United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 95-32: Thermo-Lag 330-1 Flame Spread Test Results

                                 UNITED STATES
                         NUCLEAR REGULATORY COMMISSION
                          WASHINGTON, D.C. 20555-0001

                                August 10, 1995



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 the NRC flame spread tests of
Thermo-Lag 330-1 fire barrier panels.  It is expected that recipients will
review the information for applicability to their facilities and consider this
information, as appropriate, in their review of Thermo-Lag 330-1 fire
barriers.  However, suggestions contained in this information notice are not
NRC requirements; therefore, no specific action or written response is

Description of Circumstances

On January 12, 1995, the NRC Staff conducted two flame spread tests of
Thermo-Lag 330-1 panels at U.S. Testing, Fairfield, New Jersey.  The National
Institute of Standards and Technology provided technical assistance.  The
tests were conducted in accordance with American Society of Testing Materials
E84 (ASTM E84), "Surface Burning Characteristics of Building Materials," 1994,
which is the test method referenced in the NRC fire protection guidance

Both of the Thermo-Lag test specimens were constructed of 5/8-inch nominal
thickness Thermo-Lag 330-1 panels.  A nominal 20-inch wide by 25-foot long
Thermo-Lag specimen was placed in the top of the tunnel furnace in a face-down
position.  The test specimen becomes the furnace ceiling.  A gas burner at one
end of the furnace provided about 5,000 Btus per minute for the 10-minute test
period.  An inducted air flow pulled the gas flame downstream.  Flame travel
along the surface of the Thermo-Lag specimen was observed through windows in
the side of the furnace.  The test laboratory calculated the flame spread
ratings on the basis of the distance the flame traveled down the test specimen
and the elapsed time for maximum flame spread.  

The Thermo-Lag panels for the first test specimen were purchased from Texas
Utilities Electric Company from warehouse stock for the Comanche Peak plant. 
These panels were coated at the point of manufacture with a latex top coat
that was applied by Thermal Science, Inc. (TSI), the manufacturer and supplier
of Thermo-Lag fire barrier materials.  The maximum flame spread measured was
about 2.4 meters [8 feet] at 1 minute and 23 seconds into the test.  

9508040074.                                                            IN 95-32
                                                            August 10, 1995
                                                            Page 2 of 2

This measurement equated to a flame spread rating of 37.  The Thermo-Lag
panels for the second test specimen, which were purchased from TSI, were not
topcoated.  The maximum flame spread measured for this specimen was 2.4 meters
[8 feet] at 7 minutes and 20 seconds into the test.  This measurement equated
to a flame spread rating of 25.


Flame spread tests are used to determine the surface burning characteristics
of materials when exposed to a test fire.  Flame spread test results are used
to compare the surface burning characteristics of different materials and are
one consideration in assessments of the fire hazard introduced when a material
is used in an area.  The higher the numerical flame spread rating, the greater
the flammability hazard.  For example, cement-asbestos board and red oak
flooring, which are used to calibrate the test furnace, have flame spread
ratings of 0 and 100, respectively.  

NRC staff guidelines regarding flame spread are contained in several NRC
documents.  For example, although it is not directly applicable to fire
barriers, Branch Technical Position APCSB 9.5-1 states, in part, that
"[i]nterior wall and structural components, thermal insulation materials, and
radiation shielding materials and sound-proofing should be non-combustible. 
Interior finishes should be non-combustible or listed by a nationally
recognized testing laboratory...for a flame spread 25 or less...."  In
addition, Standard Review Plan 9.5.1 addresses flame spread in its definition
of noncombustible materials.  It states, in part, that a noncombustible
material has "a structural base of noncombustible material...with a surfacing
not over 1/8-inch thick that has a flame spread rating not higher than 50...."

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 NRR project manager.

                                    /S/'D BY DMCRUTCHFIELD

                                    Dennis M. Crutchfield, Director
                                    Division of Reactor Program Management
                                    Office of Nuclear Reactor Regulation

Technical contact:  Patrick M. Madden, NRR
                    (301) 415-2854

Page Last Reviewed/Updated Monday, November 18, 2013