View source for Information Notice 1991-47, Failure of Thermo-Lag Fire Barrier Material to Pass Fire Endurance Test

{{Adams
| number = ML031190452
| issue date = 08/06/1991
| title = Failure of Thermo-Lag Fire Barrier Material to Pass Fire Endurance Test
| author name = Rossi C
| author affiliation = NRC/NRR
| addressee name = 
| addressee affiliation = 
| docket = 05000003, 05000010, 05000029, 05000133, 05000155, 05000171, 05000206, 05000213, 05000219, 05000220, 05000237, 05000244, 05000245, 05000247, 05000249, 05000250, 05000251, 05000254, 05000255, 05000259, 05000260, 05000261, 05000263, 05000265, 05000266, 05000267, 05000269, 05000270, 05000271, 05000272, 05000275, 05000277, 05000278, 05000280, 05000281, 05000282, 05000285, 05000286, 05000287, 05000289, 05000293, 05000295, 05000296, 05000298, 05000301, 05000302, 05000304, 05000305, 05000306, 05000309, 05000311, 05000312, 05000313, 05000315, 05000316, 05000317, 05000318, 05000320, 05000321, 05000322, 05000323, 05000324, 05000325, 05000327, 05000328, 05000329, 05000330, 05000331, 05000333, 05000334, 05000335, 05000336, 05000338, 05000339, 05000341, 05000344, 05000346, 05000353, 05000354, 05000361, 05000362, 05000364, 05000366, 05000368, 05000369, 05000370, 05000373, 05000374, 05000382, 05000387, 05000388, 05000389, 05000390, 05000391, 05000395, 05000397, 05000400, 05000409, 05000410, 05000412, 05000413, 05000414, 05000416, 05000423, 05000424, 05000425, 05000437, 05000438, 05000439, 05000440, 05000441, 05000443, 05000444, 05000445, 05000446, 05000454, 05000455, 05000456, 05000457, 05000458, 05000461, 05000482, 05000483, 05000498, 05000499, 05000508, 05000528, 05000529, 05000530
| license number = 
| contact person = 
| document report number = IN-91-047, NUDOCS 9108020180
| document type = NRC Information Notice
| page count = 5
}}
{{#Wiki_filter:I

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 August 6, 1991 NRC INFORMATION NOTICE NO. 91-47:    FAILURE OF THERMO-LAG FIRE BARRIER MATERIAL

TO PASS FIRE ENDURANCE TEST

==Addressees==
:
All holders of operating licenses or construction permits for nuclear power

reactors.

==Purpose==
:
This information notice is intended to alert addressees to problems that could

result from the use of or improper installation of THERMO-LAG material to

satisfy the electrical raceway fire protection requirements for safe shutdown

components specified in Section III.G.2 of Appendix R to Part 50 of Title 10
of the Code of Federal Regulations (10 CFR Part 50). It is expected that

recipients will review the information for applicability to their facilities

and consider actions, as appropriate, to avoid similar problems. However, suggestions contained in this information notice do not constitute any new

Nuclear Regulatory Commission (NRC) requirements; therefore, no specific

action or written response is required.

==Description of Circumstances==
:
The Gulf States Utilities Company, the licensee for the River Bend Station

(RBS), submitted Licensee Event Reports (LERs) 87-005, 89-009, 90-003, and an

Informational Report to the NRC concerning deficiencies identified in fire

barriers. The NRC staff reviewed test report information and associated

documents regarding the RBS electrical raceway fire barriers to determine if

the problems identified in the LERs and Informational Report could affect

other NRC licensees. The electrical raceway fire barrier material used at RBS

is THERMO-LAG, a product manufactured and supplied by Thermal Science, Incorporated, (TSI), of St. Louis, Missouri. TSI provides THERMO-LAG for

1-hour and 3-hour rated fire barriers.

A 3-hour fire endurance test of a 30-inch aluminum electrical cable tray was

performed in October 1989 at the Southwest Research Institute (SwRI) for Gulf

States Utilities Company. In this test, a THERMO-LAG envelope system failed

resulting in high temperatures inside the cable tray envelope and loss of

circuit integrity within approximately 60 minutes. Catastrophic failure and

collapse of the tray occurred within 1 1/2 hours. The failure of this test

raised concerns regarding the adequacy of THERMO-LAG cable tray enclosures

protecting 30-inch wide cable trays.

9108020180-PY-                rXat                         q9     &je           Go 4oi

IN 91-47 August 6, 1991 Discussion:
    NRC requirements and guidelines for fire barriers

documents, including Appendix R to 10 CFR 50, Generic are contained in various

"Implementation of Fire Protection Requirements",           Letter 86-10,
   Review Plan." The extent to which these requirements   and   NUREG-0800,      "Standard

able to a specific plant depends on plant age,               or  guidelines     are applic- licensee in developing the fire protection plan,  commitments       established    by the

reports (SERs) and supplements, and the license      the   staff    safety    evaluation

protection. Fire barrier wrap material is designed conditions pertaining to fire

assurance that the effects of a fire are limited         to provide reasonable

shutdown related system while another division       to  one division of a safe

will remain free of fire damage.

The Gulf States Utilities Company uses THERMO-LAG

components throughout RBS that are related to         to protect raceways and

least 40 NRC licensed facilities use THERMO-LAG safe    shutdown. In addition, at

to

assemblies with 3-hour and 1-hour ratings to encloseconstruct fire barrier

other safe shutdown components.                            electrical raceway and

During routine walkdown inspections in early 1987, identified degradation of the THERMO-LAG 1-hour         RBS fire protection personnel

and

During repairs to correct the deficiencies discovered3-hour rated barriers.

licensee found that the fire barriers had not been           during the walkdowns, the

the manufacturer's specifications. The large number     installed      in accordance with

prompted the licensee to expand these walkdown              of   observed    deficiencies

THERMO-LAG fire barriers. Hourly fire watches      inspections       to  include   all

safety-related areas pending completion of all were posted in all affected

any deficiencies found. The licensee attributedinspections and correction of

the subcontractor installation and quality controlthe deficiencies to failure of

inspection program.

During maintenance activities in early 1989, the

deficiencies indicating an apparent deficiency       licensee found-additional

control inspection program. The subcontractor     in   the installation and quality

who

fire barriers at RBS was approved by TSI as a qualified installed the THERMO-LAG

during the installation at RBS, the subcontractor               installer. However, components of the THERMO-LAG called "stress skin"      removed     the factory-installed

stress skin component, a wire mesh, is critical        and   structural     ribbing. The

the fire product during fire exposure. The RBS     to   the   structural      integrity of

considered that all barriers were degraded because fire    protection     personnel

inside Layer of the stress skin that had been            of the many sections of the

tion at RBS.                                     removed     during initial installa- The discrepancies identified between the manufacturer's

actual site installation manual and qualification                installation manual, licensee conducting additional fire endurance          fire    tests    resulted in the

tested a U-shaped 30-inch wide aluminum ladder   testing.        In  October    1989, SwRI

back cable tray enclosed in a

3-hour fire-rated barrier constructed of THERMO-LAG

constructed the cable tray protective envelope            material. RBS personnel

in   accordance      with the

manufacturer's published installation instructions.

IN 91-47 August 6, 1991 During the 3-hour fire endurance test, all thermocouples inside the THERMO-LAG

protected tray reached failure temperatures (>3251F) in times ranging from

approximately 45 minutes to 80 minutes. Conductor-to-ground failure occurred

in the power cable at 60 minutes. The THERMO-LAG enclosure disintegrated at

77 minutes, and the cable tray collapsed at 82 minutes. The SwRI test results

on the as-designed THERMO-LAG configuration prompted RBS to institute a fire

watch patrol in all areas that depend on THERMO-LAG barriers for protection of

safe shutdown capability.

Additional deficiencies, such as small holes, cracks and unfilled seams, were

found in the THERMO-LAG material during walkdowns conducted in early 1990.

The licensee conducted additional testing of as-installed barriers in November

and December 1990. Certain 1-hour and 3-hour cable tray and conduit envelope

tests failed. The envelopes were upgraded and tests of the upgraded barriers

passed with the exception of the 3-hour cable tray envelope. Final resolution

of the 3-hour envelope may include replacing existing fire wrap materials with

fully qualified fire wrap, repairing and then qualifying in-plant fire wrap

assemblies by supplemental fire tests, or rerouting the cables into acceptable

enclosures.

Additionally, other fire barrier wrap design and installation concerns have

been reported by RBS that indicate the possibility that NRC requirements for

fire protection were not being met in all aspects. The type of concerns

identified to date include the following:
1.   Lack of documentation of qualification tests which demonstrate that

aluminum conduits penetrating the THERMO-LAG protective envelope have

been tested.

2.   Lack of documentation of qualification tests for different joint

installations that demonstrate that varying fitup methods (i.e., dry

fitting) are qualified.

3.   Lack of documentation of qualification tests of THERMO-LAG installations

applicable to large cable trays. The licensee questioned the validity of

extrapolating results from small cable tray tests to its 30-inch wide

trays.

The NRC is particularly interested in obtaining information on fire barriers

that have been found with deficiencies similar to those described in this

notice. Documentation, in as much detail as practicable, of any such

deficiencies discovered, especially in cases where a fire barrier may have

been improperly installed or tested is important. Licensees may communicate

the availability of information of this type by telephone to the NRC technical

contact listed below. Information Notice No. 88-04, "Inadequate Qualification

and Documentation of Fire Barrier Penetration Seals," provides additional

discussion and considerations regarding qualification of installed fire

barriers.

IN 91-47 August 6, 1991 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

the technical contact listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

Charles E. o  S,Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

===Technical Contact:===

===Ralph Architzel, NRR===
                    301-492-0804 Attachment:  List of Recently Issued NRC Information Notices

. I

Attachment

IN 91-47 August 6, 1991 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information                                    Date of

Notice No.               Subject               Issuance  Issued to

89-56,          Questionable Certification     07/19/91  All holders of OLs or CPs

Supp. 2         of Material Supplied to                  for nuclear power reactors.

the Defense Department by

Nuclear Suppliers

91-46           Degradation of Emergency       07/18/91  All holders of OLs or CPs

Diesel Generator Fuel Oil                for nuclear power reactors.

Delivery Systems

91-45           Possible Malfunction of        07/05/91  All holders of OLs or CPs

Westinghouse ARD, BFD, and               for nuclear power reactors.

NBFD Relays, and A200 DC

and DPC 250 Magnetic Con- tactors

91-44            Improper Control of            07/08/91 All nuclear fuel facilities.

Chemicals in Nuclear Fuel

Fabrication

91-43          Recent Incidents Involving      07/05/91 All holders of OLs or CPs

Rapid Increases in Primary-               for pressurized-water

to-Secondary Leak Rate                   reactors (PWRs).

91-42           Plant Outage Events            06/27/91  All holders of OLs or CPs

Involving Poor Coordina-                 for nuclear power reactors.

tion Between Operations

and Maintenance Personnel

During Valve Testing and

Manipulations

91-41           Potential Problems with        06/27/91  All holders of OLs or CPs

The Use of Freeze Seals                  for nuclear power reactors.

88-63,          High Radiation Hazards         06/25/91  All holders of OLs or CPs

Supp. 2          from Irradiated Incore                  for nuclear power reactors, Detectors and Cables                     research reactors, and

test reactors.

OL = Operating License

CP = Construction Permit}}

{{Information notice-Nav}}