View source for Information Notice 1992-46, Thermo-Lag Barrier Material Special Review Team Final Report Finding, Current Fire Endurance Tests, and Ampacity Calculation Errors

{{Adams
| number = ML031200204
| issue date = 06/23/1992
| title = Thermo-Lag Barrier Material Special Review Team Final Report Finding, Current Fire Endurance Tests, and Ampacity Calculation Errors
| author name = Murley T E
| author affiliation = NRC/NRR
| addressee name = 
| addressee affiliation = 
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| license number = 
| contact person = 
| document report number = IN-92-046, NUDOCS 9206150492
| document type = NRC Information Notice
| page count = 5
}}
{{#Wiki_filter:'p -UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555June 23,-1992NRC INFORMATION NOTICE 92-46: THERMO-LAG'FIRE BARRIER MATERIAL SPECIALREVIEW TEAM .FINAL REPORT FINDINGS, CURRENT-FIRE ENDURANCE TESTS, AND AMPACITY' ' CALCULATION ERRORS

==Addressees==
All holders of operating licenses or construction permi~ sfor'nuclear powerreactors. _ _PurDoseThe U.S. Nuclear Regulatory Commission (NRC) is-issuing this informationnotice to inform addressees of (1)-the findings of the NRC's Thermo-LagSpecial Review Team, (2) current Thermo-Lag 330 fire resistance testing beingconducted by Texas Utilities (TU) and Thermal Science; Inc. (TSI),--and (3)errors found in the calculation of cable ampacity derating factors for Thermo-Lag fire resistive barriers. It is expected that recipients ,will review theinformation for applicability to their facilities and consider actions', as-appropriate, to avoid similar problems. However, suggestions contained in -this information notice are not-NRC requirements; therefore, no specificaction or written response is required.DiscussionFINAL REPORT BY THE SPECIAL REVIEW TEAM FOR THE REVIEW OF THERMO-LAG FIREBARRIER PERFORMANCERThe NRC has been reviewing the qualification of Thermo-Lag-'330-1 fire barriersystems. The NRC previously issued two information notices on these firebarrier systems: (1) Information Notice'91-47, "Failure 6f Thermo-Lag FireBarrier Material to Pass Fire Endurance Test," August 6, 1991, and (2)Information Notice 91-79, "Deficiencies in the Procedures for InstallingThermo-Lag Fire Barrier Materials,' December 6, 1991.On February 12, 1992,'the NRC's Special Review Team for the review of Thermo'Lag fire barrier performance met with the'Nuclear Utilities Management and'Resources Council (NUMARC) to discuss the coordination of the industry's -response to Th'ermo-Lag fire endurance, installation, and-ampacity concerns.During the meeting, the staff provided NUMARC'a proposed draft generic letteron the Thermo-Lag fire barrier issue for review and comment. The draft-generic letter was included in-the-meeting minutes which were placed in thePublic Document Room as an enclosure to a February 24, 1992, letter to NUMARCIn a letter of March 3, 1992, NUMARC commented on the proposed draft generic9206150492 PD R 5O g -\n' 3a I Lr -, IIN 92-46June 23, 1992 letter and committed to coordinate the industry's efforts associated with theissues involving Thermo-Lag. In addition, NUMARC requested that the NRC makeavailable any additional. information on the qualification of these barriers.In response to this request, the NRC provided NUMARC the "Final Report-Special Review Team for the Review of Thermo-Lag Fire Barrier Performance," ofApril 21, 1992, (Attachment 1). The final report concluded that somelicensees have not adequately reviewed and evaluated the fire endurance andampacity test results for applicability to the Thermo-Lag fire barrier systemsinstalled-in their facilities. In addition, the final report stated that somefacilities have used inadequate installation procedures to construct Thermo-Lag fire barriers on electrical raceways and equipment.CURRENT THERMO-LAG 330-1 FIRE BARRIER ENVELOPE TESTINGAs a result of the concerns in Information Notices 91-47 and 91-79, TUinstituted a fire endurance testing program to qualify the Thermo-Lag firebarrier protective system specifically for its Comanche Peak Steam ElectricStation.' This testing was conducted during the weeks of June 15 and 22, 1992.The NRC witnessed the preparation of test specimens and the actual testing ofthe TU electric test articles.The tests consist of a series of 1-hour fire endurance tests on a variety ofcable tray and conduit "mock-ups". The "mock-ups" were designed to duplicateactual plant configurations. TU installed the fire barriers using stockmaterial and actual plant procedures and personnel.The first actual tests occurred on June 17,1i992. Three-quarter-inch, andone-inch and five-inch conduit configurations were tested. All tests passedAmerican Nuclear Insurers criteria, in that electrical cable continuity was -not lost. However, several temperature readings were above specifications forthe 3/4-inch and 1-inch conduit tests, and for a junction box that was commonto all the conduits. Additionally, subsequent investigation of the cablingrevealed evidence of charring and blistering. NRC standards require that theprotected components be free of fire damage.Preliminary information from the second test of a 12-inch cable trayconfiguration on June 18, -1992, showed satisfactory results. Thermocoupletemperatures on the protected cables were less than 325 'F.The third test was conducted on June 19, 1992. This article was a wide(30-inch) ladder back cable tray configuration. At 17 minutes into the test,the Thermo-Lag panel on the bottom of the test article began to sag and thestainless steel banding was carrying the load of the panel. At 18 minutes,the joint at the interface between the tray support and the tray showed signsof weakening and separation. Internal temperatures within areas of this cabletray assembly exceeded 325 'F at 25 minutes. The joint fully separated in41 minutes resulting in cable circuit integrity failure and fire damage to thecables..,.. ., .,;~~~ -, , I Attachment 1_ , IN 92-46June 23, 1992c sUNITED STATES* of -t &#xa2;NUCLEAR REGULATORY COMMISSION-WASHINGTON. D. C. 2555April 21, 1992MEMORANDUM FOR: William T. Russell, Assiciate Directorfor Inspection and Technical AssessmentOffice of Nuclear Reactor RegulationFROM: Thomas E. Murley, DirectorOffice of Nuclear Reactor Regulation

SUBJECT: FINAL REPORT -SPECIAL REVIEW TEAM FOR THE REVIEW OFTHERMO-LAG FIRE BARRIER PERFORMANCEOn February 12, 1992, the special review team for the review of Thermo-Lagfire barrier performance met with the Nuclear Utilities Management andResources Council (NUMARC) to obtain a commitment for a coordinated industryresponse to our concerns. During the meeting, the team presented the resultsof its review and gave the attendees a proposed generic letter on Thermo-Lagfire barriers.By a letter of March 3, 1992; NUMARC committed to coordinate the industry'sefforts and requested additional technical information. The review team'sfinal technical report is enclosed for transmittal by your staff to NUMARC andthe vendor. The report, which has been reviewed by your staff, documents theresults of the team's review and provides the technical bases for its findingsand recommendations. The report identifies the full scope of the concerns andwill facilitate discussions between the staff and NUMARC needed to resolvetheir questions and proceed with the issuance of the proposed generic letter.The special review team is available to discuss its final report with you oryour staff at your convenience.Thomas E.ectorOffice of Nuclear Reactor Regulation

===Enclosure:===
As statedcc w/enclosure:J. Sniezek'"- 92X05120277--920421PDR REVGP ERONUMRCPDR IN 92-46June 23, 1992 TU has established roving fire watches for Unit 1, in accordance.-with its FireProtection Manual. The roving fire watches cover plant areas where Thermo-Lagfire barrier configurations, similar to those'which failed, are used toprovide a fire endurance barrier'for safe-shutdown equipment.TSI is also instituting a fire endurance testing program. This programincludes testing a new installation technique required for cable traysinstalled with gap widths greater than 0.030 inches. The new seam joiningtechnique requires that either (1):stainless steel tie wires be placed throughthe stress skin'at specified intervals or (2) stress skin and a layer ofThermo-Lag.trowel grade material be placed over the entire seam length andbanded in place. Preliminary results of a June 9, 1992, test using the newseam joining technique (on seams without wide gaps) on a 36-inch cable traysystem and a 3/4-inch conduit assembly were considered successful by thevendor and testing laboratory.The NRC will provide additional information on these fire endurance testingprograms as it becomes available.AMPACITY DERATING CALCULATION ERRORIn April 1992, the Washington Public Power Supply System, the licensee forWashington Nuclear Project, Unit 2,-found a mathematical error in thecalculation of the ampacity derating factor for the Thermo-Lag fire barrierenclosure of cable trays in Industrial Testing Laboratories (ITL) IncorporatedTest Report ITL-82-5-355C. The error occurred when ITL adjusted the testcurrent to baseline temperatures of 40 0C ambient and 90 0C cable. Thisadjustment is required when tests are performed at different ambient and cabletemperatures. ITL used the correct equation for adjusting to temperatureparameters that differ from the Insulated Cable Engineers Association (ICEA)publication P-46-426: I' = I X MF (where "I" is at 40 "C ambient and 90 "Ccable temperature, and "I'" is at other ambient and cable temperatureconditions). However, in calculating II," ITL multiplied WI'" by "MF" insteadof dividing. The NRC determined that the ampacity derating factor will changefrom 18 to 33 percent when the mathematical error is corrected. Whilereviewing other ITL test reports, the NRC staff found similar errors in othercalculations performed by ITL in the adjustment equation for ambient and cabletemperature conditions. The NRC also noted that the baseline currentsobtained from the test vary widely (up to 32 percent) from those published inthe ICEA publication P-54-440.I It ,
WUIN 92-46June 23, 1992 This information notice requires nonspecific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation (NRR) project manager.i.CCar es E. Rossi, Direct oDivision of Operational Events Assessment-Office of Nuclear Reactor Regulation'.Technical contacts: Ralph Architzel, NRR(301) 504-2804Patrick Madden, NRR(301) 504-2854

===Attachments:===
S e PI j loC o1. "Final Report -Special Review Team for the Review of Thermo-Lag FireBarrier Performance," April'21, 19922. List of Recently Issued NRC Information Notices}}

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