ML043510005

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555

February 10, 2005

NRC INFORMATION NOTICE 2005-03: INADEQUATE DESIGN AND INSTALLATION OF

SEISMIC-GAP FIRE BARRIERS

ADDRESSEES

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.

PURPOSE

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to inform

addressees of recently identified deficiencies in the design and installation of seismic-gap fire

barriers. 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 in this

IN are not NRC requirements; therefore, no specific action or written response is required.

DESCRIPTION OF CIRCUMSTANCES

During a quarterly fire protection inspection at the Wolf Creek Generating Station, the resident

inspectors discovered that a portion of the fire barrier in the seismic gap between the auxiliary

building main steam enclosure floor and the containment building was incomplete. 

Approximately 20 inches of fire barrier material in the four-inch-wide gap was missing. This

resulted in a degradation of the fire barrier between the main steam enclosure and all the

auxiliary feedwater system’s steam generator water level control valve rooms. The licensee

determined that the fire barrier material had been missing since initial plant construction. The

licensee performed a walkdown of all seismic gaps and identified two additional incomplete fire

barriers. The inadequate design and installation condition also existed at the Callaway Plant.

The licensee also found, during the course of resolving the missing fire barrier segment issue,

that the original seismic-gap fire barrier design was deficient. The design only included the

gaps between a single floor or wall of one building and a wall or floor of an adjacent building or

fire area. The design did not include the fire barrier configuration where floors, walls, and/or

ceilings of one building joined together, such as a corner of a room, at the seismic gap with an

adjacent building or fire area. Since the design was deficient, the licensee implemented

compensatory measures for all potentially affected fire areas. The licensee inspected 25

suspect configurations and determined that 14 were inadequate. The attached diagram

represents a typical as-found deficient seal and the associated restoration configuration where

multiple fire boundary seismic-gap seals interface.
IN 2005-03

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Through intrusive inspection, it was determined that the original fire barriers were not installed

per the design at many single-interface locations. Instead of installing fire barrier material on

just one side of a gap, the installers placed barrier material in the gaps at both sides of a wall or

floor and did not use the polyethylene backing. The polyethylene is provided for support of the

caulking material. With fire barrier material on both sides, the polyethylene backing is not

needed. Installing barrier material on both sides of the gap actually mitigated the potential

consequences of the inadequate installations at some of the room corners. The licensee

immediately corrected the deficiencies at the corner interfaces by adding fire barrier material.

Additionally, the resident inspectors asked whether the caulking compound and polyethylene

backing material used in the seismic gaps were included in the fire loading calculations for each 

fire area. The caulking material was used as a pressure and/or flooding boundary. The

licensee had stated that these materials were combustible and were consumed during the fire

barrier qualification tests. 

The licensee reviewed the calculations and found that these materials had not been included in

the fire loading calculations. The licensee performed further analysis to determine if the fire

areas’ ratings were affected. The licensee concluded that the caulking and backing material in

the seismic gaps did not significantly increase the fire area loadings. The licensee also

concluded that only the caulking and backing material on the exposed fire barrier side would be

affected. On the unexposed barrier side, combustible elements of the seal would not reach a

high enough temperature to sustain combustion. This determination was based on a review of

relevant fire testing for the design.

Using Manual Chapter 0609, Appendix F, Attachment 2, “Additional Guidance for the

Assessment of Findings Using Significance Determination Process Entry,” the inspectors made

two determinations:

• There was no credible fire scenario that would affect more than one safe shutdown area. 

This was based on a lack of combustible material, lack of ignition sources, location of

the seal with respect to safe shutdown equipment, the presence of detection and

suppression systems, the amount of seal degradation, or the distance from the seal to

any combustible material. In addition, the inspectors determined that the fire barriers did

not leave significant gaps between fire areas. In some cases, the fire seal materials

were butted up against each other at a right angle.

• These as-found conditions did not provide the required 3-hour fire rating, but would

hamper the propagation of smoke and hot gases between fire areas for some untested

amount of time. The inspectors concluded that the degraded fire barriers would provide

a minimum of 20 minutes fire endurance protection, and that the fixed and in situ fire

ignition sources and combustible or flammable materials were positioned such that, even

if the fire spread to secondary combustibles, the degraded fire barriers would not be

subjected to direct flame impingement.
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On this basis, this finding was greater than minor because it was similar to the example in

Inspection Manual Chapter 0612, Appendix E, Section 2.e. In the as-found condition, the 15 fire

penetration seals at the seismic gaps would not have performed their function as a 3-hour rated

fire barrier. This finding is of very low safety significance because, overall, the fire barriers

would have provided the protection needed for credible fire scenarios. The issue was

processed in the NRC’s significance determination process and determined to be Green. 

Please refer to NRC Inspection Report 05000482/2004002, Section 4OA5, for additional

information.

BACKGROUND

The NRC has issued other generic communications that have discussed requirements,

guidance, and potential problems with fire-barriers, especially penetration seals. For example

(1) On February 5, 1988, the NRC issued Information Notice (IN) 88-04, "Inadequate

Qualification and Documentation of Fire Barrier Penetration Seals," to alert addressees

that some installed fire-barrier penetration seal designs may not be adequately qualified

for the design rating of the penetrated fire barrier. This IN discussed an NRC staff

review which identified some instances where installed fire-barrier penetration seal

configurations were not qualified by adequate testing or were not supported by adequate

qualification documentation.

(2) On August 9, 1988, the NRC issued IN 88-04, Supplement 1, "Inadequate Qualification

and Documentation of Fire Barrier Penetration Seals," to alert addressees to problems

caused by potential misapplication of silicone foam material used in penetration

openings at nuclear power plants.

(3) In July 1996, the NRC issued NUREG-1552 “Fire Barrier Penetration Seals in Nuclear

Power Plants.” This was followed up by NUREG-1552, Supplement 1 in January 1999.

(4) On June 25, 2003, the NRC issued Information Notice 2003-08 “Potential Flooding

Through Unsealed Concrete Floor Cracks.”
1

American Society for Testing and Materials Standard E-119 was adopted by the

National Fire Protection Association (NFPA) as NFPA Standard 251

2

See Information Notice 88-04 “Inadequate Qualification and Documentation of Fire

Barrier Penetration Seals”

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DISCUSSION

NRC requirements and guidelines for fire barriers are contained in various documents, including

Appendix R to 10 CFR Part 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. The extent to which these requirements or guidelines 

are applicable to a specific plant depends on plant age, commitments made by the licensee in

developing the fire protection plan, the staff safety evaluation reports (SERs) and supplements,

and the license conditions pertaining to fire protection. 

The goal is to provide a fire barrier that will remain in place and retain its integrity when

subjected to an exposure fire, and subsequently, a fire suppressing agent. This will provide

reasonable assurance that the effects of a fire are limited to discrete fire areas and that one

division of safe-shutdown-related systems will remain free of fire damage.

Seismic gaps (commonly referred to as “shake space,” “rattle space,” “construction joint

systems,” or “building joint systems”) are a part of the overall seismic design of the structure. 

Their principal function is to allow different parts of the nuclear power plant (NPP) to move

independently during an operating-basis earthquake (OBE) or a design-basis earthquake

(DBE). To fulfill other design functions, the gaps (openings) have seals similar to penetration

seals in rated fire barriers. Other NPP-specific design functions can include fire barrier, flood

barrier, pressure boundary, and radiation shielding. The seismic gap penetration seal often has

multiple design functions and is tested, installed, and maintained accordingly.

The fire resistance rating of the seismic-gap penetration seal is equal to or greater than the fire

barrier in which it is installed. The fire resistance rating is determined by testing a

representative sample to the requirements of American Society of Testing and Materials

(ASTM) Standard E-119, “Standard Methods of Fire Tests of Building Construction and

Materials”1

 including the hose stream test. The existing staff guidance on fire barrier

penetration seals is also applicable to seismic-gap penetration seals.2

 There are also specific

test methods for building joints such as the ASTM E1966 “Standard Test Method for Fire

Resistance of Building Joint Systems” and the method in Underwriters Laboratories Inc (UL)

Standard UL 2079 “Tests for Fire Resistance of Building Joint Systems.”
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CONTACTS

This information notice requires no specific action or written response. Please direct any

questions about this matter to the technical contacts listed below or the appropriate Office of

Nuclear Reactor Regulation (NRR) project manager.

/RA/

Patrick Hiland, Chief

Reactor Operations Branch

Division of Inspection Program Management

Office of Nuclear Reactor Regulation

Technical Contacts: Ruth Reyes Frank Brush, RIV

(301) 415-3249 (620) 364-8653

e-mail: rrm1@nrc.gov e-mail: flb2@nrc.gov

Brett Rini

(301) 415-3931

e-mail: bar3@nrc.gov

Attachment: Diagram

Note: NRC generic communications may be found on the NRC public Website,

http://www.nrc.gov, under Electronic Reading Room/Document Collections.
IN 2005-03

Attachment