ML20126G655
| ML20126G655 | |
| Person / Time | |
|---|---|
| Issue date: | 12/11/1992 |
| From: | Taylor J NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | Livingston R HOUSE OF REP. |
| Shared Package | |
| ML19341F818 | List: |
| References | |
| IEB-92-001, IEB-92-1, NUDOCS 9301040188 | |
| Download: ML20126G655 (1) | |
Text
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December 11, 1992 The Honorable Robert L. Livingston U.S. House of Representatives Washington, D.C.
20515
Dear Congressman Livingston:
I am responding to your letter of November 19,-1992, on behalf of one of your constituents, Monica Peri, on concerns raised regarding the Thermo-Lag fire barrier system and our efforts to protect the public health and safety.
I 1
assure you that the Commission treats nuclear power plant fire safety
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seriously.
On June 24, 1992, the NRC' issued NRC-Bulletin 92-01 (Enclosure 1) which required licensees to submit information on their use of Thermo-Lag.
In-July 1992, the NRC sponsortd and technically directed tests at the National l
Institute of Standards and Technology.
The NRC found that Thermo-Lag in some cases does not give the level of fire protection required bi the Commission's existing fire protection standards.
To address this problet licensees with Thermo-Lag installed in.their plants are taking compensatory ceasures.
Without minimizing the gravity of this issue, the staff hat. determined that these compensatory measures are adequate for the near-term, and therefore the use of Thermo-Lag does not pose an immediate throat to the public health and safety.
_ The NRC staff sponsored additicnal tests of Thermo-Lag mat 2 rial and used those test results with information submitu d by ' Industry organisations and individual licensees to determine further-corrective actions.- On August-28, 1992, the staff issued this information in Supplement 1 to Bulletin 92-01 (Enclosure 2).
The staff is evaluating the qualification testing and.the installation applications of fire barrier systems used to protect the safe shetdown.
capability at nucitar power plants. The staff b also evaluating fire barrier materials and their applications' t verify that they give the. level of fire protection that the Cenmisshn has deemed necessr#y to adequately protect.the
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health and safety of the public.
The Commission places high pnority on ryidly resolving the issues associated with the Thermo-Lag fire barrier systein.' The. staff Will continuo to evaluate this issue to ensuye that the safety amcerns are fuily addr6sied.-
flece do not hesitate to cont ct re -if ycE need additional information.-
-Sincerely,
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3150-0012 NRCB 92-01 UNITED STATES NUCLEAR REGULATORY COMMISSION OfflCE OF NUCLEAR REACTOR REGULATION WASHINGTON, D.C. 20555 June 24, 1992 NRC BULLETIN NO. 92-01:
FAILURE OF THERM 0-LAG 330 FIRE BARRIER SYSTEM TO MAINTAIN CABLING IN WIDE CABLE TRAYS AND SMALL CONDUlTS FREE FROM FIRE DAMAGE Addresseel for Action:
All holders of operating licenses for nuclear power reactors.
For information:
All ho;ders of construction permits for nuclear power reactors.
Purcose This bulletin notifies you of failures in fire endurance testing associated with the Thermo-Lag 330 fire barrier system that is installed to protect safe shutdown capability, requests all operatir>g reactor licensees to take the recommended acti;ns, and requires that these licensees provide the U.S.
Nuclear RecJlatory Comission (NRC) with a written response describing the i
actions taken associated with this bulletin, f
Backaround On August 6, 1991< the NRC issued Information Notice (lN) 91-47, " Failure of l
l Thermo-Lag fire Barrier Material To Pass Fire Endurance. Test," which provided Oformatior on the fi*e endurance tests performed by the Gulf States Utilities
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l Company on Theru-Lag 330 fire barrier systems installed on widi aluminum cable t' rays and the atsociatet failures. On December 6, 1991, the NRC issued l
Information Notice 91-79, " Deficiencies in The Procedures For Installing l
Thermo-Lag fire Barrier Materici," which provided information on deficiencies l
in procedures that the vendor (Thermal Science, Inc.) provided for instal'ing i
l Thermo-i.ag 330 fire barrhr material.
As a result of on-ga#ng concerns associated with the indeterminate qualifications of Thermo-Lag 330 fire barrier installations, on June 23, 1992, the NRC issued Information Notice 9?.-46, "Thermo-Lag Fire Barrier Material Special Review Team ' Final Report Findings, Current Fire Endurance Testing, and Ampacity Calculation Errors."
Destriction of Circumstances Upon reviewing ins 91-47 and 91-79, Texas Utilities (TV) Electric instituted a firt endurance testing prograts to qualify its Thermo-Lag 330 electrical
-92062401E2-l
i HRCB 92-01 I
June 24, 1992 Page 2 of 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.
1 TV Electric's test program consisted of a series of 1-hour fire endurance tests (using the A51H-E119 Standard Time Temperature Curve) en a variety of cable tray and conduit " mock-ups."
TV 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 barrier installation on the test articles was performed in accordance with TV Electric's Thermo-Lag installation procedures.
These procedures were j
developed from the vendor's recommended installation procedures.
The Thermo-Lag fire barrier systems for the TV 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 trowei 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 con;isted 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 Usurer'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 thermocouple temperature on the inside cover of the junction box on the unexposed side reached 539 '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 <onduit was damaged in one location.
On June 18, 1992, TV Electric performed a 1-hour fire endurance test on a 12-inch wide tray configuration.
Preliminary test result information indicated that the configuration passed the test satisfactorily.
Throughout the fire endurance test, the thermocouple 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-Lag 330 panel on the bottom of the test article began to sag.
At 18 minutes, the joint at the interface between I
the tray support and the tray showed signs of weakening and separation.
The internal temperatures within areas of the test article showed signs of exceeding 325 'F at 25 minutes.
The joint fully separated in 41 minutes resulting in cable circuit integrity f ailure and fire damage to the cables.
Qiscussion 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
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NRCB 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 recaires 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, in 10 CFR 50.48(b), the NRC states that Appendix R to 10 CFR Part 50 establishes fire protection features required to satisfy 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 111.6, Ill.J, and !!!,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 NRC requires that all plants licensed to operate af ter January 1,1979, shall complete all fire protection modifications needed to satisfy Criterion 3 to Appendix A of 10 CFR Part 50 in accordance 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 111 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 cabling 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 l
equipment and associated non-safety circuits of one redundant train in a fire l
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 I
the fire area.
l Under fire conditions, the thermal degradation of an electrical raceway fire f
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 hot standby / shutdown conditions.
l The NRC' considered the failures of the recent Thermo-Lag fire barrier fire l
endurance testing and has determined that the 1-and 3-hour pre-formed l
assemblies installed on small conduit and wide cable trays (wider than 14 inches) do not provide the level of safety as required by NRC requirements.
- 81. quested Actions l
All holders of operating licenses for nuclear power reactors, immediately upon receiving this bulletin, are requested to take the following actions:
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 Thermo-Lag 330 fire barrier material installed and determine the plant areas which use this material for protecting either small diameter conduit or wide trays (widths greater that 14 inches) that provide safe shutdown capability.
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NRCB 92-01 June 24, 1992 Page 4 of 5 2.
In those plant areas in which Thertao-Lag fire barriers are used to protect wide cable trays, small (onduits, or both, the licensee should implement, in accordance with plant proceduras, the appropriato compensstory measures, such as fire watches, consistent with those which would be implemented by either the plant technical specifications or the operating license for an inoperable fire barrier.
3.
Each licensee, within 30 days of receiving this bulletin, is required to provide a written notification stating whether it has.or does not have Thermo-Lag 330 fire barrier systems installed in its facilities.
Each licensen who has installed Thermo-Lag 330 fire berriers is required to inform the NRC, in writing, whether it has taken the above actions and is required to describe the measures being taken to ensure or restora fire barrier operability.
Sankfit Discussion These types of fire barriers are currently installed at operating power reactor cites and are required to meet either a condition of a plant's operati i ense or the requirements of Section Ill.G of Appendix R to 10 CFR Part 50.
i.ie 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 rcsults are relevent.
Therefore, this bulletin is being issued as a compliance backfit under the terms of 50.109(a)(4).
In addition, pursuant to the Charter of the Committee to Review Generic Requirements (CRGR), this bulletin is being issued as an immediately effective action (10 CFR 50.109(a)(6)).
This bulletin is being issued with the knowledge of the CRGR.
Address the required written reports to the U. S. Nuclear Regulatory Commission, AT;N: Document Control Desk, Washington, D.C. 20555, under oath or affirmation under the provisions of Section 182a, Atomic Energy Act of 1954, as amended anc 10 CFR 50.54(f).
In addition, submit a copy to the appropriate regional admt.istrator.
This rehuest 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 60 person hours for each licensee response, including those
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needed to assess the new recommendations, search data sources, gather ana analyze the data, and prepare the required letters.
This estimate of the average number of burden hours pertains only to 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, incloding suggestions for reducing this burden, to the Information and Records Management Branch, Division of information Support Services, Office of Information Resources Management, V.
- 5. Nuclear Regulatory Commission, Washington, D.C. 20555, and to the Paperwork Reduction Project (3150-0011), Office of Information and Regulatory Affairs, NE0B-3019, Office of Management and Budget, Washington, D.C. 20503.
s-NRCB 92-01 June'24, 1992 Page 5 of S Although no specific responte is required with respect to the following information, the following information would assist the NRC in evaluating the cost of complying with this bulletin:
(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 time; and (4) an estimat( of the additional long-term costs that will be incurred as a result of implementing commitments 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 tachnical contacts listed telow or the appropriate NRR project manager.
[b5An b h b $ % m Charles E. Rossi, Director utvision of Operational faents Assessment Office of Nuclear Reactor Regulation Technical contacts:
Ralph Architzel, NRR (301) 504-2804 Patrick Madden NRR (101) 504-2854
Attachment:
k tist of Recently issued NRC Bulletins 5
t Attachment NRCB 92-01 June 24, 1992 Page 1 of 1 LIST Of RCCENTLY ISSUED NRC BULLETINS BulTetin Date o F No.
Subject Issuance issued to 91-01 Reporting Loss of 10/18/91 All fuel cycle ana uranium Criticality Safety fuel research and develop-Controls ment licensees.
89-01 Failure of Westinghouse 06/28/91 All holders of Ols or cps Supp. 2 Steam Generator Tube for PWRs.
Athenical Plugs 89 01, failure of Westinghouse 11/14/90 All holders of Ols or cps Supp. 1 Steam Generator Tube for PWRs.
Mecnanical Plugs 90-02 Loss of Thermal Margin 03/20/90 All holders of OLs or cps Caused by Channel Box Bow for BWRs.
-01 Lcss of Fill-Oil in 03/09/90 All holders of Ols or cps Transmitters Manufactured for nuclear p;wer reactors, by Rosemount 89-03 Potential Lost of Required
}l/21/89 All holders of OLs or cps Shutdown Margin During for PWRs.
Refueling Operations 88-10, Nonconforming Mnided-Case 08/03/89 All holders of OLs or cps Supp. 1 Circuit Breakers for nuclear power reactors.
89 02 Stress Corrosion Cracking 07/13/89 All holders of OLs or cps of High-Hardness Type 410 for nuclear power reactors.
Stainless Steel internal Preloaded Bolting in Anchor Darling Model S350W Swing Check Valves or Valves of Similar Design s
89-01 Failure of Westinghouse 05/15/83 All holders of Ols or cps Steam Generator Tube for PWRs.
Mechanical Plugs
- Operating License Constructon fermit
- s ENCLOSURE 2 OMB No.:
3150-0012 NRCB 92-01, SUPP. I UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE Of NUCLEAR REACTOR REGULATION WASHINGTON, D.C. 20555 August 28, 1992 NRC SULLEi!N 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 Purcosg The U.S. Nuclear Regulatory Commission (NRC) is issuing this bulletin supplement to notify licensees and construction permit holders of additional ac;arent failures in fire endurance testing associated with the Thermo-Lag 330 fire barrier system wnich many plants have installed to protect safe shutdown capability, to request cll 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 Informat, ion Notice (IN) 91-47, " Failure of Thermo-Lag fire Barrier Material To Pass Fire Endurance Test," which contained information on the fire endurance, test,s p,erformed by the Gulf States Utilities Company on Thermo-Lag 330 fire barrier systems installed on wide aluminum cable trays 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 vender (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 fire barrier system, Texas Utilities (TV)
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, TV Electric conducted the first series of these " full scale" fire endurance tests at Omega Point Laboratories in San Antonio, Texas.
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NRCB-92-01, SUPP. 1 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 implications 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 Wide Cable Trays and Small Conduits free From Fire Damage."
Descriotion of Circumstances TV Electric and the NRC recently sponsored additional testing of Thermo-Lag 330 material.
TESTS SPONSORED BY TV ELECTRIC On August 19-21, 1992, TV 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-Il9 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.
TV Electric wrote these procedures based on vendor recommended installation procedures.
The Thermo-Lag fire barrier systems for the TV 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 stee1 banding as required by TU procedures and as the system is installed in the plant.
The articies tested during this ser'ies' of tests consisted of a conduit l
I configuration, which exposed five conduits of various sizes'(3-inch, 2-inch,.
l-1-1/2-inch and two 3/4-inch) to the same test fire, a 24-in'ch wide cable tray with a T-section and a 30-inch wide cable tray.
On August 19, 1992, TV Electric performed a 1-hour fire endurance test on the l
conduit configuration.
The fire barrier systems installed on the 3-inch, L
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 Thermo-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 half 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
NRCB 92-01, SUPP. 1 August 28, 1992 Page 3 of 9 pre-shape with a wire mesh " stress skin" applied on the exterior and 1/4-inch of trowel grade Thermo-Lag applied to the stress skin.
One half of the second 3/4-inch conduit run was protected by a 1/2-inch thick conduit pre-shape with a 1/4-inch thick Thermo-Lag flexi-blanket wrap.
The other half was protected by a 1/2-inch thick conduit pre-shape with a 1/4-inch thick pre-shape overlay.
TV 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 to the fire, in addition, the cables exhibited visible fire damage to cable jackets in all conduits, 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, TV 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 vertical 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 properiy during a fire.
The thermocouples 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, TV 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, Thercoccuples 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 TV 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 to believe that potential early f ailures 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 corfigurations 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 TV 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
NRCB 92-01, SUPP. I August 28, 1992 Page 4 of 9 through was prevented.
The assemblies tested in August 1992 were cooled with water, essentially leaving the test assemblies in the condition they were in at the completion of the fire test.
Areas of burn through and seam and joint 4
failures were observed during post-fire inspection.
Further, the TV 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-hour small scale fire endurance tests on Thermo-Lag 330 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 vendor recommendation.
The average thermocouple reading on the unexposed surf ace 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 ninutes.
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 t'wo locations in 45 minutes, resulting in a corresponding drop in surface thermocouple readings as the cold air entered the furnace. After 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, 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 ter.hnicians 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 nours 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 sof t 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.
1
NRCB 92-01, SUPP. I August 28, 1992 Page 5 of 9 On August 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 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 the furnace.
The stress skin was kept from being restrained 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-Il9 temperature acceptance criterion of 163 *C (325 'F) in 45 minutes. After 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, the unexposed surface temperature reading was 756 *C (1392 'F).
At I hour 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 1-hour fire endurance test on a Thermo-Lag 330 1-hour panel, which had stress skin on one side only.
This panel was placed on the furnace with the stress skin towards the fire, although the vendor recommends that the 1-hour panel be installed with the stress skir away from the fire exposure. The deviation from the vendor recommendation aided in the determination of the material's sensitivity to installaticn 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 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 was superice to the specimen tested on July 15, 1992, at which the stress skin f aced the unext:: sed side, as recommended by the vendor.
The specimen tested on July 15, 1992, exceeded the 163 'C (325 'F) acceptance criterion in 20 minutes anc the unexposed surface reached 649 *C (1200 'F) 'in 37 minutes.
Eurn througn was observed in 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 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 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 locations.
After the burn holes formed, unexposed surface thermocouple 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 skins on the outer sides of the test specimen.
The stress skin was not trimmed away from the specimen
NRCB 92-01, SUPP. 1 August 28, 1992 Page 6 of 9 for this test; it was restrained in compression at the edges of the panel.
The average 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 test.
Visible signs of damage were 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 Skin Stress Skin Time to Burn Rating Restraint Orientation
- Exceed, Through 163 *C (hrs: min)
(hrs: min) 7/15/92 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> 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 surface thermocouple temperature
, Two 1-hour panels fitted face to face In IN 92-55, the staff listed specific 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 defiaitive 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 TV 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 pl:nt specific tests.
Discu m _on 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, " Fire Protection." GOC 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 50.48(b) states that Appendix R to 10 CFR Part 50 establishes fire protection features required to satisfy l
-____.__--___m_
-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 licensed to operate before January 1, 1979.
Sections Ill.G, 111.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 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 50 in accordance 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, Sertion 111 G.I 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 !!! G.2 of Append h R requires the separation of safe shutdown trains by separation of cables ac:d 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 Bermal degradation of fire barrier systems -(e g,,
walls, floors, equipment vaults, and electrical raceway enclosures), such n the Thermo-Lag system, could lead to both trains of safo 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 Thermo-Lag fire barrier fire endurance tests and determined that-the and 3-hour pre-formed assemblies installed on conduits, cable trays (of all_ sizes and configurations), and used to construct fire barrier walls and ceil.ings, and equipment enclosures do not provide the level of safety as required by NRC:
requirements.
The tests sponsored by-TV-Electric raised concerns relating to joint and. seam separatlon leading,t.o cable' damage." In. addition, they raise-concerns about the potential.for burn thr'ough of the Thermo-Lag material-itself.
The tests.-sponsored by the NRC appear to confirm co'ncerns relating to-i burn through of the Thermo-Lag material in certain configurations-in the absence of joints f and seams.
L Recuested Actions All holders of operating' licenses forcnuclear power reactors, immediately upon receiving'this bulletin supplement,<are requested to take-the following actions.
These actions are essentin'ily 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-hourpre-formedThermo-Lag 330f
- panels and conduit shapes, identify the areas of the plant which-have I
e
.m
. -.~
NRCB 92-01, SUPP. 1 August 28, 1992 Page 8 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.
2.
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, in accordance with plant procedures, the appropriate compensatory 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 barrier.
These compensatory measures should remain in 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 r.y 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.
Recuired 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 barrier 3 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.
Lackfit Discussion 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 the requirements of.Section Ill.G,qf Appendix R to10 CFR Part 50.
The actions requested by this bulletin sup Idbent do not repre'sent 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, D.C. 20555, under oath or af firmation 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 burcen hours is 120 person hours for each licensee response, including those needed to assess the new recommendations, search data sources, gather and
9 NRCB 92-01, SUPP. 1 August _ 28, 1992 Page 9 of 9 analyze the data, and prepare the required letters.
This estimate of the average number of burden hours pertains only to 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, D.C. 20555, and to the Paperwork Reduction Project (3150-0012), Office of Information and Regulatory Affairs, NE08-3019, 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 complying with this bulletin supplement:
(1) the licensee staff's time and costs to perform requested inspections, corrective actions, and associated testing; (2) the licensee staf f'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 time; and (4) an estimate of the additional long-term costs that will be incurred as a result of implementing commitments 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.
{h N.n f ) 4%
Charles E. Rossi, Director Division of Operational Events Assessment Office of Nuclear Reactor Regulation Technical contacts:
Ralph Architzel, NRR (301) 504-2804 Patrick Madden, NRR (301) 504-2854
Attachment:
List of Recently Issued NRC Bulletins l
l l
Attachment NRCB 92-01, SUPP. 1 August 28, 1992 Page 1 of 1 LIST OF RECENTLY ISSUED NRC BULLETINS EuTletin Date of No.
Subject I,suance 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 Small Conduits Free from Fire Damage 91-01 Reporting Loss of 10/18/91 All fuel cycle and uranium Criticality Safety fuel research and develop-Controls ment licensees.
-01, Failure of Westinghouse 06/28/91 All holders of Ols or cps app. 2 Steam Generator Tube for PWRs.
Mechanical Plugs 89-01, failure of Westinghouse 11/14/90 All t.iders of Ols or cps Supp. 1 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.
90-01 Loss of fill-0il in 03/09/90 All, holders of OLs or cps Transmitters Manufactured for nuclear power reactors.
by Rosemount 89-03 Potential loss of Required 11/21/89 All holders of Ols or cps Shutdown Margin During for PWRs.
Refueling Operations 88-10 Nonconforming Molded-Case 08/03/89 All holders of Ols or cps Supp. 1 Circuit Breakers for nuclear power reactors.
- Operating License
= Construction Permit
.