UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS

WASHINGTON, DC 20555-0001

August 13, 2007

NRC INFORMATION NOTICE 2007-26: COMBUSTIBILITY OF EPOXY FLOOR

COATINGS AT COMMERCIAL NUCLEAR

POWER PLANTS

ADDRESSEES

All holders of operating licenses for nuclear power reactors and fuel cycle facilities except

licensees for reactors that have permanently ceased operations and who 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 a fire protection issue raised by NRC inspectors at two nuclear power plants that

involves the combustibility of epoxy floor coatings over the concrete floors in various plant

areas. The issue discussed in this IN could similarly apply to fuel cycle facilities. The NRC

expects that recipients of this IN will review the information for applicability to their facilities and

consider taking actions, as appropriate, to avoid similar problems. However, suggestions

contained in this IN are not NRC requirements; therefore, no specific action or written response

is required.

DESCRIPTION OF CIRCUMSTANCES

Introduction

One of the principal goals of NRC fire protection regulation for commercial nuclear power plants

is to ensure that, in the event of fire in any area of the plant, one train of equipment needed to

achieve and maintain safe-shutdown conditions in the reactor will remain free of fire damage. 

The regulations in Title 10 of the Code of Federal Regulations (10 CFR) Part 50, “Domestic

Licensing of Production and Utilization Facilities,” require each operating nuclear power plant to

have a fire protection plan. This plan must satisfy Appendix A to Part 50, “General Design

Criteria for Nuclear Power Plants,” specifically General Design Criterion 3 (GDC 3), “Fire

protection,” as required by 10 CFR 50.48(a). 

GDC 3 states, in part, “Noncombustible and heat-resistant materials shall be used wherever

practical throughout the unit, particularly in locations such as the containment and control

room.” However, GDC 3 does not preclude the use of combustible materials. Examples of

combustible materials found in nuclear power plants are electrical cable insulation and jackets,

lubricants, hydraulic and control fluids, diesel generator fuel oils, charcoal and other filters, and

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flammable gases. In general, when such materials are properly managed, are accounted for in

the plant design and operation, and are incorporated as integral components of the plant fire

protection program, including the fire hazard analysis, they may be acceptable. NRC

inspectors at two facilities raised an issue involving the fact that epoxy floor coating may or may

not be considered combustible in the NRC-approved fire protection program depending on (1)

the thickness with which the coating is applied, and (2) an independent laboratory testing of the

flame spread rating for the specific epoxy floor coating. The inspectors found that although

these licensees considered the epoxy floor coatings non-combustible, they had not evaluated

and controlled the thickness with which the epoxy coating was applied on floors. When

subsequent evaluation and testing by these licensees showed that the epoxy coating must be

considered combustible, these licensees performed a fire hazards analysis that incorporated

the combustible epoxy coating in accordance with their NRC-approved fire protection program. 

The criteria for determining material combustibility are contained in NRC Generic Letter 86-10,

“Implementation of Fire Protection Requirements,” dated April 24, 1986, which provided

guidance for satisfying NRC regulatory requirements for fire protection. Enclosure 1 to NRC

Generic Letter 86-10 included interpretations related to compliance with Appendix R, “Fire

Protection Program for Nuclear Power Facilities Operating Prior to January 1, 1979,” to

10 CFR Part 50. Enclosure 2 to NRC Generic Letter 86-10 provided the NRC staff’s responses

to a list of industry questions. NRC staff’s response to Question 3.6.2, “In-Situ Exposed

Combustibles,” states that a non-combustible material is defined as: “a. A material which in the

form in which it is used and under the conditions anticipated, will not ignite, burn, support

combustion, or release flammable vapors when subjected to fire or heat; and b. Material having

a structural base of noncombustible material, as defined in a., above, with a surfacing not over

1/8-inch thick that has a flame spread rating not higher than 50 when measured using the test

protocol of American Society for Testing and Materials (ASTM) E 84, “Standard Test Method for

Surface Burning Characteristics of Building Materials.””

There is an exception to the Generic Letter 86-10 definition of non-combustible material. 

Appendix A to Branch Technical Position Auxiliary and Power Conversion Systems

Branch 9.5-1, ?Guidelines for Fire Protection for Nuclear Power Plants, Docketed Prior to July

1, 1976,” dated February 24, 1977, Position D.1.(d) allows the use of combustible interior

finishes when listed by a nationally recognized testing laboratory, such as Factory Mutual

Research Corporation or Underwriters Laboratory, Inc., for a flame spread of 25 or less in its

end use configuration using the test protocol of ASTM E 84.

Regulatory Guide 1.189 “Fire Protection for Nuclear Power Plants,” states that floor covering

critical radiant flux be determined by testing in accordance with National Fire Protection

Association (NFPA) 253, “Standard Method of Test for Critical Radiant Flux of Floor Covering

Systems Using a Radiant Heat Energy Source.” ASTM E 84 is the standard test method

required by NRC regulations and should be in the licensing basis, unless the licensee has

changed their test requirement for floor covering flame spread or adopted NFPA 253. Interior

finish materials, such as epoxy floor coating, should meet the NRC regulation, testing, and

qualification for surface flame spread rating when tested under approved test methods. 

NRC Inspection Procedures 71111.05T, “Fire Protection (Triennial),” and 71111.05AQ, “Fire

Protection (Annual/Quarterly),” provide guidance to the inspector on verification of combustible

material controls in plant areas containing components, equipment, or cabling relied on for
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post-fire safe-shutdown. This guidance addresses unusual configurations of combustible

materials as well as other combustible material controls.

Donald C. Cook Nuclear Power Plant, Units 1 and 2

An NRC inspection report for Donald C. Cook Nuclear Power Plant (D.C. Cook) documented an

unresolved item (URI) regarding the fire spread rating and the thickness of the epoxy floor

coating used at the plant. (NRC Inspection Report 05000315/2003005; 05000316/2003005,

dated July 16, 2003, Agencywide Documents Access and Management System (ADAMS)

Accession No. ML032100754.) Specifically, the inspectors were concerned that the epoxy floor

coating that was applied over the concrete flooring in various plant areas may have a

combustible loading that was not accounted for in the approved fire protection program. The

URI was opened pending NRC review of the licensee’s evaluation and testing of the epoxy

flooring’s flame spread characteristics. 

In response to the URI, the licensee performed additional evaluation and testing. The test

report results indicated that the epoxy floor covering of the type installed at D.C. Cook had a

flame spread rating of 140 at 0.115 inches thickness and 150 at 0.230 inches thickness. The

test results for smoke development were 516 and 545, respectively. The licensee’s overall

evaluation concluded that:

• the additional combustible loads attributed to epoxy are within the amount allowed or are

insignificant additions,

• the epoxy flooring did not affect the Appendix R separation criteria, and 

• the epoxy flooring would not cause fires to propagate between contiguous fire zones.

However, the licensee also concluded that the characteristics of the combustion process of the

coating make it undesirable as a floor coating. Considering the low ignition temperature and

the test results for flame spread rate and smoke development, the licensee concluded that the

use of epoxy as a coating on floors should be immediately discontinued from future use. In

addition, the licensee concluded that it should develop a multi-year plan to replace the current

floor coating with one that conforms to the flame spread criteria. 

The NRC closed the URI based on the results of the licensee’s fire hazards evaluation which

indicated that the additional combustible loading due to the epoxy floor coating produced no

impact on the fire load classification in the plant fire hazards analysis. There was a negligible

increase in fire hazard due to the epoxy floor coating and sufficient margin existed for

maintaining combustible loading/fire severity within the established allowable limits. 

Additionally, the fire zones that contained the epoxy floor coating did not rely on a 20-foot

horizontal separation distance in order to meet Appendix R compliance. The NRC inspection

report that closed the URI stated that no licensee performance deficiency or violation was

identified. (NRC Inspection Report 05000315/2006002; 05000316/2006002, dated

March 22, 2006, ADAMS Accession No. ML060830130.)

Duane Arnold Energy Center
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An NRC inspection report for Duane Arnold Energy Center (DAEC) documented a URI that the

epoxy floor covering applied over concrete floor—such as in the reactor building, high-pressure

coolant injection pump room, and other plant areas—may be a combustible not accounted for in

the approved fire protection program. The URI was opened pending NRC review of the

licensee’s evaluation and testing of the epoxy flooring’s flame spread characteristics. (NRC

Inspection Report 05000331/2003002, dated May 22, 2003, ADAMS Accession No.

ML031430217)

In response to the URI, the licensee performed additional evaluation and testing. The epoxy

testing report results indicated that the epoxy floor covering of the type installed at DAEC had a

flame spread rating of 110, which is greater than the criteria of 50 specified in NRC Generic

Letter 86-10, and therefore, was considered a combustible material. The licensee performed

an evaluation that determined the epoxy floor coating was acceptable.

The NRC closed the URI based on the licensee’s determination that there were no adjacent fire

areas having the relatively high reported flame spread rating epoxy. The inspectors concluded

that the coatings would not contribute towards the spread of a fire from one area to another. In

addition, the combustible fire loads due to epoxy floor coatings did not present a challenge to

the DAEC fire barriers. Also, those fire areas taking credit for 20-foot separation had epoxy

floor coatings with a relatively low flame spread rating and were less than 1/8-inch thick. No

violation was identified. (NRC Inspection Report 05000331/2005009, dated July 12, 2005,

ADAMS Accession No. ML051940049.)

BACKGROUND

The basic fire protection regulation for U.S. commercial nuclear power plants is Section 50.48,

“Fire protection,” of 10 CFR Part 50. It requires, in part, that each operating nuclear power

plant have a fire protection plan that satisfies GDC 3 in Appendix A to 10 CFR Part 50. This fire

protection plan, using guidance provided in NRC Generic Letter 88-12, “Removal of Fire

Protection Requirements from Technical Specifications,” dated August 2, 1988, is incorporated

into the operating license for the plant as a fire protection license condition. 

Each operating nuclear power plant has an approved fire protection program that is anchored in

the long-established defense-in-depth safety principle of providing multiple protective barriers to

prevent and mitigate accidents. The concept of defense-in-depth as applied to fire protection in

fire areas important to safety, is described in Section II, “General Requirements,” of Appendix R

to 10 CFR Part 50. It describes the following objectives: to prevent fires from starting; to detect

rapidly, control, and extinguish promptly those fires that do occur; and to provide protection for

structures, systems, and components important to safety so that a fire that is not promptly

extinguished by the fire suppression activities will not prevent safe-shutdown of the plant. The

multiple levels of protection that are embodied in the defense-in-depth philosophy ensure fire

safety throughout the life of the plant by minimizing both the probability and the consequence of

fires. While the NRC recognizes that no one level can be perfect or complete by itself, and

strengthening any one level can compensate in some measure for known or unknown

weaknesses in the others, each level of protection must meet certain minimum requirements.

All licensees are required to meet commitments in their fire protection program, as well as their
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fire protection license condition. Fire prevention is the first line of defense-in-depth for fire

protection. The fire prevention attributes of the program are directly related to the fire

protection plan objectives that are to minimize the potential for fire to occur, involve design and

administrative measures that provide a reasonable level of assurance of adequate protection

and management against fire hazards, and limit fire consequences for those fires that do occur.

DISCUSSION

Epoxy floor coatings have been applied to various building concrete floors at U.S. commercial

nuclear power plants as a protective coating that provides a smooth surface that is easy to

clean and helps to reduce the spread of radioactive contamination. Because the epoxy floor

coatings may be combustible depending on their thickness and flame spread rating, these

coatings must be evaluated and controlled in accordance with the NRC-approved fire protection

program. There have been instances where the installed or repaired epoxy floor coatings have

been (1) purchased from numerous vendors, (2) installed to various thicknesses, (3) installed

over a previous epoxy floor coating, or (4) purchased with various flame spreading ratings, that

were not accounted for in the NRC-approved fire protection program. 

Licensee evaluations of the epoxy floor coating serve to identify instances where the licensee

may need to include the fire loading of epoxy floor coating into plant fire hazards analysis in an

area where the rated fire barriers are provided. The purpose of the fire hazards analysis is to

evaluate the increase in hazard due to the epoxy floor coating and to verify that the increased

combustible loading due to the epoxy floor coating does not present a challenge to the plant’s

fire barriers. In addition, a licensee could have a fire protection exemption (i.e., a commitment

to have no combustibles in the areas housing safety-related systems, equipment, and

components for safe-shutdown) that would not be met with an epoxy floor coating that was

combustible. The epoxy floor coating could also cause a licensee to no longer meet the 20-foot

horizontal separation distance in order to meet Appendix R, Section III.G.2 of 10 CFR Part 50

requirements, i.e., no intervening combustible or fire hazards between opposite redundant

trains of post-fire safe-shutdown equipment. 

CONCLUSION

The problem of epoxy floor coatings that are considered combustible can be avoided by using a

product with a low flame spread rating, applying it in accordance with the manufacturer’s/

vendor’s recommendations, and providing plant procedural controls for applying the coating to

ensure it does not exceed recommended thickness. Coatings that are applied thicker than a

manufacturer’s recommendations may exceed the listed flame spread rating. 
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CONTACT

This information notice does not require any specific action or written response. Please direct

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

Office of Nuclear Reactor Regulation (NRR) project manager.

/RA/ /RA by TQuay for/

Robert C. Pierson, Director Michael J. Case, Director

Division of Fuel Cycle Safety Division of Policy and Rulemaking

 and Safeguards Office of Nuclear Reactor Regulation

Office of Nuclear Material Safety

 and Safeguards 

Technical Contacts: Naeem Iqbal, NRR Darrell L. Schrum, Region III

301-415-3346 630-829-9741

E-mail: nxi@nrc.gov E-mail: dls3@nrc.gov

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

http://www.nrc.gov, under Electronic Reading Room/Document Collections.
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CONTACT

This information notice does not require any specific action or written response. Please direct

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

Office of Nuclear Reactor Regulation (NRR) project manager.

/RA/ /RA by TQuay for/

Robert C. Pierson, Director Michael J. Case, Director

Division of Fuel Cycle Safety Division of Policy and Rulemaking

 and Safeguards Office of Nuclear Reactor Regulation

Office of Nuclear Material Safety

 and Safeguards 

Technical Contacts: Naeem Iqbal, NRR Darrell L. Schrum, Region III

301-415-3346 630-829-9741

E-mail: nxi@nrc.gov E-mail: dls3@nrc.gov

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

http://www.nrc.gov, under Electronic Reading Room/Document Collections.

Distribution:

IN Reading File

ADAMS Accession Number: ML071920090 NRR-052

OFFICE AFPB:DRA EB3:DRS:RIII TECH EDITOR BC:AFPB:DRA D:DRA

NAME NIqbal DSchrum L-ACulp SWeerakkody MCunningham

DATE 07/11/2007 07/12/2007 07/13/2007 07/18/2007 07/18/2007

OFFICE LA:PGCB:DPR PGCB:DPR FCSS:NMSS BC:FCSS:NMSS FCSS:NMSS

NAME CHawes DBeaulieu RWescott BSmith MTschiltz

DATE 07/19/2007 07/19/2007 08/02/2007 08/02/2007 08/03/2007

OFFICE BC:PGCB:DPR D:DPR D:FCSS:NMSS

NAME MMurphy TQuay for MCase RPierson

DATE 08/10/2007 08/10/2007 08/13/2007

OFFICIAL RECORD COPY