ML20035E675
| ML20035E675 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 04/12/1993 |
| From: | VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | |
| Shared Package | |
| ML18152A044 | List: |
| References | |
| 23, 23-R11, NUDOCS 9304190084 | |
| Download: ML20035E675 (4) | |
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23.
EVALUATION OF EXISTING FIRE RATED WRAP IN UNIT 1 CABLE VAULT / TUNNEL SURRY POWER STATION Descriotion 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 i
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 2 for Unit I and 3500 ft2 for Unit 2.
The floor areas of approximately 3200 ft Unit 2 area is basically a mirror image of the Unit I 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
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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 l
Building. The 4 inch block wall does not provide a 3 hr. fire rating and has a l
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 l
the fire resistance rating of the barrier or addressed by Exemption Requests 6 l
CH10-23 23-1 Revision 11 11/93 9304190084 930412 PDR ADOCK 05000200 F
PDR l
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j and 24. Normal access to the CV/T is through the Emergency Switchgear Rooms at l
the 9 ft.- 6 in elevation.
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Fire Protection Features
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Each Unit's CV/T is equipped with ionization smoke detectors which annunciate to the Control Room.
There is an automatic, total flooding Carbon Dioxide (C0 ) 2 i
fire suppression system installed in each unit's CV/T.
These systems are i
actuated by rate compensating heat detectors located throughout the area.
In 4
j addition to the CO system there is a manually actuated open head sprinkler 2
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
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are equipped with hose stations and portable fire extinguishers, t
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Safe Shutdown Eauioment Power, instrumentation, and control cables for most of the safe shutdown systems are routed throughout their respective units CV/T.
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Evaluation The station communication system consists of repeaters, handsets, antennas, hand l
i held radios, and other associated equipment including cablas, conduit, junction i
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 "A" repeater is not overloaded by additional people using the system in an emergency. The "B" and "BE" repeaters are. 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 antennas are routed from the cable spreading room CH10-23 23-2 Revision 11 11/93
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l to the Unit 1 and 2 electrical penetration areas via cable trays through the l
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 l
Building.
The spare cable is long enough to reach the antenna containment penetrations in Unit I 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 electrical penetrations are enclosed with a four sided box constructed of 1" thick Thermo-Lag attached to a steel frame.
The box is a l
" radiant energy shield" to minimize direct fire exposure and damage to the coax l
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.
t The communication system puwer feed and control circuit conduit in Unit 1 CV/T i
l 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 IM912 (1") and the control circuit is contained in conduit ICOM (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 e
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 j
not provide a 3 Hr. fire resistance rating.
The test information contained in j
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 i
east a 1 Hr. fire resistance rating.
l CH10-23 23-3 Revision 11 11/93
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i Conclusion l
Based on the above analysis, it has been determined that the 1 in. thick Thermo-Lag provides.the level of protection required by Section III.G.2.c of Appendix R.
The technical bases that justify this conclusion are summarized as follows:
a.
1.
A 1 Hr. fire resistance fire barrier, and not a 3 Hr. fire barrier, t
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 III.G.2.c of Appendix R.
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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 I hour of fire resistance.
4 4.
The radiant energy shields around containment penetrations 4C and 3D 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.
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l CH10-23 23-4 Revision 11 11/93
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es-r 2 es:53 T1 EN 3ST) NWMT PE G.J'e J cn so. M OMB No.: 3150-0012 NRC5 92-01 UNITED STATES l
NUCLEAR REGULATORY COP 9(IS$10N OFFICE OF WUCLEAR REACTOR REGULATION WASHINGTON, D.C. 20555 j
1 June 24, 1992 l
NRC BULLETIN W3. 92-01: FAILURE OF THERMS-LAG 330 FIRE BARRIER SYSTEM TO l
MAINTAIN CA8L]NG IN WIDE CABLE TRAYS AND 3 Malt.
i CONDUITS FREE FROM FIRE DAMAGE Addressees For Action:
All holders of operating licenses for nuclear power reactors.
For Information:
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All holders of construction permits for nuclear power reactors.
i Purvose b
l This bulletin notifin you of failures in fire endurance testing associated
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l with the Thermo-Lag 330 fire barrier systes that is installed to protect safe i
shutdown capability, requests all oserating reactor licensees to take the i
recessmended actions, and requires tsat these licensees provide the U.S.
Nuclear Regulatory Commission (NRC) with a written response describing the actions taken associated with this bulletin.
Battground On August 6,1991, the NRC issued Information Notice (IH) 91-47 ' Failure of l
Thermo-Lag Fire Barrier Material To Pass Fire Endurance Test," which provided
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informa, tion on the fire endurance tests performed by the Gulf 5tates Utilities Company on Therwo-Lag 330 fire barrier systems installed on wide aluminum i
cable trays and the associated failures. On Decenter 6,1991, the NRC issued Information Notice 91-79,
- Deficiencies In The Procedures for Installing l
Thermo-Lag Fire Barrier Naterial " which provided infonaation on deficiencies in procedures that the vendor (Thermal Science lt of on-going concernsInc.) provided for Therso-Lag 330 fire barrier material. As a resu associated with the indeterminate qualifications of Thermo-Lag 130 fire barrier installations, on June 23, 1992, the NRC issued Information Notice 92-46, "Thorno-Lag Fire Barrier Material Special Review Team Final Report Findings, Current Fire Endurance Testing, and Anpacity Calculation Errors."
Descrintien of Circumstances Upon reviewing ins 91-47 and 91-79, Texas Utilities (TU) Electric instituted a fire endurance testing program to qualify its Thermo-Lag 310 electrical _
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. CD-3 02 CS:59 201 EN 3Em N5fVDST 333 Pa3 NRC8 92-01 June 14, 1992 Page 2 sf 5 raceway fire barrier systems for its Comanche peak Steam Electric Station.
The testing was performed during the weeks of June 15 and June 22.'1992.
TU Electric's test program consisted of a series of 1-hour fire endurance tests (using the A$1M-E119 Standard Time Temperature Curye) on a Wariety 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 Therno-Lag fire barrier installation on the test articles was performed in accordance with Til Electric's Thermo-Lag installation procedures. These procedures were developed from the vendor's reconsonded installation procedures.
The Thorwo-Lag fire barrier systems for the TU Electric test articles were constructed using pre-formed 1-hour Thermo-Lag 330 panels and conduit shapes.
l 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.
On June 17, 1992, the first test article was tested. This article consisted of a junction box with a 3/4,1 and 5-inch conduit entering and exiting through the junction box. Throughout the 1-hour fire endurance test, the cabling routed inside the conduits was monitored in accordance with the American Nuclear Insurer's criteria for low voltage circuit integrity and continuity. Throughout the test, none of the cables experienced a failure in circuit integrity. The licensee noted that the therwocouple temperature on the inside cover of the junction box on the unexposed side reached $39 'F and that hot spots (temperatures on the cable in excess of 500 'F) on the 3/4-inch conduit and the 1-inch conduit developed. On June 18, 1992, the cables were pulled from the test article. There were no visible signs of thermal degradation on the cables routed in the 5-inch conduit. The cable inside the 3/4-inch conduit was thermally damaged in two locations and cable in the 1-inch conduit was damaged in one location.
On June 18, 1992, TU Electric performed a 1-hour fire endurance test on a 12-inch wijle tray configurattor.. Preliminary test result information indicated that the configuration pas:ed the test satisfactorily. Throughout the fire endurance test, the thermoccuple temperatures on the cables inside the test article were less than 325 'F.
On June 19, 1992, a 30-inch wide ladder back tray configuration was tested.
At 17 minutes into the test, the Thermo-Leg 330 panel on the bottom of the test article began to sag. At 18 minutes, the joint at the interface between the tray support and the tray showed signs of weakenleg and separation. The
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internal temperatures within areas of the test article showed signs of
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exceeding 325 'F at 25 minutes. The joint fully separated in 41 minutes resulting in cable circuit integrity failure and fire damage to the cables.
Diteuttien i
Section 50.48(a) of Title lo of the Code of Federal Regulations (10 CFR 50.48(a)) requires that each operating nuclear power plant have_ a fire i
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cE-Es-s es:33 3'1 EN 3sm mResT 3EIB FM i
i IRCE 92-01 June 24, 1992 page 3 of 5 protection plan that satisfies Appendix A to 10 CFR Part 50, General Design Criteria (GDC) 3. ' Fire Protection.' GDC 3 requires strectures, systems, and components taportant to safety be designed and located to sinteite, la a manner consistent with other safety requirements, the probability and effects of fires and explosions.
In lo CFR 50.48(b), the NRC states that Appendix R to 10 CFR Part 50 establishes fire pmtection features required to satisfy l
Criterion 3 of Appendix A to 10 CFR part 50 for certain generic issues for nuclear power plants licensed to operate prior to January 1, 1979.
Sections III.E. !!I.J. and III.0 of Appendix R are applicable to nuclear power plants licensed to operate prior to January 1, 1979. In 10 CFR 50.48(e), the l
NRC requires that all plants licensed to operate after January 1,1979, shall complete all fire protection modifications needed to satisfy Criterion 3 to Appendix A of 10 CFR Part 50 in accertlance with the provisions of their operating licenses.
NRC-approved plant fire protection programs as referenced by the Plant operating License Conditions and Appendix R to 10 CFR Part 50, Section I11 C.1.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.
i To ensure that electrical cabling and components are free from fire damage, i
Section 111 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 ratteg or enclosure of cable and equipment and associated non-safety circuits of one redundant train in a fire i
barrier having a 1-hour rating. In addition to providing the 1-hour barrier, fire detection and an automatic fire suppression system shall be installed in the fire area.
Under fire conditions, the thermal degradation of an electrical raceway fire barrier system, 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 het standby / shutdown conditions.
The NRC' considered the failures of the recent Theran4er fire barrier fire endurance testing and has determined that the 1-and 3-war pre-formed assemblies installed on small conduit and wide cable trays (vider than 14 inches) do not provide the level of safety as required by NRC requirements.
Recuested Actions All holders of operating licenses for nuclear power reactors, tunediately upon receiving this bulletin, are requested to take the following actioss:
1.
For those plants that use either I-or 3-hour pre-formed Thermo-Las 330 panels and conduit shapes, identify the areas of the plant which have Thorino-Las 330 fire barrier material installed and determine the plant areas which use this material for protecting either small diameter conduit or vide trays (widths greater that 14 inches) that provide safe shutdown capability.
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'c E r 3:' cE:01 321 534 3S T MfVDST 308 P2EE i
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NRC8 92-01 i
June 24, 1992 j
Page 4 of 5 I
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In those plant areas in which Thermo-Lag fire barriers are used to i
protect wide cable trays, small conduits, or both, the licenses should taplement, in accordance with plant procedures, the appropdate i
compensatory measures, such as fire watches, consistent with these which would be implemented by either the plant technical specifications or the operating license for an inoperable fire barrier.
l 3.
Each licensee, within 30 days of receiving this bulletin, is required to l
provide a written notification stating whether it has or does not have 4
f Themo-Lag 330 fire barrier systems installed in its facilities. Each j
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licensee who has installed Themo-Lag 330 fire barriers is required to j
inform the NRC, in writing, whether It has taken the above actions and is required to describe the measures being taken to ensure or restore i
fire barrier operability.
l Eacitfit Discussien 1
j These types of fire barriers are currently installed at operating power reactor sites 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 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.
j Therefore, this bulletin is being issued as a compliance backfit under the i
terms of 50.109(a)(4). In addition, pursuant to the Charter of the Committee j
to Review Generic Requirements (CRGR), this bulletta is being issued as an 1
immediately effective actica (10 CFR 50.109(a)(6)). This bulletta is being l
1ssued with the knowledge of the CRGR.
l Address the required written reports to the U. S. Noclear Regulatory.
i Connission, ATTN: Document Control Desk, Washington, D.C. 20555, under oath or j
affirmation under the provisions of Section 182a, Atomic Energy Act of 1954, i
as amended and 10 CfR 50.54(f). In addition, submit a copy to the appropriate j
t regional administrator.
i This request is covered by Office of Management and Budget Clearance Number l
j 3150-0012, which expires June 30, 1994. The estimated average number of i
burden hours is 60 person hours for each licenses response, 'seluding those 4
needed to assess the new recommendations, search data sources, gather and 1
analyze the data, and prepare the required letters, This estimate of the l
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average number of burden hours pertains only to the identified response-l related satters and does not include the time needed to implement the requested action. Send comments regardin i
aspect of this collection of information,g this burden estimate or any other including suggestions for reducing l
this burden, to the Information and Records Management granch, Division of Information support Services Office of Inforsation Resources Management U.
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- 5. Nuclear Rerulatory Connission, Washington, D.C. 20555, and to the paperwork Reduction Pro; ect (3150-0011), Office of Information and Regulatory Affairs, j
WEOB-3019, Office of Management and Budget, Washington, D.C. 20503.
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'es-= = cs: m T: 524 35m tfPMET EB PE NRCB 92-01 June 24, 1992 Page 5 of 5 Although no specific respense is required with respect to the following information, the following infomation would assist the NRC in evaluating the cost of complying with this bulletin:
(1) the licensee staff's time and costs to perfom requested inspections, corrective actions, and associated testing; (2) the licenste staff's time and costs to prepare the requestod reports and documentation; (3) the additional short-tem costs incurred to address the inspection findings such as the costs of the corrective actions or the coats of down time; and (4) an estimate of the additional long-term costs that will be incurred as a i
result of implementing comitments such as the estimated costs of i
conducting future inspections or increased maintenance.
If you should have any questions about this matter,11 ease contact one of the technical contacts listed below or the appropriate NtR project manager.
[
Charles E. Rossi. Director Division of Operational Events Assessment l
Office of Nuclear Reactor Regulation i
l Technical contacts: Ralph Architzel, NRR (301) 504-2804 i
Patrick Madden, NRR (301) 504-2854 l
Attachment:
List of Recently Issued NRC Bulletins i
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CI--I I DS:E T1534 2571 tMMET 3E F71 i
Attachment letCE 9Z-01 June 24. 1992 Page 1 of I LIST OF RECENTLY ISSUED NRC SULLETINS l
Bulletin Date of Mo.
Subject Issuance Issued to l
91-01 Reporting Loss of 10/15/91 All fuel cycle and uranime Criticality Safety fuel research and develop-Centro 11 ment licensees.
89-01, Failure of Westinghouse 06/28/91 All holders of OLs or cps j
l Supp. 2 Steam Generator Tube for PWRs.
Nechanical Plugs 89-01, Failure of Westinghouse 11/14/90 All holders of OL: or cps Supp. I Steam Generator Tube for PWRs.
Mechanical Plugs 90-02 Loss of Thermal Margin 03/20/90 All holders of OLs or cps Caused by Channel Box Bow for BWRs.
l 90-01 Loss of Fill-Oli in 03/09/90 All holders of OLs or cps l
Transmitters Manufactured for nuclear power reactors.
by Rosemount
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89 03 Potential loss of Required 11/21/89 All holders of OLs or cps Shutdown Margin During for PWRs.
Refueling Operations 88-10, Monconforming Molded-Case 08/03/89 All holders of OLs or cps l
Supp. I Circuit Breakers for nuclear power reactors.
49-02 Stress Corrosion Cracking' 07/19/89 All holders of OLs or cps l
of High-Hardness Type 410 for nuclear power reactors.
i Stainless Steel Internal Preloaded Bolting in Anchor Darling Model 5350W Swing Check Valves or Valves of l
Similar Design 89-01 Failure of Westinghouse 05/15/89 All holders of OLs or cps Steam Generator Tube for PWRs.
4 Mechanical Plugs OL = operating License CP = Constructon Fernit i
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CMB No.:
3150-0012 NRCB 92-01, SUPP. 1 i
UNITED STATES NutLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATICN r
WASHINGTON, D.C. 20555 August 28, 1992 4///G2-NRC SULLETIN 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:
i All holders of construction permits for nuclear power reactors i
Puroese The U.S. Nuclear Regulatory Commis>icn (NRC) is issuing this bulletin supplerant to notify licensees and construction permit holders of additional apparen*: 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 barr;ers to take the recommended actions, and to require that these five licensees submit a written response to the NRC describing the actions taken associated with this bulletin supplement.
i Backcround On August 6, 1991, the NRC issued Information Notice (IN) 91-47, " Failure of Thermo-Lag Fire Barrier 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 trayr and the associated failures. On December 6, 1991, the NRC issued IN 91-79 " Deficiencies'In The Procedures For Installing Thermo-Lag Fire Barrier Materials." which contained information on deficiencies in procedures that the verder'(Thermal Science, Inc.) supplied for installing Thermo-Lag 330 l
fire barrier material.
Recognizing the cencerns stated in ins 91-47 and 91-79 regarding the Thermo Lag 330 fire barrfer system, Texas utilities (TV)
Electric instituted a fire endurance testing program to qualify its lhermo-Lag 330 elect
- ital raceway fire barrier systems for its Comanche Peak Steam.
Electric station. On June 17-23, 1992, TU Electric conducted the first series of these "f*Jll scale" fire endurance tests at Onaga Point Laboratories in San Antonio, Texas.
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NRCB 92-01, SUPP. 1 August 28. 1992 Pace 2 of 9 1
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The resuit:, of tnese tests nave raised ouestions regarcing the ability of the i
Thermo-Lag 330 fire carrier system to perform its specifiec function as a 1-nour tire Darrier.
Cn June 23, 1992, the NRC issuec IN 92-46, "Thermo-Lag l
Fire Barrier Material Special Review Team final Report Finoings, Current Fire I
Enourance Testing, anc Amoacity Calculation Errors," in wnicn it discussed the On June 24, 1992, the NRC issued NRC safety 1molications cf these cuestions.
Bulletin 92-01. " Failure of Thermo-Lag 330 fire Barrier System to Maintain Caoling in W10e Catle Irays and Small concuits Free from fire Damage."
Descriotien of Circumstances TU Electric and the NRC recently sponsored additional testing of i
Thermo-Lag 330 material.
TESTS SPONSORED BY TU ELECTRIC On August 19-21, 1992, TU Electric sponsored a second series of tests at the r
Omega Point Laboratory to aid in cualifying its Thermo-Lag 330 electrical raceway fire carrier systems for its Comanche Peak Steam Electric Station.
This series of tests consisted of 1-hour fire endurance tests (using the ASTM E-119 Stancard Time Temperature Curve) on a variety of cable tray and conduit t
" mock-ups." TU Electric designed these " mock-ups" or test articles to i
duplicate existing installed plant configurationL 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 Electric wrote these procedures based on vendor recommended installation procedures.
The Thermo-Lag fire barrier systems for the TU Electric test articles wers 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-ing 330-1 and holding the assembly together with stainless steel bancing as ree,uired by TU procedures and as the system is installed in the plant.
The articles tested during this series of tests consisted of a conduit configuration, wtich 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, i
l 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, i
2-inch anc 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-incn conduits were constructed using a Thermo-Lag 330 conduit pre-shape as a base material. The two 3/4-inch conduits were dividt4 at the middle of the test specimen. and four different enhanced barrier systems were tested.
The first of the-se e-a of a 3/4-inch conduit run, i
e one half of which was protected by a 3/4-i.
u.o-Lag 330 fire barrier l
conduit pre-shape, and the other half protew v with a 1/2-inch thick conduit l
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hRCB 92-01. EUPP. 1 August 28, 1992 l
Page 3 of 9 j
pre-snape with a wire mesn " stress skin" applieo on the exterior and 1/4-inch One half of the second of trowei grace Thermo-Lag applied to the stress skin.
3/4-incn conouit run was protected by a 1/2-inch thick conduit pre-snape with a 1/4-inen thick Thermo-Lag flext-blanket wrap. The other nalf was protected by a 1/2-inch thick concuit pre-shape with a 1/4-inch thick pre-shape overlay.
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'O Electric did not conduct a hose stream test af ter the fire enourance test.
The post-fire visual inspection of the test specimen revealed that the l
interf ace ]cints between the vertical concuit runs and the cable pull boxes had openeo and exposed concuit metal surfaces to the fire.
In adoition, the i
cables exhibited visible fire damage to cable jackets in all concuits, 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 163* (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 jcint and seam type openings had occurred. These openings were both in horizontal and vertical runs of the cable tray.
Fire damage to j
ine cables was also identified during the post-fire inspection, raising l
Questions whether the cables would have functioned properly during a fire.
The tnermoccuples indicated that internal temperatur(s in certain areas of the test article exceeded 163 *C (325 *F) at 47 minutes.
The maximum moni',ored cable temperature during the tee,t was 194 *C (381 *F).
On August 21, 1992, TU Electric sponsored a test of a 30-inch wide ladder back l
tray configuration. During the post-fire inspection of this specimen, five i
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 f bare stress skin covering the tray.
Fire l
damage to the cables was identified during the post-fire inspection.
Thermocouples indicated that internal temperatures in certain areas of the l
test article exceeded 163 *C (325 *F) at 30 minutes. The maximun, monitored cable temperature during the test was approximately 371 *C (700 T1.
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Although previous tests conducted by TU Electric (see Bulletin 97-01) resulted I
in the apparent successful performance of large diameter conduitn and narrow l
trays, new information provided by these recent tests has led the NRC to l
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 tne 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 I
their specific sizes. The tests spensored 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 seas and joint separations.
Follwing the tests conducted in June 1992, the test assemblies are subjected to hose streams which altered the conditions of the barriers. Due to the hose l
stream, post-fire inspection of these assemblies for joint failures and burn i
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NRCB 92-01. SUPP. I j
August 28, 1992 Page 4 of 9
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l The assemolies testec in August 1992 were cooled with l
througn was prevente:.
.ater, essentially leaving tre test assemolies in tne concition they were in at tee completion of the fire test. Areas of burn througn and seam and joint failures were observed curing post-fire inspection.
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Furtner. the TU Electric assemblies tested in June 1992 were constructed using supports that were coverec with two layers of Thermo-Lag material.
The assemolies tested in August 1992 had supports which were insulated to only l
9 intnes, 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 l
On July 15 and 17, 1992, the NRC sponsored a series of "small scale" fire endurance tests on 1-ano 3-hour Thermo-Lag 330 pre-formed fire barrier panels at the Natienal Institute of Standards and Technology (NIST). On l
July 27, 1992, the tiRC issued the results of the first series of small scale tests in IN 92-55, " Current fire Endurance Test Results for Thermo-Lag Fire l
Barrier Material." On August 6-7 and 14, 1992, the NRC sponsored a second series of 1-and 3-hour small scale fire endurance tests on Thermo-Lag 330 j
fire barrier pre-formed panels.
On July 15, 1992, the NRC sponsored a 1-hour fire endurance test. The 1-hour panel stress skin was oriented away from the fire exposure, according to.
l vender 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 i
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 i
corresponding furnace temperature of 923 *C (1694 *F), as the material burned and added heat to the caseline furnace temperature. The panels burned through at two locations in 46 minutes, resulting in a corresponding drop in surface i
thermocouple readings as the cold air entered the furnace. After I hour, approximately 85 percent of the unexposed surface was blackened.
l l
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 average thermocouple the furnace specimen support lig )during the test.
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-l 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 i
soft and exhibited plastic deformation, and the fire-exposed stress skin crumbled upon contact. Nevertheless, visible signs of damage on the unexposed I
side were limited to off-gassing, slight browning, and crystallization at the surface.
_ 5 _.. : -
j NRCB 92-01. SUPP.
August 28, 1992 Ppe 5 of 9 I
On Auoust 5.1992. the NRC sponsorea a fire encurance test on a 3-hour Thermo-Lag fire Darrier panel wnicn had stress skin on both stoes.
The edges 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 skin contacted the support lip of i
4 ine furnace.
The stress skin was kept from Deing restrained in compression at ine eoges of the panel around the lip of the furnace.
The average thermocouple temperature of the unexposed surface exceeded the ASTM E-Il9 temperature acceptance criterion of 163 *C (325 'F) in 45 minutes. After I hour, the unexposed surface temperature reacing was 756 *C (1392 *F).
At I hour and 20 minutes, the panel was burned through. This 3-hour conf luration performed culte differently during this test than did the The. n -Lag 330 fire barrier panel in the July 17, 1992, 3-hour fire test in
=nich the stress skin was restrained on the side exposed to the fire.
In this i
previous test, the average unexposed surface temperature of the restrained I
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 specteen tested on July 17. 1992 did not burn through.
On August 6. 1992, the NRC sponsored a second 1-hour fire endurance test on a Thermo-Lag 330 1-hour panel, which W stress skin on one side only. This 1
panel was placed on the furnace with the stress skin towards the fire.
I although the vendor recommends that the 1-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 t
installation variations. The stress skin was restrained by the furnace 4
specimen support lip. The average unexposed surface temperature of the specimen exceeded 163 *C (325 'F) in 34 minutes, and at I hour, 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 teas superior to the specimen tested on July 15, 1992, at which the strest skin faced the unexposed side, as recommended by the vendor.
The specimen tuted i
or. July 15, 1992, exceeded the 163 'C (325 "F) acceptance criterion in 20 minutes and the unexposed surface reached 649 *C (1200 'F) in 37 minutes.
Burn through was observed in 46 minutes.
l 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 trimmed 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 thermoccuole reading exceeded 163 'C (325 'F) in 1 bour 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 locations. After the burn holes formed, enexposed surface themocouple readings 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, again using two 1-hour panels dry fitted together with their stress ski;s on the outer sides of the test specimen.
The stress skin was not trimmed away from the specimen l
e
'iRCB 92-01. - SUPP. 1 August 25. :992 Page 6 of 9 l
it was restrained in. mpression at the edges of the panel.
fer inis test; The average thermocouple reading exceeced 153 *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 anc reatnec 176 *C (349 *F) at the eno of the test. Visible signs of damage were limited to off-gassing ano slight crystallization at the surf ace of the unexposeo side, ano no browning was observed.
i The following table summarizes the data collected during these small scale tests.
l Test Date Barrier Stress Skin Stress Skin Time to Burn Rating Restraint Orientation
- Exceed, Through 163 *C l
(hrs: min) thrs: min) l 7/15/92 l1 hour lN/A unexposed 0:22 0:46 8/05/92 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> l restrained exoosed 0:34 lnone 7/17/92 l3 hour I restrained both sides l2:20 lnone 8/05/92 l3 hour l unrestrained both sides 0:45 I:20 l
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 f
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 surface thermocouple temperature
, Two 1-hour panels fitted face to face In IN 92-55, the staff listed sper.ific furnace specifications and test assembly parameters used in both series of tests conducted by NIST.
The NRC views the results of the NIST 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 i
conducted at NIST were not considered uefinitive in that the tests were not full scale and only panels were tested. However, the information gleared 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 l
the absence of successful, applicable plant specific tests.
~
OHeussion Section 50.48(a) of Title 10 of the Ccde 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, " Fire Protection." GDC 3 reouires that >:ructures, systems, and components important to safety be designed and located to minimize, in a manner _ consistent with other safety reouirements, the probability and effects of fires and explosions.
10 CFR 50.48(b) states that Appendix R to 10 CFR Part 50 establishes fire protection features required to satisfy i
NRCB 92-01, SUPP. 1 August 28. 1992 Page 7 of 9 Criterion 3 of Appendix A to 10 CFR Part 50 for certain generic issues for nuclear power plants licensec to c:erate before January 1,1979.
Sections III.G. III.J. and 111.0 of Appendix R apply to nuclear power plants licensed to operate before January 1, 1979.
In 10 CFR 50.48(e), the NRC i
l reoutres that all licensees for plants lic msed to ocarate after l
January 1.1979 shall ccmolete all fire protection modifications neeced to l
satisfy Criterion 3 of Appendix A to 10 CFR Part 50 in accordance with the I
provisions of their operating licenses.
NRC-approved plant fire protection programs as referenced by the Plant Operating License Conditions ano Appendix R to 10 CFR Part 50, Section l
111 G.I.a. " Fire Protection of Safe Shutdown Capability," recuire 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 !!! G.2 of Appenoix R reouires the separation of safe shutdown trains by separation of caoles ano equipment and associated circuits of reduncant trains by a fire carrier 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 5e installed in the fire area.
Under fire conditions, the thermal degradation of fire barrier systems (e.g.,
trails, floors, equipment vat.its, 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 Themo-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 raised concerns relating to joint and seam separation leading to cable damage.
In addition, they raise concerns about the potential for burn through of the Themo-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.
peonested Actions All holders of operating licenses for nuclear power reactors, immediately 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 sll 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 wnich have
l NP.CB 92-01 SUPP. 1 j
August 28. 1992 i
Page 8 of 9 Thermo-Lag 330 fire carrier material installed ano determine the plant areas wnich use this material for the protection and separation of the safe snutdown capability.
In those plant areas in which Thermo-Lag fire barriers are used in l
l 2.
l raceways, walls, ceilings, equipment enclosures, or other areas to protect cable trays, conduits, or separate reduncant safe shJtou.7, l
functions, the licensee should implement, in accoroance with plant i
proceoures, the approcriate ccmcensatory measures, such as fire watches, consistent with those that would be-implemented by either the plant technical specifications or the operating license for an inoperable fire l
These compensatory measures should remain in place until the barrier.
licensee can declare the fire barriers operable on the basis of applicable tests which demonstrate successful 1-or 3-hour barrier performance.
Althougn the specific details of tnis supplement to Bulletin 92-01 may not acply 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.
Reauired Reoort 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 l
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 i
l ensure or restore fire barrier operability. These' measures should be consistent with actions taken in response to Bulletin 92-01.
Backfit Discussion l
These types of fire barriers are installed at operating power reactor sites and are required to meet either a condition of a plant's operating license or l
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.
l 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. 5. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, D.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 ir covered by Office of Management and Budget Clearance Number i
3150-00)2, whicn expires June 30, 1994. The estimated average number of l
burden hours is 120 person hours for each licensee response, including those needed to assess the new recommendations, search data sources, gather and I
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m.. -.. :
NRCB 92-01, SUPP. I August 28. 1992 l
Page 9 of 9 1
analyze the data, and prepare the recuired letters.
This estimate of the average numoer of buroen hours pertains only to the identified response-l relatec matters and does not include the t1me needed to implement the reauested action.
Seno comments regaroing this burden estimate or any other aspect of this collection of information, including suggestions for reducing l
this ourden, to the Information anc Records Management Branen, Division of Information Support Services Office of Information Resources Management, U.
i l
S. Nuclear Regulatory Commission. Washington, D.C. 20555, and to the Paperwork Reduction Project (3150-0012), Office of Information ano Regulatory Affairs, NE0B-3019, Office of Management and Budget. Wasnington, D.C. 20503.
Although no specific response is recuired for the following information, the i
following information would assist the NRC in evaluating the cost of complying with this bulletin supplement:
(1) the licensee staff's time and costs to perform requested inspections, i
corrective actions, and associated testing; (2) the licensee staff's time and costs to prepare the requested reports and documentation; i
(3) the additional short-term costs incurred to._ address the inspection-findings such as the costs of the corrective actions or the costs of j
down time; and (4) an estimate of the additional long-term costs that will be incurred as a I
result of implementing comitments such as the estimated costs of conducting future inspections or increased maintenance.
j If you should have any questions about this matter, please contact one of the technical contacts listed below or the appropriate NRR project manager.
%tA
- r. 44 l
Charles E. Rossi, Director Division of Operational Events Assessment l
1 Office of Nuclear Reactor Regulation l
l Technical contacts:
Ralph Architzel, NRR i
(301) 504-2804 i
Patrick Madden, NRR (301) 504-2854
Attachment:
List of Recently Issued NRC Bulletins l
j i
Attachment
=
i '
NRCB 92-01, SUPP. 1 l
August 28, 1992 Page 1 of I l
LIST OF RECENTLY ISSUED NRC BULLETINS Bulletin Date of No.
Subject Issuance issued to 92-02 Safety Concerns-Rela-08/24/92 All Teletherapy Licensees.
ting to "End of Life" of Aging Theratronics Teletherapy Units 92-01 Failure of Thermo-Lag 06/24/92 All holders of Ols or cps 330 Fire Barrier System for nuclear power reactors.
to Maintain Cabling in Wide Cable Trays and l
Small Conduits Free from j
l Fire Damage 91-01 Reporting Loss of 10/18/91 All fuel cycle and uranium Criticality Safety fuel research and develop-Controls ment licensees.
l 89-01, Failure of Westinghouse 06/28/91 All holders of Ols or cps Supp. 2 Steam Generator Tube for PWRs.
Mechanical Plugs 89-01, Failure of Westinghouse 11/14/90 All holders of OLs or cps Supp. 1 Steam Generator Tube for PWRs.
Mechanical Plugs J
90-02 Loss of Thermal Margin 03/20/90 All holders of OLs or cps Caused by Channel Box Bow for BWRs.
90-01 Loss of Fill-Oil in 03/09/90 All holders of OLs or cps Transmitters Manufactured for nuclear power reactors.
by Rosemount i
89-03 Potential Loss of Required 11/21/89 All holders of OLs or cps Shutdown Margin During for PWRs.
Refueling Operations G8-10, Nonconforming Molded-Case 08/03/89 All holders of OLs or cps Supp. 1 Circuit Breakers for nuclear power reactors.
CL - Operating License CP - Construction Permit