Information Notice No. 93-41: One Hour Fire Endurance Test Results for Thermal Ceramics Kaowool, 3M Company FS-195 and 3M Company Interam E-50 Fire Barrier Systems

                                UNITED STATES 
                         NUCLEAR REGULATORY COMMISSION
                            WASHINGTON, D.C. 20555

                                 May 28, 1993

                               THERMAL CERAMICS KAOWOOL, 3M COMPANY FS-195 AND
                               3M COMPANY INTERAM E-50 FIRE BARRIER SYSTEMS


All holders of operating licenses or construction permits for nuclear power


The U.S. Nuclear Regulatory Commission (NRC) is issuing this information
notice to alert addressees to the results of fire endurance tests for Thermal
Ceramics Kaowool, Minnesota Mining and Manufacturing Company (3M Company)
FS-195, and 3M Company Interam E-50 1-hour fire barrier systems reviewed by
NRC inspectors during a reverification inspection.  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 are not NRC requirements;
therefore, no specific action or written response is required.

Description of Circumstances

In Generic Letter 92-08, "Thermo-Lag 330-1 Fire Barriers," the staff stated it
would evaluate other known fire barrier materials and systems that are used by
licensees to fulfill NRC fire protection requirements pursuant to Appendix R
to 10 CFR Part 50 of the Code of Federal Regulations.  The staff has started
its review of fire barriers manufactured by vendors other than Thermal
Science, Incorporated, to verify the capability of the fire barrier systems to
adequately perform their 1-hour or 3-hour fire-resistive functions and to meet
stated ampacity derating values.

A reverification inspection was conducted by NRC inspectors at the Salem
Nuclear Generating Station, owned by Public Service Gas and Electric Company
(the licensee), the week of May 17, 1993.  NRC inspectors reviewed fire
endurance test results for the electrical raceway fire barrier systems used by
the licensee to separate safe shutdown functions within the same fire area. 
The systems used were Thermal Ceramics Kaowool, 3M Company FS-195 and
3M Company Interam E-50.  The fire test results, as documented in the fire
barrier qualification test reports, are discussed below and are summarized in
the attached table.


                                                            IN 93-41
                                                            May 28, 1993
                                                            Page 2 of 3

Kaowool Fire Barrier

Thermal Ceramics, Inc., was formerly the Insulating Products Division of
Babcock and Wilcox, Inc., of Augusta, Georgia.  The licensee fire endurance
testing basis for Kaowool is a Babcock and Wilcox fire test report of
October 24, 1978.   According to the report, five specimens of the Kaowool
barrier were tested on cable trays in a small-scale furnace.  The maximum
length of the 45.7 cm [18 inch] wide cable trays was 61 cm [24 inches].  Cable
fill ranged from 33 percent to 35 percent.  According to the report, the fire
test acceptance criterion was circuit integrity.  The tests were not conducted
or controlled by an independent testing laboratory.  

The test report stated that the circuit integrity in one circuit was lost at
1 hour and 1 minute.  It also stated that cable temperatures exceeded 139 C
[250 F] above ambient air temperature in about 22 minutes.  At 60 minutes into
the test, the cable temperature was about 426.5 C [800 F].  Hose stream tests
were not performed.  The results section of the test report stated that cables
in all tests exhibited signs of fire damage, such as charring.  

3M Company FS-195 Fire Barrier

The licensee fire endurance qualification testing basis for the 3M Company
FS-195 fire barrier system is a 3M Company test report of October 31, 1980. 
Test acceptance criteria were not reported.  The report stated that this was a
small-scale test at the 3M test facility.  The figure in the report showing
the test specimen was conceptual and did not give dimensions.  According to
the figure, the fire barrier was constructed by placing a cable tray in a
metal air duct with the tray support in the middle of the duct.  The metal
duct was covered with FS-195, there was an air space around the cable tray,
and the tray contained 40 percent cable fill. 

According to the test report, the metal duct temperature on the unexposed side
of the fire barrier material exceeded 139 C [250 F] above ambient in about 30
minutes.  At 60 minutes the temperature was 326.5 C [620 F].  The test
specimen was not subjected to a hose stream test.  The condition of the cables
at the end of the test was not reported.

3M Company Interam E-50 Fire Barrier

The licensee fire endurance qualification testing basis for the 3M Company
Interam E-50 fire barrier system is a Twin City Testing Corporation test
report of September 1986.  The fire test acceptance criterion was stated as
circuit integrity as specified by American Nuclear Insurers.  

According to the test report, the cable tray test specimen was a 61 cm
[24 inch] wide aluminum cable tray installed in the test slab in a horseshoe
configuration.  The vertical drops into the furnace were 58.4 cm [23 inches],
and the horizontal run was 86.4 cm [34 inches].  The tray configuration was
divided into four segments.  A vertical run of solid bottom tray was connected
to a ladder-back 90 radial bend.  This bend was connected to a solid bottom
tray segment, which was connected to a vertical ladder-back tray segment.  The.

                                                            IN 93-41
                                                            May 28, 1993
                                                            Page 3 of 3

test specimen also included an air drop.  One half of the tray had 14 percent
cable fill.  The other half had 40 percent cable fill.  A second test specimen
consisted of one 12.7 cm [5 inch] diameter steel conduit and one 12.7 cm
[5 inch] diameter aluminum conduit and a 25.4 cm [10 inch] by 25.4 cm
[10 inch] by 15.2 cm [6 inch] junction box.  

The fire barrier installation procedures appended to the test report specified
multiple installation methods.  However, the fire barrier construction details
and methods of fire barrier application for the test specimens were not
documented in the test report.

The temperatures within the fire barrier and the condition of the cables at
the end of the test were not reported.

As a result of the issues raised during the inspection, the licensee posted
fire watches as compensatory measures in accordance with plant procedures.


The staff is continuing its review of these fire barrier systems including a
reassessment of any previous staff reviews of these systems.  The staff
previously requested additional information on Kaowool from Thermal Ceramics,
Incorporated, in a letter of April 27, 1993, and on the 3M fire barrier
systems from 3M Company in a letter of May 4, 1993.  The staff will evaluate
whether further generic communications are needed to address the issues
discussed above.

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.

                                       ORIGINAL SIGNED BY

                                    Brian K. Grimes, Director 
                                    Division of Operating Reactor Support
                                    Office of Nuclear Reactor Regulation   

Technical contact:  Pat Madden, NRR

1.  Summary of Test Results
2.  List of Recently Issued Information Notices
.                                                                 Attachment 1
                                                                 IN 93-41
                                                                 May 28, 1993
                                                                 Page 1 of 1

                            Summary of Test Results

    PARAMETER           KAOWOOL           FS-195(1)            INTERAM E-50  
Scale of test     Small-scale         Small-scale            Small-scale     
Test laboratory   Not independent     Not independent        Not independent,
                                                             but witnessed by
                                                             Twin City
                                                             Testing Corp.   
Hose stream test  Not performed       Not performed          Performed       
Cable damage      Charred             Unknown                Unknown         
Tested            Not                 Not                    Not 
configuration     representative of   representative of      representative of
                  in-plant            in-plant               in-plant 
                  configurations      configurations         configurations(2)
Maximum           426.5 C             326.5 C [620 F]        Unknown
temperature at 1  [800 �F]
Comments          Accepted by NRC     Accepted by NRC        Installed in
                  11/20/1979          3/18/1981              1991; not 
                                                             submitted to NRC 

    1  In a letter of May 18, 1993, to the NRC, the 3M Company stated that the
FS-195 fire barrier system is used only at Salem.

    2  3M Company provided additional test reports to the licensee on 
May 20, 1993.  The licensee is evaluating the applicability of these test
reports to the in-plant configurations.

    3  NRC acceptance criteria is 139 C [250 F] above ambient.


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