ML20081K869

Safety Evaluation Accepting Util 930226 Submittal of Confirmatory Fire Endurance Test of 36-inch Wide Cable Tray Thermo-Lag Fire Barrier

ML20081K869
Person / Time
Site:	Comanche Peak
Issue date:	08/11/1993
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20079Q777	List: ML20079Q916 ML20079Q954 ML20079R032 ML20079R417 ML20081J968 ML20081K869
References
FOIA-94-137 NUDOCS 9503290325
Download: ML20081K869 (6)

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-Enclosure 1 i

SAFETY EVALUATION BY THE'0FFICE OF NUCLEAR REACTOR REGULATION PLANT SYSTEMS BRANCH COMANCHE PEAK. UNIT-2 DOCKET NO. 50-446 I

9 AUXILIARY SYSTEMS M Other Auxiliary Systems 9.5.1 Fire Protection

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9.5.1.5 General Plant Guidelines In Supplement 27 to the Safety Evaluation Report (SSER:27), the staff.

-documented its review of the preliminary test results of the 36-inch wide Thermo-Lag 330-1 fire barrier performed by Omega Point Laboratories for Texas Utilities Electric Company.(TU Electric). This SSER. documents the staff's review of the final fire test report.

.Backaround During a meeting on September 15, 1992, the staff stated that TU Electric's test configurations did not adequately address, or bound, previous ~ test results or in-plant configurations. The staff informed TU Electric during a follow up telephone conference on September 22, 1992, that its concern would i

be resolved if it conducted a successful test of the widest cable tray installed in CPSES, Unit 2.

On September 23, 1992, TU Electric informed the NRC project manager that the widest cable tray installed at CPSES, Unit 2 was 30 inches.

It also committed to test a 30 inch wide cable tray.

This was done as Scheme 12-1, which was documented as a satisfactory test in SSER 26.

Subsequently, in its letter of January 19, 1993, TV Electric informed the staff that a 36 inch wide cable tray was installed at CPSES, Unit 2 and that it used the results of test Scheme 1-2 (36 inch wide cable tray with a tee) and Scheme 12-1 (30 inch wide cable tray).as the bases for qualifying the 36 inch wide cable tray fire barriers installed in CPSES, Unit 2.

In letters of January 25, 1993 and January 28, 1993, TU Electric provided additional information to justify the use of these two fire tests as.the licensing basis l

for installing the 36 inch wide cable tray fire barrier configuration in CPSES, Unit 2.

The staff evaluated the information provided by TU Electric and reviewed the -

fire test report for Scheme 1-2.

The staff concluded that it had reasonable assurance that the 36 inch wide cable tray Thermo-Lag fire barrier would protect one train of safe shutdown capability from fire damage. However, after further discussions with the staff about the Scheme 1-2 test, TU i

Electric, in a letter of February 1, 1993, committed to either perform a i

confirmatory test of a 36 inch cable tray, participate in an industry testing i

program to resolve concerns over a 36 inch wide barrier, or submit additional information that adequately addressed the staff's concerns.

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In a -letter of February 26, 1993,-TV Electric committed to perform a-

. confirmatory test of a 36-inch cable tray " straight run" configuration.

The-test was. observed by the NRC staff-on March 4, 1993. The licensee provided-the. final fire test report for staff review on March 19, 1993.

The licensee performed this test for two reasons:

to satisfy the commitment to perform confirmatory cable tray testing bounding the widest tray installed in the. plant, and to perform a test with a shorter cure time in order to demonstrate TU Electric's position that Thermo-Lag configurations could be considered operable less than 30 days after completion of the installation.

Test Acceptance Criteria In its letter of October 29, 1992, the staff concluded that TU Electric's acceptance criteria, as supplemented by the conditions stated in the letter, ensured that adequate cable and barrier tests would be performed and that satisfactory results from these tests would constitute an acceptable basis ~ for qualifying the CPSES, Unit 2 fire barriers.

In summary, the approved fire test acceptance criteria were:

1.

External conduit, cable tray rail, and cable jacket temperatures sh'ould not exceed 250 *F (121 *C) plus ambient temperature-(using thermocouple averaging) and no single thermocouple reading should exceed 30 percent above the specified average temperature rise.

2.

The fire barrier should not burn through or develop any. openings through which either the test specimen raceway or cables were visible.

3.

If the temperature rise criteria were not satisfied, the cables should i

be inspected. for visible cable damage. The following attributes constitute cable damsge: Jacket swelling, splitting, discoloration, hardening, blistering, cracking, or melting; conductor insulation exposed, degraded, or discolored; shield exposed; or bare copper conductor exposed.

4.

If the fire barrier burned through during the~ fire exposure, or if a visual cable inspection revealed any of the damage attributes listed above, then the barrier was considered to have deviated from the acceptance criteria. Use of the fire test.results to qualify a deviating fire barrier would require that cable functionality be demonstrated. Cable functionality test methodology and criteria were specified in the staff's letter.

Fire Endurance Test Test Soecimen Desian. Confiauration. and Construction The test specimen was constructed from raceway materials, cables, and fire barrier materials extracted from TU Electric's CPSES stock material storage areas in accordance with the licensee's site procedures. The installers buttered each joint and seam with trowel-grade Thermo-Lag material before the individual panel sections were joined together. The fire barrier included licensee-designed upgrades, which included reinforcement of longitudinal, vertical, and bottom joints with stress skin and trowel-grade Thermo-Lag i

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-material. -(The upgrades are'not specified in the vendor's recommended installation procedures.) The' licensee stated that this design was t

representative of licensee-proposed upgrades for the Unit 1 plant Thermo-Lag fire barrier configurations. The design did not include stitching of the joints as used,in previous Unit 2' tests.

The Thermo-Lag fire' barrier was measured, cut, and installed to the test

- specimen 36" x 4" ladder-back cable tray (straight run with 90 degree sweeping bends) by the licensee's contract installers using licensee-approved CPSES. '

drawings, procedures, and specifications. The installation was inspected by.

CPSES-certified quality control inspectors and the test ' laboratory's quality assurance manager.

Fire Endurance Test Results l

The test laboratory exposed the test specimen to the I hour external fire l

exposure (standard time-temperature curve) specified in ASTM E 119-88 on March 4, 1993. The laboratory controlled the furnace temperature during each i

4 test such that the area under the measured time-temperature curve was within.

10 percent of the corresponding area under the standard time-temperature curve for the I hour test period.

Following the fire exposure,.the test specimen was subjected to a hose stream test for 5 minutes. The stream was delivered through a l\\ inch (3.8 cm) fog nozzle with a spray angle of 30*, a nozzle pressure of 75-psi (517 kPa), and a i

minimum flow of 75 gpm (2841pm). The nozzle was located about 5 feet (1.5 m) from the test specimen during the test.

Based on its audit review of the test report, its' audits of the fire test specimen construction, and its fire test observations, the staff concluded that the licensee and its contract test laboratory conducted the 36 inch cable i

tray fire test in accordance with the test methodology discussed with the staff during its visits to the test laboratory, the meeting of October 27, 1992,- and the staff's letter of October 29, 1992. The staff also

. concluded that the test specimen satisfied the acceptance criteria'specified i

in the staff's letter of.0ctober 29, 1992, and was, therefore, adequate to establish the I hour fire resistance ratings of the 36 inch cable tray configuration with a seven day cure time. The results of the test are i

summarized in Table 1.

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. Jacket Stiffenina The laboratory removed the cables from each test specimen raceway and inspected them for visual damage after assessing the post-fire barrier.

condition. The licensee identified slight jacket stiffening in the radial bend areas. The remainder of the length of the cable was still flexible.

Jacket stiffening was reported in the fire test report audited by the staff.

The test report indicated that the post-fire cable insulation resistance test-I results were within acceptable specifications.

Based on its observations of i

cable condition, including the condition of the cable jacket and the insulation of the individual conductors, and the satisfactory cable insulation resistance tests, the staff concluded the jacket stiffening did not affect j

cable functionality.

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Cure Time In a letter to the staff of October 5,1991, the vendor stated that. Thermo-Lag

' trowel-grade material takes about 30 days to reach its optimum properties.

In a letter of January 19, 1993, TU Electric stated that it considered its Thermo-Lag fire barriers to be functional (capable of performing their design function) immediately'after completion of the_ barrier installation and

. inspection.- TU Electric did not provide a technical basis-for its assertion.

In its-letter of January 25, 1993, TU Electric provided additional information and a letter from the vendo'r.

In a letter, the vendor stated that it had

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revised its curing recommendation. The staff found in SSER 26 that neither TU Electric nor the vendor provided a technical basis for the revised recommendation.

TU Electric cured its previous fire test specimens for at least 30 days prior to conducting the fire endurance tests..In SSER 26, the staff expressed concern that Thermo-Lag fire barriers are not functional until they are either cured for 30 days in accordance with the vendor's original recommendation or the installed barriers reflect the tested conditions.

In a letter of January 28, 1993, TU Electric committed to provide fire watches as compensatory measures in accordance with the CPSES fire protection plan for the Thermo-Lag. fire barriers installed in areas that contain-fire-safe.

shutdown conduits or cable trays until the barriers have cured for 30 days.

i To provide a technical basis to support its position that Thermo-Lag barriers I

are functional in less than 30 days, TU Electric tested the 36 inch cable tray after it had cured only for seven days. The topcoat was applied after the assembly had cured for three days, and the fire test was conducted four days later.

The staff considers the licensee's position on cure time acceptable based on the satisfactory results of the 36 inch wide cable tray. The staff concludes that the CPSES Thermo-Lag fire barrier installations can be considered operable after a seven-day cure time.

Conclusions i

Based on its audit review of the test report, its audits of the fire test l

specimen construction, and its fire test observations, the staff concluded that the licensee and its contract test laboratory conducted the 36 inch cable tray fire test'in accordance with the test methodology discussed.with the staff during its visits to the test laboratory, the meeting of -

October 27,'1992, and the staff's letter of October 29, 1992. The staff also concluded that the test specimen' satisfied the acceptance criteria specified in the staff's letter of October 29, 1992, and was, therefore, adequate to establish the 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> fire resistance ratings of the 36 inch cable tray configuration with a seven day. cure time. Moreover, the staff concluded that the confirmatory testing of the 36 inch wide cable tray configuration, the CPSES, Unit 2 Thermo-Lag fire barriers met the guidelines of BTP CMEB 9.5-1, i

Section C.5 and was, therefore, acceptable.

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1 Test Parameter Results' Staff Conclusions l

Average Raceway Front tray rail..

244 Satisfactory Temperatures in *F Rear. tray rail...

247 (Ambient - 68 *F)

Maximum Raceway Front tray. rail..

285 Satisfactory Temperatures in *F Rear tray rail...

292 (Ambient - 68 'F)

Average Cable Power cable......

241 Satisfactory Temperatures in *F Control cable..... 210 i

(Ambient _- 68 *F)

Instrument cable.

217 i

Maximum Cable Power cable......

277 Satisfactory Temperatures in *F Control cable....

224 (Ambient - 68 *F)

Instrument cable.

240 l

Barrier Condition No openings Satisfactory l

Cable Condition Slight jacket Satisfactory stiffening.

(See evaluation of jacket stiffening-in SSER) f Table 1.

36 inch Cable Tray Test Applied to CPSES, Unit 2 (Scheme 15-1)

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.SPLB SALP INPUT Plant Name:

Comanche Peak, Unit 2 SER

Subject:

Review and approve test report on Thermo-Lag 330-1 36 inch cable tray configuration TAC No.:

M85998 Summary of Review / Inspection Activities The staff reviewed the. licensee's submittal on the testing of the Thermo-Lag 330-1 fire barriers in a 36 inch cable tray configuration and found it acceptable. The licensee conducted the test in response to the staff's concern that the fire barriers installed in Comanche Peak, Unit 2, were not completely bounded by previous tests.

Narrative Discussion of Licensee Performance - Functional Area The licensee was responsive in addressing issues raised by the staff and provided adequate technical resolution.

Author:

Isabel Miller Date:

August il,1993 i

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