ML20034D581
| ML20034D581 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 11/25/1992 |
| From: | Khadijah West Office of Nuclear Reactor Regulation |
| To: | Mccracken C Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML082410566 | List: |
| References | |
| TAC-M83330, NUDOCS 9302170304 | |
| Download: ML20034D581 (7) | |
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November 25, 1992 ENCLOSURE 5
MEMORANDUM FOR: Conrad E. McCracken, Chief Plant Systems Branch Office of Nuclear Reactor Regulation THRU:
Ralph E. Architzel, Chief Special Projects Section Plant Systems Branch Office of Nuclear Reactor Regulation FROM:
K. Steven West, Senior Fire Protection Engineer Special Projects Section Plant Systems Branch Office of Nuclear Reactor Regulation
SUBJECT:
TRIP TO OMEGA POINT LABORATORIES REGARDING TEXAS UTILITIES ELECTRIC COMPANY THERMO-LAG FIRE BARRIER TEST PROGRAM (TAC M83330)
On November 16,1992, Paul Gill, Electrical Engineering Branch, and I visited Omega Point Laboratories, San Antonio, Texas, to witness a fire endurance test of a Thermo-Lag 330-1 fire barrier for Texas Utilities Electric Company (the licensee). The licensee declared the test successful based on limited temperature rise, satisfactory post-fire inspections of the fire barriers and the cables, and satisfactory cable insulation resistance tests. Subject to staff review of OPL's test report, I concur with the licensee's conclusion.
My trip report is enclosed.
/ ORIGINAL SIGNED BY/
K. Steven West, Senior Fire Protection Engineer Special Projects Section Plant Systems Branch Office of Nuclear Reactor Regulation
Enclosure:
As stated DISTRIBUTION See next page W
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9302170304 930210 PDR COMMS NRCC CORRESPONDENCE PDR
ENCLOSURE' TRIP REPORT Facility:
Omega Point Laboratories, San Antonio, Texas Licensee:
Texas Utilities Electric Company Plant:
Comanche Peak Steam Electric Station, Unit 2 Docket No.: 50-446 Date:
November 16, 1992 Reviewer:
Steven West, NRR/DSSA/SPLB INTRODUCTION
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On November 16,1992, I visited Omega Point Laboratories (OPL), San Antonio, Texas. I was accompanied by Paul Gill, Electrical Engineering Branch. The purpose of my visit was i
to witness a fire endurance test of Thermo-Lag 330-1 fire barrier performed by OPL for Texas Utilities Electric Company (TU Electric, the licensee). My point of contact was Obaid Bhatty, TU Electric. I discussed the fire test with Mr. Bhatty; Cal Banning, i
ABB Impell; Chester Pruett, Fluor Daniel; and Deggory Priest and Herb Stansberry, OPL.
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EXECUTIVE
SUMMARY
l OPL performed a fire endurance qualification test of a 30-inch wide cable tray protected by l
ti an upgraded Thermo-12g 330-1 fire barrier. TU Electric proposed the fire barrier design for installation in Comanche Peak Steam Electric Station (CPSES), Unit 2. The test assembly was exposed to a 1-hour ASTM E-119 standard fire followed by a fog nozzle hose stream l
OPL and the licensee declared the fire endurance test successful based on limited test.
temperature rise, satisfactory post-fire inspection of the fire barrier and the cables, and satisfactory cable insulation resistance (megger) tests.
1 observed the fire test, the hose stream test, and the post-fire megger test. I also scanned the raw thermocouple data during the fire exposure and inspected the Thermo-Lag barrier and the cables after the tests. The barrier remained intact during the fire exposure and hose stream test without burning through or developing any openings through which either the raceway or the first layer of stress skin were visible. I did not see any visual cable damage.
Subject to staff review of OPL's test report, the test was satisfactory and qualified the subject Thermo-Lag 330-1 fire barrier configuration for installation at CPSES, Unit 2.
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%. The test specimen included licensee-designed upgrades. Therefore, the results of the test do not affect NRC Bulletin 92-01 or its supplement.
OPL will conduct additional fire tests for the licensee throughout November and early December. Some of the fire barrier designs to be tested are proposed by the. licensee as upgrades for the CPSES, Unit 1 Thermo-Lag barriers.
SCHEME 12-1 OPL tested Scheme 12-1 on November 16, 1992. The test assembly consisted of a straight run of 30-inch wide by 4-inch high ladder back cable tray with a 90 degree sweeping bend at each end and one layer of power, control, and instrumentation cables. It was protected with
%-inch thick preshaped Thermo-Lag 330-1 prefabricated panel sections with ribs. The vertical and bottom joints were reinforced with tie wires and a layer of stress skin. The Thermo-Lag thickness over the stress skin was increased with Thermo-Lag 330-1 trowel-grade material as specified in the licensee's site specifications. The longitudinaljoints were upgraded by reinforcing the joints with stress skin and Thermo-Lag 330-1 trowel-grade material. The test specimen was coated with the vendor's topcoat material and cured for at least 30 days before the fire test.
Thermocouples were attached to the outside surfaces of the cable tray side rails at 12-inch intervals and on the insulation along the length of one power, one control, and one instrumentation cable at 6-inch intervals. A total of 101 thermocouples were installed.
Mr. Banning informed me that Alexander Utilities Engineers (AUE), San Antonio, Texas, an OPL subcontractor, performed conductor-to-conductor and conductor-to-ground cable insulation resistance tests on November 13,1992, with megohmeters provided by the licensee. Up-to-date TU Bectric calibration stickers were affixed to the megohmeters.
On the day of the test, OPL connected the cables into a single series circuit. This circuit was energized with low voltage (12 volts DC) to monitor circuit integrity dudng the fire exposure and hose stream tests.
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OPL exposed the test assembly to the standard 1-hour time-temperature fire found m i
ASTM E119. The Thermo-Lag material began to burn about 2 minutes into the fire l
exposure and continued to burn throughout the fire test.
1 The test specimen temperatures rose slowly and fairly uniformly during the first 14 minutes of the fire exposure. Then, the thermocouples began to exhibit erratic behavior. After about 20 minutes, most of the thermocouples displayed unbelievable readings. Many read 0 *F l
while others indicated negative temperatures. At this point, OPL began to troubleshoot its
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computerized data acquisition and control system. OPL removed the multiplex system circuit boards from the Fluke HELIOS I signal processor, cleaned their contacts, and reinserted j
them. This appeared to correct the temperature monitoring and acquisition problems.
Consequently, about 46 minutes into the fire test, OPL rebooted the data acquisition j
computer and recorded the test specimen thermocouple temperatures until the end of the test.
f The specimen temperatures rose slowly and uniformly without further incident.
i Following the test, Mr. Stansberry verified the thermocouple calibration and informed me f
that the they were within specifications ( 2* C). Mr. Priest stated that the data acquisition J
breakdown was a signal processing problem that was caused by a poor multiplex system f
board connection. He informed me that the problem would be documented in the test report.
(The furnace thermocouples were connected to a separate data acquisition system and were not affected.)
The licensee's conditions of acceptance specify that the fire test is successful if the j
transmission of heat through the fire barrier does not raise the average temperature of any j
thermocouple string (cable tray side rail or cable surface) 250 *F above its initial temperature I
and if the transmission of heat through the barrier does not raise the temperature of any smgle thermocouple 30 percent in excess of the specified average temperature rise. The i
licensee's criteria also specify that the test is successful if the barrier is intact and the cables do not have any visual fire damage after the fire and hose stream tests, even if the temperature rise criteria are exceeded. Heat transfer through the subject barrier (as measured during the beginning and end of the fire exposure) did not raise the average temperature of the cable tray rails or the cable surfaces above 320 *F (250 *F above their initial temperatures) or the temperature of any single thermocouple above 395 *F (30 percent in excess of the specified average temperature rise). As discussed below, the fire test met j
the licensee's conditions of acceptance for post-fire barrier and cable condition. Therefore, l
l the loss of the test specimen temperature data during the middle portion of the test is not a concern.
The initial and final test specimen temperatures (raw data) are shown in the following table.
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Time 0 minutes l
Time 60 minutes i
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5 Iecation Average ! Maximum ; Average Maximum '
Power Cable
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71 *F 71 *F l 255 *F 311 "F Control Cable 71 *F 72 *F 228 *F l 288 *F l
l 72 *F i 232 *F 288 *F Instrument Cable 72 *F Front Tray Rail 70 *F 71 *F 270 *F 3 363 "F t
Rear Tray Rail 70 *F l
71 'F 273 *F 243 *F Scheme 12-1 Test Specimen Temperatures After the one hour fire exposure, the test assembly was lifted from the furnace.' Within about 5 minutes of its removal, the assembly was subjected to a hose stream test. OPL used a 30* fog nozzle with a nozzle pressure of 75 psi. The nozzle was located about 5 feet from the assembly. The water spray was applied for 5 minutes. The Thermo-Lag material bumed until it was extinguished by the hose stream. The hose stream dislodged negligible amounts of the char layer from the fire barrier surfaces.
AUE started the post-fire megger tests within 10 minutes of the hose stream test. It took about I hour and 15 minutes to complete the tests. The licensee informed me that with the exception of one shield-to-ground measurement for an instrumentation cable, the cable insulation resistance values obtained during the megger tests were within acceptable limits.
While AUE was conducting the megger tests, OPL and the licensee inspected the fire barrier.
After this inspection, OPL disassembled the barrier and inspected its component pieces and the cable tray. OPL and the licensee concluded that the Thermo-Lag barrier remained intact
1 t during the fire exposure and hose stream test without burning through (see the section on burnthrough, below) or developing any openings.
Next, OPL and the licensee visually inspected the cables forjacket swelling, splitting, blistering, cracking, hardening, and discoloration; exposed shielding, conductor insulation, and bare copper conductor; and conductor insulation degradation and discoloration. OPL and the licensee did not identify any of these attributes for any of the cables.
OPL and the licensee concluded that the test specimen fire barrier met the licensee's conditicas for acceptance for temperature rise through the barrier, post-fire barrier and cable condition, and satisfactory megger tests, and was, therefore, successful.
I observed the megger tests, the fire test and the hose stream test and inspected the barriers and the cables after the tests. I agree that the barrier remained intact during the fire exposure and hose stream test without burning through or developing any openings through which the raceway, the cables, or the innermost layer of stress skin were visible. I did not observe any fire barrier surfaces that did not have virgin Thermo-Lag 330-1 material remaming. I did not observe any visible cable damage. Subject to staff review of OPL's
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test repon, I believe the test was satisfactory and qualified the baniers for installation at CPSES, Unit 2.
BURNTHROUGH Burnthrough is defined as an opening in the fire barrier through which the raceway or a cable is visible. By design, Thermo-Lag barriers typically have one or more layers of stress skin between the raceway and the Thermo-Lag 330-1 matenal. Stress skin is not likely to burn away dudng the fire exposure or wash away during a fog nozzle hose stream test. The stress skin would, however, obstruct the view of the raceway. Therefore, burnthrough has l
also occurred if an opening develops in the Thermo-Lag 330-1 material through which the innermost layer of stress skin is visible.
CABLE INSULATION RESISTANCE MEASUREMENTS fMEGGER TESTING)
In a letter of October 29,1992, the staff documented the results of its review of the licensee's fire test methodology and acceptance criteda. In this letter the staff stated that
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megger tests (cable insulation resistance measurements) should be performed for
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instrumentation cables before the fire exposure, at least once during the fire exposure, and immediately after the hose stream test. AUE performed megger tests of the instmmentation i
cables before the fire exposure and after the hose stream test but did not megger them during
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the fire exposure. During my visit to OPL of November 3,1992, Mr. Bhatty informed me l
that the licensee decided not to perform megger tests of the instrumentation cables during the fire exposure because: (1) the megger tests would require that the circuit integrity circuit be disconnected, which would interrupt the circuit integrity monitoring, (2) OPL would not
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allow megger testing of cables while its data acquisition system was connected to the cable thermocouples, and (3) the cables will be at or near their maximum temperatures immediately following the hose stream test. The licensee believes that the worst case insulation resistance values would exist at the end of the test, when the cables are at their 1
maximum temperatures, rather than midway through the test.
i The licensee's test methodology and acceptance criteria specify that cable functionality be demonstrated when the cables show signs of fire damage or.when the fire barrier burns l
through or opens up. These conditions were not observed during the subject fire test.
Therefore, the licensee's failure to conduct megger tests of the instmment cables during the t
i subject test is not a concern.
i DATA ACOUISITION SOFTWARE VALIDATION OPL's computerized data acquisition and control system is a Macintosh IIsi computer connected to a John Fluke Company Model HELIOS I signal processor. During the data j
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acquisition incident, Mr. Priest informed Paul Gill and I that he programmed the computer.
j (I believe the software is Microsoft Quick Basic.) I recommend that the staff should l
determine whether or not their are regulatory requirements or staff guidance regarding data
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acquisition software validation. If so, the licensee should address software validation in a t
future test program submittal.
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