Information Notice No. 97-70: Potential Problems with Fire Barrier Penetration Seals
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555-0001
September 19, 1997
NRC INFORMATION NOTICE 97-70: POTENTIAL PROBLEMS WITH FIRE BARRIER PENETRATION
All holders of operating licenses for nuclear power reactors except those who
have permanently ceased operations and have certified that fuel has been
permanently removed from the reactor vessel.
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information
notice to alert addressees to problems in installed fire barrier penetration
seals that have gone undetected as a result of inadequate surveillance
inspection procedures and inadequate acceptance criteria. It is expected that
recipients will review the information for applicability to their facilities
and consider actions as appropriate, to avoid similar problems.
Description of Circumstances
The staff in NRC Region I inspected fire protection at Maine Yankee Atomic
Power Plant (Maine Yankee) from June 26 through 30, 1995. No safety concerns
or violations were identified at that time regarding the installed penetration
seals. However, an unresolved item was opened regarding the acceptability of
penetration seal qualification and testing, and qualifications of installers.
Subsequently, the licensee conducted a scoping study in preparation for a
walkdown of fire barrier penetration seals. The licensee reported that some
penetration seals in fire barrier walls had no damming material. On the basis
of these findings, the licensee examined its criteria for penetration seals
and conducted a technical review of its penetration seal design parameters.
The licensee also found discrepancies between available test reports,
procedural guidance, and the in-plant penetration seal configurations. In
response to the discrepancies, the licensee established compensatory fire
watches and developed a corrective action program. The planned corrective
actions were (1) determining why the discrepancies had not been found during
previous reviews, (2) evaluating the adequacy of procedures, test reports,
acceptance criteria, and field inspections, (3) evaluating the adequacy of
existing seal configurations, and (4) inspecting all fire barrier penetration
seals. In Licensee Event Report (LER) 96-017-1, �Fire Barrier Penetration
Seal Discrepancy,� dated August 28, 1996 (Accession Number 9609030377), the
licensee reported that it had found three additional types of deficiencies:
(1) inadequate thickness of silicone foam, (2) temporary seals that were not
upgraded to permanent seals for an indeterminate period, and (3) one seal in
which the expected pipe movement exceeded the design rating of the seal.
9709160254. IN 97-70
September 19, 1997
Page 2 of 3
During the week of May 12, 1997, NRR staff reviewed and observed the problems
found at Maine Yankee and the corrective actions taken by the licensee.
During a telephone conference on May 14, 1997, Office of Nuclear Reactor
Regulation (NRR) staff and Region I staff obtained detailed information from
the licensee regarding the seal problems found and the corrective actions
The penetration seals at Maine Yankee were installed around 1978. Most of the
original seals used silicone foam. Since the original installation, the
licensee has inspected all the seals visually at each refueling outage.
During the inspections and walkdowns that were documented in LER 96-017-01,
the licensee found that more than a thousand seals required further
evaluation, including destructive examination; about a thousand other seals
had defects; and a small number of seals had no defects. The licensee found
seals with inadequate thickness (the predominant problem), foreign materials
in seals, no damming material, and the wrong seal material installed.
Although the licensee's design criteria specified a minimum seal thickness of
7 inches, the average seal thickness was 5 to 6 inches, and some seals were
only 2 to 3 inches thick. Although the licensee was once planning to repair
and replace the seals with silicone foam and silicone elastomer, the licensee
has since certified permanent cessation of power operation and is now
proceeding to decommission the facility.
The licensee told the staff that the installations were deficient because the
quality assurance and quality control procedures that were used by the
installation vendor during original seal installation were inadequate. The
licensee also told the staff that it believes that the deficiencies were not
discovered for an extended period because its inspection and surveillance
procedures did not cover all important penetration seal attributes (e.g., the
presence of damming material was not a critical attribute) and because its
inspectors had not been properly trained. The licensee has since completed a
major effort, rewriting of its procedures.
NRC requirements and guidelines for fire barrier penetration seals are in
various documents: 10 CFR Part 50, Appendix R, "Fire Protection Program for
Nuclear Power Facilities Operation Prior to January 1, 1979;� Branch Technical
Position APCSB 9.5-1, Appendix A, "Guidelines for Fire Protection for Nuclear
Power Plants Docketed Prior to July 1, 1976;� and NUREG-0800, "Standard Review
Plan." The extent to which these requirements or guidelines are applicable to
a specific nuclear power plant depends on plant age, commitments established
by the licensee in developing the fire protection plan, the staff safety
evaluation reports and supplements, and the license conditions pertaining to
fire protection. These requirements and guidelines ensure that fire barrier
penetration seals will remain in place and retain their integrity when exposed
to a fire. By so doing, there is reasonable assurance that the effects of a
fire will be limited to discrete fire areas and that one division of systems
related to safe shutdown will remain free of fire damage.
. IN 97-70
September 19, 1997
Page 3 of 3
The staff is revising Inspection Procedure 64704, "Fire Protection Program,"
March 18, 1994, contained in the NRC Inspection Manual, to include specific
guidance for inspecting fire barrier penetration seals. It should be noted
that nonconforming conditions may go undetected if the surface of the seal is
covered by thermal insulation or damming material. In addition, the staff has
included guidance for inspecting fire barrier penetration seal programs in its
procedures for the new fire protection functional inspection program.
In July 1996, the NRC published NUREG-1552, "Fire Barrier Penetration Seals in
Nuclear Power Plants," to document the findings of a comprehensive technical
assessment of fire barrier penetration seals. The assessment addressed
reports of potential problems, and determined the adequacy of NRC
requirements, review guidance and inspection procedures. The staff concluded
that the general condition of penetration seal programs in the industry is
satisfactory and that there were no problems of safety significance. Previous
actions, along with continued upkeep of existing penetration seal programs and
continued inspections, are adequate to maintain public health and safety.
However, the staff is continuing to study this issue to determine if further
regulatory action is required. The staff also recommended revisions to the
NRC fire protection regulation and review guidance. The content of this
report was discussed with the NRC Commission before it was issued.
This information notice establishes no new NRC requirements; therefore, no
specific action or written response is required by this notice. However,
recipients are reminded that they are required by 10 CFR 50.65 to take
industry-wide operating experience (including information presented in NRC
information notices) into consideration, where practical, when setting goals
and performing periodic evaluations. If you have any questions about the
information in this notice, please contact the technical contact listed below
or the appropriate NRR project manager.
Jack W. Roe, Acting Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contact: Christopher Bajwa, NRR
Attachment: List of Recently Issued NRR Information Notices
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