ML20057E486
| ML20057E486 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 08/06/1993 |
| From: | Miller I Office of Nuclear Reactor Regulation |
| To: | Mccracken C Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9310120203 | |
| Download: ML20057E486 (10) | |
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Isabel M. lliller Special Projects Section Plant Systems Branch Division of Systems Safety and Analysis SUBJlC1:
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MAf1AGfMfill AllD RfSOURCES COUllC)L'S IHIRHO-LAG fIRL BARRifR 1[S1 PROGRAMS lhe enclosed trip report. documents the f1RC's observation of lhermo-lag j
f tre barrier test specimen construction by the lexas Utilities Electric (ompany for the qualification of Thermo-Lag fire barriers installed in the Comanche Peak Steam fla t rir St at ion, Unit !, and the fluclear Management and Resources Council f or the generic qualificat ion of 1hermo-l ag fire barriers throughout the industry, lhls report covers the construction perf ormed during the week of July 26, 1993, at Omega Point t.aboratories (OPl) in San Antonio, Texas.
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ENCLOSURE TRIP REPORT Facility:
Omega Point Laboratories, San Antonio, Texas l
Licensee:
Texas Utilities Electric Company Plant:
Comanche Peak Unit 1 I
l Docket No.:
50-445 Trip dates:
July 26 through 30, 1993 Reviewer:
Isabel Miller, NRR INTRODUCTION On July 26-30, I. Miller visited Omega Point Laboratories (OPL) in San Antonio Texas. One purpose of this visit was to witness and monitor the construction of specific Thermo-Lag fire barrier test assemblies by the Texas Utilities Electric Company (TV). The other purpose of the visit was to observe the construction of Thermo-Lag fire barrier test assemblies by the Nuclear Management and Resources Council (NUMARC), which is documented on pages 4 through 9 of this report. TV personnel and contractors contacted in reference to the TU test program during this visit included C. Banning and R. Dible of j
ABB Impell Corporation, C. Pruett of TU, and L. Griffin of Brown and Root, i
Inc.
In addition, D. Priest and C. Humphrey of OPL were contacted for information on the TV testing.
CONSTRUCTION ACTIVITIES i
Backaround During a teleconference with the NRC staff on June 29, 1993, TV informed the l
staff of preliminary plans for the qualification testing of Thermo-Lag fire barrier installations in Comanche Peak Unit 1.
By letter dated July 13, 1993, TV forwarded preliminary details of the testing planned for Unit 1, which included 5 test schemes. After several discussions with the NRC staff, TU agreed to test the schemes after moisture readings reached equilibrium in accordance with ASTM E-119, " Standard Test Methods for Fire Tests of Building Construction and Meterials".
Construction of these assemblies began in July 1993, and this report documents observations made by I. Miller during the week of July 26, 1993.
Observations I
I. Miller observed the partial construction of 3 test schemes, Scheme 11-2, Scheme 11-4, and Scheme 15-2.
The following procedures and specifications were reviewed:
CPES-M-1061 Rev. O, " Fire Rated, Radiation Shielding, and Pressure l
Penetration Seals" i
. CMP-CV-1018 Rev. O, " Installation, Rework, and Repair of Penetration Seal s" Stone & Webster Engineering Corp. Specification 2323-55-30 Rev. 4,
" Structural Embedments" Stone & Webster Engineering Corp. Specification 2323-ES-100 Rev. 10,
" Electrical Installation" CPES-M-2032 Rev. O, " Procurement & Installation of Fire Barrier and Fireproofing Materials" CMP-CV-1005 Rev.1, " Application of Fire Protection Materials" Stone & Webster Engineering Corp. Specification 2323-MS-38H Rev. 3,
" Cable Raceway Fire Barrier Materials" TU originally planned on curing each test assembly for 7 days prior to testing. The staff questioned this approach, since the vendor recommends a 30 day cure time. During a phone conversation on July 20, 1993, TV agreed to take moisture readings from each test assembly in accordance with ASTM E-Il9 and run the fire endurance tests when the moisture content had reached equilibrium. The staff approved this approach. Members of the OPL staff began taking moisture readings with a Delmhorst moisture detector when the first assembly, Scheme 11-5, was completed on July 21, 1993.
The readings fluctuated significantly during the following week, so OPL and TU representatives decided to test samples of Thermo-Lag panels and the trowel grade materials in a controlled setting to calibrate the moisture data.
Although these data were still being analyzed at the completion of the site visit, TU used the available data and prior experience to set tentative test dates. Based on moisture readings taken the week of July 26, 1993, the following test dates were set:
Scheme 11-5 August 10, 1993 Scheme 13-2 August 11, 1993 Scheme 11-2 August 12, 1993 Scheme 11-4 August 16, 1993 Scheme 15-2 August 17, 1993 The construction of Schemes 11-5 and 13-2 was witnessed by A. Singh and observations will be documented in another trip report.
Scheme 11-2 consisted of a 24" x 4" ladder back cable tray with two air drop configurations, 2" and l\\" in diameter. The cable air drop bundles were protected with two layers of Thermo-Lag 330-660 "flexi-blanket" material, and the cable tray was protected with " nominal thick pre-buttered Thermo-Lag board sections with ribs. Vertical and bottom butt joints of the cable tray were reinforced with a layer of stress skin with trowel grade Thermo-Lag material. The stress skin was overlapped and stapled onto the panels.
The trowel grade material thickness was approximated. According to the installers, they were verbally instructed to continue to add trowel grade material in coats until the underlying stress skin was no longer visible. The 2" airdrop and a single cable protruding airdrop were reinforced where they entered the cable tray using flexible stainless steel mesh and trowel grade material. The trowei grade material was applied until the flexible mesh was no longer visible.
Scheme 11-4 consisted of cables airdropping from embedded wall sleeves into two stacked, 24" x 4" ladder back cable trays. The installers had just begun
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a the construction of the Thermo-Lag enclosures at the end of the week. The design of the enclosure included a Thermo-Lag box design to cover the airdrop i
cables, including both trays, and continue over to the wall penetration.
The installers were observed constructing the box with pre-buttered " nominal i
thickness Thermo-Lag board sections with ribs. The remaining portions of the 2 cable trays were also to be constructed with pre-buttered %" nominal thickness Thermo-Lag board sections with ribs.
The enclosures were to be reinforced with a layer of stress skin and trowel grade Thermo-Lag material after they were assembled.
Scheme 15-2 consisted of two cable bundles wrapped in Thermo-Lag 330-660 "flexi-blanket" material installed in an unprotected 36" x 4" ladder back cable tray. The flexi-blanket was wrapped around each cable bundle and held in place with stainless steel banding. Trowel grade Thermo-Lag material was used to fill in the flexi-blanket seams,-and the steel bands were then pulled tight. Two layers of flexi-blanket material were observed on both cables bundles, although the testing design called for one bundle to be wrapped in three layers.
TU planned on placing only the wrapped bundles in an i
unprotected cable tray.
In a phone call with TU on July 26, 1993, however, the staff questioned whether in-pant installations were properly represented in the test assembly. The staff asked if any cable trays in Comanche Peak, Unit 1, included both wrapped and unprotected cable bundles. TU agreed to check the in-plant installations and place unprotected cables in the test specimen if such situations actually existed in the plant.
SUMMARY
Based on the NRC's observations, the fabrication of the TV test specimens was accomplished in a skilled and professional manner. The installers were observed carefully following procedures and consulting with the engineering staff whenever any questions arose. Quality control personnel monitored the construction closely and properly verified the adequacy of the installations.
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Facility:
Omega Point Laboratories, San Antonio, Texas Licensee:
N/A - Construction of Test Specimens by the Nuclear Management and Resources Council (NUMARC) for the Generic Application by NRC Licensees Trip dates:
July 26 through 30, 1993 Reviewer:
Isabel Miller, NRR INTRODUCTION This section documents observations made during a visit to Omega Point Laboratories from July 26-30, 1992 on the construction of specific Thermo-Lag fire barrier test assemblies by NUMARC.
Contractors contacted in association l
with the NUMARC testing during this visit included C. Banning and R. Dible of ABB Impell Corporation and M. Jordan of Promatec, Inc.
In addition, D. Priest of OPL was contacted for information on the NUMARC testing program.
CONSTRUCTION ACTIVITIES Backaround NRC staff met with representatives of NUMARC on June 28, 1993, to discuss details of NUMARC's Thermo-Lag test program, a copy of which had been sent to the NRC on June 22, 1993. The meeting was to provide a forum for the NRC and NUMARC to follow up on the industry test program outline provided to the NRC during the meeting of June 3, 1993. The NRC staff requested additional information on the NUMARC test program by letter on July 13, 1993, and 4
l NUMARC's response was received on July 29, 1993. The following discussions l
pertain to several issues under debate in the correspondence between NUMARC and the NRC, the resolution of which will be necessary before final acceptance of the test reports used to qualify Thermo-Lag installations.
l The NUMARC test program includes two phases.
Phase 1 includes 7 upgraded test configurations which are funded by Thermal Science, Inc., the vendor, and Phase 2 includes 10 test configurations (existing industry installations and additional upgrades) which are funded by NUMARC.
Construction for Phase 1 began on July 26, 1993.
Observations ABB Impell personnel conducted the installer training on July 26, 1993. The installers are employees of Peak Seals, Inc., a subsidiary of Promatec, Inc.
The completion of training was verified, and the lesson plan was reviewed.
The installers partially completed one test scheme, Scheme 1-3, during the week of July 26, 1993, and a second scheme, Scheme 1-2, was prepared for Thermo-Lag assembly construction by the installation of cables and l
thermocouple wires in a cable tray.
Scheme 1-3 represented a 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> installation on a 36" x 4" galvanized steel ladder back cable tray.
This test specimen utilized 1" nominal thickness v-rib panels with stress skin l
on both inner and outer surfaces. The panels were dry fitted and held in 1
. i place by steel bands on the straight run portion of the tray, and the radial bends were enclosed with differing installation techniques (discussed below).
The design of Scheme 1-2, a 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> test utilizing a 36" x 4" aluminum ladder back cable tray, also included the two different installation techniques at the radial bends. As in Scheme 1-3, the design of the scheme included dry fitted, post buttered joints. The 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> (\\" nominal thickness) panel to be installed contains v-ribs and stress skin to be oriented on the inner surface of the panel. NUMARC also plans to construct the same configuration with a steel calle tray at a later date, although representatives stated that if the
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aluminum tray configuration passed the fire endurance test, that test would be used to bound similar installation techniques which enclosed both steel and aluminum cable trays.
Thermocouple Placement on Raceway t
NUMARC chose a thermocouple placement configuration which the staff believes is less conservative than the placement proposed by Supplement I to Generic j
Letter (GL) 86-10, " Fire Endurance Test Acceptance Criteria for Fire Barrier i
Systems Used to Separate Redundant Safe Shutdown Trains within the Same Fire i
Area".
Figure 1 shows the configuration of the thermocouples on the aluminum l
raceway in Scheme 1-2, as observed during the site visit.
While reviewing i
Revision 5 of NUMARC's test plan (July 29, 1993) after returning from OPL,_it was observed that the NUMARC did not accurately represent the configuration of l
the raceway in its test plan.
Figure 2 shows the depiction of the raceway in l
the NUMARC test plan.
The configuration shown in Figure 1 contains two non-conservatisms.
cable tray rungs should be placed below the rungs (see Figure 1).
Placing the l
copper conductor directly adjacent to the center cable results in a less l
severe test. The thermal properties of the cable may lower the temperatures that the copper conductor would achieve.
Placing the copper conductor under the rungs for the fire endurance test would more definitively bound the j
temperatures that cables in such a tray would be exposed to in an actual fire.
The second non-conservatism involves the design of the cable tray itself.
The l
cable tray in Scheme 1-2 observed at OPL did not have flat sides as shown in Figure 2.
The sides were actually I-shaped, as shown in Figure 1.
This configuration places an air gap between the copper conductors along the sides of the tray and the unexposed side of the Thermo-Lag enclosure.
This air gap could significantly lower the temperatures measured by the thermocouples j
during the fire endurance test.
Reports of tests performed using the configuration as shown in Figure 1 should only be permitted to qualify barriers enclosing the same cable tray design. The fact that the NUMARC test plan submitted to the NRC contains inaccurate information should be further i
pursued by the NRC.
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f Bare copper c6nductor on j
top of center cable Bare copper conductor between center cable and cable tray rungs l
Individual thermocouples on
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outside of cable tray rail l
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i Actual shape of cable tray rails Individual thermocouples on j outside of cable tray rail i
l location of bottom center bare copper conductor as recommended by GL 86-10, Supplement 1 Figure 1 Location of Copper Conductors as Observed in Cable Trays
1 Page A-1-23 REV 3 - July 1993 FIGURE 23 LOCATION OF BARE COPPER CONDUCTOR IN CABLE TRAY TEST ARTICLES l
ONE OR THREE HOUR Bare copper conductor on top of cable layer held in place by nylon ties c:--
S O O O O O O bO O O O OO i n
Bare copper conductor on cable tray rungs Figure 2 Location of Copper Conductors as Depicted in NUMARC Test Plan
. Cable Fill According to observations made during the site visit and a review of the test plan, one layer of cables was installed in cables trays for the purpose of providing thermal mass, which aids in improving the performance of the barrier. NUMARC expressed no plans to perform functionality testing of the cables. The staff views this approach as non-conservative. According to NUMARC, the cables were installed and will continue to be installed in the test specimens because, "this thermal mass is important to the performance to the fire barrier." During the site visit, NUMARC-representatives asserted that the maximum 15% fill in the test specimens will bound most in-plant configurations. The NRC staff verified that NUMARC was carefully documenting the quantity, size, and type of cables installed in the test specimens.
However, in its letter of July 13, 1993, to NUMARC, the NRC expressed the assertion that the internal temperature profiles could be inapplicable to cable fills other than those tested. The NRC staff is concerned that licensees will attempt apply the test results to in-plant barrier configurations, which have a wide range of cable fill, cable types, and cable sizes. The staff explained to NUMARC that tests without cables would resolve this issue, since the NRC would view a test of an empty cable tray to be applicable to a tray with any fill. However, NUMARC plans to continue to construct test specimens with cables.
Multiple Installation Technioues The installers were observed constructing the 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> Thermo-Lag envelope on Scheme 1-3.
The panels were dry fitted and held in place by steel bands on the straight run portion of the tray, and the radial bends were enclosed with differing installation techniques. One radius was enclosed with scored panels, held in place by 2 steel bands on each scored section, and the other radius was enclosed with mitered pieces, held in place by 2 tie wires on each mitered section. After the dry fit enclosure was completed, installers applied Thermo-Lag 330-0 trowel grad material to the seams and joints of the prefabricated panels such that seams and joints were completely covered.
Installers did not construct a Thermo-Lag enclosure for Scheme 1-1 during the week of July 26, 1993, although the tray was observed with cables and thermocouples installed. The design of Scheme 1-1 also included the two different installation techniques at the radial bends, scoring and mitering.
Discussions with NUMARC revealed thot a fire stop was to be installed at the center of the straight run portion of the tray to prevent the failure of one side from affecting the other. The NRC raised a concern that the installation of this fire stop could mask the potential failure of this straight run portion of the tray, since prior experience with TV testing has shown that this center portion is vulnerable to failure.
The fire stop could support the center portion of the tray and cause the failure of that part of the tray to be circumvented.
The NRC's position was stated as follows:
each side of the tray could be used to qualify the installation techniques used on the radial bends, but the test data could not be used to qualify the straight run portion of the tray.
C. Banning of ABB Impell considered the comments and, after consulting with NUMARC representatives, decided to move the fire stop to the interface between one of the radial bends and the straight run portion of the tray. The structural supports of the tray are located at these interfaces.
NUMARC felt that by moving the fire stop to one of the supports, the straight
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1 l 2 run of the tray would remain unsupported by a fire stop.
The test would be used to qualify either one type of radial bend (the one located next to the fire stop), or the other type of radial bend and the straight run (with no
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fire stop at the interface), or both.
i Despite the improvement in the test assembly design, the NRC continued to j
raise concerns about the use of differing installation techniques on a single i
test assembly. Any testing bias created by the impact of one technique's i
thermal performance on another cannot be quantified. The staff is concerned
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that these types of test specimens do not adequately qualify a fire barrier system design. The performance of a representative construction technique and its applicability to vertical radial bends and horizontal raceway runs may not be fully determined by tests which apply multiple techniques to a single test j
specimen. Although NUMARC responded to the staff's concerns by modifying
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certain assemblies, the use of multiple construction techniques will still be employed. This issue warrants technical resolution prior to the acceptance of l
test reports documenting qualification of the installations.
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SUMMARY
j The construction of the Thermo-Lag test specimens observed was performed with i
competence and proficiency. The installers were observed correctly following l
procedures, although they required frequent assistance from the engineering staff. Several open issues pertaining to the design of the test specimens remain.
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