ML20202H368
| ML20202H368 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 02/13/1998 |
| From: | Terry C TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TAC-M85536, TXX-98028, NUDOCS 9802200364 | |
| Download: ML20202H368 (26) | |
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bi .:5 Log # TXX 98028 i r C File # 10010, 909.5B M# ELECTRIC Ref. # 10 CFR 50.48 feDruary 13, 1998 C. lance Drey Senior Mce 1*rrMent
& l'rincipwlFuclear Oplcer U. S. Nuclear P gulatory Commission j
Attn: Document Control Desk -
Washington DC 20555
SUBJECT:
CCMANCHE PEAK STEAM ELECTRIC STATION (CPSES). UNIT 1 DOCKET NOS. 50 445 THERMO. LAG MCEWAY TESTING (TAC NO. M85536)
REF: 1) TV Electric Letter. logged TXX 97252, from C. L. Terry to the NRC dated December 10. 1997
- 2) NRC letter from Suzanne C. Black to William J. Cahill dated October 29, 1992
- 3) Generic Letter 86 010 Cup.1
- Fire Endurance Test Acceptance Criteria for Fire Barrier Systems Used to Separate Redundant Safe Shutdown Trains Within the Same Fire Area (Supplement 1 To Generic Letter 86 10. ' Implementation of Fire Protection Requirements')" dated March 25, 1994
- 4) NUREG 0797 Supplement 26 of February 1993
- 5) NUREG 0797 Supplement 27 of April 1993
- 6) NRC letter from T. J. Polich to C. L. Terry dated May 22, 1996 Gentlemen: i This lettea is a follow up to the letter provided in reference 1). In reference 1). TV Electric stated that it intended to perform a
" confirmatory / qualification" test of selected fire barrier configurations to resolve the two remaining Open items perthining to the NRC's final
-acceptance of the fire barriars for CPSES Unit 1. TV Electric committed '
to perform this test using the criteria agreed upon in reference 2).
Revised fire test assembly drawings are attachted. The NRC staff pointed out in subsequent phone calls that reference 3) provides more recent NRC guidance concerning the criteria to be used for fire barrier testing.
TV Elactric has reviewed this guidance and has concluded that it is importet that TV Electric not change testing criteria *mid stream."
Having multiple sets of criteria in the licensing basis and design basis could create potential problems in the future and makes it difficult to compare test results in a meaningful way. The criteria in reference 2),
which were clarified by references 4) 5), and 6). M ve been accepted by the NRC as assuring that all regulatory requirements for fire barrier testing are met for CPSES. This finding by the NRC continues to be true. '
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To provide further assurance, TV Electric has evaluated the differences between references 2) and 3) and has concluded that, in spite of these differences, the criteria in reference 2) continue to provide the assurance needed to conclude that the CPSES fire barriers will meet all applicable regulatory requirerents. This evaluation is attached. The evaluation identifies the appropriate criteria from the October 29, 1992, letter and the as:t.:iated criteria from Generic Letter 8610 suo91ement 1. For each criterion, a remarks column explains the acceptability of the difference, if any.
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This communication contains the following new commit
- ant which will be completed as noted:
j CDF Number Commitment 27124 The cable used in the fire test described in TXX 98028 of February 13, 1998, will be visually inspected following the fire test and any potential cable damage will be addressed.
Tll :lectric is very interested in expeditiously resolving these fire barrier matters and in obtaining NRC approval of the fire barriers for CPSES Unit 1. The testing discussed in this letter is viewed as an effcetive means of accomplishing these goals. If you have questions concerning the content or meaning of this letter, please contact Mr. Obaid Bhatty (254 897 5839) of my staff. If upon reviewing this letter, the NRC staff feels that technical aspects of the TV Electric proposal deserve further discussion, or that alternate methods may be more effective in resolving the barrier matters, please notify Mr. Bhatty and TV Electric will gladly meet with the NRC staff to discuss their ideas or suggestions.
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Attachments OB/ob c- E. W. Herschoff, Region IV J. 1. Tapia. Region IV T. J. Polich, NRR Resident Inspectors, CPSES i
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I Attachment I to TXX-98028 Page 1 of 16 .
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FIRE TEST CRITERIA COMPARISON .
NO OCTOBER 29. 1992 CRI IRIA GL 86-10 SUPPLEMENT 1 CRITERIA REMARKS 1 TEMPERATURE TEMPERATURE With respect to determining the The average unexposed side Crn cia are the same.
temperature acceptance criteria, temperature of the fire barrier the NRC staff considers system, as measured on the thermocouple averaging exteric.' surface of the raceway acceptable. provided similar or componant. did not exceed series of thermocouples (e.g.. 139' C [250' F] above its initial cable tray side rail) are temperature: and averaged together. It was determined that the temperature (. . .For the purposes of this performance of the cable tray criterion, thermocouple ;
fire barrier would be based on averaging can be used provided temperature average (i.e.. the similar series of thermocouples l thermocouples on each side rail. (e.g., cable tray side rail) are and the thermocouples on each of averaged together to determine the three instrumented cables) temperature performance of the and would be independently raceway fire barrier system. In evaluated against the addition. conditions of temperature acceptance criteria. acceptance are placed on the
.... It is our understanding temperatures measured by a that your temperature acceptance single thermocouple. If any criteria would find the test single thermocouple exceeds 30
- results in deviation if the percent of the maximum allowable average temperature of any temperature rise (i.e.. ...
thermocouple series exceeds the [250'F + 75T = 325T]). the test
, 2501: plus ambient condition or exceeded the temperature .
. if any single thermocouple criteria limit.) !
exceeds 30 percent above the '
maximum allowable temperature 1
! rise (i.e. 250'F + 75T - 325T.
above ambient) during the test. j l
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. to TXX-98028 l Page 2 of 16 l NOl0CTOBER 29. 1992 CRITERIA GL 86-10 SUPPLEMENT i CRITERIA REMARKS l 2 VISUAL EXAMINATION VISUAL EXAMINATION L
If this [the temperature Irrespective of the unexposed The acceptance criteria for the !
acceptance criteria exceeded] side temperature rise during the inspection of the cables are the occurs. under your criteria a fire test. if cables or same. The letter criteria does visual inspection of the cables components are included in the not require the cable inspection !
for sign of thermal damage is fire barrier test specimen, a if all the temperature criteria !
required. visual inspection should be are met while the GL requires ,
performed. Cables should not "the cable inspection. The test i Your visual cable acceptance show signs of degraded procedures used by TU Electric !
criteria ... stated that none of conditions resulting from the equires an inspection of the the following attributes should thermal affects of the fire cable and any potential cable ,
be identified: jacket swelling. exposure; damage would be addressed. !
splitting, or discoloration: l shield exposed; or jacket Examples of thermal cable hardening. The NRC staff has degradation are: jacket determined that the following swelling, splitting, cracking, attributes also indicate thermal blistered. selted. or degradation: Jacket blistering, discoloration: shield exposed: ;
cracking or melting; conductor conductor insulation exposed.
insulation exposed. degraded, or degraded or discolored; bare discolored; and bare copper copper conductor exposed. ;
conductor exposed. l __
Attachment I to TXX-98028 Page 3 of 16 -
NO OCTOBER 29. 1992 CRITERIA GL 86-10 SUPPLEMENT 1 CRITERIA REMARKS 3 BARRIER CONDITION BARRIER CONDITION
[B]urnthrough is now a deviation The cable tray. raceway, or Criteria are the same.
requiring cable functionality component fire barrier system testing. If burnthrough occurs, remained intact during fire based upon visual examination exposure and water hose streas and notwithstanding the size of test without developing any the defect. the NRC views the openings through which the cable fire barrier as deviating from tray. raceway. or component the fire barrier requirements (e.g.. cables) is visible... No and would require that cable visible signs of component.
functionality be demonstrated. raceway or cable: after fire and
, hose streas test.
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t Attachment I to TXX-98028 -
Page 4 of I6 -
l NO OCTOBER 29. 1992 CRITERIA GL 86-10 SUPPLEMENT 1 CRITERIA REMARKS -
4 THERMOCOUPLE PLACEMENT THERMOCOUPLE PLACEMENT a) Thermocouples at 12 inch a) ...every 152 mm [6 inch] on a) See b) below.
intervals on exterior conduit the exterior conduit surface i' surface. underneath the fire barrier material.. attached ...
opposite the test deck and ;
closest to the furnace fire source.
b) Thermocouples at 12 i".ch u)1) ...every 152 mm [6 inch] b) The appropriate thermocouple intervals on exterior of tray down the longitudinal center interval and location are based side rails. along the outside surface of the on the ability of the i cable tray side rails.... thermocouples to provide a good average temperature and to b)2) AWC 8 stranded bare copper adequately reflect temperature conductor ... installed on the peaks. The steel raceway used bottom of the cable tray rungs by CPSES provides adequate along the entire length and down thermal conductivity without the longitudinal center of the using bare copper wire.
cable tray run . . thermocouples Attaching the thermocouples -
placed every 152 mm [6 inch] ... directly to the cable tray side along the baie copper ails is representative of as-conductor.... installed conditions. Cable trays. ct CPSES. are manufactured in accordance with site specific technical requirements. These documents .
invoke NEMA VE-1 titled ;
-Metallic Cable Tray Systems.-
This standard requires that an electrical continuity test be ;
performed at a cable tray joint.
The resistance. measured between l 2 points 6 inches on each side of the joint. shall be a maximum l' of 0.00033 ohns. This test
Attachment I to TXX-98028 Page 5 of 16 .
NO OCTCBER 29. 1992 CRITERIA GL 86-10 SUPPLEMENT 1 CRITERIA REMARKS .
4 THERMOCOUPLE PLACEMENT THERMOCOUPLE PLACEMENT demonstrates that the cable trays are good conductors of electrical energy. and are therefore good conductors of thermal energy. Since all trays previously tested are representative of installed configurations. and this test is designed to validate actual field conditions. attaching the thermocouples to the cable tray side rails at 12 inch intervals is appropriate. For the testing :
conducted by CPSES using the 1992 criteria, these thermocouples will provide the temperature readings necessary to properly assess the .
performance of the fire barrier j material -
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Attachment I to TXX 90028 Page 6 of 16 -
i NO OCTOBER 29. 1992 CRITERIA GL 86-10 SUPPLEMENT 1 CRITERIA REMARKS -
4 THERMOCOUPLE PLA. CEMENT THERMOCOUPLE PLACEMENT c) 6 inch intervals on the c) AWG 8 stranded bare copper c) The primary purpose of this cables. conductor ... installed along measurement is cable the outer top surface of the functionality. The NRC has cables closest to the top and approved a cable functionality towards the center of the fire methodology (see item NO. 9 barrier ...thermocouples placed below) for CPSES using every 152 mm [6 inch] ... along thermocouples on the cable. The the bare copper conductor.... use of thermocouples on cables was found acceptable for CPSES based on the types of cable used by CPSES and the fact that only CPSES plant specific cables were being used/ qualified in the fire test. As a result, the NRC concluded that the CPSES testing was acceptable using this plant specific approach of placing the thermocouples on cables instead of the generic approach of placing the thermocouples on a bare copper wire.
d) thermocouples should also be d) thermocouples should also be d) Criteria are the same.
placed immediately adjacent to placed immediately adjacent to all structural members, all structural members, supports, and barrier supports. and barrier penetrations. penetrations.
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Attachment I to TXX-98028 Page 7 of 16 i
NO OCTOBER 29. 1992 CRITERIA GL 86-10 SUPPLEMENT 1 CRITERIA ' REMARKS 5 HOSE STREAM HOSE STREAM A hose spray test will be For raceway fire barrier The letter criteria is an conducted, using the guidance of systems. the staff adopted the acceptable option within the BTP CMEB 9.5.1 and IEEE Std. hose stream testing methodology criteria provided in the G*m.
634-1978 for penetration specified in NUREG-0800.
seals.. . . Fog Nozzle Test " Standard Review Plan (SRP) for the Review of Safety Analysis Reports for Nuclear Power Plants. "Section 9.5.'1.
" Guidelines for Fire Protection i for Nuclear Power Plants.-
Revision 2. July 1981. position t F.a. This SRP position established the acceptability of using the fog nozzle method for ,
hose stream testing of fire 6 barrier penetration seals. The fog nozzle hose stream test method is an acceptable option !
for test of the entire raceway fire barrier system under the new staff position.
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Attachment 1 to TXX-98028 Page 8 of 16 -
NO OCTOBER 29. 1992 CRITERIA GL 86-10 SUPPLEMENT 1 CRITERIA REMARKS 6 CABLE CIRCUIT INTEGRITY TEST CABLE CIRCUIT INTEGRITY TEST
[SSER 27] The staff does not [C]ircuit integrity monitoring The GL criteria and the letter consider circuit integrity is not required to satisfy NRC criteria (as modified by SSER ,
measurements an adequate test of acceptance criteria for fire 27) are the same.
cable functionality. and has barrier qualification.
determined that post-fire megger testing (described in the acceptance criteria as appropriate cable functionality testing) should be conducted as soon as 'ssible following the test. Therefore. TU Electric's minor change to their test methodology (not performing circuit integrity seasurements) is acceptable.
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Attachment 1 to TXX-98028 Page 9 of 16 -
i NO IOCTOBER 29. 1992 CRITERIA 'GL 66-10 SUPPLEMENT 1 CRITERIA REMARKS _
7 CABLE INSULATION TESTS CABLE INSULATION TESTS
[A]t time intervals (at lecst To provide reasonable assurance Even though TU Electric has a ;
once) during your one-hour fire that the cables would have cable functionality methodology l
exposure test, a megger test functioned during and afte' the which has been accepted by the should be performed for fire exposure. Megger tests need NRC (see NO. 9 below) and which instrementation cables in order to be performed before the fire relies on cable temperatures in to assure that the cable will test. at multiple time intervals lieu of megger readings, the use maintain sufficient insulation during the fire exposure (i.e.. of megger tests during the fire resistance levels necessary for every 20 minutes during the 1- test was evaluated. The proper operation of instruments. hour fire test and every hour Insulation Resistance (IR) during the 3-hour fire test) for testing required by the NRC has The megger tests (pre-fire. instrumentation cables only, and not been performed in '
1 during the fire [if performed]. immediately after the fire conjunction with a fire barrier !
i and immediately after the fire endurance test to assess the acceptance test. There are i 1
test conditions) should be done cable insulation resistance several factors which have i conductor-to-conductor for levels. This testing will contributed to why TU Electric multiconductor and conductor-to- assure that the cables will does not feel it is prudent to ground for all cables. saintain the insulation introduce this test protocol resistance levels necessary for into the CPSES testing at this Additionally. NUREG-0797 proper operation of instruments. tias. '
Supplement 27 (page 9-4) states that. "[T]he staff . . . has The Hegger tests (pre-fire. Of primary concern is TU ;
determined that post-fire during the fire [if performed]. Electric's desire to ensure the testing (described in the and immediately after the fire accuracy of the cable j acceptance criteria as test conditions) should be done temperature data collected appropriate cable functionality conductor-to-conductor for during the fire test. The testing) should be conducted as multi-conductor and conductor- presence of a test voltage on soon as possible following the to-ground for all cables. the cable samples will test." potentially affect the thermocouple readings of the monitored cables. The i thermocouples used to monitor .
cable temperatures are extremely sensitive (1 millivolt of noise induced onto the thermocouple will cause a 40' F error in its
Attachment I to TXX-98028 Page 10 of 16 .
NO OCTOBER 29. 1992 CRITERIA GL 86-10 SUPPLEMENT 1 CRITERIA REMARKS temperature reading). the possibility that cable leakage currents or ground loops could !
affect the thermocouple readings !
is a significant concern. Since a noise induced inaccurate reading could cause a thermocouple to read high. or >
low. the entire test methodology could become suspect.
While the possibility of noise induced error is TU Electric's ,
primary concern. it is not the only area of concern. 1 Conducting the segger tests at i the prescribed time intervals may jeopardize the validity of the one-hour fire test. In order to obtain IR values at 60 minutes the test samples must be left in the furnace while the zegger tests are completed. -
This could result in a 70 to 80 minute fire test because of the ;
-baking
- of the cables samples !
while the 60 minute megger I readings are being completed. t i
The testing laboratory performing the testing for TU l Electric has stated that performing the wegger test I during the fire test introduces additional safety hazards for .
personnel and equipment. When !
these potential safety hazards :
. i Attachment I to TXX-98028 Page 11 of 16 -
(
NO OCTOBER 29. 1992 CRITERIA GL 86-10 SUPPLEMENT 1 CRITERIA REMARKS -
are considered in concert with the complicating technical factors discussed above. TU Electric has concluded it is not prudent to introduce this new aspect to the testing methodology for CPSES. TU Electric should continue to implement the cable -
functionality methodology allowed by the NRC letter of May
- 22. 1996, to establish cable functionality, if required. As noted in item NO. 9 below this CPSES sethodology has been found acceptable for the fire testing as performed by TU Electric when testing is performed in accordance with the 1992 criteria.
8 MEGGER AND HI-P0T VOLTAGES AND MEGGER AND HI-POT VOLTAGES AND The criteria in the October 29.
ACCEPTABLE RESISTANCE VALUES ACCEPTABLE RESISTANCE VALUES 1992. letter are identical to the criteria in GL 86-10 supp.
1.
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Attachmer.t I to TXX-98028 Page 12 of 16 -
NO OCTOBER 29. 1992 CRITERIA 'GL 86-10 SUPPLEMENT 1 CRITERIA REMARKS 9 CABLE FUNCTIONALITY CABLE FUNCTIONALITY Any sign of thermal cable damage For those cases where signs of Under both sets of criteria.
would be a deviation to the fire thermal degradation are present, cable functionality must be bcrrier requirements which would the fire barrier did not perform demonstrated if the test does require the functionality of the its intended fire-resistive not satisfy the temperature, cabling to be demonstrated by function. For those barriers visual cable inspection or testing. which are not capable of burnthrough criteria, as performing their intended applicable.
If burnthrough occurs, based function, a deviation based or.
upon visual examination and demonstrating that tne notwithstanding the size of the functionality of thermally defect. the NPC views the fire degraded cables or component was barrier as deviating from the maintained and that the cables fire barrier requirements and or component would have would require that cable adequately performed their functionality be demonstrated. intended function during and after a postulated fire exposure may be granted. The attachment to this position provides a methodology for demonstration the functionality of cables during and after a fire test exposure. The purpose of the functionality tests is to justify observed deviations in fire barrier performance.
. to TXX-98028 Page 13 of 16 -
NO OCTOBER 29. 1992 CRITERIA GL 86-10 SUPPLEMENT 1 CRITERIA REMARKS 9 CABLE FUNCTIONALITY (CONT.) CABLE FUNCTIONALITY (CONT.)
[I]n determining the insulation Alternate methods to assess TU Electric intends to apply the resistance levels required for degradation of cable cable functionality criteria nuclear instrumentation cables. functionality will be evaluated approved by the NRC. if cable an assessment of the minimum by the staff for acceptability functionality evaluation is insulation resistance value on a case-by-case basis. required.
(e.g. one mega-ohm) and its potential impact on the functionality of these cables should be evaluated.
[NRC letter of May 22, 1996.
from T. J. Polich to C. L. Terry and enclosed safety eva?uation]
A test is accepted if all of the cables within the test article meet the staff acceptance criterion of 1.0E6 C2-1000ft when calculated using the SNL composite cable analysis method.
This calculation is based on the actual measured cable temperatures. If the calculated cable IR values exceed the above criterion. then the effects of power cable operation are assumed to be bounded by the margin within the above criterion. Test articles that passed this initial criterion exhibited no other evidence of cable degradation indicating significant barrier failure (e.g.. severe cable damage through charring. burn through of barrier raaterial).
Attachment 1 to TXX-98023 Page 14 of 16 NO OCTOBER 29. 1992 CRITERIA GL 86-10 SUPPLEMENT 1 CRITERIA REHARKS 9 CABLE FUNCTIONALITY (CONT.) CABLE FUNCTIONALITY (CONT.)
[NRC letter of May 22. 1996. Alternate methods to assess TU Electric intends to apply the from T. J. Polich to C. L. Terry degradation of cable cable functionality criteria and enclosed safety evaluation] functionality will be evaluated approved by the NRC. if cable by the staff for acceptability functionality evaluation is If the staff acceptance on a case-by-case basis. required.
criterion is not met. SNL
[Sandia National Laboratory]
performed a single-point hot-spot analysis based on the measured hot-spot IR performance. The single hot-spot temperature for each cable in each test article was used as the worst-case peak temperature measured along the length of the cable specimen in the test article. This value corresponds to the single highest surface temperature measured along the length of a given cable during the entire test.
Attachment I to TXX-98028 Page 15 of 16 NO OCTOBER 29. 1992 CRITERIA GL 86-10 SUPPLEMENT 1 CRITERIA REMARKS 9 CABLE FUNCTIONALITY (CONT.) CABLE FUNCTIONALITY (CONT.)
[NRC letter of May 22. 1396. Alternate methods to assess TU Electric intends to apply the from T. J. Polich to C. L. Terry degradation of cable cable functionality criteria and enclosed safety evaluation] functionality will be evaluated approved by the NRC. if cable by the staff for acceptability functionality evaluation is on a case-by-case basis. required.
For those tests which failed to meet the acceptance criteria.
the staff agreed to accept the SNL recommendation that cable hot-spot per!ormance be used in the final determination for acceptability of fire barrier configurations. This recommendation is based on past cable-testing experierce in both E0 and fire safety arets. This experience indicates that the failure of an electrical cable due to high temperature exposures is likely to occur at a localized point rather than along the full length of an exposed cable...An evaluation of the cable performance at the hot-spot location during the fire cxposure tests would most accurately reflect this experience.
Attachment I to TXX-98028 Page 16 of 16 NO OCTOBER 29. 1992 CRITERIA GL 86-10 SUPPLEMENT 1 CRITERIA REMARKS 9 CABLE FUNCTIONALITY (CONT.) CABLE FUNCTIONALITY (CONT.)
[NRC letter of May 22. 1996. Alternate methods to assess TU Electric intends to apply the from T. J. Polich to C. L. Terry degradation of cable cable functionality criteria and enclosed safety evaluation] functionality will be evaluated approved by the NRC. if cable by the staff for acceptability functionality evaluation is In addition. a value of 1.0E3 on a case-by-case basis. required.
[2-1000 ft should be utilized as the minimum acceptable IR limit for the predicted hot-spot behavior because (1) the level of circuit degradation associated with instrumentation.
control, and power cable applications would be acceptable and (2) a good correlation between fire exposure testing and severe accident steam exposures indicates that cable IR values in the range of the threshold limit provide a modest margin to thermal damage despite the uncertainty associated with the characterization of potential cable hot soots based on the test data.
SUMMARY
As can be seen from the table abcve. the differences between the two criteria are not significant. The criteria in the present CPSES licensing basis has been found acceptable by the NRC for CPSES Unit 2 and most of the configurations for Unit 1. TU Electric has experience testing in this manner as hcs the test laboratory used by TU Electric. Changing the criteria at this time is not warranted when the current CPSES licensing basis is acceptable and essentially equivalent to the criteria in Generic Letter 86-10. Supplement 1.
Attachment 2 to TXX 98028 Page 1 of 3 IS$UES ADDRESSED BY THE NRC DURING FEBRUARY 2.1998 TELEPHONE CONFEREEE
- 1) CONFIRMATORY TEST V.S. OVALIFICATION TEST TU electric is proposing to perform a fire endurance teat to obtain temperature data for specific Unit 1 Thermo Lag fire barrier configurations installed on 2 inch conduits and 12 inch wide cable trays c(ntaining low cable fills. The primary objective of this test is to confirm the results of a similar test performed in 1993 (Scheme 13 2), which also evaluated the performance of as installed Unit 1 Thermo Lag barriers on 2 inch conduits and 12 inch cable trays. However, in the Scheme 13 2 test, although the .:able fills used were representative of actual plant configurations, they did not bound low fill conditions. Moreover, during the test, temperatures recorded on the external surfaces of the conduit and cable tray exceeded those allowable by the acce)tance criteria, Additionally, a localized area of
- burnthrough" occurrec for the cable tray barrier. In accordance with the test acceptance methodology, TV Electric used cable insulation resistance measurementF (recorded before and after firc exposure), in conjunction with the maxim / ,emperatures recorded on cable surfaces, to demonstrate that the enclosed cables would be capable of performing their design function. The NRC accepted this method for demonstrating cable functionality for the Scheme 13 2 test via safety evaluation dated May 22, 1996. However, since the enclosed cable fills for the tested barriers did not bound those for all installed plant configurations, NRC acceptance of this test for qualification of Unit 1 barriers on 12 inch cable trays and 2 inch conduits is currently limited to those fire barrier configurations containing equivalent or greater cable fill.
To address this issue, one 2 inch conduit and one 12 inch cable tray article to be included in the proposed test will specifically replicate as installed barrier designs protecting bounding case cable fill conditions. However, for the proposed test, TU Electric anticipates that although raceway surface temperatures in excess of those allowable by the acceptance methodology will be reached, acceptable temperatures should be maintained on cable surfaces.
On this basis. TV Electric intends to use the same, previously accepted, methodology to demonstrate functionality of the cables in the proposed test.
Accordingly. TU Electric believes that changing the methods used to 1) measure cable insulation resistance or 2) obtain temperature data within the barrier enclosures, will invalidate the confirmatory nature of the proposed test.
In summary, bounding case plant cable fill conditions will be utilized for the proposed test articles, and the type, number and construction of enclosed cables will replicate specific plant configurations. Additionally, the barriers to be installed on one 2 inch conduit a'id one 12 inch cable tray will replicate as installed Unit 1 barrier systems for these commodities.
- 2) HEGGER TESTING Provided in attachment 1
- 3) INSTRUMENTATION Provided in attachment 1
Attachment 2 to TXX 98028 Page 2 of 3
- 4) INSTRUMENTATION OF FIRESTOP Open Item 4 involves the acceptability of fire stop? constructed of. silicone foam material installed within cable trays protected with I hour rated Thermo.
Lag fire barrier systems, where such cable tray protective envelopes terminate away from structural surfaces such as walls, floors, etc.
Several Unit 1 cable tray fire barrier configurations utilize Dow Corning 3-6548 Silicone RTV Foam material at locations where Thermo Lag coverage on cable tray runs is no longer required. Their purpose is to effectively seal the cable tray protective envelope by preventing excessive thermal transmission through the fire stop and into the protective envelope due to exposure of the unprotected portion of the cable tray to a postulated fire. In this capacity, these fire stops function as >enetration seals for the cable tray barrier enclosure. In essence, althoug1 these fire stops are an integral part of the one hour Thermo Lag fire barrier, the most appropriate methodology for evaluating the performance of the silicone foam cable tray fire stop configuration that TV Electric plans to include in the proposed fire test will be based on IEEE 634 (1978), ' Standard Cable Penetration Fire Stop Qualification Test."
The proposed test configuration will consist of a vertically oriented 12" x 4" cable tray segment. A Thermo Lag fire barrier system representative of those installed on 12" cable trays in Unit 1 (i.e., without design upgrades) will enclose the tray except for the lowermost 12" portion, which will remain exposed in the test furnace. At the point where the Thermo Lag coverage terminates, a fire stop consisting of a 10" depth of Dow Corning 3 6548 Silicone RTV Foam material (with 1" thick damming board on both sides of the stop) will be installed. In accordance with IEEE 634, the
{ performance of the fire stop assembly for fire endurance acceptance purposes will be based on the temperature of-its unexposed surface. The thermocouples for determining acceptance of the fire stop will be located as follows (REFER TO DIAGRAMS):
One (1) thermocouple will be positioned on the unexposed surface of the fire stop at a point approximately 1" from one of the tray '
side rails.
One (1) thermocouple will be positioned on the unexposed surface '
of the fire stop at a point approximately 1" from a penetrating cable.
One (1) thermocouple will be positioned on the unexposed surface !
of the fire stop at a point near the center which is approximately l equidistant from the penetrating cables and the edge of the fire i stop.
The performance of the fire stop for the fire endurance portion of the test will be deemed-acceptable provided the temperature rise recorded by each of the thermocouples described above does not exceed 325'F above their initial (ambient) temperature. This acceptance temperature is consistent with the scximum temperature rise for a single thermocouple based on reference 2).
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Attachment 2 to TXX 98028 Page 3 of 3 Additionally, the temperature of the cable tray side rails will be monitored near the unexposed surface of the fire stop for information purposes only.
Specifically, one (1) thermocouple will positioned on-the inside surface of each side rail approximately I' from the unexposed surface of the fire stop.
For the hose stream portion of the test, the methodology employed for previous TV Electric fire endurance tests, Reference 2) is more conservative than that prescribed by IEEE 634, and will therefore be used for the fire sto) assembly.
Specifically immediately following the fire endurance test, the ca)1e tray fire stop assembly will be subjected to a water hose stream applied using a
- 30. degree angle spray nozzle with a minimum pressure of 75 psi at a distance .
of 5 feet, for a 5 minute duration. The minimum flow from the nozzle will be i 75 gpm. The performance of the fire stop for the hose stream portion of the i test will be deemed acceptable provided a sufficient quantity of material is '
not dislodged as to result in a through opening in the fire stop assembly.
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a Attachment 3 to TXX-98028
. Page 2 of 5 PROPOSED TEST SCHEWE 13 3 12x4 CABLE TRAY AND 2'8 CONDulf f
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. ' Attachment 3 to TXX-98028 Page 3 of 5 PROPOSED TEST SCHEWE 13 3 12x4 CABLE TRAY FIRE STOP f
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. Attachment 8 to TXX-98028
. Page 4 of 5 PROPOSED TEST SCHEME 13-3 {
12x4 CABLE TRAY AND 2'O CONDUlf CONDUIT CONFIGURATION Conduit Thermocouple located at G" intervals l l Cable Thermocouple located at 12" intervals TRAY CONFIGURATION I I Cable (Ty;0 [f'[;E*in$e"r a$s C ble Tray fa
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