Information Notice No. 91-79: Supplement 1:Deficiencies Found in Thermo-Lag Fire Barrier Installation
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555
August 4, 1994
NRC INFORMATION NOTICE 91-79, SUPPLEMENT 1: DEFICIENCIES FOUND IN THERMO-LAG
FIRE BARRIER INSTALLATION
All holders of operating licenses or construction permits for nuclear power
The U. S. Nuclear Regulatory Commission (NRC) is issuing this information
notice (IN) supplement to alert addressees to additional problems that could
result from improperly installing Thermo-Lag 330-1 fire barriers to satisfy
NRC fire protection requirements for safe shutdown components. 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.
On December 6, 1991, NRC issued IN 91-79, "Deficiencies in the Procedures for
Installing Thermo-Lag Fire Barrier Materials." The IN discussed Thermo-Lag
fire barrier configurations that were not installed in accordance with the
installation procedures published by the vendor, Thermal Science, Incorporated
(TSI). Most of the deficiencies were found by comparing TSI installation
procedures with records of methods and procedures used by licensees during
actual installation of Thermo-Lag fire barriers. In some cases, the
installation methods that deviated from installation procedures recommended by
the vendor were found to be unacceptable when subsequent qualification fire
endurance testing resulted in fire barrier failures. In other cases, fire
endurance test or engineering analysis had not been performed to support the
Description of Circumstances
On July 15, 1994, Detroit Edison Company, the licensee for Enrico Fermi Atomic
Power Plant, Unit 2, (Fermi 2) notified NRC pursuant to Part 21, "Reporting of
Defects and Noncompliance," of Title 10 of the Code of Federal Regulations (10
CFR Part 21). The Notification reported deviations and defects in Thermo-Lag
fire barrier installation at Fermi 2. While removing and replacing Thermo-Lag
fire barriers, the licensee found deficiencies such as insufficient Thermo-Lag
trowel grade material on interferences, inconsistently positioned ribbed
9408030006. IN 91-79, Supp. 1
August 4, 1994
Page 2 of 3
faces, insufficient cable protection at the fire stops, expanded metal missing
from wall assembly, Thermo-lag panels used in place of support steel, failure
to fasten the panels to the floor as required, and insufficient
clearance around fire dampers. It appears that installation records did not
reflect the "as-built" condition of these barriers. Employees from the P. R.
Sussman Company of Toledo, Ohio, installed the Thermo-Lag fire barriers at
The findings at Fermi 2 substantiate NRC concerns stated in IN 92-46, "Thermo-
Lag Fire Barrier Material Special Review Team Final Report Findings, Current
Fire Endurance Tests, and Ampacity Calculation Error," June 23, 1992. The
concerns are that records of methods and procedures used during installation
of Thermo-Lag barriers may be inaccurate, incomplete, or missing.
On December 17, 1992, NRC issued Generic Letter (GL) 92-08, "Thermo-Lag 330-1
Fire Barriers." The GL requested licensees to confirm that qualified Thermo-
Lag fire barriers had been installed with appropriate procedures and quality
controls. Most licensees responded that they had followed the procedures
recommended by the vendor, TSI. The responses also indicated that most
licensees were waiting for the results of the industry test program sponsored
by the Nuclear Energy Institute (NEI) before taking corrective actions.
By December 1993, it had become apparent to the NRC staff that the NEI test
program, alone, would not be sufficient to resolve the Thermo-Lag fire barrier
issues. Therefore, in accordance with 10 CFR 50.54(f), NRC issued requests
for additional information (RAI) to the licensees relying on Thermo-Lag to
meet Appendix R requirements. The RAI asked each licensee to submit detailed
information on such test assembly elements as material thickness, joints,
bands, tie-wires, stress skin and supports. The RAI also requested each
licensee to state whether the parameters defining these elements were obtained
and verified and to describe the type and extent of the unknown parameters.
Many licensees did not supply the information requested but stated how they
would get it in the future.
In responding to the RAI, Detroit Edison Company advised NRC that it would not
wait for the results of the NEI test program and would resolve Thermo-Lag
issues at Fermi 2 by either removing or reclassifying Thermo-Lag fire
barriers. During these modifications the licensee found installation
deficiencies described above and reported them to NRC.
As noted in GL 86-10, Supplement 1, "Fire Endurance Test Acceptance Criteria
for Fire Barrier Systems Used to Separate Redundant Safe Shutdown Trains
Within the Same Fire Area," dated March 25, 1994, test specimens intended for
fire endurance qualification testing of fire barriers should represent the
construction of these barriers in material and workmanship. The findings at
Fermi 2 illustrate that examination of installation records may not be
sufficient to determine how the original Thermo-Lag fire barriers were
. IN 91-79, Supp. 1
August 4, 1994
Page 3 of 3
Related Generic Communications
. IN 91-47, "Failure of Thermo-Lag Fire Barrier Material to Pass Fire
Endurance Test," August 6, 1991.
. IN 92-46, "Thermo-Lag Fire Barrier Material Special Review Team Final
Report Findings, Current Fire Endurance Tests, and Ampacity Calculation
Errors," June 23, 1992.
. Bulletin (BL) 92-01, "Failure of Thermo-Lag 330 Fire Barrier System to
Maintain Cabling in Wide Cable Trays and Small Conduits Free from Fire
Damage," June 24, 1992
. BL 92-01, Supplement 1, "Failure of Thermo-Lag 330 Fire Barrier System
to Perform its Specified Fire Endurance Function," August 28, 1992.
. GL 92-08, "Thermo-Lag 330-1 Fire Barriers," December 17, 1992.
. GL 86-10, Supplement 1, "Fire Endurance Test Acceptance Criteria for
Fire Barrier Systems Used to Separate Redundant Safe Shutdown Trains
Within the Same Fire Area," March 25, 1994.
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.
/S/'D BY BKGRIMES
Brian K. Grimes, Director
Division of Operating Reactor Support
Office of Nuclear Reactor Regulation
Technical contact: Daniele H. Oudinot, NRR
Page Last Reviewed/Updated Friday, May 22, 2015