ML20206Q009

Safety Evaluation Accepting GL 92-08, Thermo-Lag 330-1 Fire Barriers, Dtd 921217,for Comanche Peak Electric Station,Unit 1

ML20206Q009
Person / Time
Site:	Comanche Peak
Issue date:	05/14/1999
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20206Q006	List: ML20206Q003 ML20206Q009
References
GL-92-08, GL-92-8, NUDOCS 9905190039
Download: ML20206Q009 (4)

Text

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SUPPLEMENTAL SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO THERMO-LAG FIRE BARRIERS MAY 22.1996. SAFETY EVALUATION TEXAS UTILITIES ELECTRIC COMPANY l

COMANCHE PEAK STEAM ELECTRIC STATION (CPSESL UNIT 1  ;

DOCKET 50-445

1.0 INTRODUCTION

By letter dated May 22,1996, the U.S. Nuclear Regulatory Commission (NRC) staff issued its safety evaluation (SE) to Texas Utilities Electric Company (the licensee) concerning the J Thermo-Lag fire barriers installed at Comanche Peak Steam Electric Station (CPSES), Unit 1.

The May 22,1996, SE addressed seven open items concerning the qualification and application of the Thermo-Lag fire barriers and fire stops, and the silicone foam fire stops installed at CPSES, Unit 1, to meet NRC fire protection requirements. On December 5,1996, the NRC staff met with the licensee at NRC's Region IV offices in Arlington, Texas, to discuss the resolution for the seven open items. By letter dated October 1,1997, the NRC staff closed open items 2,5,6, and 7 from the May 22,1996, SE. By letters dated November 6 and December 10,1997, February 13 and Ncvember 25,1998, and March 2,1999, the licensee provided additional information, including a fire endurance test report, to address the remaining l seven open items from the May 22,1996, SE. I I

The NRC staff has reviewed the information provided by the licensee in the referenced submittals and has concluded that the licensee has adequately resolved the technical issues related to items 1,3, and 4 from the May 22,1996, SE, such that these remaining items can be closed.

2.0 EVALUATION On October 27,1998, the licensee conducted a fire endurance test of Thermo-Lag fire barriers

! and a silicone foam fire stop design (Test Scheme 13-3) at Omega Point Laboratories in Glen Rose, Texas. The fire test was conducted in accordance with a test plan submitted to the NRC by letter dated December 10,1997, as amended by letters dated February 13,1998, and April 9,1998, to rescNe staff comments provided to the licensee in a letter dated April 1,1998.

The 1-hour fire exposure followed the time-temperature curve established by the American Society for Testing Materials (ASTM) Standard E-119-88," Standard Methods of Fire Tests of e nclosure 9905190039 990514 PDR ADOCK 05000445 P PDR

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. Building Materials." The NRC staff documented the acceptance criteria for the Thermo-Lag fire barriers at CPSES in a letter to the licensee dated October 29,1992.

Test Scheme 13-3 Descriotion This test deck consisted of five test articles; two conduit assemblies and three cable tray assemblies as described below.

Article A consisted of a single 2-inch diameter galvanized rigid steel conduit enclosed in

%-inch thick Thermo-Lag 330-1 preshaped sections and a condulet fitting enclosed in %-inch Thermo-Lag 330-1 panels. Alljoints were prebuttered with Thermo-Lag 330-1 trowel grade material. The barrier materials were secured with 0.50 inch by 0.020 inch stainless steel banding. All joints and interfaces with the condulet fitting enclosure were reinforced with a layer of external stress skin secured with staples and covered with Thermo-Lag trowel grade material. The preshaped sections on the conduit were upgraded with a 1/4-inch layer of Thermo-Lag trowel grade material. After curing, the entire article envelope was covered with Thermo-Lag 311 topcoat.

Article B consisted of a single 2-inch diameter galvanized rigid steel conduit enclosed in

%-inch thick Thermo-Lag 330-1 preshaped sections and a condulet fitting enclosed in %-inch Thermo-Lag 330-1 panels. Alljoints wee prebuttered with Thermo Lag 330-1 trowel grade l

- material. The barrier materials were secured with 0.50 inch by 0.020 inch stainless steel i banding. All joints and conduit interfaces with the condulet fitting enclosure were reinforced with a layer of external stress skin secured with staples and covered with Thermo-Lag trowel grade material. After curing, the entire article envelope was covered with Thermo-Lag 311 topcoat.

Articles A and B were filled with a single control cable (5C/#12 AWG 600v) to represent a fill of 8.6 percent.

Article C consisted of a 12-inch wide by 4-inch deep steel ladder back cable tray enclosed in

%-inch thick Thermo-Lag 330-1 panels. The panel joints were prebuttered with Thermo-Lag trowel grade material and secured with 0.50 inch by 0.020 inch stainless steel banding. An j upgrade consisting of a 1/4-inch layer of Thermo-Lag trowel grade material was applied to the bottom and side panels of the envelope. After curing, the entire envelope was covered with Thermo-Lag 311 topcoat. This test article was filled with 19 instrumentation cables (5-Twisted Quad, #16 AWG 600v and 14-Shielded Twisted Pair, #16 AWG 600v) to represent a fill of 5.5 percent.

Article D consisted of a 12-inch wide by 4-inch deep steel ladder back cable tray enclosed in

%-inch thick Thermo-Lag 330-1 panels. The panel joints were prebuttered with Thermo-Lag trowel grade material and secured with 0.50 inch by 0.020 inch stainless steel banding. After curing, the entire envelope was covered with Thermo-Lag 311 topcoat. No upgrades were applied to this test article. This test article was filled with 19 inctrumentation cables (5 Twisted Quad, #16 AWG 600v and 14-Shielded Twisted Pair, #16 AWG 600v) to represent a fill of 4.6 percent.

Article E consisted of a 12-inch wide by 4-inch deep steel ladder back cable tray provided with a 10 %-inch thick silicone foam fire-stop with ceramic fiber blanket as a perrranent damming

3-material. The cable tray was enclosed with %-inch thick Thermo-Lag panels. After curing, the entire envelope was covered with Thermo-Lag 311 topcoat. This test article was filled with

- 40 instrumentation cables (8-Twisted Quad, #16 AWG 600v and 32 Shielded Twisted Pair,

1. 16 AWG 600v) to represent a cable fill of 11.4 percent.

Test Results -

Article A passed the fire endurance and hose stream test acceptancie criteria and is qualified as a 1-hour fire barrier assembly. During the detailed examination following the hose stream test, ,

the enclosure showed no evidence of bum through or barrier openings and the cable inside the conduit showed no indication of thermal degradation, insulation resistance testing conducted on the cable was also acceptable.

Article B exceeded the temperature acceptance criteria at 44 minutes into the test and recorded  !

a maximum single point temperature over 1000 *F above the maximum allowed. During the detailed examination following the hose stream test, the enclosure showed cpenings in two locations and the cable inside the conduit showed signs of thermal degradation, insulation resistance testing of the cable also indicated significant insulation damage as a result of the fire )

exposure. This assembly did not rnset the acceptance criteria for a 1-hour fire resistance

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rating. I Article C exceeded the temperature acceptance criteria at 59 minutes into the test and recorded an average temperature of 8 'F above the maximum allowed. During the detailed examination following the hose stream test, the enclosure showed no evidence of burn-through or barrier openings and the cables inside the cable tray enclosure showed no indication of thermal degradation. Insulation resistance testing conducted on the cables was also acceptable.

Based on the licensee's cable functionality evaluations for Test Scheme 13-2 that bound the data recorded on this test article, which was reviewed and accepted by the staff in the May 22, 1996, SE, this configuration is acceptable.

Article D exceeded the temperature criteria at 46 minutes into the test and recorded an average temperature of 98 'F above the maximum allowed and a single point temperature of 53 'F above the maximum allowed. During the detailed examination following the hose Weam test, the enclosure showed no evidence of burn through or barrier openings and the cables inside i the cable tray enclosure showed no indication of thermai degradation. insulation resistance  ;

testing conducted on the cables was also acceptable. Based on the licensee's cable 1 functionality evaluations for Test Scheme 15-2 that bound the data recorded on this test article, ,

which was reviewed and accepted by the staff in the May 22,1996, SE, this configuration is l

acceptable. l Article E passed the fire endurance and hose stream test acceptance criteria and is qualified as a 1-hour fire-stop assembly.

Ooen item 1 - Raceways at CPSES. Unit 1. where the total enclosed thermal mass is less than the total enclosed thermal mass of the tested confiourations.

In its letter dated December 10,1997, the licensee committed to upgrade electrical raceways with a thermal mass less than the thermal mass of the tested articles in Test Scheme 13 3, in M m

L. .e  !

l accordance with a tested configuration previously reviewed and accepted by the staff for l CPSES, Unit 2, in NUREG 0797, Supplements 26 and 27. j i

i In its letter dated November 25,1998, the licensee committed to upgrade the 2-inch dicmeter conduit barriers for enclosures with a thermal mass equal to or greater than the thermal mass of Articles A and B in accordance with the configuration tested in Article A of Test Scheme 13-3. For 12-inch wide cable trays with a thermal mass equal to or greater than the thermal mass of Articles C and D, the licensee has elected to rely on the configuration tested in l Article D of Test Scheme 13-3.

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The licensee has adequately resolved the concems associated with this item. This item is

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closed.

Ooen Item 3 - Thermo-Lao fire stoos installed in cable travs at CPSES. Unit 1.

In its letter dated November 6,1997, the licensee provided additional information conceming the qualification of the Thermo-Lag fire-stops installed at CPSES, Unit 1. This information

} included the test results reported from Nuclear Energy Institute (NEl) Test 2-8, which exceeded the single point temperature criteria at 58 minutes, and achieved a maximum recorded temperature on a cable tray side rail of 16 'F above the maximum allowed at the conclusion of l

the 1-hour test. The November 6,1997, letter also included the licensee's engineering l evaluation provided in ER-ME-067, Rev. 5, " Evaluation of Thermo-Lag Fire Barrier Systems," P which provided a technical basis for the licensee's conclusion that the fire endurance performance Thermo-Lag fire-stop configurations at CPSES, Unit 1, would meet or exceed the performance of the configuration represented by NEl Test 2-8. l l

The licensee has adequately resolved the concerns associated with this item. This item is  !

closed. l Open item 4 - Silicone fire-stoos installed in cable travs at CPSES. Unit 1. where the aualification is based on fire tests that used silicone elastomer.

The fire endurance test performance of Article E of Test Scheme 13-3 is acceptable as previously stated.  ;

The licensee has adequately resolved the concems associated with this item. This item is  !

closed.

3.0 ' CONCLUSION l

The licensee has resolved the three remaining open items from the SE dated May 22,1996, as I specified in the staff's October 1,1997, letter to the licensee. By letter dated December 22, f 1998, the licensee stated that all corrective actions for Thermo-Lag fire barriers at CPSES, Unit 1, have been completed.

Principal Contributors: E. Connell A. Pal Date: May 14, 1999 .

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