Information Notice No. 88-04, Supplement 1:Inadequate Qualification and Documentation of Fire Barrier Penetration Seals
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555
August 9, 1988
Information Notice No. 88-04, SUPPLEMENT 1: INADEQUATE QUALIFICATION AND
DOCUMENTATION OF FIRE BARRIER
PENETRATION SEALS
Addressees:
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose:
This information notice supplement is being provided to alert addressees to
problems caused by potential misapplication of silicone foam material used in
penetration openings at nuclear power plants. 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 con-
tained in this information notice do not constitute NRC requirements;
therefore, no specific action or written response is required.
Description of Circumstances:
Diablo Canyon. Since August 9, 1979, Diablo Canyon has experienced four fires
in which the penetration seal material ignited and burned:
� On May 10, 1988, during the performance of a diesel generator 24-hour
load test, the Dow Corning silicone foam material, through which the
diesel generator exhaust pipe passes, caught fire. The penetration
design provides for isolation of the foam from the pipe by metal-clad
insulation. This insulation was degraded by the pressure oscillations
from repeated thermal expansion and contraction of the pipe. The
licensee observed dense smoke and two-to three-foot flames coming from
the penetration seal material.
� On February 11, 1983, after 1.7 hours of diesel engine operation, the
penetration seal material for another diesel generator exhaust pipe was
involved in rapid combustion.
� On September 21, 1982, during a diesel generator 24-hour load test, the
penetration seal material burned under similar circumstances. One mea-
surement with a pyrometer indicated that the exhaust pipe temperature was
about 600�F.
8808040062
. IN 88-04, Supplement 1
August 9, 1988
Page 2 of 3
� On August 9, 1979, the penetration seal material burned under similar
circumstances.
Davis-Besse. On March 25, 1986, the licensee, Toledo Edison, reported that
the silicone foam sealant in a fire barrier penetration in the main steam line
room appeared to have baked and pulled away from the pipe (Licensee Event
Report 50-346/86-17). This penetration was filled with low-density silicone
foam (SF-20), which is rated for a maximum temperature of 425�F. The main
steam lines normally operate near 600�F. The licensee's corrective actions
were to stuff ceramic fiber (Kaowool) into the seal for increased fire
resistance and to expand the existing fire watch. The licensee determined
that a high-temperature boot seal could not be properly installed because of
interferences. The licensee revised the fire barrier penetration test from a
check that a seal is intact to a comparison of an as-built seal to a
fire-tested seal configuration.
Discussion:
The NRC requirements and guidelines for fire barrier penetration seals are
contained in various documents, including Appendix R to 10 CFR 50, Appendix A
to Branch Technical Position (BTP) APCSB 9.5-1, "Guidelines for Fire
Protection for Nuclear Power Plants Docketed Prior to July 1, 1976," and
NUREG-0800, Standard Review Plan. These requirements and guidelines are
summarized in Appendix A of Information Notice No. 88-04, "Inadequate
Qualification and Documentation of Fire Barrier Penetration Seals." In
addition, as stated in Section D.1 (I) of Appendix A to BTP APCSB 9.5-1,
"Interior wall and structural components, thermal insulation materials and
radiation shielding materials and sound-proofing should be noncombustible."
The silicone foam seal material in the diesel generator exhaust pipe penetra-
tions at Diablo Canyon was used as replacement material for the combustible
foam plastic-type seals, which were involved in the 1975 fire at the Browns
Ferry nuclear power plant. In addition to diesel generator exhaust pipe
penetrations, some main steamline penetrations may be sealed with this ma-
terial. The material is apparently designed to withstand maximum ambient
temperatures of 400�F and temporary exposure to 500�F, but not long-term
exposure to higher temperatures. Although the measurement at Diablo Canyon in
1982 indicated a pipe temperature of about 600�F, average pipe temperatures
are probably much higher.
The licensee for Diablo Canyon determined that only six penetrations (all
associated with diesel generator exhaust pipes) potentially exposed the sili-
cone foam penetration seal material to high temperatures. For these penetra-
tion openings, the licensee plans to install a penetration seal material
designed to withstand long-term exposure to high temperatures.
This subject is also discussed in Information Notice No. 88-56, "Potential
Problems With Silicone Foam Fire Barrier Penetration Seals." The present
notice is being issued separately to highlight the potential misapplication
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August 9, 1988
Page 3 of 3
of silicone foam sealant material for uses in which the sealant must withstand
significant exposure to high temperature. Information Notice No. 88-56
focuses on nonconforming conditions of silicone foam sealing materials that
have been found in inspections of fire barriers.
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact one of the techni-
cal contacts listed below or the Regional Administrator of the appropriate
regional office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contacts: Chuck Ramsey, RV
(415) 943-3767
Dennis Kubicki, NRR
(301) 492-0825
Attachment: List of Recently Issued NRC Information Notices
. Attachment
IN 88-04, Supplement 1
August 9, 1988
Page 1 of 1
LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
_____________________________________________________________________________
Information Date of
Notice No._____Subject_______________________Issuance_______Issued to________
88-59 Main Steam Isolation Valve 8/9/88 All holders of OLs
Guide Rail Failure at or CPs for nuclear
Waterford Unit 3 power reactors.
88-58 Potential Problems with 8/8/88 All holders of OLs
ASEA Brown Boveri ITE-51L or CPs for nuclear
Time-Overcurrent Relays power reactors.
88-57 Potential Loss of Safe 8/8/88 All holders of OLs
Shutdown Equipment Due to or CPs for nuclear
Premature Silicon Controlled power reactors.
Rectifier Failure
88-56 Potential Problems with 8/4/88 All holders of OLs
Silicone Foam Fire Barrier or CPs for nuclear
Penetration Seals power reactors.
88-55 Potential Problems Caused 8/3/88 All holders of OLs
by Single Failure of an or CPs for nuclear
Engineered Safety Feature power reactors.
Swing Bus
88-54 Failure of Circuit Breaker 7/28/88 All holders of OLs
Following Installation of or CPs for nuclear
Amptector Direct Trip power reactors.
Attachment
88-53 Licensee Violations of NRC 7/28/88 All manufacturers
Regulations, Which Led to and distributors
Medical Diagnostic of radio-
Misadministrations pharmaceuticals
for human use,
nuclear
pharmacies, and
medical licensees.
88-52 Failure of Intrauterine 7/27/88 Medical licensees.
Tandem of Fletcher
Applicator Brachytherapy
Devices During Patient
Treatment
_____________________________________________________________________________
OL = Operating License
CP = Construction Permit
Page Last Reviewed/Updated Tuesday, March 09, 2021