resistance (megger) values met test acceptance criteria.

Based on the performance of Article D, in conjunction with cable functionality evaluations previously accepted by the NRC staff, Article D will be used as the basis for qualification of CPSES Unit 1 Thermo-Lag barriers installed on 12 inch wide cable trays.

Article E 12 inch wide x 4 inch high cable tray test article fabricated the same as Article D with addition of a Dow Coming 3-6548 silicone RTV foam fire stop to seal the termination of the Thermo-Lag protective envelope:

. Average and single maximum temperatures recorded on the unexposed surface of the fire stop met test acceptance criteria.

. Barrier condition following the hose stream test met test acceptance criteria.

. Cable visual inspection met test acceptance criteria.

The performance of this test article can be used as a basis for qualification of silicone foam fire stops installed at CPSES for sealing terminations of Thermo-Lag envelopes on cable trays.

With respect to Reference 2, TU Electric stated that it shall complete final implementation of Thermo-Lag 330-1 fire barrier corrective actions at Comanche Peak, Unit 1 described in the TU Electric submittals to the NRC dated April 9 and May 1,1998, by December 31,1998.

These aforementioned actions are complete, moreover, the rework to upgrade the 2 inch conduit is also scheduled to be complete by December 31,1998.

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TXX-98256 Page 6of 6

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Should you have any questions or require additional information, please contact Obaid Bhatty I i

at (817) 897-5839.  ;

i Sincerely, L

C. L. Terry  ;

By: @ '

RogerD. Walker i Regulatory Affairs Manager l t

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OB:ob }

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l cc: Mr. E. W. Merschoff, Region IV  !

Mr. T. J. Polich, NRR 3

' Mr. J. I. Tapia, Region IV  :

Resident inspectors, CPSES l l l i

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