ML18152A043

Ad-Hoc Endurance Test of Unprotected Steel Duct Sys Final Rept

ML18152A043
Person / Time
Site:	Surry
Issue date:	10/31/1988
From:	Hafer C, Stamp N, Wenzel A SOUTHWEST RESEARCH INSTITUTE
To:
Shared Package
ML18152A044	List: ML18152A043 ML18153D297 ML18153D298 ML20035E675
References
NUDOCS 9304190082
Download: ML18152A043 (33)

Text

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I SOUTHWE'T RESEARCH f\\T/ A-c HM E r-JT I I'S T ITUTE f'\\

POST OFFICE DRAWER 28510

• 6220 CULEBRA ROAD* SAN ANTONIO. TEXAS. USA 7828'

• 15121 6U-5111

• TELEX 2.. 8'6 DEPARTMENT OF FIRE TECHNOLOGY AD-HOC FIRE ENDURANCE TEST OF UNPROTECTED STEEL DUCT SYSTEMS FINAL REPORT SwRJ PROJECT N0. 01-2427-001 OCTOBER 1988 Prepared for:

HUGHES ASSOCIATES, INCORPORATED 2730 UNIVERSITY BOULEVARD WEST, SUITE 902 WHEATON, MARYLAND 20902

~e,~p Reviewed by:

Approved by:

Nigel R. Stamp

(;°:f:!/!f P[ f!!:{1cf 7J Research Scientist Fire Testing Services Manager Fire Testing Services Director, Fire Technology for Dr. Robcn E. Lyle Vice President, Chemistry and Chemical Engineering Th,s r*oon 1s for the 1nforma1,on of the Chent. II may ba us.a,n 1t1 en11t1t1Y lor UHi ouroosa of 1ecu11n9 oroc:1uct *cceo1*nc* hom auly cons111u1ed *ooroval *u1hon1,e1. Ne,fher 1tu1 reoon nor,,,. n*m* 01 the ln1111u1e sn*n De used,n cuo1ic,1v or *oven,1,na S A N A N T O N I 0, T E X,;;. S DAllAS I FT WORTH TEXAS. HOUSTON. TEX.AS. DETROIT. MICHIGAN. WASHINGTON. DC

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OBJECTIVE The objective of this program was to demonstrate whether an unprotected steel duct that does not contain a fire damper at the fire barrier opening, will remain in place throughout a 120-minute fire exposure and effectively maintain the integrity of the fire barrier at that opening, *consistent with the criteria for fire dampers.

The results ob-tained from this test program will be used to determine whether fire dampers are needed in existing steel duct systems at 2-hour fire barriers or what modifications to the duct system would be required to protect the fire barrier opening.

ll.

INTRODUCTION The test exposes the test specimens to a standard fire exposure (AS1M El 19-83.

Standard Methods of Fire Tests of Building Construction and Materials) controlled to achieve specified temperatures throughout a specified time period, as shown below:

TIME 0 minutes 5 minutes 10 minutes 30 minutes 45 minutes 60 minutes 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 4 hours TEMPERATURE Ambient lOOO"F (538"C)

I300"F (704"C) 1550"F (843"C) 1638"F (892"C) 1700"F (927°C)

I850"F (1010"C) 2000"F (1093"C) lbis rcpon describes the analysis of three distinct assemblies, and includes descriptions of the test procedure followed, the assemblies tested, and all results obtained.

The results presented in this rcpon apply only lo the malerial lesled, in lhe manner tested, and not to any identical or similar materials or malerial combinations.

All test data arc on file and are available for review by authorized persons.

DEPARTMENT OF FIRE TECH~OLOGY

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TF.Sr PROCEDURE SwRI's large horizontal exposure furnace is capable of exposing a maximum test specimen of 12 ft long and 16 ft wide.

The 80-in. deep furnace is equipped with 14 premixed air/natural gas burners located across the walls, 18 in. up from the bottom and controlled by a variable air/gas ratio regulator.

Capable of a maximum heat output of 14 million Btu/hour, these burners are arranged well below the exposed face of the specimen to ensure an even temperature at the face of the specimen.

Windows are located on all sides of the furnace to allow observation of the surface exposed to flame.

The conduct of the fire test is controlled according to the standard time/

temperature curve, as indicated by the average temperature obtained from the readings of ten thermocouples symmetrically located across the face of the specimen, 12 in. away.

The thermocouples are enclosed in protection tubes of such material and dimensions that the time constant of the thermocouple assembly lies between_ 5.0 and 7.2 minutes, as required by the standard.

The furnace temperature during a test is controlled such that the area under the time/temperature curve is within 10 percent of the corresponding area under the standard time/temperature curve for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or less tests, 7.5 percent for those less than 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, and 5 percent for those tests of 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> or more duration.

Temperatures of both the unexposed and exposed surfaces are measured with No. 20 B&S gauge, type K (Chromel-Alumel) welded thermocouples.

The furnace pressure was controlled at the Client's request to be approximately

+0.03 in. of water pressure, measured 0.78 in. (20 mm) below the insulated cover slabs.

N.

TFSI' ASSEMBLY A.

Duce No. 1 A rectangular steel duct, constructed of 36 x 30-in. x 22-ft long 22-gauge galvanized steel sheet, was comprised of three 5-ft sections and two 3.5-ft sections.

The duct construction conformed to the Sheet Metal and Air Conditioning Contractors National Association, Incorporated (SMACNA), HV AC Duct Construction Standards, Metal and Flexible, First Edition, 1985.

The longitudinal scams were of the

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p 'j '4 of Io bunon punch snap-lock type, identified as L-2 in the SMACNA standards. The transverse (ginh) joints were of the Standing S type, identified as T-11 in ijle SMACNA standards to give a minimum rigidity of Class D.

The duct section was supponed by a trapeze comprising 0.375-in. diameter steel hanger rods and 2.5 x 0.25-in. steel angle, located at the midpoint of the span (6 ft from the furnace walls).

Both of the hanger rods were positioned 2 in. away from the sides of the duct. The trapeze was adjusted so the top surface of the duct was located approximately 30 in. below the underside of the insulated cover slabs.

B.

Duct No. 2 A circular duct, constructed of 36-in. diameter x 22-ft long 20-gauge stainless steel sheet, was comprised of four 4-ft sections and two 3-ft sections. All joints between the duct sections were continuously welded together. The duct construction con-formed to SMACNA, HVAC Duct Construction Standards, Metal and Flexible, First Edition, 1985. It was supported at the mid-point (6 ft from the furnace walls) by a 3-in.

wide x 20-gauge stainless steel band wrapped around the duct which was attached to an adjustable clevis type hanger suspended from a 0.5-in. diameter steel hanger rod.

Toe hanger assembly was adjusted so that the top surface of the duct was located approx-imately 24 in. below the underside of the insulated cover slabs.

C.

Duct No. 3 A rectangular steel duct, constructed of 36 x 30-in. x 22-ft long 22-gauge galvanized steel sheet, was comprised of three 5-ft sections and two 3.5-ft sections. The duct construction conformed to SMACNA, HY AC Duct Construction Stan-dards, Metal and Flexible, First Edition, 1985. The longitudinal scams were of the button punch snap-lock type, identified as L-2 in the SMACNA standards. The transverse (ginh) joints were of the Standing S type, identified as T-11 in the SMACNA standards to give a minimum rigidity of Class D.

The duct was reinforced with 1.5 x 1.5-in. x IO-gauge (0.138-in.) steel angle tack welded to the duct (see SMACNA, HY AC Construction Standards, Metal and Flexible, First Edition, 1985). The angle reinforcement was located a minimum of 2 in. away from both the inside and outside of the furnace wall.

The duct was supported by a pair of trapezes located 4 ft on center, comprising 0.375-in. diameter steel rods and 2.5 x 0.25-in. thick steel angle. The hanger rods were adjusted so that the DEPARTMENT OF FIRE TECHNOLOGY 3

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top surface of the duct was located approximately 30 in. below the underside of the cover slabs.

They were insulated with 0.5-in. diameter x 1-in. \\,hick x 14-lb/ft3 Manville Toermo-12 calcium silicate pipe insulation. Toe insulation was cut to fit on-site and the longitudinal joints were tightly butted together and wired in place with 16-gauge stainless steel wire, 12 in. on center.

Toe two ducts with mechanical joints (Duct Nos. 1 and 3) were assembled at SwRI and all three were laid across the 12-ft dimension of SwRI's large horizontal furnace. They were spaced 1.5 ft from the inside furnace walls and 2 ft apart (Figure 1).

The height of the furnace walls were then increased by an additional 69 in., using masonry blocks, to ensure that the ducts were exposed on all four sides. A minimum 1-in.

clearance was maintained around the perimeter of all three ducts (except for the base of each which was in contact with the masonry).

The ducts extended a minimum of 5 ft beyond the furnace on either side.

Toe furnace was then covered with concrete cover slabs insulated with ceramic fiber. Toe hanger rods for all three ducts extended through the cover slabs and were secured on the unexposed surf ace. Toe gaps bet ween the ducts and the masonry block wall were then fire stopped with ceramic fiber blank.ct.

V.

INSTRUMENT AT/ON Toe temperatures of the outside (exposed and unexposed) surfaces of the steel ducts were measured with No. 20 B&S gauge, type K (Chromel-Alumel) welded thermo-couples.

Temperature readings were taken on the duct walls, at the duct joints, the hanger rods and the steel angle-section suppons. Toe locations of all thermocouples are shown in Appendix A, Construction Drawings. The radiant heat flux from the unexposed face of Duct No. 3 was measured using a heat flux transducer (radiometer) with a view restrictor anachrnent producing a 30" angle of view.

Toe radiometer was positioned so that its field of view was entirely filled with the steel duct section and nothing else.

VI.

RESULTS On September 9, 1988, at 4:25 P.M.. the thermocouple connections were verified and the furnace ignited with the following people in attendance: Mr. Richard G. Gcwain and Mr. Joseph Sd:effy representing the Client: Mr Bruce G. Campbell representing Rockwell International: and Mr. Andrew Pryor representing the Dcpanmcm of Energy.

DEPARTMENT OF FIRE TECHNOLOGY 4

The furnace was controlled according to the requirements of AS1M E 119-83, Standard Method of Fire Tests of Building Construction and Materials, Section 4, Furnace Temperatures.

The furnace pressure was controlled as per the Client's request to be approximately +0.03 in. of water pressure, measured 0.78 in. below the concrete cover slabs.

There were no significant observations recorded throughout the 120-minute fire exposure.

None of the duct sections collapsed or fell into the furnace and the integrity of each system, where it extended through the fire wall, remained intact.

No through-opening developed between a fire stop and a duct at any wall penetration.

VII.

POST-TEST OBSERVATIONS After the furnace had been allowed to cool down for several days, a thorough investigation was conducted to confinn the condition of the exposed portion of each duct system (see Appendix B, Photographic Documentation).

A.

Duct No. I The duct had warped such that the top of the duct had buckled downward by a maximum of 11 in. in the center. The sides of the duct had warped and buckled inward by a maximum of 5.5 in. at the center of the 12-ft span. Where the duct extended through the masonry wall, there was a maximum warpage of 2 in. at the top and sides. The hanger assembly was intact and still in place.

B.

Duce No. 2 There was minimal, if any, visible distonion of this duct or the hanger.

C.

Duct No. 3 The duct had warped such that the top of the duct had buckled downward by a maximum of 8.75 in. in the center. The sides of the duct had warped and buckled inward by a maximum of 3.5 in. at the center of the 12-ft span. Where the duct DEPARTMENT OF FIRE TECHNOLOGY 5

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extended through the masonry wall, there was a maximum warpage of 0.5 in. at the top and sides. Two of the spot welds between the angle rcinforcclJ}ent and the duct had been broken inside the furnace. The hanger assembly was intact and still in place.

A complete listing, with graphical presentation of data from the radiometer and all thermocouples monitored, is presented in Appendix C.

Vil/.

CONCLUSIONS All conclusions relating to this project will have to be drawn by the Oient.

All necessary temperature data and observations are contained in the appropriate appendices.

DEPARTMENT OF FIRE TECHNOLOGY G

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APPENDlXA CONSTRUCTION DRAWINGS DEPARTMENT OF FIRE TECHNOLOGY

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-- e UNITE[) STATES NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION WASHINGTON, D.C. 20555 July 27, 1992 AiTrTc:..H ME~ z f~ Io{~

NRC INFORM~TION NOTICE 92-55: CURRENT FTRE ENDURANCE TEST RESULTS FOR THERMO-LAG FIRE BARRIER MATERIAL Addresatea All holders of operating lioenaes or construction permits fur nuclear power roactoni.

Purpase The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notico to inform addre31eea of the results of current Thenno-Lag J:\\O fire endurance *tests tconducted for tht NRC at the National Institute of Standards and Tuchnology! (NIST). It is expected that recipients will review the information for applicability to t}teir facilities and consider actions as appropriate. H*wever, suggestions contained in this information notice ure not NRC requi~ments; therefore, no specific uction or written r~ponse is

requitM, Di&eussic,n The NRC haa been reviewing Tlierm<>4Lag 330 fire barrier !l.ystems to determine their ability to l${equatGly perforn1 their 1-hour or 3-hour fire re§istive function*. The t,IRC: has issued three information notices and a bulletin on this subject

1.

Information' Notice 91-47, "Failure of Thermo-Lag Fire Barrier Material lo Pass Fire E$.durence ~t, 11 J\\,ugust 6, 1991

2.

Infotmadon: Notice 91-79, "Deficiencies in the Procedures for Installing Thenno-La~ Pirc* Barrier Minerialr.," December 6, l 991

3.

Information' Notlce 9246, "Thermo-Lag Fire Barrier Material Special Review Tea~ Pinal Roporl Pindings, Current Fire Endurance Tests, and Ampadly ~l<<>ubltion Errors," June 23, 1992

4.

Bulletin 92-01. "P11ilure of Thermo-Lag 330 Fire Barrier System 10 Maintain ~Una in Wide atble Tra~ and Small Conduits Free from Fire DaIIUlF," J~ne J4, 1992 NIST conducted small scale l*hour and 3-hour fire endurance tests 10 determine the fire reaistiva properties of Tltcnno-Lag pre-formed panels.

On July 15, 1~, NIST conduclod the 1-hour fire.: c.:ndurnm;e test. The averuge thermocouple r+ading on the un,xpose<l surfuce exceeded 162.7xC (32.'5xF) (NRC cold sida temperature Jfmft) In approximately 22 minutes and the unexposed surface o( the n,aterial reached ~n average temperature of 652xC (1206xF) at l

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IN 92-55 July 27. 1992 Page 2 of 3 4S minu~. Th~ unexposed surf.. ce of the material eJChibited visible browning in 35 minutes. t>uring the teat, dne thermooouple on the unexposod surface rnached a peak reading of 933xC1 (1716xF), exceeding the corresponding furnace tempernture of t2!xC (1694xF), as the material burned and added heat to the baseline furnaca tomperature. The panels burn~ through at two locations in 46 minutes, rcst41ting in H corresponding drop in surface thermocouple readings as cold HJ.r entelbi the furnace. At the end of 1-hour, approximately 85 percent of thp unexposed sur~ce was blackened.

I The 3-hour te.,t iwas conducted oh July 17, 1992. The average thermocouple reading oxoeeded 16!..7xC (325xR) In 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and 20 minutes, the average temperature at the end of 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> was 206xC (403xF), and the peak thermocouple reading w&1 222aC (432xF). At the conclusion of the test, the material was soft and exhibitod plastic deform.lion, and the fire-exposed stress skin crumbled upon contact. Neverthblt..-ss, visible signs of dnmage on the unexposed side wl!re Umiled to off-gaasing,,light browning, and crystalli7..ation at the Kurface.

The furnace uscai to conduct thcae tests was n natural gas-fired small scale type with internal dimensions uf b.94 m by 0.94 m by 1.09 m (37 inches by 37 by 42.9 lnchs). The top of t~e furnace wos equipped with a frame for supporting hori*>ntal tost apeciritens of up to 0.81 m by 0.81 m (31.. 75 inches by 31.7S inches)~ An 86.5-mm (l375-inch) wide steel lip attached around tho lower edge of tije frame supporltd the sample. This lip was insulateJ along its bottom, cdg", and top with a ~uminal 13-mm (O.!-inch) thick ceramic-fiber blanket. Thus, the actual area of the sample exposed to the furnace was approximately OlS84 m by 0.584 ~ (23 inches by 2.1 inchc.c.).

To conduct this 1Seriss o( lctSIS, n*minally square samples were cut with dimensjon1 Crom 0.794 m to 0.80b m (31.25 inches to 31.5 inches) on a side.

After beina phsdt:d in the horizodtal sample frame and centered, with rihi.

facing upward (i.e., the ribbed face being the unexposed face), the gaps between the cdf of the sample 4tmJ the frame were loosely pucked with strips uf cc11Kmic~fibcr. blanket. The t~t configuration used bricks placed side-by-side almtg th~ pcri111cter pf the sample to hold the test samples in place. The streas skin on the 3-Hour material W85 thereby restrainod fn compression at the odgcs of the panel around the lip of the furnace and rostricted from teparating Crom tlie panel.

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1 The 1-hour fire,endurance test ~s conducted on a Thermo-Lag J30 fire-harrier panel, "nominal' thiokne.,s 13 mrb (O.S inch). The actual thickness of the test sample rangod from 13.7 to 18.3 imm (0.540 to 0.720 inches). This material had stress sldn on otaly the ribbed (ujexposed) surface. The three-hour fire cndurunce test wu conducted 011 e Thermo-Lag 330 fire-barrier panel, "nominal" thickness 25 m1', (1 inch). The ~ctual thicknes.~ of the te5t sample ranged from 27.7 to 39.6 mnt (1.09 to 1.S6 indhe.~). This material had stress skin on both surface&. The rfbbed surface wet on the unexposed sioo during tho test.

The furnace teroperaturc was mda.sured with three slow-response chromel ulumcl thermocouples, *which mel the requirements in American Society for Testing and MateriaiJ (ASn,i) Standard E-lt9. The furnace temperature during the tests followed the.Afl'l't\\lFB-119 Stand,rd time-temperature curve.

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IN 92-55 July 27, 1992 Page 3 or 3 The unexposed tnatorinl sul'face (empernlures were monitored nt five points, placing ones theffllocouple appro*mately at the center or the specimen, and one at the approximate oonter or cac~ of its quarter sections. The temperature acceptance criterion was that th<:! temperature rise un the unexposoo surface not exceed 138.$xC (250xF) above its initinl temperature of 23.9xC (75xF) as specified in the National Fire Pr~tection Association (NFP A) Standard 251.

The N'RC will provide addltional:information on fire endurance testing as it becomes availalje, This information notice requires 110 specific action or written response. If you have any q~tions about the, information in this notice, please contact one of the technical contams list~ below or the appropriate Office of Nuclear Reactot Re1ulatio1r (N~R) project manager.

Charles E. Rossi, Director Oivis~n of Operational Ev~nts Assessment Offic~ of Nuclear Reactor Regulation Technical conta$ts: Ralph* Archi~zel, NR R (301) 504-28()4 I

Attachment:

Patrick ~dden,, NRR (301) 504-2854 '

Lilt a{ Reoently, Issued NRC lnf~rmation Notict:s 3

23.

EVALUATION OF EXISTING FIRE RATED WRAP IN UNIT 1 CABLE VAULT/TUNNEL SURRY POWER STATION Description of Evaluation One inch Thermo-Lag 330-1 material was installed to satisfy Section III.G.2.a of 10CFR50 Appendix R for protection of emergency communication system cable in the Cable Vault/Tunnel (CV/T). Full area detection and suppression are installed in the CV/T.

Since detection and suppression are installed, the one inch thick Thermo-Lag material is only required to meet an one hour fire resistance rating per 10CFR50 Appendix R Section III.G.2.c. This evaluation assesses the ability of the Thermo-Lag installed on the Emergency Communication system in the CV/T to meet the intent of Section III.G.2.c.

Area Description The Cable Vault/Tunnels (Fire Areas 1 & 2 for Units 1 & 2 respectively) have floor areas of approximately 3200 ft 2 for Unit 1 and 3500 ft 2 for Unit 2.

The Unit 2 area is basically a mirror image of the Unit 1 area.

The combustible loading for both CV/Ts are high with cable insulation contributing the majority of the combustible loading.

The CV/T fire areas are bounded to the north by the respective unit's Primary Containment Building and to the south by their respective Emergency Switchgear Room.

The adjacent area to the east for Unit 1 and west for Unit 2 is the Auxiliary Building. The boundaries of the CV/T are constructed of a minimum of 18 inch reinforced concrete except for two areas. One is a 4 inch concrete block wall separating the containment electrical penetration area from the Auxiliary Building.

The 4 inch block wall does not provide a 3 hr. fire rating and has a fire watch in place until modification can be implemented.

The second is an 8 inch concrete block wall separating Unit 1 CV/T from Unit 2 CV/T.

This wall is addressed by Exemption Request 16. Openings through the barriers are sealed to the fire resistance rating of the barrier or addressed by Exemption Requests 6

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Normal access to the CV/Tis through the Emergency Switchgear Rooms at the 9 ft.- 6 in. elevation.

Fire Protection Features Each Unit's CV/Tis equipped with ionization smoke detectors which annunciate to the Control Room.

There is an automatic, total flooding Carbon Dioxide (CO2 )

fire suppression system installed in each unit's CV/T.

These systems are actuated by rate compensating heat detectors located throughout the area.

In addition to the CO2 system there is a manually actuated open head sprinkler system installed at the ceiling of each Service Building Cable Vault and a manually actuated closed* head sprinkler system in the Cable Tunnel.

Both CV/Ts are equipped with hose stations and portable fire extinguishers.

Safe Shutdown Equipment Power, instrumentation, and control cables for most of the safe shutdown systems are routed throughout their respective units CV/T.

Evaluation The station communication system consists of repeaters, handsets, antennas, hand held radios, and other associated equipment including cables, conduit, junction boxes, selector switches, etc. The communication system is designed to provide an alternative channel of communication during an emergency.

The "A" system is dedicated to plant operations and is common to both units and is made up of the A and AE repeaters. The A repeater is for normal operations. The "AE" repeater is dedicated for emergency use only so the 11A" repeater is not overloaded by additional people using the system in an emergency.

The "B" and "BE" repeaters are a duplicate system of the A system and are to be used if the A system is disabled. The A system repeaters are located in Unit 1 Cable Spreading Room and the B system repeaters are located in the Auxiliary Building.

Each unit's containment is provided with an antenna. The antenna feed lines for the Unit 1 and 2 containment antsnnas are routed from the cable spreading room CHl0-23 23-2 Revision 11 11/93

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to the Unit 1 and 2 electrical penetration areas via cable trays through the cable vaults. Spare lengths of antenna cable to reach the antenna containment penetrations is installed on reels at the 13 ft. elevation of the Auxiliary Building.

The spare cable is long enough to reach the antenna containment penetrations in Unit 1 and 2 Cable Vaults.

The containment penetrations are 4C and 3D for Units 1 and 2 respectively. The containment antenna penetrations are equipped with coax type connectors to allow for quick connection.

The two containment electri-cal penetrations are enclosed with a four sided box constructed of 1" thick Thermo-Lag attached to a steel frame.

The box is a "radiant energy shield to minimize direct fire exposure and damage to the coax connectors. The box is approximately 15" wide, 18" high, and 14" deep. The box enclosure around the containment penetrations 4C and 3D was installed as an enhancement to the system and is not intended to be a fire barrier since the enclosure is open on one side.

The communication system power feed and control circuit conduit in Unit 1 CV/T is wrapped with 1 inch thick Thermo-Lag as it passes from the Auxiliary Building to Unit 1 ESGR.

The power feed is contained in conduit 1M912 (1") and the control circuit is contained in conduit lCOM (3/4"). The two conduits were fire wrapped to protect against a fire in the CV/T disabling communication between the Control Room and Unit 1 Containment.

The Thermo-Lag installed on the two conduits is 1 inch thick and normally associated with a 3 Hr. fire resistance rating.

Section III.G.2.c of Appendix R requires only a 1 Hr. fire resistance rating when detection and automatic suppression is installed in the area.

The NRC has indicated in Bulletin 92-01 and Supplement 1 to the Bulletin (see Attached) that 1 inch thick Thermo-Lag will not provide a 3 Hr. fire resistance rating.

The test information contained in the NRC documents indicate that 1 in. thick Thermo-Lag did not fail within 1 Hr.

into the test. Therefore the 1 in. thick Thermo-Lag would be expected to provide at least a 1 Hr. fire resistance rating.

CHl0-23 23-3 Revision 11 11/93

Conclusion Based on the above analysis, it has been determined that the 1 in. thick Thermo-Lag provides the level of protection required by Section 111.G.2.c of Appendix R.

The technical bases that justify this conclusion are summarized as follows:

1.

A 1 Hr. fire resistance fire barrier, and not a 3 Hr. fire barrier, is required for Appendix R compliance since the CV/T is provided with detection and an automatic fire suppression system.

2.

The 1 in. thick Thermo-Lag wrap on the two conduits is expected to provide at least a 1 Hr. fire resistance rating as required by Section 111.G.2.c of Appendix R.

3.

The combustibility of the Thermo-Lag material is not a factor since intervening combustibles are acceptable when suppression and detection are present.

Even though Thermo-Lag is combustible, 1 inch thick Thermo-Lag is expected to provide at least 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> of fire resistance.

4.

The radiant energy shields around containment penetrations 4C and 30 are not fire barriers.

The Thermo-Lag enclosure around the containment penetrations was provided only as an enhancement to the system and is not required by Appendix R.

CHl0-23 23-4 Revision 11 11/93

06-25-92 08:58 UNITED STATES NUCLEAR REGULATORY C0ft1ISSION OFFICE OF NUCLEAR REACTOR RE&ULATION WASHINGTON, D.C. 20555 June 24, 1192 e

0MB No.:

SJS0-0012 NRCB 12-01 NRC BULLETIN NO. 92-0l:

FAJLUR£ OF THEJN).LAG 330 FIRE BARRIER SYSTEM TO MAINTAIN CABLJN; IN WIDE CABLE TRAYS AND SMALL CONDUITS FREE FRON FIRE DAMAGE Addreu,u For Action:

All holders of operating licenses fer ~ueleQr p~r reactors.

For In format ion:

All holders of construction peratts for nucl1ar power reactors.

Purpose This bulletin notifies you of failures 1n fire endurance testing associated

• with the Thenna-Lag 330 fire b1rrier 5y,t111 th1t is installed to protect safe shutdown capab111ty, requests 111 operating reactor licensees to take the r,connanded actions. and requires th,t these licensees provide the U.S.

Nuclear Regulatory Canw1ss1on (ffRC) wtth I written response describing the actions taken associated with this bullattn.

Background

On August 6, 1991, the NRC issued Inforaation Notice (IN) 91-47, *failure of The1"110-L1g fire Barrier Material To.. Pass F1ra Endurance test.* vh1ch provided 1nfaraaiion on the fira endurance tests p1rfon11d by the Gulf States Ut111t1as Corapany on Thar,ia-Lag 330 fire b1rrier sy*t*ms installed on wide alumtnum eabla trays and the associated failures.

Otl December 61 1991, th1 NRC issued lnforaation Notice 91-79, *oet1c11nc11s In Tbe Procedures For Installing Thenao-L1g Fire Barrier Material,* which provided 1nfon11t1on on deficiencies in pracaduras that th@ vQndor (TharM&l Sctance, Inc.) providad for 1nstal11ng Thermo-Lag 330 rtre barr;er *1teri1l. As I result of on-going concerns associated with the 1ndatann1nat1 qu111f1c1ttons of Thermo-Lag 330 ftr1 barrier inst1ll1t1ons 1 on Juna 23 1 1992, th1 NRC tssued Jnfonu.tton Notice 92-45, *Thenno-Lag Fire Barrier Material Special R1v1aw Team Final Report Findings, Current Fire £ndurance Testing, and Anipac1ty Calculation Errors.*

Description 9f Circumstances Upnn reviewing INs 91-47 and 91-79, Texas Utilities (TU) Electric institut,d a fire endurance testing prograffi to qua1ify it5 Theraa-Lag 330 electrical_

~

NRCB 12-01 June 24. 1992 Page Z of 5 racaway fire barrier syst~s for tts Coaanche Peak St1111 Electrtc ~t1tion.

Tha test11\\Q was parfonaed during the weeks of June 15 ind June zz. 1992.

3E P03 TU Electric 1 1 test program consisted of I sertes of 1-hour f1rt anduranet tests (using the ASTM-Ell9 Standard 11111 Temperature Curve) on* vari,t, of cablw tray 1nd conduit *mock-ups.*

TU El1ctric d11ign1d these *.oek-ups* or tast articles to duplitatt txist1fig 1~:te111d plant configurations. Plant parsonnal usad stack material to construct th! test articlis. The Thtl"IID-Lag fire birri,r instillation an the test articles was perforaed in accordince with TU Electrtc*s Than110-Lig installation procedures. These procedures were developed fro* the vendor's recomnended in1t1ll1tion procedures.

The Then110-Lag fire barrier systems for the TU Electric test articles wtr*

eonstructed using pre-formed 1-hour Thar11D-Lag 330 panels and conduit shapes.

Th; joints and seams vere construct!d by pre-buttering seams and jo1nts wtth trowel gr1de Then10-Lag 330-l and holding the assembly togathar with statnl1ss stael banding.

On June 17, 1992. the first t*st *rticl, was t,sttd, Th1s article consisted of a junction box with 1 3/4-, 1-, ind s-;nch conduit ent*r1ft9 and axtttng through the junction box.

Throughout the 1-hour ftre endurtnee tast, the cabling routed inside the conduit,~!~ aon1torad in accordance with the AaQr1can Nuclear lnsurer*s criteria for low voltage cir~utt tnttir1t.y and continuity. Throughout the test. none of the cables expert1nc1d I failure 1n

. circuit 1nttgr1ty. The licensee noted that the therwocouple temperature on the inside cover of the junction box on the unexposed side reached 639 *f and that hot spots (temperatures en the cable 1n exc1ss ef SDD *F) on the 3/4-tnch conduit and the 1-inch conduit dtvelop1d, On ~yn1 18, J992, the cables wer1 pu11ed from the test article. There were no visible 1i9n1 of thtnaa1 d~gradation on the cables routed tn th1 S-inch conduit. The cablt in1tde the 3/4-inch conduit was theraally daaagad in two locations and cable 1n the 1-1nch conduit was damaged 1n one location.

On Jun, 18, 1992, TU Electric perfonned a I-hour fire endurance test on a 12*

inch wi~e tr1y configurat1on. Prllfminary test result tnfonaation indtcat*d that the configuratton passed the t,st s1tf1f1ctorily. Throughout the ftr*

• ndurance test, the thennocouple temperatures on the cables 1nstda tha test article were less than 325 *f.

On Jun@ 19, 1992, a 3D-inch wide ladder back tray conf1gurat1an was tastld.

At 17 minutes into the test. the TberiiD-L;g 330 panel on the bottom of the test article began ta sag. At 18 mtnut1s, the joint at the intirfac~ between the tray support and the tray showed signs of wtaklnt*g and separation. The internal temperatures *ithin ar**s of th* test art1c1* showed st9ns of

,xc*ad1ng 325 *Fat 25 *inutes. The Joint fully separat*d 1n 41 a1nutas resulting 1n cable circuit integrity failure and f11"e da..ge to th@ cable,.

D1scvss1gn

~ctton 50.48(*) Df T1t1e JO of the Code of Feder11 Regulations (10 CFR 50,48(1)) requires that e&th operatin; nuclear power plant have_ 1 fire

/

06-25-92 09:00

Jl04 3S'1'l NFR/OST NllCI 92-Dl June 24, 1992 Pit@ 3 of 5 3J3 P04 protection plan that satisfies Appendix A to 10 CFR P*rt SD, General Design Critar1& (GOC) 3, *fire Protection.* GDC 3 requires structures 1yst111s, and components 1*portant to safety be d111gnld and located to *1n1atze, 1ft

• manner consistent with other safety requ1reaants, the probability and effects of f1ras and explosions.

In 10 CFR 50.48(b), th, KRC st1tes that Appendix R to 10 CFR Part so e&tab11shes fire protection features required to satisfy Criter;on 3 of Appendix A to JO CFR Part 50 far cert1ia generic issues for nuclear power plants Hcansed to op1rat1 prior to Jarwary 1, 1979.

S1ct1ans III.&, 111.J, and III.O of Appendix R ire 1pp11eable to nucl1ar powtr plants 11cans1d to operate prior to January 1, 1979.

In 10 CFR 50.t8(@), the NRC requires th1t 111 plants 11cansld ta op1rat11ft1r January 1, 1979, shall CD11Plete 111 fire protection *odif1cat1ons nttdtd to satisfy tr1ter1on J to Appendix A of 10 CFR P1rt SO tn 1ccord1nce with the provisions af their operating 11~;nses.

NRC-approved plant ftra protection progriffls as raferenced by th1 Plant Operating License Conditions ind Appendix R to 10 CFR Part 50, Section Ill G.l.a, *rtre Protection of Safe Shutdown Capability,* require one train of systeMs necessa~y to achieve and maintain hot shutdown cond1ttons from either the control room or emergency control stations to bt free froa fire d.maga.

To insure that elactrical cabling and CDl'll;>Onents are free fro11 fire d1111ge, S*ction IJJ G.2 of Appendix R requires the separation of safe shutdown trains by 1*p1ration af cables and equ1p11ent and assoc1attd circuits of redundant tra;ns by I fire barrier having a 3-hour rattng or tnclosur1 of cable and equipment and associated non-safety circuits of an1 r1dund1nt tr1tn in I f1r1 barrier having a I-hour rating. In addition to prov1d1ng the I-hour barrier, fire detection and an aut0111iti~ fire suppression system shall be in,ta11ed in the fire area.

U~dar f1ra cond1t1ons. the thermal degradation of an 11ectr1cal raceway f1ra barr;er system. such as the Tharmo-Lag syst.., could l**d to both trains of safe shutdown systams being d11n1ged by fire. This may s1gn1f1cantly affect th, plant's ab111ty to achieve and a11nt11n hat standby/shutdown condtt1ans.

The NRC considered the failures of the recent Thel'IID*Lag ftre b~rri,r ftr, endurance testing and has determined that the 1-and 3-hour pre-fonaed 1ssembltes installed on s*all candu1t and wfd1 cable t~iys (wtdar than 14 inches) do not provide the level of saftty 11 raquirtd by NRC requ1rlllfnts.

Requested Actioni All holdars of operat;ng licenses for nucl11r power rtactors, tlllledi1tely upon receiving th;, bu11et1n. &re requested ta tat, tha fD11aw1ng actions:

1.

For those pl~nts that ust *1th*~ l-or 3-hou~ P'"'-foraed Thermo-lag 330 panels and conduit shapes, identify the 1re1s of the plant whtch have Tharmo-Lag 330 fire barrier *ater1a1 tnstalled and determine the pl~nt

rc

as which us@ thts material for protecting either small d1aatter conduit or *1de trays (widths gre1tftr that 14 inches) that provide safe shutdown capability.

01:i-25-92 0!3: 01 NRCB 92-01 Jun1 24, 1992 Page 4 of S 3E P05

2.

In those plant areas in which Ther11D-L1g f1r. barr1ars are us1d ta protact wide c1ble trays. swill conduits, or both1 the 11c1ns11 should tapleaent, 1n accordance with plant procedures, tne 1pprapri1t1 coapensatory *easuras, such as fire ~tcbes, consistent witb those which

~uld be 111Pleaented by either the pl1nt t,thn1ta1 spet1f1cat1ans or the op&rat1ng license f~r an inoperable f1re barrier.

3.

Each licensee, with;n 30 days of re~tiving tht1 bulletin, is required to provide a written notification stating whether it has or does not ha~,

Tharmo-Lag 330 fire barrier syst1as installed 1n 1ts fae111t1es.

Each licensee who has 1nstallad Ther11a-La9 330 fire barrt1rs is requtrad to inform the HRC, in-writing, whether it his taken tht abov1 actions ind ts required ta describe the ae&sures being taken to insure or re,tore fire b1rr1er operability.

Backfjt 01scussjon These types of fire barriers are currently installed at operating pover reactor sites ind are required to aeet either I condition af a p1ant's operating license or the requirements of Section JII.G of Appendix R to JO CFR Part 50.

The act1ofls requested by thts bulletin do not represent a new staff position but are considered necessary to bring 11ctn!1es into conp11ance with existing NRC rules and regulatiofts where th1s1 t1st resu1ts are... 11vant.

Therefore, this bu11et1n is being issued as I ca11plt1nce backftt under the tanns of S0.109(a)(4).

In addition, pursuant to the Charter of the Cana1ttee to Rav1ew,anar1c Requirements (CRGR), this bull1t1n 1s being issued as an i1nediately effect;v, actton (10 CFR S0.J09(a)(6)), This bulletin ts bt1ng issued with the knowledge of the CRGR.

Address the required written reports to the U, S. Nucle1r Ragulatory Conm1ssion, ATTN: Docuaent Control Desk, Washington, D.C. 20555, under 01th or aff1nut1on under the provisions of Section IB2a, AtDllic Energy Act of 1954, 1s amended and 10 CFR S0.54(f). ln addition, sublltt I copy ta the appropriate regional administrator.

Th1s raquast 1s covered by Office of Management and Budget Clearance Number 3150-0012, which expires June 30 1 1994. Th* *sttaated ***r*g* number of burdan hours 1s 60 parson hours for e1ch licensee responset 1ncludtng those needed to 15sess the new rec011111end1tions, search data sources. gather and analyze the data, and prepare tho required lttters. This estimate of th*

average number of burda" hours pertains only to the id1nttfted response-related matters and does not include the tt111 n11dld to implement the requested iction. Send comments regarding thts burden estt111t1 ar any other aspect of this collect1an cf fnfon11tion 1 including suggestions for reducing this burden, to the lnfonnatfon and Records N1n1yement Branch, D1vts1on of lnfonnation Support Sarvices, Office of lnfonaat on Resources Management, U.

S. Nuclear Reijulitory C01111t1ss1an, Washington, D.C. 205!5, and to the Paperwork Reduction Project (3150-0011}, Office of lnformation and Regulatory Affaira, NEOB-3019, Office of M1nage1n1nt ind Budget, V1shington, D.C. 20503.

06-i:5-92 09: 02 NRCB 92-01 Juna 24, 19SIZ Pagt 5 uf S Although no specific response 1s required with respect to the following 1nfor111tion. the following 1nfonnat1on would assist the NRC 11 *valu1ting the cost of COllplytng with this bull*ttn:

(1)

(2)

(3)

(4) the licens,, &tiff's t1ae and casts to per,ora requested 1*sptct1on1, corrective 1ct1ons. and 1ssociat1d testing; the 11censae staff's ti.e ind costs to prep1re the r'aquest8d reports and docu11ent1t1on; the additional shart-term costs incurred to address the 1nsp1ctton f1ndings such as the costs of the corrective 1ct1ons or th* coats of down ti111; Ind

.n ast1~ate of the iddit1on!1 long-ten11 costs that wtll bt incurred as a result of implementing conn1tments such as thi ilt1~ated costs of conducting futura iospaction1 or 1ncr,11ed ffliinten1nc1.

If you should have any questions about this *attar& p1easa contact one of the technical contacts listed below or the 1pprgpri1te NRR project 111n1gar.

c~t'-~*

Charles E. RDsst. Director Division cf Operattonal Events Assessaent Office of Nuclear Reactar R1gul1t1on Technical contacts:

Ralph Arch1tze1 1 NRR (301) 504-2804

Attachment:

P1tr1ck Madden, NRR (301) 504-2854 L1st cf Recently lss~ed NRC Bulletins

05-25-92 09:02 3!:l-4 3S'Tl NFFVDST su1 htfo No.

91-01 89-01, Supp. Z S9-0l.

Supp. 1 90-0Z 90-01 89*03 88-10, Supp. 1 89-0Z 89-01 LIST OF RECENTLY ISSUED NRC BULLETINS bat. of Subject l!!Ylnc*

Repgrting Loss of Crtt1ca11ty Saftty Controls 10/18/91 ta11ure of Westinghouse Steam G~nerator Tube 06/28/91 Mechanical Plugs Failure of Westinghouse Steam Genarator Tubt 11/14/90 Mach1n1cal P1uis Loss cf Thermal Margin Caused by Channal Box Bow 03/20/to Loss of F111-0il in 03/01/90 Trans~itters Manufactured by Rosamaunt Potential Loss of Raqu1r1d 11/21/H Shutdovn Margin During Refueling Oparations Nonconfo1"11;nl Molded-Case 08/03/89 C1rcu1t Brea ers Stress Corrosion Cracking*

07/19/89 of Hiyh-H&rdness Type 41 Stain ess Steal Int1rn11 Preloaded Bolting in Anchor Darling Model S350W Swing Check Valves or Valves of S1m11ar Design Failure of Westinghouse St1aa Generator Tube 05/15/89 Mech&nical Plugs OL

• Operating License CP

• Constructon Pera1t e

Attachment NRCB 92-01 June 24, lH!

Page 1 af l Issued ta All futl cycle and ur1ni111 fu1l research and dev1lap.

aent 11 can11es.

A11 holders of OLs or CPs for Ms.

All holders of Ols or CPs for PWRs.

All holders of Ols or CP1 for BVRs.

All holders of Ols or CPs far nuclear power reactors.

All holders of Ols or CPs for PWRs.

All holders af Ols ar CPs for nuclear power reactors.

All hnld1rs af Ols ar CPs for ~uclear power rt1ctors.

All hald1rs of Ols ar CPs far PWRs.

I t;

e t

UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION WASHINGTON. O.C. 20555 August 28, 1992 9/ ! /t:;2..

e 0MB No.:

3150-0012 NRCB 92-01, SUPP. 1 NRC BULLETIN NO. 92-01, SUPPLEMENT 1:

FAILURE OF THERMO-LAG 330 FIRE BARRIER SYSTEM TO PERFORM ITS SPECIFIED FIRE ENDURANCE FUNCTION Addressees For Action:

All holders of operating licenses for nuclear power reactors For Information:

All holders of construction permits for nuclear power reactors Purpose The U.S. Nuclear Regulatory Corrmission (NRC} is issuing this bulletin supplement to notify licensees and construction permit holders of additional apparent failures in fire endurance testing associated with the Thermo-Lag 330 fire barrier system which many plants have installed to protect safe shutdown capability, to request all operating reactor licensees that have Thermo-Lag fire barriers to take the recommended actions, and to require that these licensees submit a written response to the NRC describing the actions taken associated with this bulletin supplement.

Background

On August 6, 1991, the NRC issued Information Notice (IN) 91-47 1 1Failure of Thermo-Lag Fire Barr;er Material To Pass Fire Endurance Test," which contained information on the fire endurance tests performed by the Gulf States Utilities Company on Thermo-Lag 330 fire barrier systems installed on wide aluminum cable trays and the associated fa11ures.

On December 6, 1991, the NRC issued IN 91-79, 11Deficiencies In The Procedures For Installing Thermo-Lag-Fire Barrier Materials," which contained information an deficiencies in procedures that the vendor (Thermal Science, Inc.) supplied for installing Thermo-Lag 330 fire barrier material.

Recognizing the concerns stated in INs 91-47 and 91-79 regarding the Thermo-Lag 330 f1re barrier system, Texas Utilities (TU)

Electric instituted a fire endurance testing program to qualify its Thermo-Lag 330 electrical raceway fire barrier systems for its Comanche Peak Steam Electric Station.

On June 17-23, 1992, TU Electric conducted the first series of these "full scale" fire endurance tests at Omega Point Laboratories in San Antonio, Texas.

9208280460 -

e e

NRCB 92-0 l, SUPP. l August 28, 1992 Page 2 of 9 The results of these tests have raised questions regarding the ability of the Thermo-Lag 330 fire barrier system to perform its specified function as a 1-hour fire barrier.

On June 23, 1992, the NRC issued IN 92-46, "Thermo-Lag Fire Barrier Material Special Review Team Final Report Findings, Current Fire Endurance Testing, and Ampacity Calculation Errors," in which it discussed the safety imolications of these questions.

On June 24, 1992, the NRC issued NRC Bulletin 92-01 "Failure of Thermo-Lag 330 Fire Barrier System to Maintain Cabling in Wid; Cable Trays and Small Conduits Free From Fire Damage."

Description of Circumstanc~s TU Electric and the NRC recently sponsored additional testing of Thermo-Lag 330 material.

TESTS SPONSORED BY TU ELECTRIC On August 19-21, 1992, TU Electric sponsored a second series of tests at the Omega Point Laboratory to aid in qualifying its Thermo-Lag 330 electrical raceway fire barrier systems for its Comanche Peak Steam Electric Station.

This series of tests consisted of 1-hour fire endurance tests (using the ASTM E-119 Standard Time Temperature Curve) on a variety of cable tray and conduit

• "mock-ups."

TU Electric designed these "mock-ups" or test articles to duplicate existing installed plant configurations. Plant personnel used stock material to construct the test articles. The Thermo-Lag fire barriers were installed on the test articles in accordance with TU Electric's Thermo-Lag installation procedures.. TU Electr;c wrote these procedures based on vendor recommended installation procedures.

The Thermo-Lag fire barrier systems for the TU Electric test articles were constructed using pre-formed 1-hour Thermo-Lag 330 panels and conduit shapes.

The joints and seams were constructed by pre-buttering seams and joints with trowel grade Thermo-Lag 330-1 and holding the assembly together with stainless steel banding as required by TU procedures and as the system is installed in the plant.

The artic1es tested during this series of tests consisted of a ~onduit configuration, which exposed five conduits of various sizes (3-inch, 2-inch,

.1-1/2-inch and two 3/4-inch) to the same test fire, a 24-inch wide cable tray with a T-section and a 30-inch wide cable tray.

On August 19, 1992. TU Electric performed a 1-hour fire endurance test on the conduit configuration.

The fire barrier systems installed on the 3-inch, 2-inch and 1-1/2-inch conduits and their associated cable pull boxes were constructed using 1-hour Thermo-Lag 330 conduit pre-shapes and panels, respectively.

The 3/4-inch conduits were constructed using a Thenno-Lag 330 conduit pre-shape as a base material.

The two 3/4-inch conduits were divided at the middle of the test specimen, and four different enhanced barrier systems were tested.

The first of these consisted of a 3/4-inch conduit run, one ha1f of which was protected by a 3/4-inch Thermo-Lag 330 fire barrier conduit pre-shape, and the other half protected with a 1/2-inch thick conduit

e e

NRCB 92-01, SUPP. l August 28, 1992 Page 3 of 9 pre-shape with a wire mesh "stress skin" applied on the exterior and 1/4-inch of trowe1 grade Thermo-Lag applied to the stress sk~n.

One ~alf of the se~ond 3/4-inch conduit run was protected by a 1/2-inch thick conduit pre-shape w1th a 1/4-inch thick Thermo-Lag flexi-blank~t wrap.

'.he oth~r half was protected by a 1/2-inch thick conduit pre-shape with a l/4-1nch thick pre-shape overlay.

TU Electric did not conduct a hose stream test after the fire endurance test.

The post-fire visual inspection of the test specimen revealed that the interface joints between the vertical conduit runs and the cable pull boxes had opened and exposed conduit metal surfaces ~o the f~re.

In add~tion, the cables exhibited visible fire damage to cable Jackets in a11 condu1ts, except for the 3/4-inch conduit protected by the 1/2-inch thick conduit pre-shape with the 1/4-inch pre-shape overlay.

Throughout the fire endurance test, the thermocouple temperatures on the cables inside the 3/4-inch conduit protected by the overlay never reached 163 *c (325 "F). All other conduit configurations exceeded 153* (325 "F) on the cables during the test.

On August 20, 1992, TU Electric sponsored a test of a 24-inch wide ladder back tray with a T-tray configuration.

Post-fire inspection of this specimen revealed that five joint and seam type openings had occurred.

These openings were both in horizontal and vertica1 runs of the cable tray. Fire damage to the cables was also identified during the post-fire inspection, raising questions whether the cables would have functioned properly during a fire.

The thennocoup1es indicated that internal temperatures in certain areas of the test article exceeded 163 *c (325 *F) at 47 minutes.

The maximum monitored cable temperature during the test was 194 *c (381 *F).

On August 21, 1992, TU Electric sponsored a test of a 30-inch wide ladder back tray configuration.

During the post-fire inspection of this specimen, five joint and seam type openings were identified in horizontal and vertical runs of the cable tray.

The Thermo-Lag barrier also experienced areas of loss of its material, leaving spots of bare stress skin covering the tray.

Fire damage to the cables was identified during the post-fire inspection.

Thermocouples indicated that internal temperatures in certain areas of the test article exceeded 163 *c (325 *F) at 30 minutes.

The maximum monitored cable temperature during the test was approximately 371 *c (700 *F).

Although previous tests conducted by TU Electric (see Bulletin 92-01) resulted in the apparent successful performance of large diameter conduits and narrow trays, new information provided by these recent tests has led the NRC ta believe that potential early failures of Thermo-Lag barriers are not limited to specific sizes. The NRC considers the. openings at the joints and seams of the Thermo-Lag material to be of high significance. The characteristics of the configurations of the material protecting the trays or conduits in question seemed to impact the effectiveness of the barrier material more than their specific sizes.

The tests sponsored by TU Electric revealed that the Thermo-Lag material lost its structural integrity primarily at the seams and joints and that cable damage was most significant at these seam and joint separations.

Following the tests conducted in June 1992, the test assemblies were subjected to hose streams which altered the conditions of the barriers.

Due to the hose stream, post-fire inspection of these assemblies for joint failures and burn

7 e

e NRCB 92-01, SUPP.

August ~8. 1992 Page 4 of 9 through was orevente:.

The assemblies tested in August 19~2 were cooled with water. essentially leaving the test assemblies 1n the condition they wer~ in at the completion of the fire test.

Areas of burn through and seam and Joint failures were observed during post-fire inspection.

Further. the TU Electric assemblies tested in June 1992 were constructed using supports that were covered with two layers of Thermo-Lag material.

The assemblies tested in August 1992 had supports which were insulated to only 9 inches, corresponding to the TU Electric actual plant installations. Thus, the June 1992 tests did not model the installed plant configuration, as was the case in the August 1992 tests.

TESTS SPONSORED BY THE NRC On July 15 and 17, 1992,* the NRC sponsored a series of "small scale" fire endurance tests on 1-and 3-hour Thermo-Lag 330 pre-formed fire barrier panels at the National Institute of Standards and Technology (NIST).

On July 27, 1992, the NRC issued the results of the first series of small scale tests in IN 92-55, "Current Fire Endurance Test Results for Thermo-Lag Fire Barrier Material."

On August 6-7 and 14, 1992, the NRC sponsored a second series of 1-and 3-haur small scale fire endurance tests on Thermo-Lag 330 fire barrier pre-formed panels.

On July 15, 1992, the NRC sponsored a I-hour fire endurance test. The I-hour panel stress skin was oriented away from the fire exposure, according to vendor recommendation.

The average thermocouple reading on the unexposed surface exceeded 162.7 *c (325 °F) in approximately 22 minutes, and the unexposed surface of the material reached an average temperature of 652 *c (1206 °F} at 45 minutes.

The unexposed surface of the material exhibited visible browning in 35 minutes.

During the test, the thermocouple on the unexposed surface reached a peak reading of 935 °C (1716 °F), exceeding the corresponding furnace temperature of 923 °C (1694 °F), as the material burned and added heat to the baseline furnace temperature.

The panels burned through at two locations in 46 minutes, resulting in a corresponding drop in surface thermocouple readings as the cold air entered the furnace.

After l hour, approximately 85 percent of the unexposed surface was blackened.

On July 17, 1992, the NRC sponsored a 3-hour test. The 3-hour panels had stress skin installed on both sides of the Thermo-Lag material.

To prepare for the test, the technicians installed the ribbed side of the specimen on the unexposed side with the non-ribbed side of the material towards the furnace side.

The stress skin on the furnace side of the specimen was restrained by the furnace specimen support lif during the test.

The average thermocouple reading exceeded 162.7 *c (325 F) in 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and 20 minutes, the average temperature at the end of 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> was 206 *c (403 °F), and the peak of thermocouple reading was 222 *c (432 °F).

After the test, the material was soft and exhibited plastic deformation, and the fire-exposed stress skin crumbled upon contact.

Nevertheless, visible signs of damage on the unexposed side were limited to off-gassing, slight browning, and crystallization at the surface.

r

< I e

e NRCB 92-01, SUPP. 1 August 28, 1992 Page 5 of 9 On Auoust 5, 1992, the NRC sponsored a fire endurance test on a 3-hour Thermo-Lag fire barrier panel, which had stress skin on both sides.

The e~ges of the stress skin of the 3-hour material were cut away from the exposed side of the panel so that the outer edges of the stress sk~n contact~d the support l~p of the furnace.

The stress skin was kept from being restra1ned in compression at the edges of the panel around the lip of the furnace.

The average thermocouple temperature of the unexposed surface exceeded the ASTM E-119 temperature acceptance criterion of 163 *c (325 "F} in 45 minutes.

After l hour, the unexposed surface temperature reading was 75~ *c (1392- "F}.

At 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and 20 minutes, the-panel was burned through. This 3-hour configuration performed quite differently during this test than did the Thermo-Lag 330 fire barrier panel in the July 17, 1992, 3-hour fire test in which the stress skin was restrained on the side exposed to the fire.

In this previous test, the average unexposed surface temperature of the restrained specimen did not exceed 163 *c (325 °F) until 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and 20 minutes into the test, and the maximum temperature at the end of the 3-hour test was 194 *c (381 °F).

The specimen tested on July 17, 1992 did not burn through.

On August 6, 1992. the NRC sponsored a second I-hour fire endurance test on a Thermo-Lag 330 I-hour panel, which had stress skin on one side only. Th;s panel was placed on the furnace with the stress skin towards the fire, although the vendor reconvnends that the I-hour panel be installed with the stress skin away from the fire exposure.

The deviation from the vendor recommendation aided in the determination of the material's sensitivity to installation variations.

The stress skin was restrained by the furnace specimen support lip. The average unexposed surface temperature of the specimen exceeded 163 °C (325 *F) in 34 minutes, and at 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, the maximum temperature of the unexposed surface was 237 *c (458 "F). However, the specimen was not burned through.

The performance of the specimen in this test was superior ta the specimen tested on July 15, 1992, at which the stress skin faced the unexposed side, as recomnended by the vendor.

The spec;men tested on July 15, 1992, exceeded the 161 *c {325 "F) acceptance criterion in 20 minutes and the unexposed surface reached 649 *c (1200 *F) in 37 minutes.

Burn through was observed ;n 46 minutes.

On August 7, 1992, the NRC sponsored a third 3-hour fire endurance test.

Two 1-hour fire barriers were dry fitted together with their stress skins on the outer sides of the test specimen.

As in the test conducted on August 5, the exposed side stress skin was trirrmed away to prevent the material from being restrained.

One hour into the test, the specimen abruptly began releasing gases, and the thermocouple readings inside the furnace indicated that the thermocouple had come into contact with burning material.

The average thermocouple reading exceeded 163 *c (325 "F) in I hour and 26 minutes. After 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, burn holes were observed in several locat;ons. After the burn holes formed, unexposed surface thermocouple read1ngs oscillated dramatically, with a peak reading of 947 *c (1737 "F) at the end of the test. Nonetheless, this test specimen performed better than did the prefabricated 3-hour panel with its stress skin trimmed away.

On August 14, 1992, the NRC sponsored a final 3-hour test, aga;n using two 1-hour panels dry fitted together with their stress skins on the outer sides of the test specimen.

The stress sk1n was not trimmed away from the specimen

1

~-

e NR~92-01, SUPP. 1 August 28, ! 992 Page 6 of 9 for this test; it was restrained in _Jmpression at the edges of the panel.

The averaqe thermocouple reading exceeded 163 *c (325 "F) in 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and 40 minutes and reached 176 *c (349 "F) at the end of the ~est'.

Visible signs of damage ~ere limited to off-gassing and slight crystallization at the surface of the unexposed side, and no browning was observed.

The following table summarizes the data collected during these small scale tests.

Test Date Barrier -Stress Sic.in Stress Sic.in Time to Burn Rating Restraint Orientation Exceed Through 163 *c*

(hrs:min}

(hrs:min) 7/15/92 l hour N/A unexposed 0:22 0:46 8/06/92 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> restrained exposed 0:34 none 7 /17 /92 _

3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> restrained both sides 2:20 none 8/05/92 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> unrestrained both sides 0:45 1:20 8/07/92 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> **

unrestrained both sides 1:26 2:03 8/14 /92 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> **

restrained both sides 2:40 none

• .. Average unexposed s~rface thermocouple temperature Two 1-hour panels fitted face to face In IN 92-55, the staff 1isted specific furnace specifications and test assembly parameters used in both series of tests conducted by NIST.

The NRC views the results of the N1ST tests as indicative of an inability of the Thermo-Lag material itself to provide protection according to its specified fire resistive rating, depending on its configuration.

The tests conducted at NIST were not considered definitive in that the tests were not full scale and only panels were tested.

However, the information gleaned from the tests provided enough evidence to the NRC to confirm doubts raised during the TU Electric tests, such as the bare stress skin observed following the TU 30-inch wide cable tray test on August 21, 1992, discussed above, leading to a conclusion that Thermo-Lag fire barriers should be treated as inoperable in the absence of successful, applicable plant specific tests.

Discussion Section 50.48(a) of Title 10 of the Code of Federal Regulations (10 CFR 50.48(a)) requires that each operating nuclear power plant have a fire protection plan that satisfies Appendix A to 10 CFR Part 50, General Design Criteria (GDC) 3, 11 Fire Protection."

GDC 3 requires that structures, systems, and components important to safety be designed and located to minimize, in a manner consistent with other safety requirements, the probability and effects of fires and explosions.

10 CFR S0.48(b} states that Appendix R to 10 CFR Part 50 establishes fire protection features required to satisfy

e NRCB '-01, SUPP. 1 August 28. 1992 Page 7 of 9 Criterion 3 of Appendix A to 10 CFR Part SO for certain generic issues for nuclear power plants licensed to operate before January l, 1979.

Sections III.G, III.J, and III.O of Appendix R apply to nuclear power plants licensed to operate before January 1, 1979.

In 10 CFR 50.48(e), the NRC requires that all licensees for plants licensed to operate after January 1, 1979 shall complete all fire protection modifications needed to satisfy Criterion 3 of Appendix A to 10 CFR Part SO in accordance with the provisions of their operating licenses.

NRC-approved plant fire protection programs as referenced by the Plant Operating License Condi"tioris and Appendix R to 10 CFR Part 50, Section Ill G.l.a, ~Fire Protection of Safe Shutdown Capability," require one train of systems necessary to achieve and maintain hot shutdown conditions from either the control room or emergency control stations to be free from fire damage.

To ensure that electrical cables and components are free from fire damage,Section III G.2 of Appendix R requires the separation of safe shutdown trains by separation of cables and equipment and associated circuits of redundant trains by a fire barrier having a 3-hour rating or enclosure of cable and equipment and associated non-safety circuits of one redundant train in a fire barrier having a 1-hour rating.

In addition to providing the 1-hour barrier, a fire detection and an automatic fire suppression system shall be installed in the fire area.

Under fire conditions, the thennal degradation of fire barrier systems (e.g.,

walls, floors, equipment vaults, and electrical raceway enclosures), such as the Thermo-Lag system, could lead to both trains of safe shutdown systems being damaged by fire. This may significantly affect the plant's ability to achieve and maintain hot standby or shutdown conditions.

The NRC considered the apparent failures of the recent Thenno-Lag fire barrier fire endurance tests and determined that the 1-and 3-hour pre-formed assemblies installed on conduits, cable trays (of all sizes and configurations), and used to construct fire barrier walls and ceilings, and equipment enclosures do not provide the level of safety as required by NRC requirements.

The tests sponsored by TU Electric ra;sed concerns relating to joint and seam separation leading to cable damage.

In addition, they raise concerns about the potential for burn through of the Thermo-Lag material itself. The tests sponsored by the NRC appear to confirm concerns relating to burn through of the Thermo-Lag material in certain configurations in the absence of joints and seams.

Reguested Actions All holders of operating licenses for nuclear power reactors, i11111ediately upon receiving this bulletin supplement, are requested to take the following actions.

These actions are essentially the same as those listed in Bulletin 92-01, but the scope has been expanded to include all sizes of conduits and trays and to include walls, ceilings, and equipment enclosures.

1.

For those plants that use either 1-or 3-hour pre-formed Thermo-Lag 330 panels and conduit shapes, identify the areas of the plant which have

,1,.

,._ I

-~-*

e

2.

NRC~2-0l, SUPP. 1 August 28. 1992 Page 6 of 9 Thermo-Lag 330 fire barrier material installed and determine the plant areas which use this material for the protection and separation of the safe shutdown capability.

In those plant areas in which Thermo-Lag fire barriers are used in raceways, walls. ceilings, equipment enclosures. or other areas to protect cable trays, conduits, or separate_redundant safe.shutdown functions the licensee should implement, 1n accordance with plant procedure;, the appropriate compensatory measures, s~ch as fire watches, consistent with those that would be implemented by either the plant technical specifications or the operating license.fa~ an inoperable fire barrier. These compensatory measures should remain 1n place until the licensee can declare the fire barriers operable on the basis of applicable tests which demonstrate successful 1-or 3-hour barrier performance.

Although the specific details of this supplement to Bulletin 92-01 may not apply to holders of construction permits for nuclear power reactors, it is requested that the general concerns of this bulletin supplement be reviewed for current or future applicability.

Required Report Each licensee who has installed Thermo-Lag 330 fire barriers must inform the NRC in writing within 30 days of receiving this bulletin supplement, whether or not it has taken the above actions. Where fire barriers are declared inoperable, the licensee is required to describe the measures being taken to ensure or restore fire barrier operability. These measures should be consistent with actions taken in response to Bulletin 92-01.

Backfit Ojscyssion These types of fire barriers are installed at operating power reactor s;tes and are required to meet either a condition of a plant's operating license or the requirements of Section III.G of Appendix R to 10 CFR Part 50.

The actions requested by this bulletin supplement do not represent a new staff position but are considered necessary to bring licensees into compliance with existing NRC rules and regulations where these test results are relevant.

Therefore, the NRC is issuing this bulletin supplement as a compliance backfit under 10 CFR 50.109(a)(4).

Address the required written reports to the U.S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, O.C. 20555, under oath or affirmation under the provisions of Section 182a, Atomic Energy Act of 1954, as amended and 10 CFR 50.54(f).

In addition, submit a copy to the appropriate regional administrator.

This request is covered by Office of Management and Budget Clearance Number 3150-0012, which expires June 30, 1994.

The estimated average number of burden hours is 120 person hours for each licensee response, including those needed to assess the new recommendations, search data sources, gather and

---~----.*:

e NRCs4111-01, SUPP. l August 28. 1992 Page 9 of 9 analyze the data, and prepare the required letters. Th;s estimate of the averaqe numoer of burden hours pertains only ta the identified response-related matters and does not include the time needed to implement the requested action.

Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to the Information and Records Management Branch, Division of Information Support Services, Office of Information Resources Management, U.

S. Nuclear Regulatory Commission, Washington, O.C. 20555, and to the Paperwork Reduction Project (3150-0012), Office of Information and Regulatory Affairs, NEOB-3019, Office of Management and Budget, Washington, D.C. 20503.

Although no specific response is required for the following information, the following information would assist the NRC in evaluating the cost of comp1ying with this bulletin supplement:

(1) the licensee staff's time and costs to perform requested inspections, corrective actions, and associated testing; (2) the licensee staff's time and costs to prepare the requested reports and documentation; (3) the additional short-term costs incurred to address the inspection findings such as the costs of the corrective actions or the costs of down timei and (4) an estimate of the additional long-term costs that will be incurred as a result of implementing COll'lllitments such as the estimated costs of conducting future inspections or increased maintenance.

If you should have any questions about this matter, please contact one of the technical contacts listed below or the appropriate NRR project manager.

et,...... &~ ~. Jl-,~'

Charles E. Rossi, o;rector Division of Operational Events Assessment Office of Nuclear Reactor Regulat1on Technical contacts:

Ralph Architzel, NRR (301) 504-2804

Attachment:

Patrick Hadden, NRR (301) 504-2854 List of Recently Issued NRC Bulletins

Bui letrn No.

92-02 92-01 91-01 89-01, Supp. 2 89-01, Supp. l 90-02 90-01 89-03 88-10, Supp. l LIST OF RECENTLY ISSUED NRC BULLETINS Date of Subject Issuance Safety Concerns-Ra1a-08/24/92 ting to "End of Life" of Aging Theratronics Teletherapy Units Failure of Thermo-Lag 06/24/92 330 Fire Barrier System to Maintain Cabling in Wide Cable Trays and Small Conduits Free from Fire Damage Reporting Loss of 10/18/91 Criticality Safety Controls Failure of Westinghouse 06/28/91 Steam Generator Tube Mechanical Plugs Failure of Westinghouse 11/14/90 Steam Generator Tube Mechanical Plugs Loss of Thermal Margin 03/20/90 Caused by Channel Box Bow Loss of Fill-Oil in 03/09/90 Transmitters Manufactured by Rosemount Potential Loss of Required 11/21/89 Shutdown Margin During Refuel;ng Operations Nonconforming Molded-Case 08/03/89 Circuit Breakers

~~ - ~p2r?t~~g License CP

• Construction Permit At.hment NRCB 92-01, SUPP~ 1 August 28, 1992 Pagel of 1 Issued to All Telitherapy Licensees.

All holders of OLs or CPs for nuclear power reactors.

All fuel cycle and uranium fuel research and develop-ment licensees.

All holders of Ols or CPs for PWRs.

All holders of Ols or CPs for PWRs.

All holders of Ols or CPs for BWRs.

All holders of Ols or CPs for nuclear power reactors.

All holders of Ols or CPs for PWRs.

All holders of Ols or CPs for nuclear power reactors.