NUREG-1552

Fire Barrier Penetration Seals

in Nuclear Power Plants

U.S. Nuclear Regulatory Commission

Office of Nuclear Reactor Regulation

C. S. Bajwa, K. S. West
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NUREG-1552

Fire Barrier Penetration Seals

in Nuclear Power Plants

Manuscript Completed: June 1996

Date Published: July 1996

C. S. Bajwa, K. S. West

Division of Systems Safety and Analysis

Office of Nuclear Reactor Regulation

U.S. Nuclear Regulatory Commission

Washington, DC 20555-0001

ABSTRACT

As part of fire protection defense in depth, nuclear power

plants are divided into separate fire areas by fife-rated

structural barriers. Fire-rated penetration seals are

installed to seal certain openings in these barriers. The

seals maintain the fire-resistive integrity of the barriers

and provide reasonable assurance that a fire will be

confined to the area in which it started. The staff of the

Fire Protection Engineering Section, Office of Nuclear

Reactor Regulation, U.S. Nuclear Regulatory

Commission, conducted a comprehensive technical

assessment of penetration seals to address reports of

potential problems, to determine if there were any

problems of safety significance, and to determine if NRC

requirements, review guidance, and inspection

procedures are adequate. The staff did not find plantspecific problems of safety significance or concerns with

generic implications. The staff concluded that the

general condition of penetration seal programs in

industry is satisfactory. The staff also concluded that

actions it had taken in 1988 and 1994 to address

potential penetration seal problems increased industry

awareness of such problems and resulted in more

thorough surveillances, maintenance, and corrective

actions. These previous staff actions, together with

continued licensee upkeep of existing penetration seal

programs and continued NRC inspections, are adequate

to maintain public health and safety. The staff

recommended several minor revisions to the NRC fire

protection regulation and review guidance.

iii NUREG-1552

TABLE OF CONTENTS

Page

ABSTRACT ................................................................................... iii

EXECUTIVE SUMMARY............................................................. ........... vii

I DISCUSSION .................. ......................................................... 1I

1.1 Defense in Depth and the Role of Penetration Seals ......................................... 1

1.2 Background ....................................................................... 2

1.3 Fire Protection Program Reassessment................................................... 3

1.4 AEOD Penetration Seal Review ........................................................ 3

2 FIRE BARRIER PENETRATION SEAL MATERIALS ............................................ 3

2.1 Population and Types of Seals ......................................................... 3

2.2 Silicone Foams .................................................................... 4

2.3 Silicone Elastomers ................................................................. 4

2.4 Silicone Gels ...................................................................... 4

2.5 Other Sealants ..................................................................... S5

2.6 Damming Materials....................... .......................................... 5

3 QUALIFICATION TESTS OF PENETRATION SEALS ........................................... 5

3.1 Test Methods and Acceptance Criteria................................................... 5

3.2 Fire Testing Laboratories............................................................. 6

4 FIRE PROTECTION REGULATIONS, GUIDANCE, AND INSPECTION PROCEDURES ................ 7

4.1 Background .............................................................. 7

4.2 Regulations ....................................................................... 8

4.2.1 GDC 3andI10CFR 50.48 ..................................................... 8

4.2.2 Appendix R to 10 CFR Part 50 .................................................. 8

4.3 Review Guidance................................................................... 8

4.3.1 Appendix Ato BTPAPCSB 9.5-1 ............................. 9

4.3.2 Standard Review Plan (NUREG-0800) ........................................... 9

4.3.3 Generic Letter 86-10 .............. *.......-........................'***.........9

4.4 Inspection Procedures............................................................... 10

5 TECHNICAL ASSESSMENT............................................................... 10

5.1 Review of Penetration Seal Part 21 Reports .............................................. 10

5.2 Review of Reactor Operating Experience ................................................ 11

5.2.1 Review of Licensee Event Reports .................................... 11

5.2.2 Review of Reactor Fire Experience.............................................. 11

5.3 Review of Previous NRC Inspection Results ............................................. 12

5.4 Review of Plant-Specific Corrective Action Programs....................................... 12

5.4.1 Wolf Creek Generating Station ................................................. 13

5.4.2 Virgil C. Summer Nuclear Station .............................................. 13

5.4.3 Vermont Yankee Nuclear Power Station.......................................... 14

5.4.4 Diablo Canyon Nuclear Power Plant ............................................ 14

5.5 Focused Audits and Inspections of Nuclear Plants ......................................... 14

5.5.1 Davis-Besse Nuclear Power Station ............................................. 15

5.5.2 Waterford 3 Nuclear Power Plant ............................................... 15

5.5.3 Susquehanna Steamn Electric Station ............................................. 15

5.5.4 Calvert Cliffs Nuclear Power Plant .............................................. 15

v NUREG-1552
Contents

Page

5.5.5 W ashington Nuclear Project 2 .............................................. ....... 15

5.5.6 W atts Bar Nuclear Power Plant .................................................... 16

5.6 V endor Inspections ..................................................................... 16

5.6.1 Dow Com ing Corporation ........................................................ 16

5.6.2 Brand Fire Protection Services, Incorporated ......................................... 16

5.6.3 B&B Progressive Materials and Technologies, Incorporated ............................ 17

5.7 Installation, Surveillance, Maintenance, and Repair ........................................... 17

5.8 Combustibility of Silicone-Based Seal Materials ............................................. 18

5.9 Dow Coming Corporation Silicone Foam Formulation Change ................................. 19

5.10 A ging and Shrinkage ................................................................... 19

5.11 Silicone-Based M aterial Curing ........................................................... 20

5.12 Comparison of Tested to As-Built Configurations ............................................ 20

5.12.1 Size of Sealed Openin g ........................................................... 21

5.12.2 Penetrating Item s ................................................................ 21

5.12.3 Cable Type and Fill ............................................................... 21

5.12.4 D am m ing M aterials .............................................................. 22

5.12.5 Configuration Orientation ................ ........................................ 22

5.12.6 M aterial Type and Thickness ....................................................... 22

5.12.7 Type Testing ..... ..................................................... ) .......... 22

5.13 Comparison of Thermo-Lag Fire Barriers to Penetration Seals .................................. 22

6 SUM M ARY OF FINDINGS ..................................................................... 23

7 CONCI.USIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. . .. .. 2 4

8 RECOM M ENDA TION S ........................................................................ 24

9 B IBLIO G RA PHY ............................................................................. 24

Appendix A Summaries of NRC Generic Communications Regarding Penetration Seals

Appendix B Action Plan Summary, Technical Assessment of Fire Barrier Penetration Seals

Appendix C Comparison of Industry Fire Endurance Test Standards

Appendix D Acronyms and Abbreviations

Appendix E SECY-96-146: Technical Assessment of Fire Barrier Penetration Seals in Nuclear Power Plants

NUREG-1552 vi
EXECUTIVE SUMMARY

As part of fire protection defense in depth, nuclear power

plants are divided into separate fire areas by fire-rated

walls and fire-rated floor-ceiling assemblies. These fire

barriers offer reasonable assurance that a fire will not

spread from one jlIant area to another. Openings in these

fire barriers, which are known as penetrations, allow

such items as cables, conduits, cable trays, pipes, and

ducts to pass from one fire area to another. Fire barrier

penetration seals are installed to seal these openings and

maintain the fire-resistive integrity of the fire barriers.

Penetration seals are not technically complex, nor are

they unique to the nuclear industry. In fact, they are

universally accepted building components that are used

in a variety of residential, commercial, and industrial

buildings wherever fire-resistive separation is needed.

The same penetration seal materials, fire test standards,

and installation techniques that are used by the nuclear

industry are used in these other industries. A large body

of fire test results (nuclear and non-nuclear) and fire

experience (non-nuclear) has proven the fire-resistive

capabilities and effectiveness of penetration seals.

In about 1985, the staff had become aware of the

possibility that some licensees may not have been

complying with U.S. Nuclear Regulatory Commission

(NRC) requirements and guidance for fire barrier

penetration seals. In response to these concerns, in 1987

and 1988, the NRC staff had assessed aspects of fire

barrier penetration seals. The staff had reviewed such

relevant data as licensee event reports, inspection

findings, and fire test reports; interviewed industry staff;

inspected licensees and vendors; and reviewed a sample

population of as-built fire barrier penetration seal

installations and the substantiating documentation.

Although it did not find widespread problems or safetysignificant generic issues, the staff addressed potential

problems in a series of information notices.

Since 1992, potential problems have again been

reported. In response, the Office of Nuclear Reactor

Regulation (NRR) conducted a second technical

assessment of fire barrier penetration seals. The principal

purposes of the second assessment, which is documented

here, were to address potential problems, to determine if

there were any problems of safety significance or with

generic implications, and to determine if NRC regulatory

requirements, review guidance, and inspection

procedures for penetration seals are adequate. In support

of this assessment, the staff conducted inspections at

reactor and vendor facilities; witnessed fire endurance

tests of penetration seals; reviewed operating experience

and previous NRC inspection and assessment results; and

assessed the data and information obtained from the field

work and document reviews.

The staff found several minor weaknesses. with some of

the plant-specific penetration seal programs that it

reviewed. However, these weaknesses did not result in

problems with the penetration seals installed in the

plants. On the basis of the totality of the information it

found and assessed, including the "Report on the

Reassessment of the NRC Fire Protection Program" that

had been conducted by NRR, the review of fire barrier

penetration seals that had been conducted by the Office

for Analysis and Evaluation of Operational Data

(AEOD), reports that had been prepared by Sandia

National Laboratories on the population of fire barrier

types installed in nuclear power plants and penetration

seal aging, and the other documents referenced in this

report, the staff concluded that the general condition of

penetration seal programs in industry is satisfactory. The

staff did not find plant-specific problems of safety

significance or concerns with generic implications.

Even though the staff found the condition of penetration

seal programs in industry to be satisfactory, it expects

that minor plant-specific deficiencies will occasionally

be found during future licensee surveillances and NRC

inspections. However, potential fire barrier penetration

seal problems are understood; industry consensus fire

test standards are available and are followed; and fire test

results and qualified fire-resistant seal materials and

designs are available. Therefore, licensees have the

means to correct problems, and staff oversight will

continue to ensure corrections on a case-by-case basis.

Fire protection defense in depth provides reasonable

assurance that such deficiencies will not present an

undue risk to public health and safety. Finally, the staff

concluded that the actions it had taken in 1988 and 1994

to address potential penetration seal problems increased

industry awareness of such problems and resulted in

more thorough surveillances, maintenance, and

corrective actions. These actions, together with

continued licensee upkeep of existing penetration seal

programs and continued NRC inspections, are adequate

to maintain public health and safety.

On the basis of the technical assessment documented

here, the staff recommends the following: (1) revise the

NRC fire protection guidance documents to reflect the

current National Fire Protection Association position on

testing laboratories (Section 3.2); (2) delete the

vii NUREG-1552
Executive Summary

noncombustibility criterion for seal materials from the

NRC fire protection regulation and review guidance

(Section 5.8); (3) develop guidance for comparing firetested penetration seal configurations to as-built

configurations (Section 5.12); and (4) make this

assessment report available to the general public and

industry (Section 7).

The Fire Protection Engineering Section of NRR

conducted the technical assessment documented here.

The Special Inspection Branch of NRR and Brookhaven

National Laboratory helped with the reactor and vendor

inspections. Staff of NRR, AEOD, the Office of Nuclear

Material Safety and Safeguards (NMSS), Region I,

Region II, Region III, and Region IV conducted a peer

review of this assessment report. An Independent

Management Review Panel chaired by NRR and

represented by NMSS and the Office of Nuclear

Regulatory Research conducted a final review of this

report.

The staff of the Fire Protection Engineering Section

made presentations on fire barrier penetration seals and

this assessment at the International Conference on Fire

Protection and Prevention in Nuclear Facilities,

Barcelona, Spain (December 5 through 7, 1994); the

Nuclear Energy Institute Fire Protection Forum, St.

Petersburg, Florida (January 29, 1996); and NRC

Regulatory Information Conferences (May 1994 and

April 1996). On March 7, 1996, the staff of the Fire

Protection Engineering Section presented the results of

this technical assessment to the Advisory Committee on

Reactor Safeguards, Fire Protection Subcommittee.

In addition, the staff informed the Commission of the

findings of this report in SECY-96-146, "Technical

Assessment of Fire Barrier Penetration Seals in Nuclear

Power Plants," dated July 1, 1996. That paper is

appended to the text.

NUREG-1552 viii
1 DISCUSSION

1.1 Defense in Depth and the Role

of Penetration Seals

Nuclear power plants licensed to operate by the U.S.

Nuclear Regulatory Commission (NRC) use the defensein-depth concept of echelons of fire protection features

to achieve a high degree of fire safety. The objective of

defense in depth is to (1) prevent fires from starting;

(2) detect rapidly, control, and extinguish promptly those

fires that do occur; and (3) provide protection for

structures, systems, and components important to safety

so that a fire that is not promptly extinguished will not

prevent the safe shutdown of the plant. The multiple

layers of fire protection provided by the defense-in-depth

concept provide reasonable assurance that weaknesses or

deficiencies in any echelon will not present an undue risk

to public health and safety. To achieve defense in depth,

each operating reactor has an NRC-approved fire

protection program.' The licensees have designed the fire

protection programs by analyses that (1) considered

potential fire hazards, (2) determined the effects of fires

in the plant on the ability to safely shut down the reactor

or on the ability to minimize and control the release of

radioactivity to the environment, and (3) specified

measures for fire prevention, fire confinement, fire

detection, automatic and manual fire suppression, and

post-fire safe-shutdown capability. To confine a fire and

limit fire damage, licensees divide nuclear power plant

buildings into separate fire areas. These are generally

rooms or plant areas that have fire-rated walls and firerated floor-ceiling assemblies. These fire-rated walls and

floor-ceiling assemblies (structural fire barriers) have

sufficient fire resistance to withstand the fire hazards

located in the fire area and, as necessary, to protect

important equipment within the area from a fire outside

the area. Most nuclear power plant fire barriers are of

substantial reinforced-concrete construction and have a

fire-resistance rating of 3 hours (see Section 3). This

passive fire protection concept, which is called

"compartmentation," is a fundamental fire safety

measure. It is not unique to nuclear power plants. The

fire barriers, which accomplish their intended design

function simply by being in place during a fire, are

'When properly designed, implemented, and

maintained, a fire protection program satisfies

Section 50.48, "Fire protection," of Title 10 of the Code

of Federal Regulations, Part 50.

important because they are the first and last lines of

defense against a fire. That is, during the early stages of

a fire, the barriers confine the fire and protect important

equipment until the fire detection and automatic fire

suppression systems operate. In addition, in the unlikely

event that an automatic fire protection system fails to

operate, the structural barriers continue to provide

passive fire protection.

Penetrations are openings in structural fire barriers that

allow such services as piping and instrument tubing;

conduits, cables, and cable trays; and heating,

ventilation, and air conditioning ducts to pass from one

fire area to another. Penetrations may also be left empty

for future modifications. To maintain the fire-resistive

integrity of the fire barriers, fire-rated penetration seals

are installed in the penetrations and in the gaps and

annular spaces around the penetrating items.' The seals

are one element of fire protection defense in depth and,

like the structural fire barriers in which they are installed,

are passive fire protection features. Their design function

is to confine a fire to the area in which it started or to

protect important equipment within the area from a fire

outside the area.

Fire barrier penetration seals are not technically

complex, nor are they unique to the nuclear industry. In

fact, they are universally accepted building components

that are used in residential, commercial, and industrial

buildings wherever fire-resistive separation is needed.'

The same penetration seal materials, fire test standards,

and installation techniques that are used by the nuclear

industry are used in these other industries. A large body

of fire test results and fire experience (non-nuclear),

spanning decades, has proven the fire-resistive

capabilities and effectiveness of penetration seals. (As an

example, in the 1995 edition of its Fire Resistance

Directory,' Underwriters Laboratories, Incorporated

(UL), listed more than 800 penetration seal designs that

2

Fire doors and fire-rated duct dampers are also used

to close fire barrier penetrations. These fire protection

features are not addressed here.

3

Outside the nuclear industry, penetrations are

sometimes called "poke-throughs," penetration seals are

commonly called "firestops," and sealing fire barrier

penetrations are called "fire stopping."

4

Architects, engineers, building code officials, and

others use the Fire Resistance Directory to identify firetested penetration seal designs.

I NUREG-1552
Discussion

it had tested and approved.) It is generally accepted

among fire protection engineers, building code officials,

and other professionals responsible for building design

and fire safety, that properly designed, tested, installed,

inspected, and maintained penetration seals provide

reasonable assurance that the fire-resistive integrity of

the fire barriers in which they are installed will be

maintained.

The effectiveness of structural fire barriers is largely

dependent on their inherent fire resistance, details of

construction, and protection of penetrations. Some fire

barriers (both structural barriers and penetration seals)

are more important to fire protection defense in depth

than others. The importance of specific fire barriers

depends on many factors, such as the importance of the

equipment in the fire area (and adjacent areas); the

configuration and location of combustible materials and

other fire hazards, if any, in the areas; the potential for

fire growth in the areas; the other fire protection features

installed in the areas; and the accessibility of the areas to

the plant fire brigade. The importance of specific

penetration seals depends on these factors and on such

factors as their size, their location or position in the fire

barrier, and the number and sizes of the other seals in the

barrier.

In order of overall importance to fire protection defense

in depth, structural fire barriers are generally more

important than fire barrier penetration seals. Qualified

fire protection engineers determine the significance of

individual fire barriers by fire hazards analyses.

Although a detailed discussion of such analyses is

beyond the scope of this report, the following discussion

illustrates this point.

If a structural fire barrier fails and collapses under fire

exposure, the adjacent fire area can become involved in

the fire in a short period of time. (Because of the

substantial construction of nuclear power plant fire

barriers and fire protection defense in depth, the staff

does not consider this a credible fire scenario.) Failure

of a penetration seal is generally not as significant a fire

threat as a failure of a structural fire barrier. In most

cases, a seal failure would initially create a localized hot

spot in the adjacent fire area in the area of the seal. If

there are no combustible materials in the adjacent fire

area in the vicinity of the failed seal (for example, if the

penetration seal is for a pipe), smoke and hot gases will

move into the adjacent area, but the spread of fire into

the area will be limited. Conversely, if there are

combustible materials in the vicinity of the failed seal

(for example, if the penetration seal is for a loaded cable

tray), the fire could spread into the adjacent area more

readily. In this instance, a more detailed fire hazards

analysis is needed to assess the effects of the fire spread.

The staff, in Generic Letter 86-10, "Implementation of

Fire Protection Requirements," April 24, 1986, provided

guidance for evaluating fire area boundaries (see

Section 4.3.3).

1.2 Background

In about 1985, the staff had become aware of the

possibility that some licensees may not have been

complying with NRC requirements and guidance for fire

barrier penetration seals. In response to these potential

problems, in 1987 and 1988, the NRC staff had assessed

aspects of fire barrier penetration seals. The staff had

reviewed such relevant data as licensee event reports,

inspection findings, and fire test reports; interviewed

industry staff, inspected licensees and vendors; and

reviewed a sample population of as-built fire barrier

penetration seal installations and the substantiating

documentation. In parallel with these efforts, the staff

had formed an NRC roundtable group to assess what it

had found and to determine whether or not regulatory

action was warranted.

The staff did not fmd widespread problems or safetysignificant issues. Following its assessment, the staff

issued a series of information notices.' Information

Notice (IN) 88-04, "Inadequate Qualification and

Documentation of Fire Barrier Penetration Seals,"

February 5, 1988, addressed what the staff had found

during its assessment and summarized existing staff

guidance related to fire barrier penetration seals. It did

not address or identify plant-specific problems.

IN 88-56, "Potential Problems With Silicone Foam Fire

Barrier Penetration Seals," August 4, 1988, informed

licensees that nonconforming conditions such as splits,

gaps, voids, and lack of fill might exist in silicone foam

penetration seals. IN 88-04 Supplement 1, "Inadequate

Qualification and Documentation of Fire Barrier

Penetration Seals," August 9, 1988, addressed several

plant-specific cases of misapplication of silicone foam

materials. (Later, the staff issued IN 94-28, "Potential

Problems With Fire Barrier Penetration Seals," April 5,

1994, to inform licensees of potential problems that

5

Each licensee maintained a program for reviewing

information notices and determining whether or not the

information is applicable to its facilities. The staff

reviewed these programs during NRC inspections.

Therefore, the staff decided that information notices

were an appropriate vehicle for disseminating what it

learned during its assessment.

NUREG-1552 2
Discussion

could go undetected as a result of inadequate

surveillance inspection procedures and inadequate

acceptance criteria.) Appendix A is a summary of NRC

generic communications related to fire barrier

penetration seals.

Since 1992, new potential problems with penetration

seals have been reported. In response, the Fire Protection

Engineering Section of the Office of Nuclear Reactor

Regulation (NRR) conducted a second technical

assessment of fire barrier penetration seals. The principal

purposes of the second assessment, which is documented

in this report, were to address potential problems, to

determine if there were any widespread problems of

safety significance or with generic implications, and to

determine if NRC requirements, review guidance, and

inspection procedures for penetration seals are adequate.

The staff audited the fire barrier penetration seal

programs at two nuclear power plants, inspected the fire

barrier penetration seal programs at four nuclear plants,

inspected the manufacturer and supplier of the most

widely used seal materials, and inspected two contractors

that installed penetration seals. The staff also witnessed

fire endurance tests of penetration seals, reviewed

operating experience and previous NRC inspection

results, assessed the data and information obtained from

the document reviews and field work, sought out any

commonality or correlation of evidence that may suggest

additional technical problems or trends;, and determined

whether or not there are generic problems of safety

significance. Appendix B is a summary of the staff

action plan for the technical assessment documented

here.

1.3 Fire Protection Program

Rea ssessment

In 1993, the staff of NRR had completed a reassessment

of the reactor fire protection program. NRR had

documented that reassessment in "Report on the

Reassessment of the NRC Fire Protection Program,"

February 27, 1993. The staff had concluded that

licensees were complying with regulatory requirements

and that there were no major or recurring issues with

penetration seals. The report had recommended that the

staff confirm the adequacy of the NRC review and

inspection programs to address fire barrier elements,

including fire barrier penetration seals. However, it made

no recommendations regarding penetration seal

operability.

1.4 AEOD Penetration Seal Review

The Office for Analysis and Evaluation of Operational

Data (AEOD) had performed a review of fire barrier

penetration seals which it documented in a memorandum

of May 23, 1995, from C.E. Rossi, AEOD, to*

G.M. Holahan, NRR. It had included reviews of the Dow

Coming Part 21 silicone cure issue (see Section 5. 1) and

of ongoing NRR activities relating to the technical

assessment documented here. AEOD had reached many

of the same conclusions about penetration seals that

NRR had found. AEOD did, however, raise questions

about NRC procedures for inspecting penetration seals

(see Section 4.4) and aging of silicone seals (see

Section 5. 10).

2 FIRE BARRIER

PENETRATION SEAL

MATERIALS

2.1 Population and Types of Seals

Most of the fire barrier penetration seals installed in

nuclear power plants are designed to achieve a fireresistance rating of 3 hours. Penetration seals, with fireresistance ratings of 1 hour and 2 hours are also used.

Seals are generally classified as either mechanical

penetration seals or electrical penetration seals

depending on the seal penetrants, e.g., piping or cable

trays, respectively. The results of a survey of 32 nuclear

power units conducted by Sandia National Laboratories

(SNL) and reported in a letter report of May 29, 1992,

entitled "A Determination of the Population of Fire

Barrier Types in Generating Stations," is summarized in

Table 1. The objective of the survey was to identify the

fire barrier materials installed in nuclear power plants.

The survey revealed that silicone-based materials are the

predominant penetration seal materials. The survey also

revealed that the average number of penetration seals per

nuclear power plant unit is about 3000 and a single unit

can have up to 10,000 seals. The selection of materials

for a particular penetration seal depends on a number of

factors, including the fire resistance needed, the type of

penetrants, the environment, and the need for the seal to

serve multiple functions (e.g., radiation protection,

pressure boundary, and flood protection).

3 3 N-UREG- 1552
Seal Materials

Table 1 Representative Population of Seal Types

Silicone foam 1668 0-3700

Silicone elastomer 820 0 - 8500

Mineral wool 436 0-2000

Cement (mortar and grout) 424 0 - 3502

Mechanical 33 0-250

2.2 Silicone Foams

The silicone foam most widely used in nuclear power

plants is manufactured and supplied by Dow Coming

Corporation (product information available from Dow

Coming, Midland, MI). Silicone foam is also

manufactured by General Electric and others. The

vendors that install fire barrier penetration seals purchase

silicone foam from the manufacturers, add proprietary

ingredients, and resell the material under proprietary

trade names. For example, ingredients can be added for

radiation protection, to increase the density of the

materials, or to change the cure rate.

Silicone foam seals are formed in place. The formulation

has two components which are mixed in a 1: 1 ratio, by

weight or volume, by a special mixing apparatus that

combines the two parts at the point of application. For

small applications, special applicator kits are available

that allow the two parts to be mixed shortly before

application. The chemical reaction that occurs after the

two components are mixed causes the foam to rise or

expand in volume. Because the silicone foam material

expands as it cures, a tight-fitting seal forms in the

penetration opening. The continued transition of the seal

material from the liquid to the solid state is referred to as

"curing." Silicone foam cures in 2 to 24 hours.

Shrinkage of the foam material is normal within 24 to 48

hours after it is injected in the penetration. Gaps created

by shrinkage are filled with adhesive/sealant (see

Section 2.5).

2.3 Silicone Elastomers

After silicone foam, the most common seal materials are

low-density silicone elastomers (LDSEs) and highdensity silicone elastomers (HDSEs). Some vendors also

supply medium density silicone elastomers. SNL

reported that the average number of elastomer

penetration seals per nuclear power plant unit exceeds

800. The silicone elastomers most widely used in nuclear

power plants are manufactured and supplied by Dow

Coming Corporation. As with silicone foam, vendors

add proprietary ingredients to the elastomer material to

increase density or add various capabilities to the

elastomer, such as radiation protection properties.

Like silicone foam seals, elastomer seals are formed in

place from two components which are mixed in a 1: 1

ratio, by weight or volume, either manually or by a

special mixing apparatus at the point of application. The

mixed components form a dense, firm, rubber-like

material that cures in from 10 minutes to 8 hours,

depending on the formula of the elastomer and

conditions at the place of installation. Unlike silicone

foam, silicone elastomers do not expand appreciably

when curing. Generally, because of the higher density,

structural strength, and thermal stability of silicone

elastomer materials, less thickness is needed in a silicone

elastomer seal than in a silicone foam seal, to achieve a

similar fire rating.

2.4 Silicone Gels

Another silicone product used in penetration seal

applications is silicone gels. Gels display characteristics

of both liquids and solids, and they have a specific

gravity similar to that of water. With added fillers, the

silicone gel is also an effective fire/radiation barrier. The

gel material is usually held together in field applications

by a flexible boot. Gel is supplied to vendors as a twocomponent clear material that is mixed together, usually

in a 1:1 ratio. Gel seals are used to allow significant

penetrant movement and are less widely used than the

silicone foam and silicone elastomers.

NUREG-1552 4
Seal Materials

2.5 Other Sealants

A silicone adhesive product, usually supplied in caulking

gun tubes, is used to repair visible shrinkage in foam

seals, seal openings that are too small for an injection of

other firestop materials, and flexible boot seal

applications.

In addition to silicone-based materials, fire-rated

penetration seals are also made of cement materials

(grouts and mortars) and such fire-retardant materials as

Flamnmastic. In most cases, these materials are installed

after packing the penetrations with fire-resistant

materials such as mineral wool (e.g., Kaowool).

Mechanical penetration seals are also used. Such seals

are typically incorporated in concrete walls during

construction or are retrofitted by drilling out wall

material and casting a seal housing in place. They

perform their sealing function by mechanically

compressing a resilient, fire-resistant synthetic material

around the penetrating item.

2.6 Damming Materials

Damming materials are used to close the cross-sectional

areas of barrier penetrations that are to be sealed.

Damming materials, which may be either permanent or

temporary, are used to contain the seal material until it

has cured or hardened. Permanent damming materials,

which are left in place as integral parts of the penetration

seal assembly, are fire resistant and have low thermal

conductivity and, therefore, contribute to the overall fireresistance rating of the seal assembly. In general, the

damming materials are left in place if they were part of

the fire-tested penetration seal assembly (see

Section 3.1). Examples of permanent damming materials

include ceramic fiber (alumina-silica), ceramic fiber

blankets (e.g., Johns-Manville Corporation Cerafiber),

ceramic fiberboard, and calcium silicate board

(e.g., Johns-Manville Corporation Marinite board).

Temporary damming materials include particle board,

plywood, duct tape, and rigid foams. These materials are

removed after the.seal has cured.

3 QUALIFICATION TESTS OF

PENETRATION SEALS

3.1 Test Methods and Acceptance

Criteria

To gain reasonable assurance that a fire barrier

penetration seal will have the required fire-resistance

capability or fire rating (1, 2, or 3 hours), a

representative penetration seal test assembly is subjected

to a qualification fire endurance test. (Fire tests are also

conducted for research purposes and for product

development.) The test methods involve the furnace-fire

exposure of a full-scale fire barrier penetration seal test

specimen. The test specimens are representative of the

construction for which a fire-resistance rating is desired,

as to materials, workmanship, and such details as the

dimensions of parts. The heat input to the test furnace is

controlled so that the average temperature in the furnace

follows as closely as possible the time-temperature curve

specified in the test standard. In the United States, the

standards used to test and rate penetration seals specify

the standard time-temperature curve defined in American

Society for Testing and Materials (ASTM) E- 119,

"Standard Test Methods for Fire Tests of Building

Construction and Materials." This time-temperature

curve, which is generally accepted for evaluating and

rating the fire resistance of all types of building fire

barriers, is considered to represent a severe fire

exposure. However, the fire endurance tests are not

intended to model any specific room fire or the

conditionsunder which the seals will be exposed during

a fire, but rather provide a specific standard fire exposure

against which similar fire-rated assemblies can be

evaluated.

The test standards and the NRC regulations and guidance

documents specify fire test acceptance criteria that

involve the measured response of the test specimen at the

time into the standard fire exposure that corresponds to

the desired barrier rating. In most cases, the test

specimen is also exposed to a hose stream test after the

fire exposure. For example, a fire barrier penetration seal

design is said to have a fire-resistance rating of 3 hours if

the tested specimen meets the specified acceptance

criteria during at least 3 hours of the standard fire

exposure and the hose stream test. In this example, the

fire-resistance rating qualifies the seal design for use as a

3-hour fire-rated barrier.

The staff has accepted the following industry standards

for qualifying penetration seals: (1) ASTM E-119;

(2) National Fire Protection Association (NFPA) 251,

5 NUREG-1552
Qualification Tests

"Standard Methods of fire Tests of Building

Construction and Materials"; (3) ASTM E-814,

"Standard Method of Fire Tests of Through-Penetration

Fire Stops"; and (4) Institute of Electrical and

Electronics Engineers (IEEE) 634, "Standard Cable

Penetration Fire Stop Qualification Test." In addition,

UL tests and approves penetration seals in accordance

with American National Standards Institute/UL 1479,

"Fire Tests of Through-Penetration Firestops," and other

organizations, such as American Nuclear Insurers (ANI)

and Factory Mutual (FM), also have test methods and

standards for conducting penetration seal fire endurance

tests. The staff has also accepted the installation of

penetration seals that had been qualified in accordance

with these test standards.

There are variations between the test standards and the

test acceptance criteria. Therefore, assessments of fire

test results consider both the test standard that was used

and the acceptance criteria that apply. In general, the

acceptance criteria ensure that the penetration seal does

not burn through during the fire exposure, remains in

place during the fire and hose stream exposure, prevents

the passage of flames or gases hot enough to ignite

combustibles that may be on the nonfire side of the test

specimen, and limits the transmittal of heat through the

seal and any penetrating items (as determined by

measuring the temperature rise on the nonfire side of the

seal and any penetrating items). Section 4 gives the

acceptance criteria that are specified in the NRC

regulations and guidance documents. Appendix C

provides a summary and comparison of the fire barrier

penetration seal fire endurance test standards that have

been endorsed or accepted by the staff.

The ability of a particular penetration seal design to

achieve a specific fire rating is configuration dependent.

The type and thickness of the penetration seal material is

a significant factor. Moisture content; material density;

presence or absence of filler materials or damming

materials; cross-sectional area and free area of seal

material; number, type, and arrangement of penetrants;

seal orientation (horizontal or vertical); and construction

methods also influence the fire-resistance rating. Specific

design considerations for penetration seals are discussed

in Section 5.12 of this report.

Decades of experience with the test standards by the

nuclear and general building industries have provided

adequate assurance that they are appropriate for

qualifying fire barrier penetration seals. Hundreds of

qualification-type fire endurance tests of a wide variety

of penetration seal designs and materials have been

performed by material manufacturers, installation

contractors, test laboratories, research organizations,

licensees, and others. The staff observed fire endurance

tests of fire barrier penetration seals and reviewed fire

test reports during licensing reviews and inspections. On

the basis of these eyewitness accounts and reviews, the

staff has concluded that fire endurance tests have established the fire-resistive capabilities of the penetration

seal materials, designs, and configurations installed in

nuclear power plants.

3.2 Fire Testing Laboratories

During this assessment, the staff did not find technical

issues or problems regarding fire testing laboratories.

However, there has been confusion about NRC

regulatory requirements and review guidance regarding

such laboratories. It has been suggested, for example,

that fire endurance tests that are not performed by a

nationally recognized testing laboratory cannot meet

NRC fire protection regulatory requirements.

NRC fire protection regulations6 do not cover either fire

endurance testing or fire test laboratories. NRC fire

protection guidance documents address these topics in a

limited fashion. For example, they define "fire barrier" as "components of construction.. that are rated by

approving laboratories." They also defime "approved" as

"tested and accepted for a specific purpose or application

by a nationally recognized testing laboratory."

The mission of the National Fire Protection Association,

which was organized in 1896, is to safeguard people,

property, and the environment from fire using scientific

and engineering techniques and education. More than

225 NFPA committees, which are represented by

affected interests, develop and publish standards

intended to minimize the possibility and effects of fires.

NFPA is the principal source of fire protection standards

and codes in the United States. When the staff developed

its fire protection guidance documents in the 1970s, it

adopted a large number of NFPA standards by reference

in its guidance documents. At that time, the staff adopted

the term "nationally recognized testing laboratory" from

6

The NRC fire protection regulations are contained in

General Design Criterion 3, 10 CFR 50.48, and

Appendix R to 10 CFR Part 50. NRC fire protection

review guidance is contained in various branch technical

positions and the Standard Review Plan (NUJREG-0800).

The regulations and guidance are discussed at length in

Section 4.

NUREG-1552 6
Qualification Tests

NFPA. Neither NFPA nor NRC defined the term.7

Consequently, there has been recurring confusion about

what constituted a nationally recognized testing

laboratory. In the 15th edition of the Fire Protection

Handbook, 1981, NFPA stated that it had dropped the

term "nationally recognized testing laboratory" from

documents it published because there was always a doubt

about the definition of a nationally recognized testing

laboratory. The staff did not update its guidance

documents to reflect this NFPA position.

There is no regulatory requirement that fire tests be

conducted by a nationally recognized testing laboratory.

Historically, during licensing reviews, the staff had

accepted the use of fire barriers without reviewing the

fire test results if the barriers were tested and approved

by UL or FM. Such barriers included fire doors, fire

walls, and penetration seals. As discussed in Section 4,

the guidance documents present approaches that are

acceptable to the staff for meeting regulatory

requirements. However, licensees can use approaches

that differ from those specified in the guidance

document. Therefore, the staff had also accepted barriers

that were tested by organizations other than UL and FM.

In such cases, the staff may have reviewed the fire test

results.8

NRC does not certify or accredit testing laboratories and

has not issued guidance for evaluating or assessing the

acceptability of fire testing laboratories to perform fire

tests. In the 17th edition of the Fire Protection

Handbook, 1991, NFPA stated that there are many

laboratories in the United States capable of performing

fire-related research and fire testing. These include

private and industrial laboratories, university

laboratories, and government laboratories. NFPA

indicated that evaluations of laboratories should be based

on criteria that generally focus on their overall operation,

including organization and technicaldirection, ethical

and professional business practices, and the quality

control system used by the laboratory. Other more

specific criteria focus on the personnel, equipment,

facility, procedures, and recordkeeping for performing

and reporting test results. The industry fire test standards

7

At that time, it appeared that UL and FM, two

organizations with historical preeminence in the fire

testing field, were generally considered to be nationally

recognized testing laboratories.

8

The staff review of the Watts Bar Nuclear Power

Plant fire protection program was a recent example of

this (see Sections 5.5.6 and 5.6.3).

also provide guidance for the conduct and

documentation of fire endurance tests.

The term "nationally recognized testing laboratory" is

undefined and obsolete. In addition, national prominence

is not needed to conduct valid fire endurance tests.

Finally, satisfactory ways of selecting suitable test

facilities are available within the fire protection

engineering community. Therefore, the staff

recommends that the NRC fire protection guidance

documents be revised to reflect the current NFPA

position.

4 FIRE PROTECTION

REGULATIONS, GUIDANCE,

AND INSPECTION

PROCEDURES

4.1 Background

NRC requirements and guidelines for penetration seals

are contained in a number of documents. The extent to

which these requirements or guidelines are applicable to

a specific plant depends on the age of the plant and the

commitments established by the licensee in developing

its fire protection plan. Some of the potential problems

that were raised about penetration seals reflected a poor

grasp of NRC fire protection regulations and guidance

and the regulatory process. For example, Appendix R,

"Fire Protection Program for Nuclear Power Facilities

Operating Prior to January 1, 1979," to Title 10 of the

Code of Federal Regulations (10 CFR) Part 50, was

thought to be a generically applicable set of

requirements; staff review guidance had been mistaken

for regulatory requirements, and the flexibility afforded

by guidance documents had not been recognized.

In 1971, the Atomic Energy Commission (AEC)

promulgated General Design Criterion (GDC) 3, "Fire

protection." GDC 3 states, in part, "structures, systems,

and components important to safety shall be designed

and located to minimize, consistent with other safety

requirements, the probability and effect of fires and

explosions. Noncombustible and heat-resistant materials

shall be used wherever practical throughout the unit,

particularly in such locations as the containment and

control room." The AEC did not issue guidelines for

implementing GDC 3.

On March 22, 1975, the Browns Ferry Nuclear Power

Plant had the worst fire ever to occur in a commercial

nuclear power plant operating in the United States. Two

7 7 NUREG-1552
Regulations, Guidance, and Inspection Procedures

recommendations made by the Special Review Group

that investigated the Browns Ferry fire pertained to

assurance that the fire protection programs at operating

nuclear power plants conform to GDC 3. The first

recommendation was that NRC should develop specific

guidance for implementing GDC 3. The second was that

the NRC should review the fire protection program at

each operating plant comparing it to the guidance

developed per the first recommendation.

In response to the first recommendation, the staff

developed Branch Technical Position (BTP) Auxiliary

Power Conversion Systems Branch (APCSB) 9.5-1,

"Guidelines for Fire Protection for Nuclear Power

Plants," May 1, 1976; and its appendix, "Guidelines for

Fire Protection for Nuclear Power Plants Docketed Prior

to July 1, 1976," Appendix A, February 24, 1977. In

response to the second recommendation, each operating

plant compared its fire protection program to either the

guidelines of BTP APCSB 9.5-1 or to the guidelines of

Appendix A to BTP APCSB 9.5-1 and the staff reviewed

the fire protection programs for compliance with the

guidance. Most licensees complied with most of the

implementing guidance. However, the staff and some

licensees disagreed on 17 issues. To resolve the

contested issues, on May 29, 1980, the NRC proposed

10 CFR 50.48, "Fire protection," and Appendix R, "Fire

Protection Program for Nuclear Power Facilities

Operating Prior to January 1, 1979," to 10 CFR Part 50

(45 FR 36082). The NRC published in the Federal

Register (45 FR 76602) the final fire protection rule

(10 CFR 50.48) and Appendix R to 10 CFR Part 50 on

November 19, 1980.

4.2 Regulations

4.2.1 GDC 3 and 10 CFR 50.48

The basic fire protection regulation for nuclear power

plants is Section 50.48 of 10 CFR Part 50. It requires, in

part, that each operating nuclear power plant have a fire

protection plan that satisfies GDC 3. It references

Appendix R to 10 CFR Part 50 and several NRC fire

protection guidance documents. GDC 3 and

10 CFR 50.48 do not explicitly address penetration seals.

4.2.2 Appendix R to 10 CFR Part 50

When the staff proposed Appendix R, it intended that the

requirements be applicable only for the resolution of

unresolved disputed fire protection features. The staff

did not intend that the requirements be applicable to

features that it had previously accepted. However, when

it issued Appendix R, the Commission decided, as a

result of its continuing review of fire protection matters,

to retroactively apply the requirements for fire protection

of safe-shutdown capability, emergency lighting, and

reactor coolant pump oil collection systems to all plants

operating prior to January 1, 1979, even if the staff had

previously approved an alternative approach. The

remaining sections were backfit to plants only to the

extent needed to resolve the contested issues, the

Commission having decided that the features previously

approved by the staff provided an equivalent level of

safety to that provided under these specific provisions of

Appendix R.

Section III.M, "Fire barrier cable penetration seal

qualification," of Appendix R resolved the disputed issue

of fire barrier penetration seals and is, therefore, of

interest here. It applied to 13 nuclear power plants.

Section III.M states that penetration seal designs shall

utilize only noncombustible material (see Section 5.8)

and shall be qualified by tests that are comparable to

tests used to rate fire barriers. Section III.M contains the

following acceptance criteria:

(1) Cable fire barrier penetration seal has withstood

the fire endurance test without passage of flame or

ignition of cables on the unexposed side.

(2) Temperatures recorded on the unexposed side are

analyzed and the maximum temperature is

sufficiently below the ignition temperature of the

cable insulation temperature.

(3) The fire barrier penetration seal remains intact and

does not allow a projection of water beyond the

unexposed surface during the hose stream test.

4.3 Review Guidance

The staff did not backfit Appendix R to plants licensed

to operate after January 1, 1979. For these plants, the

staff reviewed the fire protection programs during

licensing against the licensees' commitments. Most

licensees for plants licensed to operate after

January 1, 1979 committed to meet the combination of

the guidance of Appendix A to BTP APCSB 9.5-1 and

the criteria of certain sections of Appendix R. In such

cases, the sections of Appendix R that the licensee

committed to meet apply to the plant as licensing

commitments, but not as regulatory requirements. The

other licensees committed to meet the guidelines of

Section 9.5-1 "Fire Protection Program," of

NUREG-0800, "Standard Review Plan" (SRP), which

incorporated the guidance of Appendix A to BTP

NUREG-1552 8
APCSB 9.5-1 and the criteria of Appendix R. Therefore,

plants licensed to operate after January 1, 1979, can

implement the guidance contained in SRP Section 9.5-1

to establish a fire protection program that complies with

10 CFR 50.48 and GDC 3. In either case, the fire

protection programs are essentially equivalent from plant

to plant. However, the regulatory process used to

establish the program can differ.

The NRC guidance documents do not have the same

status as NRC regulations or regulatory requirements.

Rather, the purpose of the guidance documents is to

ensure the quality and uniformity of NRC staff reviews

and to present a set of acceptable methods of complying

with the NRC regulations. The guidance documents

present solutions and approaches that are acceptable to

the staff, but they do not represent the only possible

approaches to solutions. Licensees can use approaches

that differ from those specified in the guidance

document. In these cases, the staff performs more

detailed reviews to ensure that the alternative approaches

are equivalent to the guidance.

4.3.1 Appendix A to BTP APCSB 9.5-1

In Position D. .(j) of Appendix A to BTP APCSB 9.5-1,

the staff specified that floors, walls, and ceilings

enclosing separate fire areas should have a fire rating of

3 hours. Penetrations in these fire barriers, including

conduits and piping, should be sealed or closed to

provide a fire-resistance rating at least equal to that of

the fire barrier itself. In Position D.3.(d), the staff also

specified that cable and cable tray penetrations through

fire barriers should be sealed to give protection at least

equivalent to that of the fire barrier itself.

4.3.2 Standard Review Plan (NUREG-0800)

In SRP Section 9.5-1, "Fire Protection Program,"

Position C.5.a, "Building Design," paragraph 3, the staff

stated that openings through fire barriers for pipes,

conduits, and cable trays which separate fire areas should

be sealed or closed to provide a fire-resistance rating at

least equal to that required of the barrier itself. In

conduits larger than 4 inches in diameter, openings

should be sealed at the fire barrier penetration. In

conduits 4 inches or less in diameter, openings should be

sealed at the fire barrier unless the conduit extends at

least 5 feet on each side of the fire barrier and is sealed

either at both ends or at the fire barrier with

noncombustible material to prevent the passage of smoke

and hot gases. Fire barrier penetrations that must

maintain environmental isolation or pressure differentials

Regulations, Guidance, and Inspection Procedures

should be qualified by test to maintain the barrier

integrity under such conditions.

In addition, Position C.5.a, paragraph 3, specifies that

penetration designs should utilize only noncombustible

materials (see Section 5.8 of this report) and should be

qualified by tests. The tests use the time-temperature

exposure curve specified by ASTM E- 119. The test

acceptance criteria include:

(1) The penetration seal has withstood the fire

endurance test without passage of flame or ignition

of cables on the unexposed side for the period of

time equivalent to the fire-resistance rating

required of the barrier.

(2) The temperature levels recorded on the unexposed

side are analyzed and the maximum temperature

does not exceed 325 'F.

(3) The seal remains intact and does not allow

projection of water beyond the unexposed surface

during the hose stream test. The hose stream can be

delivered through a 11⁄21⁄4-inch nozzle set at a

discharge angle of 30 degrees with a nozzle

pressure of 75 pounds per square inch (psi) and a

minimum discharge of 75 gallons per minute (gpm)

with the tip of the nozzle a maximum of 5 feet

from the exposed face; or the stream can be

delivered through a 11⁄4-inch nozzle set at a

discharge angle of 15 degress with a nozzle

pressure of 75 psi and a minimum discharge of

75 gpm with the tip of the nozzle a maximum of

10 feet from the exposed face; or the stream can be

delivered through a 21/

2-inch national standard

playpipe equipped with a 1 1 h-inch tip, nozzle

pressure of 30 psi, located 20 feet from the exposed

face.

4.3.3 Generic Letter 86-10

Generic Letter (GL) 86-10, "Implementation of Fire

Protection Requirements," April 24, 1986, provided

guidance for satisfying NRC regulatory requirements for

fire protection. Enclosure 1 to GL 86-10 included

interpretations of Appendix R requirements.

Interpretation 4, "Fire Area Boundaries," stated, in part:

The term "fire area" as used in

Appendix R means an area sufficiently

bounded to withstand the [fire] hazards

associated with the area and, as necessary,

to protect important equipment within the

area from a fire outside the area. In order

9 NUREG-1552
Regulations, Guidance, and Inspection Procedures

to meet the regulation, fire area

boundaries need not be completely sealed

floor-to-ceiling, wall-to-wall boundaries.

However, all unsealed openings should be

identified and considered [in] evaluating

the effectiveness of the overall barrier.

Where fire area boundaries are not wallto-wall, floor-to-ceiling boundaries with

all penetrations sealed to the fire rating

required of the boundaries, licensees must

perform an evaluation to assess the

adequacy of fire boundaries in their plants

to determine if the boundaries will

withstand all hazards associated with the

area.

This regulatory position established that certain

penetration seals need not have the same fire rating as

the barrier in which they are installed. Licensees evaluate

such seals on a case-by-case basis. The engineering

evaluations performed to assess the effectiveness of the

penetration seals are based on the expected fire-resistive

performance of the seal and on the fire hazards and fire

protection features in the fire area.

4.4 Inspection Procedures

NRC fire protection inspection procedures are contained

in NRC Inspection Manual Inspection Procedure 64704,

"Fire Protection Program," March 18, 1994; Inspection

and Enforcement Manual Inspection Procedure 64100,

"Post-Fire Safe Shutdown, Emergency Lighting and Oil

Collection Capability at Operating and Near-Term

Operating Reactor Facilities," March 16, 1987; and

Inspection and Enforcement.Manual Inspection

Procedure 64150, "Triennial Post-Fire Safe Shutdown

Capability Reverification," March 16, 1987.

The NRC inspection procedures do not give specific

guidance for inspecting fire barrier penetration seals.

However, the staff has routinely inspected fire barrier

penetration seal programs during fire protection program

and other inspections (see Section 5.3). Nevertheless, the

staff concluded that the lack of inspection guidance

could be viewed as a potential weakness in the NRC

reactor fire protection program. The staff is now

-preparing the new Fire Protection Functional Inspection

(FPFI) Program that it had described in SECY-95-034,

"Status of the Recommendations Resulting from the

Reassessment of the NRC Fire Protection Program,"

February 13, 1995. The staff will include guidance for

inspecting fire barrier penetration seal programs in the

FPFI procedures and guidelines for use by NRC

inspectors on an as-needed basis.

5 TECHNICAL ASSESSMENT

5.1 Review of Penetration Seal

Part 21 Reports

NRC maintains a database of reports submitted in

accordance with 10 CFR Part 21, "Reporting of Defects

and Noncompliance." The staff searched the database to

find reports that involved penetration seal materials that

had been submitted since it completed its first

penetration seal assessment in 1988. The staff found only

two Part 21 notifications. These were submitted by Dow

Coming Corporation.'

On November 17, 1994, Dow Coming submitted a Part

21 notification cohcerning Dow Coming 96-081 RTV

Adhesive/Sealant and on November 28, 1994, it

submitted a Part 21 notification concerning

SYLGARD 170 Silicone Elastomer and SYLGARD 170

Silicone Fast Cure Elastomer. According to the

notifications, certain lots of the RTV Adhesive/Sealant

deviated from Dow Coming sales specifications for

flame self-extinguishing time and certain lots of

SYLGARD deviated from Dow Coming sales

specifications for cure rate. Dow Coming also informed

each of its customers of the deviations:

Later, on the basis of its testing and analysis, Dow

Coming determined that the deviations were traceable to

a pigment that was contaminated with sulphur. Dow

Coming also concluded that the deviations were limited

to specific lots. As part of its technical review of the

Dow Coming Part 21 notifications, the staff met with

Dow Coming representatives at NRC Headquarters

during a public meeting on January 31, 1995. The staff

also inspected Dow Coming facilities (see Section 5.6.1)

and witnessed fire endurance testing activities that were

performed at UL to determine if the deviations adversely

impacted the fire-resistance performance of seals, if any,

that used the contaminated component.

By letter of July 21, 1995, Dow Coming submitted the

UL fire test results. On the basis of the fire endurance

tests, which consisted of side-by-side tests of test

specimens constructed with suspect and nonsuspect

9

As explained in Section 5.6.1 of this report, the

deficiency reporting requirements of 10 CFR Part 21 are

not applicable to the products that Dow Coming supplied

to nuclear power plant fire barrier vendors. However,

Dow Coming has conservatively elected to inform the

NRC and its customers of potential product deviations.

NUREG- 1552 10
Technical Assessment

materials, UL concluded that there were no significant

deviations or irregularities in fire barrier performance

between the penetration seal materials. UL also

concluded that these materials would not be precluded

from being used in UL-classified penetration seals. The

staff reviewed the test results and concurred with the

conclusions made by UL. The staff also concluded that

the material deviations regarding self-extinguishing time

and cure rate do not have a significant affect on material

performance as a fire barrier. On the basis of its

document reviews, fire test observations, inspection

activities, and discussions with Dow Coming

manufacturing and corporate personnel, the staff also

concluded that the actions taken by Dow Coming to

address the issues were appropriate, timely, and

satisfactory.

5.2 Review of Reactor Operating

Experience

5.2.1 Review of Licensee Event Reports

Oak Ridge National Laboratory maintains a licensee

event report (LER) database for the NRC. In 1994, the

database contained about 58,000 LERs that had been

submitted since 1980. SNL searched the database in

1994 and found that 318 LERs, or about 0.5 percent of

the LERs in the database involved fire barrier

penetration seals. In support of the assessment

documented here, the staff searched the LER database

and found that licensees for about 20 plant sites had

submitted 141 LERs related to fire barrier penetration

seals between 1989 and 1993, inclusive.1 0 Since almost

one-half of the LERs related to penetration seals have

been submitted during this four-year period, it appeared

that staff efforts to alert licensees to potential penetration

seal problems in 1988 (see Section 1.2) increased

industry's awareness of penetration seal problems and

resulted in more thorough surveillances. The types of

problems that had been reported by the licensees are

shown in Table 2.

The staff found that the predominant problems involved

improper installation, seal degradation, and seal breach.

Most of the problems associated with installed

penetration seals involved seals constructed of silicone

foam. To a lesser extent, problems involved the failure to

install seals where required. It appeared that most

problems concerning improper seal construction and

failure to install seals occurred during original plant

construction. In some cases, it appeared that licensees

may have conservatively reported such superficial

problems as surface imperfections, and small cracks,

splits, and gaps. Such conditions would not have

precluded the seals from performing their intended fire

protection design function. In many other cases, the

inherent fire-resistive capabilities of the penetration seal

materials installed in nuclear power plants would have

provided some measure of fire protection. For example,

weaknesses with fire test documentation or missing a

scheduled surveillance would not adversely impact the

fire-resistive capabilities of the penetration seals.

The LERs did not indicate generic problems with

penetration seal materials. In addition, the staff found no

reports of safety-significant failures of penetration seals.

On the basis of its review of LERs, the staff concluded

that licensee penetration seal surveillance programs have

been effective in revealing penetration seal deficiencies.

The staff also concluded that licensees appeared to be

taking timely and appropriate actions to correct

identified discrepancies." It is the staffs opinion that

continued licensee surveillances in accordance with

existing plant procedures are adequate to ensure that

penetration seal problems are discovered and resolved.

See also Section 5.3.

5.2.2 Review of Reactor Fire Experience

The staff reviewed the fire event databases compiled by

SNL, which contained data from 1965 thorough 1985,

and the Electric Power Research Institute, which

contained data from 1965 through 1988. The staff found

no reports of nuclear power plant fires that challenged

the ability of fire-rated structural barriers or fire-rated

penetration seals to confine a fire in accordance with

their fire protection design function. The staff also

reviewed the LER database discussed in Section 5.2.1,

which includes data from 1980 to the present, and again,

found no reports of nuclear power plant fires that caused

the failure of a fire-rated structural barrier or a fire-rated

penetration seal.

"°This was the period of time between when the staff

had completed its first penetration seal assessment

(1988) and when it started its substantive work on the

technical assessment documented here (1994).

"The staff also used the insights it gained from its

LER review to help plan the vendor and plant site

inspections discussed in Sections 5.5 and 5.6.

I1I NUREG-1552
Technical Assessment

Table 2 Penetration Seal Problems Reported in LERs

Reported Problemis j Num ber of LERsjofotlL s

Seal inoperable or deficient due to improper installation, 82 58

degradation, or seal breach

Seal not installed or missing 37 26

Seal surveillances not performed 14 10

Inappropriate or unqualified penetration seals 6 4

Temporary or improper seal installed 2 2

Total number of LERs 141

5.3 Review of Previous NRC

Inspection Results

The staff reviewed region-based and resident

inspector-based reactor inspections that addressed

penetration seal programs."2 These inspections are

identified in Table 3.

The inspections of Calvert Cliffs, Diablo Canyon (see

Section 5.4.4), Ginna, Haddam Neck, San Onofre,

Susquehanna, and Washington Nuclear Project 2 (see

Section 5.5.5) were routine fire protection program

inspections which included inspections of the penetration

seal programs. The inspections of Indian Point 3 (IP3),

Oyster Creek, and River Bend Station (RBS) were

special or routine resident inspector inspections. The

inspectors reviewed the adequacy of penetration seal

installations, qualification, and surveillances. They also

followed up on issues reported in LERs and weaknesses

noted during previous NRC inspections.

The inspection reports for San Onofre and Haddam Neck

stated that the licensees had completed penetration seal

reevaluation programs in response to NRC and industry

concerns regarding the adequacy of fire barrier

penetration seals in 1988. The inspection reports

indicated that these programs were comprehensive,

timely, and acceptable.

At RBS, the inspectors had found that the licensee's

corrective actions were not adequate in response to the

misapplication of seal material in 1991. The seals were

not designed for the high ambient temperatures to which

they were exposed; therefore, the seals degraded. Later,

during the 1995 inspections, the inspectors concluded

"

2

Unlike the audits and inspections summarized in

Section 5.5, the staff did not conduct these inspections as

part of this assessment.

that the licensee had addressed the seal degradation

effectively, and the inspectors closed the unresolved

item. At IP3, the inspectors had questioned the

methodology used by the licensee to determine the selfignition temperature of cables that pass through

penetration seals. However, the inspectors had found the

licensee's penetration seal analyses and supporting

documentation to be generally sufficient.

The NRC is currently tracking corrective actions for

penetration seal deficiencies at Diablo Canyon and IP3.

The inspection reports, like the LERs summarized in

Section 5.2.1, revealed that licensees occasionally find

plant-specific deficiencies; However, the inspection

reports also indicated that the licensees maintained

satisfactory fire barrier penetration seal programs and

have taken appropriate and timely actions to correct any

penetration seal deficiencies found during surveillances.

The NRC inspection reports did not reveal widespread or

potentially generic problems of safety significance.

5.4 Review of Plant-Specific

Corrective Action Programs

The staff reviewed the status of the penetration seal

programs at several plants that had undertaken

penetration seal corrective action programs since it

completed the first penetration seal assessment. The staff

had originally reviewed the programs for two of these

plants (Wolf Creek Generating Station and V.C. Summer

Nuclear Station) during its first penetration seal

assessment. Two other plants (Vermont Yankee Nuclear

Power Station and Diablo Canyon Nuclear Power Plant)

initiated programs after the staff issued the information

notices in 1988 that addressed the findings of the first

assessment.

NUREG-1552 12
Technical Assessment

Table 3 NRC Inspections of Penetration Seal Programs

Plant Report Dates ]

Calvert Cliffs Nuclear Power Plant May 6, 1994

Diablo Canyon Nuclear Power Plant Units I and 2 March 15, 1994 and May 1, 1995

R.E. Ginna Nuclear Power Plant June 13, 1994

Haddam Neck Power Station June 19, 1995

Indian Point 3 Nuclear Power Plant July 26, 1995

Oyster Creek Nuclear Generating Station July 21, 1995

River Bend Station March 8, May 3, and June 9, 1995

San Onofre Units 2 and 3 January 28, 1994

Susquehanna Steam Electric Station July 31, 1995

Washington Nuclear Project 2 February 25 and November 9, 1994; and

June 29, 1995

The LERs discussed in Section 5.2.1, the NRC

inspections discussed in Section 5.3, and the

plant-specific corrective action programs summarized

below showed that the licensees knew and understood

the fire resistive capabilities of the penetration seal

materials and configurations; potential penetration seal

testing, design, installation, inspection, and maintenance

problems; and possible remedies and corrective actions.

These findings also indicated that the actions taken by

the staff in 1988 had increased industry awareness of

possible penetration seals problems, leading industry to

more comprehensive inspections, maintenance, and

corrective actions.

5.4.1 Wolf Creek Generating Station

In December 1984, the licensee had issued a

nonconformance report because 22 penetration seals

lacked document traceability. The licensee had

completed corrective actions in 1985. Later, in early

1987, Promatec, the penetration seal installation

contractor, notified the NRC that 20 of 40 seals inspected

exhibited voids and shrinkage of the silicone foam

material. It was found that the problems had involved

installation methodology, inadequate quality control

(QC) methods, and rapid chemically induced silicone

foam material expansion. The licensee issued LER 87-

010 on February 6, 1987. Several other nuclear reactors

were affected by this problem. Promatec informed the

industry of the problems and submitted a Part 21

notification. Later, after the first penetration seal

assessment, the NRC had issued IN 88-56 to advise

licensees of the problems discovered at Wolf Creek.

In 1987, the licensee had established a task force to

develop a corrective action plan. The inspection plan

included the removal of damming boards and inspection

of accessible foam penetrations. The scope of the

program included inspections of more than 1700 silicone

foam penetration seals. As a result of the inspections, the

licensee repaired more than 600 seals during 1987. Since

1987, the licensee has found only minor problems during

routine inspections. The licensee addressed these

problems promptly.

5.4.2 Virgil C. Summer Nuclear Station

In February 1987, after a vendor inspection at Brand

Industrial Services Company, Incorporated (see

Section 5.6.!2), the licensee for V.C. Summer Nuclear

Station, had performed an evaluation of silicone foam

penetration seals. During the evaluation, which it

completed in July 1987, the licensee evaluated 642 seals.

It found that about 94 percent of the seals were 3-hour

qualified on the basis of fire endurance test results. It had

also accepted the configurations of 21 seals on the basis

of engineering evaluations and modified 15 seals to

achieve acceptable configurations.

Problems identified earlier by visual inspections

involved only minor degradation of the seal material;

these were readily repaired. During inspections of the

fire protection program in 1987 and 1988, the regional

staff inspected a sampling of fire barrier seals and

reviewed the inspection procedures which are used by

the licensee to perform periodic visual inspections. No

problems were noted during these inspections.

13 NUREG-1552
Technical Assessment

5.4.3 Vermont Yankee Nuclear Power

Station

On March 19, 1992, during an inspection of fire barrier

penetration seals at Vermont Yankee Nuclear Power

Station, the licensee found a penetration containing

unapproved material. The next day, another penetration

seal was found to be degraded. The licensee

implemented compensatory measures and began an

investigation into the cause of the degradation. Later,

while implementing corrective actions in

December 1992, the licensee found additional problems.

It performed additional seal inspections and found that

the seal discrepancies were more widespread than

originally believed. On January 15, 1993, the licensee

issued LER 93-001. The licensee declared 57 penetration

seals inoperable and established a task force to inspect

all fire barrier penetration seals. Ultimately, the licensee

repaired more than 900 of the 1400 fire barrier

penetrations installed at Vermont Yankee and upgraded

almost 300 penetrations. The licensee attributed most of

the as-found unacceptable penetrations to inadequate

design or installations made by the installation contractor

between 1979 and 1980. (The seal contractor is no

longer in business.) The licensee attributed the failure to

identify these issues to inadequate surveillance

procedures. The licensee completed the repairs to

affected barriers and the required surveillances in

May 1993.

5.4.4 Diablo Canyon Nuclear Power Plant

In January 1994, the licensee for Diablo Canyon Nuclear

Power Plant, found that certain fire barrier penetration

seals may not have met the required 3-hour fire rating

because damming boards were not installed on both

sides of silicone foam seals. This deficiency was

discovered and reported by utility construction personnel

during routine repair of an existing penetration seal. The

seal that needed the damming board was repaired and an

engineering review revealed that many of the silicone

foam seals needed damming boards to meet the 3-hour

criterion. A walkdown of additional seals was conducted

and revealed approximately 100 representative silicone

foam fire barrier penetration seals with missing damming

boards. The licensee initiated roving fire watches as a

compensatory measure. It was believed that this

condition had existed since the plant was constructed. On

February 24, 1994, the licensee issued LER 1-94-001-00.

The licensee has established a program to qualify the

penetration seals with respect to fire endurance tests or

representative plant fire hazards, has completed

walkdowns to document the adequacy of penetration seal

configurations, has reviewed design and installation

procedures for penetration seals, has reviewed

engineering procedures and design change documents,

and has clarified responsibilities for control of

penetration seals. The staff had followed up on the

licensee's activities during inspections in February 1994

and March 1995. The inspectors concluded that the

licensee had taken appropriate corrective actions. The

staff is continuing to follow the licensee's actions.

5.5 Focused Audits and Inspections

of Nuclear Plants

In support of this generic assessment, the staff audited

the penetration seal programs at Davis-Besse Nuclear

Power Station and Waterford 3 Nuclear Power Plant and

inspected the penetration seal programs at Susquehanna

Steam Electric Station, Calvert Cliffs Nuclear Power

Plant, and Washington Nuclear Project 2 (WNP2). In

addition, as part of its licensing review of the Watts Bar

Nuclear Power Plant (WBN), the staff reviewed and

inspected the WBN fire barrier penetration seal program

in detail. The staff selected these plants on the basis of

reports of problems (Davis-Besse, Waterford 3, and

Susquehanna), combination of old and new seal

installations (Calvert Cliffs), significant corrective action

program and rework by licensee after self-identification

of problems (WNP2), and new construction including

testing and engineering (WBN).

During these audits and inspections, the staff

(1) followed up on potential problems regarding fire

barrier penetration seals; (2) gathered information on

qualified penetration seals; and (3) assessed whether the

seals were designed, tested, installed, inspected, and

maintained in accordance with licensee commitments,

NRC fire protection requirements and guidance, and

standard industry practice. The staff selected seals for

inspection on the basis of several factors, including

(1) seal type and material, (2) seal location, (3) seals that

had been repaired or reworked, and (4) seals for which

there were potential technical problems. The staff

examined procurement documentation for penetration

seal materials, seal compatibility with barriers in which

they were installed, fire endurance tests associated with

the seal qualification designs, and training programs for

seal installers and inspectors, and reviewed penetration

seals installed at the plant sites, the QC and quality

assurance (QA) programs relating to installation and

maintenance of penetration seals, deviations of installed

seals from NRC requirements, and surveillance

requirements and programs for technical specification

penetration seals.

During some of these audits and inspections the staff

found several minor weaknesses. However, the staff

concluded that the weaknesses did not result in

deficiencies with the installed penetration seals. The staff

did not find safety-significant problems or potential

problems with generic implications. Moreover, during

NUREG-1552 14
Technical Assessment

these activities, the staff found that the licensees and

vendors are aware of and familiar with the possible

problems that can exist with penetration seals, that fire

test results and qualified fire-resistant penetration seal

designs and materials are widely available, and that

licensees have the means to correct penetration seal

deficiencies and problems. The results of the plant site

audits and inspections are summarized below.

5.5.1 Davis-Besse Nuclear Power Station

From May 9 through 12, 1994, NRR staff audited the

penetration seal program at the Davis-Besse Nuclear

Power Station. On the basis of the audit, the staff

concluded that the licensee had implemented and

maintained an acceptable fire barrier penetration seal

program and that no significant problems existed with

the fire barrier penetration seal installations at

Davis-Besse. The staff did not find information that

suggested problems with generic implications.

5.5.2 Waterford 3 Nuclear Power Plant

NRR staff audited the Waterford 3 penetration seal

program from July 11 through 14, 1994. The staff found

several minor weaknesses with fire test results and

training records. The staff concluded, however, that the

fire barrier penetration seal program was satisfactory and

that the discrepancies did not create any problems with

the penetration seal installations at Waterford 3. The

staff did not find safety-significant problems or evidence

to suggest that generic problems existed with penetration

seals.

5.5.3 Susquehanna Steam Electric Station

From January 30 through February 1, 1996, NRR staff

inspected the fire barrier penetration seal program at

Susquehanna Steam Electric Station. The inspectors

found the damming material missing from one

penetration seal. The licensee took immediate corrective

actions. The inspectors concluded that the licensee had

implemented and maintained an acceptable fire barrier

penetration seal program. The inspectors did not find

safety-significant problems or evidence of generic

problems with penetration seals.

5.5.4 Calvert Cliffs Nuclear Power Plant

From February 13 through 15, 1996, the NRR staff

inspected the fire barrier penetration seal program at

Calvert Cliffs Nuclear Power Plant. The inspectors

concluded that the licensee had an acceptable fire barrier

penetration seal program. The inspectors did not find

safety-significant problems or evidence of generic

problems. Ongoing licensee efforts to improve the

penetration seal program were seen as positive.

5.5.5 Washington Nuclear Project 2

In December 1993, the licensee for WNP2 started a

review of issues related to its penetration seal inspection

program. The licensee found deficiencies with the

original installations, periodic inspections, and repairs.

Licensee evaluations of the deficiencies involving

original seal construction found that some seals did not

meet existing acceptance criteria and design drawings

and that work practices were not in accordance with the

installation procedures. The licensee identified five

major contributing factors: (1) inadequate construction,

(2) inadequate management methods, (3) inadequate

design configuration and analysis, (4) inadequate work

practices, and (5) inadequate training. The licensee

declared all penetration seals at WNP2 inoperable,

established compensatory measures, and initiated a

comprehensive penetration seal upgrade program.

The penetration seal upgrade program included seal

calculations backed by fire endurance tests; new seal

design guide, typical seal details, and barrier functional

list; revised plant specifications and procedures which

reference the aforementioned documents; closure of

penetration seal impairments; GL 86-10 engineering

evaluations for certain non-rated barriers; updated

installation and surveillance procedures for training seal

installers and inspectors; and qualified and operable

penetration seals.

NRC Region IV had identified the penetration seal

problems as an unresolved issue pending completion of

the penetration seal upgrade program and had conducted

three inspections of the program (see Section 5.3). The

inspectors had concluded that the licensee was taking

aggressive corrective action to resolve this issue. Later,

from August 7 through 17, 1995, in support of the

technical assessment documented here, an NRC

integrated assessment team inspected the licensee

activities mentioned above. The team assessed licensee

effectiveness in identifying issues, performing root cause

analyses, and implementing corrective actions. The

inspection focused on the areas of maintenance and

engineering. The team inspected activities involving

procurement, storage, installation, quality control, and

long-term maintenance associated with the installation

and maintenance of penetration seals. The team

concluded that the licensee's current performance in the

areas of receipt inspection and storage control, quality

control, and inspection and surveillance was adequate.

The assessment team also considered the licensee's

corrective action program on penetration seals to be a

strength.

15 NUREG-1552
Technical Assessment

5.5.6 Watts Bar Nuclear Power Plant

As part of its licensing review of the WBN fire

protection program, and in support of this technical

assessment, the staff reviewed and inspected the fire

barrier penetration seal program for WBN in detail. As

part of its review, the staff observed a penetration seal

fire endurance test program conducted by the licensee

and Promatec (see Section 5.6.3). The staff also

reviewed the WBN engineering report on the penetration

seal program, audited a number of typical seal details

and the corresponding fire qualification test reports, and

inspected in-plant penetration seal configurations.

The fire barrier penetration seal materials installed at

WBN consist of silicone foam, silicone elastomers, and

boot-type seals. Each mechanical and electrical fire

barrier penetration seal was fabricated to a specific

design detail and each design detail is supported by one

or more fire endurance tests. In addition, for about

4 percent of the mechanical penetration seals, which

deviated from the typical design details, the licensee

performed additional engineering evaluations in

accordance with GL 86-10. The evaluations either

addressed the adequacy of the seals as designed or their

adequacy to perform their intended design function on

the basis of the fire hazards and the fire protection

features in the area.

The staff had documented its review and evaluation of

the WBN fire penetration seal program in Section 9.5.1,

"Fire Protection Section," of NUREG-0847, "Safety

Evaluation Report Related to the Operation of Watts Bar

Nuclear Plant, Units I and 2." On the basis of its

comprehensive safety evaluation of the WBN penetration

seal program, the staff had concluded that the program

satisfied applicable NRC requirements and guidelines.

5.6 Vendor Inspections

The staff inspected Dow Coming Corporation; Brand

Fire Protection Services, Incorporated; and B&B

Progressive Materials and Technologies, Incorporated

(Promatec), in support of this assessment. In general, the

areas reviewed during these inspections were seal

materials, dedication of commercial-grade seal materials,

storage and shelf life'of materials, procurement

documentation control, quality assurance and quality

control, design control, and methods for qualifying

penetration seal configurations. The inspectors also

considered aspects of the vendors' programs that were in

place during the 1980s, when most nuclear power plant

penetration seals were installed, and those that are in

place today. As documented in the NRC inspection

reports, and summarized below, the inspectors did not

find problems that could adversely affect reactor safety

or the quality of the services and materials that the

vendors provide to the nuclear industry.

5.6.1 Dow Corning Corporation

Dow Coming Corporation is the primary supplier of

silicone-based fire barrier seal materials to the nuclear

industry. The NRC inspected Dow Coming facilities in

Midland, Michigan, and Elizabethtown, Kentucky,

during March 23 through.24 and April 3

through 5, 1995. The inspectors did not find any

problems that could adversely affect reactor safety and

determined that Dow Coming effectively executed the

portions of the product manufacturing controls that were

reviewed.

A significant aspect of the inspection was the review of

Dow Coming's processes and procedures for reporting

and resolving potential product defects (see also,

Section 5.1). The inspectors determined that Dow

Coming had not employed unique nuclear requirements

for design, manufacture, testing, or supply of its siliconebased penetration seal products. Some customers had

contractually imposed the requirements of 10 CFR

Part 21 on Dow Coming for products supplied for use in

nuclear power plant fire barrier penetration seals.

However, the inspectors determined that the seal

products were neither safety-related nor basic

components (as described in 10 CFR Part 21). Therefore,

from a regulatory standpoint, the deficiency reporting

requirements of Part 21 are not applicable. However, the

inspectors determined that the Dow Coming defect

reporting system appeared to provide a mechanism for

informing the fire barrier installation vendors of potential

deviations of the penetration seal materials manufactured

by Dow Coming Corporation.

5.6.2 Brand Fire Protection Services,

Incorporated

During January 1987, in support of its first penetration

seal assessment, the staff inspected Brand Industrial

Services Company (BISCO). The staff found that

penetration seal test documentation used by certain

nuclear plants may not have represented the as-built

penetration seal configurations. The staff communicated

this finding to the potentially affected licensees and

included the issue in IN 88-04. Later, this issue was

reviewed during NRC penetration seal inspections of

licensees (see Sections 5.3, 5.4, and 5.5).

BISCO is now Brand Fire Protection Services,

Incorporated (Brand). In support of the assessment

documented here, the staff inspected Brand facilities in

Addison, Illinois, from November 6 through 9, 1995.

The inspectors determined that the areas that were

inspected were satisfactory. The inspectors did not find

NUREG-1552 16
Technical Assessment

issues that could adversely affect reactor safety or the

quality of the services and materials that Brand provides

to its nuclear power plant customers.

5.6.3 B&B Progressive Materials and

Technologies, Incorporated

From December 6 through 9, 1995, the staff inspected

B&B Progressive Materials and Technologies,

Incorporated (Promatec), facilities in Cypress, Texas. As

part of this inspection, the staff also witnessed the

construction and testing of 14 cable slot penetration seal

test specimens at Omega Point Laboratories (OPL),

Elmendorf, Texas. Six of the cable slots contained

control and instrumentation cables, six slots contained

power cables, and two slots were empty spares (no cable

fill). The penetration seals consisted of fire-resistive

permanent damming boards and silicone foam. The test

specimens were subjected to a 3-hour fire endurance test

which conformed to the ASTM E-I 19 standard timetemperature curve followed by a fog nozzle hose stream

test. The acceptance criteria of IEEE 634 were used to

evaluate the fire-resistive performance of the seals. All

of the test specimens met the acceptance criteria. On the

basis of its observation of the construction and testing of

the test specimens, and its review of the fire test reports,

the staff concluded that the silicone cable slot penetration

seals were acceptable for installation at WBN.

During its inspection of the Promatec facilities in

Cypress, Texas, and the fire test program at OPL, the

inspectors did not find problems that could affect reactor

safety or the quality of the services and materials that

Promatec provides to nuclear power plants. The

inspectors determined that the areas inspected were

satisfactory. This inspection also provided a real-time

example of a penetration seal vendor's ability to conduct

a satisfactory penetration seal fire test program.

5.7 Installation, Surveillance,

Maintenance, and Repair

Proper installation, surveillance, maintenance, and repair

are important to the ability of penetration seals to

perform their intended fire protection design function.

Potential problems include (1) incomplete or inadequate

fire test documentation, (2) in-plant penetration seal

configurations not bounded by fire tests, (3) seals not

installed where required, (4) seals not installed properly,

(5) seals not repaired, (6) seals repaired improperly,

(7) seals modified without a supporting engineering

evaluation, and (8) seals not inspected in accordance

with plant surveillance procedures.

The licensees have fire barrier penetration seal

surveillance and maintenance programs that are

governed by written procedures. In general, the licensees

inspect a portion of the total population of seals every

refueling outage (about every 18 months). If penetration

seals are found to be degraded or inoperable (e.g.,

breached, degraded, or improperly repaired), the

licensees document the deficiencies and take appropriate

corrective actions. If such conditions are found during

power operations, the licensees establish such NRCapproved compensatory measures as fire watches until

the degraded condition is corrected.

During this assessment, the staff reviewed procedures,

specifications, and training programs for installation,

surveillance, maintenance, and repair of penetration seals

at both plant sites and seal vendor facilities. Most of the

problems associated with installed penetration seals

found by the staff involved silicone foam seals. Potential

installation problems include voids within the seal, splits

or gaps in foam caused by contamination or poor

installation techniques, and failure to find installation

problems because they are hidden by permanent

damming materials.

Silicone foam and silicone elastomer seals with voids or

holes can be repaired using like materials or silicone,

caulk. In general, procedures developed by penetration

seal vendors for repair of silicone seals specify that

repairs of holes or voids greater than 0.5 inch can be

made using silicone caulk. Vendors have conducted

satisfactory fire tests for this type of repair. Repaiis of

holes or voids greater than 0.5 inch should be made

using the same seal material as that used to construct the

original penetration seal. Using materials other than the

original seal material could render the seal inoperable if

the repaired configuration is not qualified by a fire test or

justified with an engineering evaluation. For example, if

a seal of a given depth and given seal material density

was qualified as a 3-hour seal, it may not be acceptable

to use a different seal material to repair the original seal

unless the alternative material was qualified in a similar

configuration.

Although the staff observed several minor weaknesses

during some of its plant site inspections, it did not find

evidence that the weaknesses resulted in problems with

installed penetration seals. Overall, the staff concluded

that licensees and vendors are aware of the importance of

proper design, installation, surveillance, maintenance,

and repair of penetration seals, including installer and

inspector training. During its review of repair records

and plant walkdowns, the staff did not find any instances

of repairs using improper or dissimilar seal materials.

The staff had previously addressed potential problems in

IN 88-04, IN 88-56, and IN 94-28 (see Appendix A). On

the basis of the assessment documented here, it is the

staffs view that existing licensee and vendor seal

installation programs are adequate to prevent potential

penetration seal installation problems. In the event seals

17 NUREG-1552
Technical Assessment

are improperly installed or breached, or become

degraded, existing licensee surveillance, maintenance,

and repair programs are adequate to reveal and correct

potential problems.

5.8 Combustibility of Silicone-Based

Seal Materials

Although silicone-based penetration seal materials are

fire resistant, they are classified as "combustible" when

tested in accordance with ASTM E- 136, "Behavior of

Materials in a Vertical Tube Furnace at 750 'C,'' 1 3 which

is a combustibility test method accepted by the NRC. It

has been asserted that silicone-based seals should not be

installed in nuclear power plants because (1) NRC fire

protection regulations prohibit the use of combustible

materials in nuclear power plants and (2) Appendix R

and the SRP specify that penetration seal materials be

noncombustible.

Section 50.48 of 10 CFR Part 50 does not address the

use of combustible materials. GDC 3 states that

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 that are installed in nuclear power plants are

cable insulation and cable jacket materials, diesel

generator fuel oil, turbine-generator lubricating and

hydraulic control fluids, reactor coolant pump

lubricating oils, charcoal and other filters, and flammable

gases and liquids. 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 hazards analysis, they are acceptable.

The staff evaluated the potential fire hazards associated

with silicone-based penetration seal assemblies and

concluded that properly tested, configured, installed, and

maintained silicone-based penetration seal assemblies are

not credible fire hazards. Silicone-based penetration seal

materials are usually distributed throughout the fire area

(as opposed to representing concentrations of

combustibles), are relatively difficult to ignite, and burn

slowly. The rate of combustion and flame propagation

depends on factors such as seal location and

configuration, total mass, surface area, surface covering

"

3

Dow Coming Corporatioin had reported the results

of ASTM E-136 tests in a paper entitled "Flammability

Characteristics of a New Silicone RTV Foam," Kathy M.

Kelly, Society of Plastics Engineers, Progress in Plastics

Through Education, 34th Annual Technical Conference,

April 26-29, 1976, Atlantic City, New Jersey.

(such as fire-resistant damming boards), if any, and the

air supply present. For the typical nuclear power plant

design, silicone-based penetration seal materials

contribute only a little to the overall combustible load in

terms of both quantity of material and surface area. For

example, in many nuclear power plant fire areas, the

surface area of the penetration seals is much less than the

surface area of the cable jackets in the vicinity of the

seals. In addition, the potential amount of fuel that can

be contributed by silicone-based penetration seal

materials is less than the fuel that could be contributed

by the cable jacket and insulation materials. Moreover,

despite the fact that a silicone-based penetration seal

assembly could contribute some fuel to a fire, its relative

contribution to the overall fire severity would be

negligible.

In the unlikely event that a large fire exposes a siliconebased penetration seal to high temperatures for an

extended period of time, the silicone-based material will

decompose and be replaced with char or ash. Due to the

nature of the silicone-based materials and the limited air

supply present within the seal assembly (as opposed to

the air present around the burning combustibles outside

the seal), the propagation of the fire through the seal

assembly will be very slow. Again, this has been

observed during and demonstrated by full-scale

qualification fire endurance tests of a wide variety of

silicone-based penetration seal configurations. 4 These

tests have also demonstrated that silicone-based seals can

provide the necessary fire resistance and the reasonable

assurance that a fire will not spread from one side of the

fire barrier to the other in configurations where cables,

pipes, conduits, ducts, and other combustible and

noncombustible entities penetrate the silicone-based

penetration seal.

Silicone foam and silicone elastomer can be combined

with other materials to form radiological shields; fill

complex irregular openings (e.g., around cables in cable

trays) and adhere to the penetration and the penetrants;

cure rapidly; and can be removed and restored to their

original effectiveness (e.g., when making such plant

modifications as installing new cables); have hightemperature stability; are flexible; and resist the effects

of radiation exposure and aging. Silicone elastomers can

also be used as flood and pressure seals. A wide variety

of silicone-based penetration seal designs have been

tested and listed by material manufacturers and

installers: by UL in its Fire Resistance Directory and by

FM in its Factory AMutual System Approval Guide. It is

also notable that other countries, government agencies,

'

4

For example, when exposed to an ASTM E-1 19 fire,

which is a severe fire exposure, silicone foam bums at a

rate of about 3 inches of thickness per hour. Silicone

elastomer bums at a slower rate.

NUREG- 1552 18
Technical Assessment

insurance bodies, and building codes accept the use of

silicone-based penetration seals. For these reasons,

silicone foam and silicone elastomers are accepted for

use in penetration seals in a wide variety of residential,

commercial, and industrial buildings where fire-resistive

separation is needed."5

The staff concluded that qualified silicone-based fire

barrier penetration seals can accomplish their intended

design function and are not credible fire hazards. The

staff also concluded that the benefits of the siliconebased penetration seal materials outweigh any potential

concerns regarding material combustibility.

The staff also reviewed the requirements of Appendix R

to 10 CFR Part 50 and the guidance of SRP

Section 9.5.1. The staff reviewed the record for

Appendix R (and interviewed the principal author of

Appendix R) and found no technical basis for including

the noncombustibility criterion in Appendix R. The

noncombustibility criterion is included in the SRP

because the SRP simply embodied the criterion of

Appendix R. The staff noted that the noncombustibility

criterion is not included in BTP APCSB 9.5-1,

Appendix A to BTP APCSB 9.5-1, or the industry fire

endurance test standards. The ability of a particular

penetration seal to achieve its intended design function

(i.e., to contain a fire), as determined by a fire endurance

test conducted in accordance with an industry standard

(see Section 3.1), is the foremost design consideration. In

addition, because of the severity and duration of the fire

exposure, the industry standards would ensure that fireresistant seal materials are used and would preclude the

qualification of materials that present fire hazards. The

staff recommends, therefore, that the material

noncombustibility criterion be removed from

Appendix R and the SRP.

5.9 Dow Corning Corporation

Silicone Foam Formulation

Change

In a letter of November 12, 1984, Dow Coming

informed its customers that it had reformulated Dow

Coming 3-6548 Silicone RTV Foam. During a meeting

with the staff on January 31, 1995, Dow Coming

representatives informed the staff that it changed the

"

5There are configurations for which silicone-based

materials may not be appropriate. For example, it may

not be appropriate to seal a diesel generator exhaust pipe

penetration with silicone foam because during operation

the exhaust pipe could exceed the upper temperature

limit for the silicone foam (see IN 88-04, Supplement 1).

formula to improve the manufacturing process by

allowing wider tolerances for the amounts of several of

the basic ingredients used in the foam.

To demonstrate that the fire resistance of the modified

formulation was equivalent to that of the old

formulation, Dow Coming conducted comparison tests at

Construction Testing Laboratories (CTL). The staff

reviewed the results of five 3-hour fire endurance tests

(10 test specimens) and supporting information

regarding the formulation change to determine if the

change adversely affected the fire-resistive performance

of Dow Coming 3-6548 Silicone RTV Foam in the

tested configurations."6

The test specimens were subjected to the standard timetemperature fire exposure specified in ASTM E-1 19.

Hose stream tests were performed at the end of the full

3-hour fire exposure and used a solid hose stream. On

the basis of its review of the test reports, the staff

concluded that the tests were conducted in accordance

with accepted industry standards. On the basis of its

evaluation of interface, cable, cable tray, and seal

temperatures, the thicknesses of unburned silicone seal

materials, and the other observations documented in the

test reports, the staff concluded that the change in

formulation of Dow Coming 3-6548 Silicone RTV Foam

did not materially affect the fire-resistive performance of

the foam in the tested configurations. The staff also

concluded that the tests were an appropriate method for

assessing the effects of the formulation change.

5.10 Aging and Shrinkage

In its letter report entitled "Aging of Fire Barriers in

Nuclear Power Plants," September 30, 1994, SNL

reported that many fire barrier materials are resistant to

thermally accelerated aging and that the material

properties of silicone-based materials, which dominate

the industry, are particularly age independent. SNL

concluded that these materials are not expected to exhibit

problems as they age. Moreover, on the basis of its

review of operating experience and the technical

literature, SNL did not find any penetration seal

problems that were directly related to aging. SNL

reported that it did not fimd information on thermal aging

"

6The NRC staff reviews nuclear power plant fire

protection features within the scope of nuclear power

plant-specific applications after the licensee has

determined that the feature meets NRC regulations and

its licensing commitments. Therefore, staff comments

on the CTL tests should not be interpreted as NRC staff

approval or rejection of the test results for specific

nuclear power plant applications.

19 NUREG-1552
Technical Assessment

or radiation testing of grout, cement, and gel-type seals.

SNL did not recommend an experimental aging program.

The staff reviewed additional information on shrinkage

of silicone foam penetration seals after they are installed.

As discussed in Section 2.2, some shrinkage is normal.

Dow Coming, the major manufacturer of silicone-based

materials, has informed its customers that shrinkage

occurs and has stated that shrinkage at interfaces of i/8-

inch-wide or less while extending not more than onethird of the seal thickness (into the seal) is acceptable for

fire protection purposes. On the basis of the information

that the staff has reviewed, and the experience of the

industry regarding shrinkage in silicone penetration

seals, the staff has concluded that normal shrinkage does

not have a significant impact on the function and

capabilities of silicone foam or elastomer as a fire barrier

penetration seal material.

It is the staffs position that vendor and licensee

penetration seal surveillance and repair programs, as

described in Section 5.7, are adequate to address

potential penetration seal problems associated with seal

aging and shrinkage.

5.11 Silicone-Based Material Curing

As part of this assessment, the staff considered potential

curing problems in silicone-based penetration seal

materials. Vendors may add ingredients (such as lead

fines and iron oxide) to the basic silicone components to

impart special properties to the finished penetration seals

(such as radiation shielding). Silicone foams, elastomers,

and gels use a platinum catalyst that causes the two

components to react and solidify. The catalytic

mechanism can be adversely affected by moisture and

contaminants. Sulphur is the most prevalent

contaminant. When present at high enough levels,

sulphur can inhibit the curing of silicone-based materials

during penetration seal installation. Some amines can

also inhibit cure. In one case that the staff is aware of, a

seal vendor tested a sample of a filler product from a

supplier and found it to be satisfactory according to the

vendor's specifications. It was later discovered that the

vendor received an inferior product from the supplier,

and the sample that the vendor tested was not

representative of what it had received. The use of this

contaminated filler led to curing problems in some

silicone products. Dow Coming has experienced cure

time deviations with its 96-081 RTV Adhesive/Sealant,

SYLGARD 170 Silicone Elastomer, and SYLGARD 170

Silicone Fast Cure Elastomer (see Section 5.1). These

problems were also traced to sulphur contamination.

In addition to cure inhibition that can be caused by

material contamination, certain cable jacket types can

prevent silicone seal materials from curing in the

immediate vicinity of the cable jacket (the silicone

material is affected but the cable jacket is not). Seal

installers prevent this condition by coating the cable

jackets with a releasing agent before installing the

penetration seal materials.

During its vendor inspections, the staff found that seal

materials vendors are well aware of conditions and

circumstances that can cause curing problems and take

appropriate steps to avoid or correct such problems. For

example, the vendors have strict controls on the fillers

and other ingredients that they use in their penetration

seals. The vendors also send random samples of the

materials they receive to independent laboratories for

analysis against their design specifications and test

samples of their finished products for structure and

density, to ensure that they have cured properly.

The staff also reviewed this issue during its plant site

audits and inspections. The staff addressed a potential

problem that material impurities could have affected the

original installation of penetration seals. The inspectors

found that sufficient material coptrols were in place

during the installation of penetration seals to prevent

cure inhibition. Evidence of incomplete curing, such as

cold flow (a slow flowing or creeping of the seal

material from the penetration due to retarded or

incomplete curing) or other seal deficiencies, was not

found in direct seal inspections by the NRC, or in the

seal surveillance records reviewed by NRC inspectors.

Interviews with licensee and vendor personnel indicated

that these types of problem were rare, and most

personnel could not recall having ever encountered such

problems.

In its review of LERs (see Section 5.2), the staff found

no reports of problems related to lead content, cure time,

or reactions between cable jackets and penetration seal

materials. Although certain cable jacket materials can

inhibit or prevent curing at the cable jacket-seal

interface, the staff found no operating experience to

indicate that this is a problem within industry. It has been

asserted by some that cure inhibition is created simply by

the addition of lead fines to the silicone materials.

However, for the reasons stated above, this assertion

appears to be wrong.

The staff concluded that industry, including material

manufacturers, penetration seal installers, and licensees,

are well aware of the potential causes and problems

associated with cure inhibition.

5.12 Comparison of Tested to AsBuilt Configurations

As discussed in Sections 3 and 4 of this report, to

provide reasonable assurance that a fire barrier

NUREG-1552 20
Technical Assessment

penetration seal can accomplish its intended fire

protection design function, a penetration seal test

assembly is subjected to a fire endurance test. The

accepted industry standards specify that the penetration

seal test specimens be representative of the design and

construction for which a fire rating is desired. However,

in view of the large numbers of possible penetration seal

configurations that are installed throughout the nuclear

industry (e.g., a change in the cable fill in a cable tray

penetration represents a change in configuration), the

staff recognized that it was not practical to test and

qualify each and every penetration seal configuration

installed in nuclear power plants. Therefore, the staff has

accepted the results of fire test programs that included a

limited selection of test specimens that had been

specifically designed to encompass or bound the entire

population of in-plant penetration seal configurations.

Using such test results, licensees and vendors have

performed engineering evaluations (such as those

addressed in GL 86-10) to demonstrate that in-plant fire

barrier penetration seals are comparable to or bounded

by fire-tested configurations. In some cases, the vendors

or licensees had used the results of two or more fire

endurance tests to justify a single in-plant penetration

seal configuration. In such cases, the engineering

evaluation that the licensee had performed to justify the

in-plant seal design considered the results of fire tests for

a number of test specimens that were similar but not

identical to the in-plant seal assembly. Design

parameters and attributes that should have been

considered in such evaluations are not explicitly stated in

existing NRC fire protection regulations or review

guidance. It is the staffs opinion that, in general, the fire

test standards themselves and good engineering practice

were adequate to identify the penetration seal design

parameters that should have been considered in such

engineering evaluations. Nevertheless, the lack of

specific NRC review guidance for comparing tested

configurations to as-built configurations can lead to

technical questions regarding the adequacy of a

particular seal design. This is a potential, albeit minor,

weakness in the NRC fire protection program.

As part of the assessment documented here, the staff

revisited a draft version of IN 88-04 that it had prepared

in 1987. The draft contained general considerations

about the use of fire test results to qualify fire barrier

penetration seal designs. Even though these

considerations were not included in the final version of

the information notice, the draft information notice

appears to be widely available to industry. In addition,

industry fire protection engineers informed the staff that

some licensees follow the considerations stated in the

draft information notice even though the staff did not

issue them. This indicates that such guidance would be

useful to the industry for future penetration seal design

evaluations.

On the aforementioned bases, the staff recommends that

guidance be included inany future fire protection

guidance document (e.g., a regulatory guide) to clarify

the important parameters for designing and qualifying

fire barrier penetration seals. Examples of the design

considerations that could be included as guidance are

presented in the following subsections. These

considerations are not existing staff positions, but are

proposed as starting points for preparing guidelines that

could be used for designing fire test programs, for

assessing fire test results, and for performing engineering

evaluations of penetration seal designs installed in the

future.

5.12.1 Size of Sealed Opening

In some cases, a successful fire endurance test of a

particular fire barrier penetration seal configuration for a

particular size opening may be used to justify the same

configuration for smaller openings. The converse may

not be true.

5.12.2 Penetrating Items

In some cases, a satisfactory test of a seal configuration

that contains a particular pattern of penetrating items can

be used to qualify variations of the tested pattern.

Variations that may be acceptable without additional

testing include eliminating or repositioning one or more

of the penetrating items, reducing the size (crosssectional area) of a particular penetrating item, or

increasing the spacing between penetrating items.

However, because penetrating items provide structural

support to the seal, the free area of the seal material and

the dimensions of the largest free span may also be

factors that affect the fire-resistive performance of the

seal assembly. In some cases, the thickness of the seal

material needed to obtain a particular fire rating may also

be a function of the free area or the distance between the

penetrating items and outside edge of the seal assembly.

In other cases, consideration of the penetrating items

takes on special importance because of the heat sink they

provide.

5.12.3 Cable Type and Fill

In some cases, a satisfactory test of a seal configuration

with certain electrical penetrations containing a specified

cable fill ratio (cable cross-sectional area divided by the

cable tray or conduit cross-sectional area) and cable type

(power, control, or instrumentation) can be used to

qualify similar configurations containing the same or a

smaller cable fill ratio and the same cable jacket material

or a less combustible jacket material. The thermal

conductivity of the penetrating cables is also important.

For example, a penetration seal fire test of a cable tray

with a 30-percent power cable fill would be more

21 NUREG-1552
Technical Assessment Technical Assessment

challenging (thermally) than a test of a tray with a

30-percent instrumentation cable fill due to the higher

thermal mass of the power cables.

5.12.4 Damming Materials

The fire-resistive performance of a given seal

configuration can be improved if a fire-resistant

damming material covers one or both surfaces of the

seal. A satisfactory test of a seal configuration without a

permanent fire-resistant dam can be used to qualify the

same configuration with a permanent fire-resistant dam,

all other seal attributes being equal. The converse is not

true.

5.12.5 Configuration Orientation

A satisfactory test of a particular seal configuration in

the horizontal orientation (with the test fire below the

seal) can be used to qualify the same configuration in a

vertical orientation if the symmetry of the design

configurations are comparable. For example, if a

nonsymmetric penetration seal configuration (e.g., a seal

with a damming board on the bottom, but not on the top)

is qualified for a floor-ceiling orientation with the

damming board on the fire side of the test specimen, the

configuration could only be qualified for a wall

orientation if a damming board was installed on both

sides of the seal or if the potential fire hazard is limited

to the side with the damming board.

5.12.6 Material Type and Thickness

Satisfactory testing of a particular seal configuration

with a specific seal material thickness can be used to

qualify the same configuration with a greater seal

material thickness of the same type of seal material.

However, the converse is not true.

5.12.7 Type Testing

In cases in which a single test of a particular seal

configuration is to serve as a qualification test for the

same or similar design configurations with different

design parameters, the tested configuration should be the

worst-case design configuration with the worst-case

combination of design parameters. This would test and

qualify a condition that would fail first, if failure occurs

at all. Successful testing of the worst-case condition can

then serve to qualify the same or similar design

configurations for design parameters within the test

range. In some cases, it could be appropriate to conduct

multiple tests to assess a range of design parameters.

5.13 Comparison of Thermo-Lag

Fire Barriers to Penetration

Seals

During this assessment, it was reported that there are

similarities between Thermo-Lag fire barriers and

penetration seals with respect to technical issues and

potential problems. The staff evaluated these assertions.

The principal purpose of Thermo-Lag fire barriers

differs from that of penetration seals. Thermo-Lag fire.

barriers are typically used to enclose one train of

redundant electrical cables that are located in the same

plant fire area and needed to achieve and maintain

shutdown after a fire. The intended design function of

the Thermo-Lag barrier is to provide reasonable

assurance that the safe-shutdown train it encloses will

remain free of fire damage despite the fire and, therefore,

will remain available to achieve shutdown."7 Penetration

seals are used to close openings through such structural

fire barriers as walls and floor-ceiling assemblies. The

intended design function of the penetration seal is to

confine a fire to the area in which it started and to protect

important equipment within the area from a fire outside

the area. This difference in design function is significant.

Protecting the functionality of a component located

within a relatively small Thermo-Lag enclosure (as

compared to the volume of the fire area), which is

designed to be totally engulfed in a fire, is technically

more challenging than preventing the spread of fire

through a fire-resistive barrier that is exposed to the fire

on only one surface.

Thermo-Lag fire barriers, which were manufactured and

tested by one company, Thermal Science, Incorporated

(TSI), have been installed in most plants. In 1991, when

the staff first identified generic concerns with

Thermo-Lag fire barriers, it questioned the validity of the

available fire test data and the fire-resistance ratings of

the Thermo-Lag fire barriers. For example, the staff

could not find evidence that Thermo-Lag had been tested

and certified as a fire wrap by third-party testing

laboratories, such as FM and UL. (Although such tests

are not required by the NRC, the results of such tests can

help establish the capabilities and limitations of products

absent other credible information and data.) Conversely,

a number of companies manufacture, test, and install

penetration seals and a large number of penetration seal

designs and penetration seal materials have been tested

and approved by UL and FM.

"

7

Fire barriers that are used to enclose safe shutdown

equipment are commonly called "fire wraps."

NUREG-1552 22
Technical Assessment

In addition, in 199 1, there were questions regarding the

test standards, methods, and acceptance criteria that had

been used to conduct fire endurance tests of the

Therino-Lag fire barriers for the protection of electrical

raceways. On the other hand, at that time, industry

consensus test standards, methods, and acceptance

criteria for determining the fire-resistance ratings of

penetration seals had existed for decades. Furthermore,

fire endurance tests conducted by the staff and the

nuclear industry after the staff raised concerns about

Thermo-Lag revealed that many Thermo-Lag fire barrier

configurations, even when installed in accordance with

the procedures recommended by the vendor, could not

achieve their intended fire-resistance ratings. These tests

also demonstrated that certain Thermo-Lag fire barriers

were susceptible to structural failure. Conversely, a large

body of qualification-type fire endurance tests of a wide

variety of penetration seal materials and designs that are

used in the nuclear industry have been successfully

completed by various manufacturers, installers, and test

laboratories. On the basis of its direct observations of fire

endurance tests and its reviews of numerous fire

endurance test reports, the staff has concluded that

suitable fire endurance tests have established the fire

endurance ratings of a large number of fire barrier

penetration seal designs, configurations, and materials.

Properly designed penetration seals are not susceptible to

structural failure.

On these bases, the staff concluded that the technical

issues and potential problems associated with fire barrier

penetration seals and Thermo-Lag fire barriers are not

comparable. The staff also concluded that the

Thermo-Lag experience does not in any way provide

bases for questioning the ability of fire barrier

penetration seals to achieve their fire protection design

function.

6 SUMMARY OF FINDINGS

(1) Fire barrier penetration seals are not unique

nuclear components. They are universally

accepted for use in residential, commercial, and

industrial buildings wherever fire-resistive

separation is needed.

(2) There are no reports of fires that challenged the

ability of nuclear power plant fire-rated

structural barriers or fire-rated penetration seals

to confine a fire.

(3) There is no evidence of problems with the

materials used to construct nuclear power plant

fire barrier penetration seals.

(4) The general condition of penetration seal

programs in industry (licensees and vendors)

appears to be satisfactory.

(5) Plant-specific deficiencies have been, and will

continue to be found on occasion during

licensee surveillances and NRC inspections.

Fire protection defense in depth provides

reasonable assurance that such deficiencies will

not present an undue risk to public health and

safety.

(6) A large body of fire endurance tests has established the fire-resistive capabilities of the

penetration seal materials, designs, and configurations installed in nuclear power plants. The

test results support the conclusion that the

regulatory requirements can be met by these

materials.

(7) If penetration seals are properly designed,

tested, configured, installed, inspected, and

maintained, there is reasonable assurance that

they will provide the fire resistance of the tested

configuration, maintain the fire-resistive

integrity of the fire barriers in which they are

installed, and confine the fire to the area of

origin."8

(8) Operating experience and inspection results

show that the licensees and vendors understand

the fire-resistive capabilities and limitations of

the penetration seal materials and

configurations; potential penetration seal

testing, design, installation, inspection, and

maintenance problems-and possible remedies

and corrective actions.

(9) The term "nationally recognized testing

laboratory" is undefined and obsolete. There is

no need for the NRC fire protection guidance to

1

8"Properly tested" means that a representative seal

had been tested in accordance with an accepted fire

endurance test standard. "Properly configured" means

that the design of the installed seal had been determined

by a fire test and/or an engineering evaluation. "Properly

installed" means that the seal had been installed in

accordance with the methods and procedures used to

construct the test specimen (typically the seal vendor's

recommended installation procedures). "Properly

maintained" means that the quality and configuration of

the barrier had been maintained through routine

surveillances and, as appropriate, maintenance and

repair.

23 23 N-LREG- 1552
Findings

reference fire endurance tests by a nationally

recognized testing laboratory.

.(10) There is no basis for the criterion in

Appendix R and the SRP that specifies that

penetration seal materials be noncombustible.

(11) Overall, satisfactory staff review guidance and

industry practices, methods, and procedures are

available and are used to meet the regulatory

requirements for fire barrier penetration seals.

New guidance for comparing fire tested seal

configurations to as-built configurations may be

useful to the industry.

(12) The potential problems that were raised about

penetration seals have been addressed. The staff

did not find safety-significant plant-specific

problems nor did it find problems with potential

generic implications.

7 CONCLUSIONS

On the basis of the totality of the information it found

and assessed, including the "Report on the Reassessment

of the NRC Fire Protection Program" that had been

conducted by NRR, the review of fire barrier penetration

seals that had been conducted by AEOD, reports that had

been prepared by SNL on the population of fire barrier

types installed in nuclear power plants and penetration

seal aging, and the other documents referenced here, the

staff concluded that the general condition of penetration

seal programs in industry is satisfactory. The staff did

not find plant-specific problems of safety significance or

concerns with generic implications.

Even though the staff found the condition of penetration

seal programs in industry to be satisfactory, it expects

that plant-specific deficiencies will occasionally be

found during future licensee surveillances and NRC

inspections. However, potential fire barrier penetration

seal problems are understood; industry consensus fire

test standards are available and are followed; and fire test

results and qualified fire-resistant seal materials and

designs are available. Therefore, licensees have the

means to correct problems, and staff oversight will

continue to ensure corrections on a case-by-case basis.

Fire protection defense in depth provides reasonable

assurance that such deficiencies will not present an

undue risk to public health and safety. Finally, the staff

concluded that the actions it had taken in 1988 and 1994

to address potential penetration seal problems increased

industry awareness of such problems and resulted in

more thorough surveillances, maintenance, and

corrective actions. These actions together with continued

licensee upkeep of existing penetration seal programs

and continued NRC inspections are adequate to maintain

public health and safety.

The technical assessment documented here has been the

subject of substantial public and industry interest. The

staff informed the Commission of the findings of this

report in SECY-96-146, "Technical Assessment of Fire

Barrier Penetration Seals in Nuclear Power Plants," dated

July 1, 1996. (See Appendix E.)

8 RECOMMENDATIONS

(1) Revise the NRC fire protection guidance

documents to reflect the current NFPA position

on testing laboratories. (Section 3.2)

(2) Remove the noncombustibility criterion from

Appendix R to 10 CFR Part 50 and SRP Section

9.5.1. (Section 5.8)

(3) Develop and issue guidance for comparing fire

test configurations to as-built configurations.

(Section 5.12)

(4) Make this technical assessment report available

to the general public and industry.

9 BIBLIOGRAPHY

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American Society for Testing and Materials, Standard

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American Society for Testing and Materials, Standard

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American Society for Testing and Materials, Standard

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Dow Coming Corporation, "Flammability

Characteristics of a New Silicone RTV Foam," Kathy M.

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NUREG-1552 24
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Stops."

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Position, Auxiliary Power Conversion System Systems

Branch, 9.5-1, Appendix A, "Guidelines for Fire

Protection for Nuclear Power Plants Docketed Prior to

July 1, 1976," February 24, 1977.

U.S. Nuclear Regulatory Commission, "Fire Protection

Program for Nuclear Power Plants Operating Prior to

January 1, 1979," Federal Register, Vol. 45, No. 105,

May 29, 1980, pp. 36082-36090.

U.S. Nuclear Regulatory Commission, "Fire Protection

Program for Operating Nuclear Power Plants," Federal

Register, Vol. 45, No. 225, November 19, 1980, pp.

76602-76616.

U.S. Nuclear Regulatory Commission, Generic Letter

(GL) 86-10, "Implementation of Fire Protection

Requirements," April 24, 1986.

U.S. Nuclear Regulatory Commission, SECY-95-034,

"Status of the Recommendations Resulting From the

Reassessment of the NRC Fire Protection Program,"

February 13, 1995.

25 NUREG-1552
Bibliography

U.S. Nuclear Regulatory Commission, Information

Notice (IN) 88-04, "Inadequate Qualification and

Documentation of Fire Barrier Penetration Seals,"

February 5, 1988.

U.S. Nuclear Regulatory Commission, Information

Notice (IN) 88-04, Supplement 1, "Inadequate

Qualification and Documentation of Fire Barrier

Penetration Seals," August 9, 1988.

U.S. Nuclear Regulatory Commission, Information

Notice (IN) 88-56,"Potential Problems With Silicone

Foam Fire Barrier Penetration Seals," August 4, 1988.

U.S. Nuclear Regulatory Commission, Information

Notice (IN) 94-28, "Potential Problems With Fire Barrier

Penetration Seals," April 4, 1988.

U.S. Nuclear Regulatory Commission, Inspection

Manual, Inspection Procedure 64704, "Fire Protection

Program," March 18, 1994.

U.S. Nuclear Regulatory Commission, Inspection and

Enforcement Manual, Inspection Procedure 64100,

"Postfire Safe Shutdown, Emergency Lighting and Oil

Collection Capability at Operating and Near-Term

Operating Reactor Facilities," March 16, 1987.

U.S. Nuclear Regulatory Commission, Inspection and

Enforcement Manual, Inspection Procedure 64150,

"Triennial Postfire Safe Shutdown Capability

Reverification," March 16, 1987.

U.S. Nuclear Regulatory Commission, Inspection Report

No. 50-213/95-09, Inspection of Haddam Neck Power

Plant, June 19, 1995. Inspection conducted April

10-14, 1995.

U.S. Nuclear Regulatory Commission, Inspection

Report No. 50-219/95-11, Inspection of Oyster Creek

Nuclear Generating Station, July 21, 1995. Inspection

conducted May 22 - June 25, 1995.

U.S. Nuclear Regulatory Commission, Inspection Report

No. 50-244/94-14, Inspection of R.E. Ginna Nuclear

Plant, June 13, 1994. Inspection conducted

May 9-13, 1994.

U.S. Nuclear Regulatory Commission, Inspection Report

No. 50-275/323 94-01, Inspection of Diablo Canyon

Units I and 2, March 15, 1994. Inspection conducted

January 31 -February 10, 1994.

U.S. Nuclear Regulatory Commission, Inspection Report

No. 50-275/323 95-03, Inspection of Diablo Canyon

Units I and 2, May 1, 1995. Inspection conducted

March 27-31, 1995.

U.S. Nuclear Regulatory Commission, Inspection

Report No. 50-286/95-10, Inspection of Indian Point 3

Nuclear Power Plant, July 26, 1995. Inspection

conducted May 23-26, and June 19-20, 1995.

U.S. Nuclear Regulatory Commission, Inspection Report

No. 50-317/318 94-15, Inspection of Calvert Cliffs

Nuclear Power Plant, May 6, 1994. Inspection conducted

April 4-8, 1994.

U.S. Nuclear Regulatory Commission, Inspection Report

No. 50-317/318 96-201, Inspection of Calvert Cliffs

Nuclear Power Plant, May 6, 1996. Inspection conducted

February 13 -February 15, 1996.

U.S. Nuclear Regulatory Commission, Inspection Report

No. 50-361/362 94-01, Inspection of San Onofre,

January 28, 1994. Inspection conducted

January 10-14, 1994.

U.S. Nuclear Regulatory Commission, Inspection Report

No. 50-387/388 95-14, Inspection of Susquehanna Steam

Electric Station, July 31, 1995. Inspection conducted

June 5-9, 1995.

U.S. Nuclear Regulatory Commission, Inspection Report

No. 50-387/388 96-201, Inspection of Susquehanna

Steam Electric Station, April 15, 1996. Inspection

conducted January 30 - February 1, 1996.

U.S. Nuclear Regulatory Commission, Inspection

Report No. 50-397/94-08, Inspection of Washington

Nuclear Project 2, February 25, 1994. Inspection

conducted January 31 - February 4, 1994.

U.S. Nuclear Regulatory Commission, Inspection Report

No. 50-397/94-28, Inspection of Washington Nuclear

Project 2, November 9, 1994. Inspection conducted

September 26 - October 7, 1994.

U.S. Nuclear Regulatory Commission, Inspection Report

No. 50-397/95-18, Inspection of Washington Nuclear

Project 2, June 29, 1995. Inspection conducted

May 15-19, 1995.

U.S. Nuclear Regulatory Commission, Inspection Report

No. 50-397/95-201, Washington Nuclear Project 2

Integrated Assessment Team Inspection,

October 3, 1995. Inspection conducted

August 7-17, 1995.

U.S. Nuclear Regulatory Commission, Inspection Report

No. 50-458/95-01, Inspection of River Bend Station,

March 8, 1995. Inspection conducted January 1 -

February 11, 1995.

NUREG-1552 26
Bibliography

U.S. Nuclear Regulatory Commission, Inspection Report

No. 50-458/95-02, Inspection of River Bend Station,

May 3, 1995. Inspection conducted February 12 -

March 25, 1995.

U.S. Nuclear Regulatory Commission, Inspection Report

No. 50-458/95-17, Inspection of River Bend Station,

June 9, 1995. Inspection conducted April 10-14, 1995.

U.S. Nuclear Regulatory Commission, Inspection Report

No. 99901020/87-01, Inspection of Brand Industrial

Services, Incorporated (BISCO) and V.C. Summer

Nuclear Station, May 22, 1987. Inspection conducted

January 20-23, 1987, and February 25-27, 1987.

U.S. Nuclear Regulatory Commission, Inspection Report

No. 99901020/95-01, Inspection of Brand Fire

Protection Services, February 6, 1996. Inspection

conducted November 6-9, 1995.

U.S. Nuclear Regulatory Commission, Inspection Report

No. 99901284/95-01, Inspection of Dow Coming

Corporation, May 31, 1995. Inspection conducted

March 21-24, April 3-5, and April 18-21, 1995.

U.S. Nuclear Regulatory Commission, Inspection Report

No. 99901292/95-01, Inspection of Promatec

Incorporated, April 8, 1996. Inspection conducted

December 6-8, 1995.

U.S. Nuclear Regulatory Commission, Memorandum of

October 7, 1994, from Amarjit Singh, Plant Systems

Branch, to Conrad E. McCracken, Chief, Plant Systems

Branch, "Trip Report, Fire Barrier Penetration Seal

Audit, Waterford 3 Nuclear Power Plant."

U.S. Nuclear Regulatory Commission, Memorandum of

November 23, 1994, from Amarjit Singh, Plant Systems

Branch, to Conrad E. McCracken, Chief, Plant Systems

Branch, "Trip Report, Fire Barrier Penetration Seal

Audit, Davis-Besse Nuclear Power Station."

U.S. Nuclear Regulatory Commission, Memorandum of

February 9, 1995, from Conrad E. McCracken, NRR, to

Gary M. Holahan, NRR, "Summary of January 31, 1995

Meeting Concerning Products Manufactured by Dow

Coming Corporation Used for the Construction of Fire

Barrier Penetration Seals."

U.S. Nuclear Regulatory Commission, Memorandum of

May 23, 1995, from Charles E. Rossi, AEOD, to

Gary M. Holahan, NRR, "AEOD Review of Fire Barrier

Penetration Seals (Fire Seals)."

U.S. Nuclear Regulatory Commission, Section 9.5-1,

"Fire Protection Program," of NUREG-0800, "Standard

Review Plan."

U.S. Nuclear Regulatory Commission, NUREG-0847,

"Safety Evaluation Report Related to the Operation of

Watts Bar Nuclear Plant, Units I and 2," Supplements 18

and 19.

U.S. Nuclear Regulatory Commission, "Proceedings,

NRC Regulatory Information Conference," April 9-10,

1996.

U.S. Nuclear Regulatory Commission, Memorandum of

February 27, 1993, from Ashok C. Thadani, NRR, to

Thomas E. Murley, NRR, "Report on the Reassessment

of the NRC Fire Protection Program."

U.S. Nuclear Regulatory Commission, Title 10 of the

Code of Federal Regulations, Part 21, "Reporting of

Defects and Noncompliance."

U.S. Nuclear Regulatory Commission, Title 10 of the

Code of Federal Regulations, Part 50, General Design

Criterion 3, "Fire protection."

U.S. Nuclear Regulatory Commission, Title 10 of the

Code of Federal Regulations, Part 50, Section 50.48,

"Fire protection."

U.S. Nuclear Regulatory Commission, Title 10 of the

Code of Federal Regulations, Part 50, Appendix R, "Fire

Protection Program for Nuclear Power Facilities

Operating Prior to January 1, 1979."

Vermont Yankee Nuclear Power Corporation, Letter of

January 15, 1993, to NRC Document Control Desk,

submitting Licensee Event Report 93-001: "Degraded

Vital Fire Barriers."

Vermont Yankee Nuclear Power Corporation, Letter of

March 5, 1993, to NRC Document Control Desk,

submitting Licensee Event Report 93-001-01:

"Degraded Vital Fire Barriers due to inadequate

documentation of assumptions and inadequate

procedures."

Vermont Yankee Nuclear Power Corporation, Letter of

July 7, 1993, to NRC Document Control Desk,

submitting Licensee Event Report 93-001-02:

"Degraded Vital Fire Barriers Due to Inadequate

Documentation of Assumptions and Inadequate

Procedures."

Wolf Creek Nuclear Operating Corporation, Letter of

February 6, 1987, to NRC Document Control Desk,

submitting Licensee Event Report 87-001-00:

"Discovery of Breached Fire Barrier Seal."

Wolf Creek Nuclear Operating Corporation, Letter of

March 24, 1987, to NRC Document Control Desk,

submitting Licensee Event Report 87-001-01:

"Discovery of Breached Fire Barrier Seal."

27 NUREG- 1552
Bibliography

Wolf Creek Nuclear Operating Corporation, Letter of

March 30, 1988, to NRC Document Control Desk,

submitting Licensee Event Report 87-001-02:

"Technical Specification Violation Inoperable Fire

Barriers Caused by Personnel Errors."

NUREG-1552 28
Appendix A

Summaries of NRC Generic Communications

Regarding Penetration Seals

The NRC has issued a number of generic

communications regarding fire barrier penetration seals.

This included Generic Letter (GL) 86- 10,

"Implementation of Fire Protection Requirements," April

24, 1986 (see Section 4.3.3 of technical assessment

report), and four information notices (INs). Sunmmaries

of the issues that were addressed in the information

notices are presented below.

Information Notice 88-04

Information Notice 88-04, "Inadequate Qualification and

Documentation of Fire Barrier Penetration Seals,"

February 5, 1988, informed licensees that some installed

fire barrier penetration seal designs may not be

adequately qualified for the design rating of the

penetrated fire barriers. The IN also indicated that

deficiencies included test qualification documentation

being unavailable, incomplete, or inadequate. The IN

also summarized existing staff guidance related to seals.

Information Notice 88-04, Supplement 1

Information Notice 88-04, Supplement 1, "Inadequate

Qualification and Documentation of Fire Barrier

Penetration Seals,' August 9, 1988, addressed

misapplication of silicone foam materials and resultant

exposure of penetration seal materials to ambient

temperatures above design specifications. Specific

examples of this included Diablo Canyon where seal

material in place around a diesel generator exhaust pipe

caught fire, and Davis-Besse where a penetration seal

around a main steam line baked and pulled away from

the pipe.

Information Notice 88-56

Information Notice 88-56, "Potential Problems With

Silicone Foam Fire Barrier Penetration Seals," August 4,

1988, informed licensees of the possibility that silicone

foam penetration seals may contain nonconforming

conditions such as splits, gaps, voids, and lack of fill.

Specific example was the May 1987, Part 21 notification

by B&B Promatec regarding nonconforming silicone

foam seals at Wolf Creek. The IN stated that the "NRC

believes that if generic problems exist, then they may be

limited to only silicone foam fire barrier penetration

seals but not~to any particular vendor or installer."

Information Notice 94-28

Information Notice 94-28, "Potential Problems With Fire

Barrier Penetration Seals," April 5, 1994, informed

licensees of potential problems that could go undetected

as a result of inadequate surveillance inspection

procedures and inadequate acceptance criteria. Plants

specifically mentioned were Nine Mile Point, James A.

Fitzpatrick, and Vermont Yankee, where nonconforming

or degraded conditions were discovered during licensee

inspections of penetration seals. The IN listed where

NRC requirements and guidelines for fire barrier

penetrations could be found.

A-1 A-l NUJREG-1 552

Appendix B

Description:

Background:

Action Plan Summary

Technical Assessment of Fire Barrier Penetration Seals

Action plan for technical assessment of fire barrier penetration seals installed in nuclear

power plants.

In 1988, the staff had completed an assessment of fire barrier penetration seals. Since

1992, the NRC received new reports of potential problems regarding seals. On the

basis of the assessment it had completed in 1988, NRC inspections, and licensee event

reports, the staff assumed that it would find plant-specific deficiencies regarding

documentation of fire tests, comparisons of in-plant seals to fire tests, seals not

installed where required, seals not installed or repaired properly, seals modified

without a supporting engineering evaluation, and seals not inspected in accordance

with plant surveillance procedures. The staff initiated a technical assessment to

deternine if the actions it had taken in 1988 to address potential penetration seal

problems had increased industry awareness of such problems, if there were any

widespread or generic problems of safety significance, and if NRC requirements,

reviewv guidance, and inspection procedures for penetration seals are adequate.

Proposed Actions:

Regulatory Assessment:

Inspect reactor and vendor penetration seal programs; observe fire endurance tests,

review operating experience and previous NRC inspection results;, assess the data and

information obtained from the field wvork and document reviews; identify commonality

or correlation of evidence, if any, that suggests trends, widespread plant-specific

problems., or generic concerns of safety significance; determine if NRC requirements,

review guidance, and inspection procedures for penetration seals are adequate; and

determine if existing industry (licensee and vendor) programs are adequate.

Each reactor uses the defense- in-depth concept to achieve a high degree of fire safety.

Each reactor has an NRC-approved fire protection program that, if properly designed,

implemented, and maintained, satisfies Section 50.48, "Fire protection," and General

Design Criterion 3, "Fire protection," of Title 10 of the Code of Federal Regulations

Part 50. Therefore, each reactor has an adequate level of fire safety pending completion

of the assessment.

B-1 B-i NUREG- 1552
Action Plan Summary

SUMMARY TASK NOTES

I. Identify types of seals installed in

nuclear power plants.

2. Identify and prioritize potential

technical issues and problems.

3. Determine whether or not there

are safety-significant problems

with penetration seal materials.

Sandia National Laboratories, Letter Report of May 29, 1992, from William

Lowrey, for NRC, "A Determination of the Population of Fire Barrier Types in

Generating Stations."

Materials.

Seal design and configuration.

Qualification tests.

Comparisons of tested to as-built.

Installation.

Surveillances and inspection.

Maintenance and repairs.

Configuration control.

Aging.

Obtain data from licensee event reports, NRC inspection reports, Part 21

database regarding reports of materials problems.

Conduct a vendor inspection of a materials manufacturer. (Dow Coming

Corporation was selected, in part, because (1) it is the principal manufacturer of

the silicone-based penetration seal materials and (2) it had submitted Part 21

reports.)

Conduct vendor inspections of seal installation vendors. (Brand and Promatec

were selected, in part, because of the length of time in business, volume of

business, and current activities.)

Review results of previous NRC inspections of penetration seals.

Observe fire endurance tests.

Review during vendor inspections and during new focused inspections at

representative sample of nuclear plants. Review reported concerns, if any;

gather information on qualified seals; and determine if the seals were designed,

tested, installed, inspected, and maintained in accordance with licensee

commitments and NRC requirements.

Examine procurement documents, seal compatibility with barriers, fire

endurance tests associated with the seal qualification designs, engineering

evaluations, installer and inspector training programs, sample of installed seals,

quality control and quality assurance programs for installing and maintaining

seals, deviations from NRC requirements, and surveillance requirements, and

programs for technical specification seals.

Select seals for inspection based, for example, on seal type and material; seal

location; seals that had been inspected, repaired or reworked; and seals for

which there were reports of specific concerns.

Select plants based on reports of problems (Davis-Besse, Waterford 3, and

Susquehanna), old and new seal construction (Calvert Cliffs), significant

rework by licensee after self-identification of problems (WNP2), and new

construction including testing and engineering (Watts Bar).

4. Determine whether or not there

are safety-significant problems

regarding seal design,

qualification tests, seal

installation, seal surveillances and

inspection, seal maintenance and

repairs, and configuration control.

NUREG-1552 B-2
Action Plan Summary

SUMMARY TASK NOTES

5. Determine whether or not there

are concerns or problems

regarding comparisons of tested

to as-built seal configurations.

6. Identify and assess sundry

technical issues.

7. Assess potential problems

regarding seal aging.

8. Assess the data and information

obtained from the field work and

document reviews; identify

commonality or correlation of

evidence, if any, that suggests

trends, widespread problems, or

generic concerns of safety

significance.

9. Determine if NRC requirements,

review guidance, and inspection

procedures for penetration seals

are adequate.

10. Document results of technical

assessment with

recommendations.

Review industry standards.

Review NRC review guidance.

Review industry practice during vendor and plant site inspections. Review in

real time during Watts Bar licensing.

Silicone foam formulation change.

Dow Coming Part 21 reports.

Combustibility of silicone-based seal materials.

Sandia National Laboratories, Letter Report of September 30, 1994, from

Tina J. Tanaka, to NRC, "Aging of Fire Barriers in Nuclear Power Plants."

Technical assessment report.

Peer review.

Independent management review panel.

NUREG-1552 reoort.

B3-3 NUREG-1552
I
Appendix C

Comparison of Industry Fire Endurance Test Standards

standar~d [F ASTM E-1 19.. T ASTM E-814 T ANI 4176 UL 1479 1IEEE 634J

Title Standard Test Methods for Standard Test Method for Fire NEL-PIA/MAERP Standard Standard for Fire Tests of IEEE Standard Cable

Fire Tests of Building Tests of Through-Penetration Method of Fire Tests of Cable Through-Penetration Fire Penetration Fire Stop

Construction and Materials Fire Stops and Pipe Penetration Fire Stops Qualification Test

Stops

NRC NUREG-0800, Standard Information Notice 88-04 None None Information Notice 88-04

Reference Review Plan, Section 9.5.1

(1981)

Test 8. The test specimen shall be 7. Construction of the test fire 2.A.1 A wall or floor 4.1 Each representative 5.2.2 Selection of the sizes,

Specimen truly representative of the stops shall be of sufficient size construction of previously construction type of through- construction, and materials of

Construction construction for which the and include all conduits, pipes, proven fire resistance rating of penetration firestop for which the cable penetration opening

classification is desired, as to cables (jacket types, sizes, at least 3 hours is to be used rating is desired shall be fill to be used in the test shall

materials, workmanship, and conductor types, percent fills) for the test. It may be modified tested. When a through- be representative of the cables

details such as dimensions of required supports, or other to a minimum acceptable size penetration firestop is used in the fire stop under

parts, and shall be built under through-penetrating items so as of 3' by 3 with the intended for use in both floor actual installed conditions. It is

conditions representative of to produce a truly representative understanding that this will and walls, each orientation is not the intent that different

those obtaining as practically fire stop for which the evaluation result in approval by NEL- to be tested unless it is construction types, that is,

applied in building is desired PIA/MAERP for restricted size demonstrated that testing in instrumentation and medium

construction and operation. applications in the field. a single orientation does not voltage power cable, be

The physical properties of the affect the test results. installed in the same test

materials and ingredients 2.A.2 Size and configuration cable penetration unless this is

used in the test specimen of test penetrations to be as 4.2 Penetrating items are to indicative of actual conditions.

shall be determined and shown in test standard, be installed so that they

recorded. extend 12 ± 1 inch from the exposed side, and 36 ± 1

inch from the unexposed

side. The extended portions

of the penetrating items on the unexposed side are to be

supported by methods

intended to be employed in

I field installation.

Time Temp ASTM E-119 ASTM E-1 19 ASTM E-1 19 ASTM E-1 19 ASTM E-1 19

Curve
I

.L1

Standard ASTM E-119 ASTM E414 ANI 4/776 UL 1479) IEEE 63

Temperature

Acceptance

Criteria

17,1.3 Transmission of heat

through the wall or partition

during the fire endurance test

shall not have been such as

to raise the temperature on

its unexposed surface more

than 250 IF above its initial

temperature

6.4 Where the conditions of

acceptance place a limitation

on the rise of temperature of

the unexposed surface, the

temperature end point of the

fire endurance period shall be

determined by the average of

the measurements taken at

individual points; except that

if a temperature rise 30% in

excess of the specified limit

occurs at any one of these

points, the remainder shall be

ignored and the fire

endurance period judged as

ended.

10.2.1 A fire stop shall be

considered as meeting the

requirements for the T rating

when it remains in the during

the fire test ...within the following

limitations:

10.2.1.1 The transmission of

heat through the fire stops

during the rating period shall

have not been such as to raise

the temperature of any

thermocouple on the unexposed

surface of the fire stop or on any

penetrating item more than 325

IF above its initial temperature.

Also the fire stops shall have

withstood the passage of flame

through openings, or the

occurrence of flaming on any

element of the unexposed side

of the fire stops.

C.2 No individual

thermocouple of the

unexposed surface of the fire

stop shall exceed 325 °F

above ambient conditions.

For a T rating:

7.1 A through-penetration

firestop shall remain in the

opening during the fire

test...and shall comply with

the following:

A. The transmission of heat

through the sample during

the rating period shall not

raise the temperature

measured by any

thermocouple on the

unexposed surface of the fire

stop or on any penetrating

item more than 325 °F

above its initial temperature.

Foreword - The maximum

allowable temperature

selected for a cable

penetration fire stop should be

based on the self-ignition

temperature of the outer cable

covering the fire stop materials

in contact with the cable

penetration fire stop,

whichever has the lower selfignition temperature. For cable

penetration fire stops the selfignition temperatures of the

outer cable covering and fire

stop material are generally

above 700 IF. The maximum

allowable temperature is the

actual measured temperature

on the unexposed side and not

the temperature rise.

6.1.2 Transmission of heat

through the cable penetration

fire stop shall not raise the

temperature on its unexposed

surface above the self-ignition

temperature as determined in

ANSI K65.111-1971 of the

outer cable covering, the cable

penetration fire stop material,

or material in contact with the

cable penetration fire stoop etc.

0

0

0

___________________ IL _____________________________________ J & & I I I
Standard ASTM E-119 ASTM "414 ANI 4/76 UL 1479 IEEE 634

Flame Criteria 17.1.1 The wall or partition 10.1.1 A fire stop shall be CA1 Fire shall not propagate For an F rating: 6.1 The test can be

shall have withstood the considered as meeting the to the unexposed side of the considered acceptable and the

endurance test without requirements for an F rating test assembly nor shall any 6.1 A through-penetration cable penetration fire stop

passage of flame or gases when it remains in the opening visible flaming be observed. firestop shall remain in the suitable for use in accordance

hot enough to ignite cotton during the fire test and hose opening during the fire test with the fire rating provided the

waste, for a period equal to stream test within the following and hose stream test and following is met:

that for which classification is limitations: shall comply with the

desired. following: 6.1.1 The cable penetration 10.1.2 The fire stops shall have fire stop shall have withstood

withstood the fire test for the A. The sample shall *the fire endurance test as

rating period without permitting withstand the fire test for the specified without passage of

the passage of flame through rating period without the flame or gases hot enough to

openings, or the occurrence of passage of flame through ignite the cable or other fire

flaming on any element of the openings, or the occurrence stop material on the

unexposed side of the fire stops. of flaming on any element of unexposed side for a period

the unexposed side of the equal to the required rating

10.1.3 During the hose stream sample.

test, the fire stop shall not

develop any opening that would B. The sample shall not

permit a projection of water from develop any opening during the stream beyond the the hose stream test that

unexposed side. would permit a projection of

water from the stream

10.2.1 A fire stop shall be beyond the unexposed side.

considered as meeting the

requirements for the T rating For a T rating:

when it remains in the during

the fire test and hose stream A. the sample shall

test within the following withstand the fire test during limitations: the rating period without

permitting the passage of

10.2.1.2 ... the fire stops shall flame through openings, or

have withstood the fire test the occurrence of flaming on

during the rating period without any element of the

permitting the passage of flame unexposed side of the

through the openings, of sample.

unexposed side of the fire stops.

B. See B above

10.2.1.2 See 10.1.3 above I____________ I___________ 1______1______

0
LI)

Statidar~d ASTM E-119 J ASTM &.814 AN! 4/76 UL 1479 IMEE 634

Thermocouple

Locations

Outside Furnace

6.2 Temperature readings shall be taken at not less

than 9 points on the surface

[wall, floor,etc.]. Five of these

shall be symmetrically disposed, one to be. ...at the

center of the specimen, and

four at... .the center of its

quarter sections. The other

four shall be located at the

discretion of the testing authority to obtain

representative information on

the performance of the

construction under test. None

of the thermocouples shall be

located nearer to the edges of the test specimen than one

and one-half times the

thickness of the construction,

or 12 in.

Inside Furnace

5.1 The temperature fixed by

the curve shall be deemed to

be the average temperature

obtained from the reading of

not less than nine

thermocouples for a floor,

roof, wall, or partition and not

less than eight thermocouples for a structural

column symmetrically. disposed and distributed to

show the temperature near all

Darts of the sample, etc.

Outside Furnace

As specified in test standard,

"Temperature Measurement

Locations"

Inside Furnace

6.2.1 Minimum of three

thermocouple with not fewer

than five thermocouples per 100

It2 of floor surface and not fewer

than nine thermocouples per

100 ft2 of wall specimen surface.

Thermocouple locations not

specified; However,

ANI/MAERP Standard Fire

Endurance Test Method to

Qualify A Protective Envelope for Class 1 E Electrical Circuits

states in Section 3.4.4.5

"Thermocouples shall be

'located strategically on the

surface and at one foot

intervals in the cable system and temperatures recorded

throughout the test."

Outside Furnace

4.14 Temperature

measurements are to be

made by thermocouples

placed on the unexposed side of the test sample and

test assembly.

Inside Furnace

4.9 A minimum of three

thermocouples are to be

used, and there are to be no

fewer than five

thermocouples per 100

square feet of floor surface, and no fewer than nine

thermocouples per 100

square feet of wall surface.

The floor surface or wall

surface area is to be the

gross area of test-assembly

and sample areas.

Outside Furnace

5.3.10 Temperatures on the

penetration cold side surfaces

shall be measured with

thermocouples. A minimum of

three thermocouples shall be

located on the surface of each

fire stop under test. The

maximum temperature on the

face of the cable penetration fire stop shall be measured.

As a minimum, temperatures shall be measured at the cable

jacket, cable penetration, fire

stop interface, the interface

between the fire stop and

through metallic components, other than the insulated cable

conductor, and on the surface

of the fire stop material.

Inside Furnace

5.3.7 The temperature fixed by

the curve shall be deemed to

be the average temperature obtained from the reading of

not less than three

thermocouples symmetrically disposed and distributed to

show the temperature for each

cable penetration fire stop. Additional thermocouples shall

be used as necessary, for

larger test specimens.

0

0

0
Stadar II ASTM E-119 f .- ASTM 814 AMI 4/76 UL IEEE 634

Hose Stream

Test

10.1 Where required by the

condition of acceptance,

subject a duplicate specimen

to a fire exposure test for a

period equal to one half of

that indicated as the

resistance period in the fire

endurance test, but not for

more than one hour,

immediately after which

subject the specimen to the

impact, erosion and cooling

effects of a hose stream

directed first at the middle

and then at all parts of the

exposed face, changes in

direction being made slowly.

10.4 The stream shall be

delivered through a 21⁄2 in.

hose discharging through a

National Standard playpipe of

corresponding size equipped

with a 1-1/8 in. discharge tip

of the standard-taper smoothbore pattern without shoulder

at the orifice. The water

pressure and duration of

application shall be as

described in Table 1:

"Conditions For Hose Stream

Test," of the standard.

From Table 1:

For a desired resistance

period of greater than 2 hours

and less than four hours, the

pressure at the base of the

nozzle is to be 30 psi with

2-1/2 minute duration for

each 100 ft2 exposed area.

9.3.1 Subject a duplicate

specimen to a fire exposure test

for a period equal to one half of

that indicated as the resistance

period in the fire test, but not

more than 60 minutes,

immediately after which subject

the specimen to the impact,

erosion, and cooling effects of a

hose stream as described in

Table 1: "Pressure and Duration

- Hose Stream Test." The

stream is directed first at the

middle and then at all parts of

the exposed face, with changes

in direction being made slowly.

9.3.2 The test sponsor may

elect with the advice of the

testing body, to have the hose

stream test made on the

specimen subjected to the fire

test and immediately following

the fire test.

9.3.3 Deliver the stream

through a 21⁄2 in. hose and

discharge through a National

Standard playpipe of

corresponding size equipped

with a 1-1/8 in. discharge tip of

standard taper, smooth bore

pattern without a shoulder at the

orifice. The water pressure and

duration of application shall be

as specified in Table 1 (of the

standard).

B. Immediately following the

fire endurance test the fire

stops shall be subjected to a

hose stream applied to the

exposed surface for a period

qalculated on the basis of 21⁄2

minutes for each 100 sq. ft of

exposed area. The hose

stream shall comply with one

of the following procedures:

1. The stream shall be

delivered through a 1 1⁄2 inch

nozzle set at a discharge

angle of 300 with a nozzle

pressure of 75 psi and a

minimum discharge of 75 gpm

with the tip of the nozzle a

maximum of 5 ft. from the

exposed face OR

2. The stream shall be

delivered through a 1 1

1⁄2 inch

nozzle set at a discharge

angle of 150 with a nozzle

pressure of 75 psi and a

minimum discharge of 75 gpm

with the tip of the nozzle a

maximum of 10 ft. from the

exposed face OR

3. The stream shall be

delivered through a 21⁄2 inch

National Standard playpipe

equipped with 1 o inch tip,

nozzle pressure of 30 psi,

located 20 feet from the

exposed face

For acceptance: No opening

develops that permits a

projection of water beyond the

unexposed surface during the

hose stream test.

5.3 The stream is to be

delivered through 21⁄2 inch

hose and discharged through

a National Standard playpipe

of corresponding size

equipped with a 1-1/8 inch

discharge tip of the

standard-taper, smooth bore

pattern without a shoulder at

the orifice. The water

pressure and duration of

application is to be as

specified in Table 5.1,

"Pressure and Duration -

Hose Stream Test."

5.3.12 A hose stream test

shall be conducted

immediately following the end

of the fire endurance test and

removal, if necessary of the

test slab.

For power generating stations

including nuclear-generating

stations, a 1 in. hose

discharging through a nozzle

approved, for use on fires in

electrical equipment producing

a long-range narrow-angle (30-

900 set at 300 angle) high

velocity spray only shall be

used. The hose stream shall

be applied to the exposed

side. The water pressure shall

be 75 psi, calculated, at the

base of the nozzle and

minimum flow of 75 gal/min

with a duration of application

of 21⁄2 minutes per 100 ft2 of

test slab.

_____________________ JI I __________________________________________

0

0

0

-I

I
C)

E Standard ATM E7119 ASTM E-9.14 ANI 4/76 UL 1479 WEEE 634

Nozzle 10.5 The nozzle orifice shall 9.3.4 The nozzle orifice shall be See Hose Stream Test section 5.4 The nozzle orifice is to 5.3.12 The nozzle distance

Distance be 20 ft from the center of the 20 feet from the center of the above for Nozzle Distance be 20 feet from the center of shall be 10 ft from the center

exposed surface of the test exposed surface of the test specifications the exposed surface of the of the exposed surface of the

specimen if the nozzle is so specimen if the nozzle is so test specimen if the nozzle is test specimen

located that when directed at located that when directed at so located that, when

the center its axis is normal the center, its axis is normal to directed at the center, its

to the surface of the test the surface of the test axis is normal to the surface

specimen. If otherwise specimen. If otherwise located, of the test specimen. If

located, its distance from the its distance from the center shall otherwise located, its

center shall be less than 20 be less than 20 feet by an distance from the center is to

feet by an amount equal to 1 amount equal to 1 foot for each be less than 20 feet by an

foot for each 10' of deviation 10° of deviation from the amount equal to 1 foot for

from the normal. normal, each 10* of deviation from

the normal.

0

0

0

ON
Appendix D

Acronyms and Abbreviations

AEC Atomic Energy Commission

AEOD Office for Analysis and Evaluation of Operational Data

ANI American Nuclear Insurers

ANSI American National Standards Institute

APCSB Auxiliary Power Conversion Systems Branch

ASTM American Society for Testing and Materials

BISCO Brand Industrial Services Company

BTP Branch Technical Position

CFR Code of Federal Regulations

CTL Construction Testing Laboratories

FM Factory Mutual

FPFI Fire Protection Functional Inspection

GDC General Design Criteria

GL generic letter

HDSE high-density silicone elastomer

IEEE Institute of Electrical and Electronics Engineers

IN information notice

IP3 Indian Point 3

LER licensee event report

LDSE low-density silicone elastomer

NFPA National Fire Protection Association

NMSS Office of Nuclear Material Safety and Safeguards

NRC U.S. Nuclear Regulatory Commission

NRR Office of Nuclear Reactor Regulation

OPL Omega Point Laboratories

PSTS penetration seal tracking system

QA quality assurance

QC quality control

RBS River Bend Station

SNL Sandia National Laboratories

SRP Standard Review Plan

TSI Thermal Science, Incorporated

UL Underwriters Laboratories, Incorporated

WBN Watts Bar Nuclear Power Plant

WNP2 Washington Nuclear Project 2

D-I

Appendix E

Technical Assessment of Fire Barrier Peneteration Seals in Nuclear Power Plants

•G•tR REGU( O.

POLICY ISSUE

(Information)

July 1, 1996 SECY-96-146

FOR: The Commissioners

FROM: James M. Taylor

Executive Director for Operations

SUBJECT: TECHNICAL ASSESSMENT OF FIRE BARRIER PENETRATION SEALS IN

NUCLEAR POWER PLANTS

PURPOSE:

To inform the Commission that the U.S. Nuclear Regulatory Commission (NRC)

staff has completed its technical assessment of nuclear power plant fire

barrier penetration seals. The staff documented its assessment in a report

entitled: "Technical Assessment of Fire Barrier Penetration Seals in Nuclear

Power Plants," June 14, 1996. A copy of the report is attached.

BACKGROUND:

As part of fire protection defense in depth, nuclear power plants are divided

into separate fire areas by fire-rated walls and fire-rated floor-ceiling

assemblies. These fire barriers offer reasonable assurance that a fire will

not spread from one plant area to another. Openings in these fire barriers,

known as fire barrier penetrations, allow such items as cables, conduits,

cable trays, pipes, and ducts to pass from one fire area to another. Fire

barrier penetration seals are installed to seal these openings and maintain

the fire-resistive integrity of the fire barriers. Penetration seals are not

technically complex, nor are they unique to the nuclear industry. In fact,

they are universally accepted building components that are used in a variety

of residential, commercial, and industrial buildings wherever fire-resistive

separation is needed. The same penetration seal materials, fire test

CONTACTS: Steven West, NRR NOTE: TO BE RELEASED AT COMMISSION MEETING

301-415-1220 ON TUESDAY, JULY 9, 1996

Chris Bajwa, NRR

301-415-1237

E-1 NUREG-1552
Fire Barrier Penetration Seals

The Commissioners - 2 -

standards, and installation techniques that are used by the nuclear industry

are used in these other industries. A large body of fire test results and

fire experience (non-nuclear) has proven the fire-resistive capabilities and

effectiveness of penetration seals.

In about 1985, the staff had become aware of the possibility that some

licensees may not have been complying with NRC requirements and guidance for

fire barrier penetration seals. In response to these concerns, in 1987 and

1988, the NRC staff assessed fire barrier penetration seals. This assessment

involved reviewing relevant data such as licensee event reports, inspection

findings, and fire test reports; interviewing industry staff; inspecting

licensees and vendors; and reviewing a sample population of as-built fire

barrier penetration seal installations and the substantiating documentation.

Although it did not find safety-significant generic issues, the staff

identified potential problems. These included, for example, incomplete test

documentation and improper seal installation techniques. The staff addressed

the potential problems in a series of information notices that it issued in

1988.

Since 1992, similar potential problems have again been reported. In response,

the Office of Nuclear Reactor Regulation (NRR) conducted a second technical

assessment of fire barrier penetration seals. The principal purposes of the

second assessment were to address the potential problems, to determine if

there were any problems of safety significance or with generic implications,

and to determine if NRC regulatory requirements, review guidance, and

inspection procedures for penetration seals were adequate.

DISCUSSION:

In support of its second technical assessment of-penetration seals, the staff

inspected reactor and vendor facilities; witnessed fire endurance tests of

penetration seals; reviewed operating experience and previous NRC inspection

and assessment results; and assessed the data and information obtained from

the field work and document reviews.

The staff found'several minor weaknesses with some of the plant-specific

penetration seal programs that it reviewed. These included, for example,

inadequate documentation of seal installer training and failure to mark inplant seals with their seal identification numbers. The staff also found

several potential weaknesses with the NRC fire protection inspection and

review guidance. These potential weaknesses, which were also minor, included:

(1) the NRC fire protection guidance documents do not reflect the current

National Fire Protection Association (NFPA) position on fire testing

laboratories; (2) there is no technical basis for the noncombustibility

criterion for penetration seal materials that is specified in the NRC fire

protection regulation and review guidance; (3) there is no staff guidance for

comparing fire-tested penetration seal configurations to as-built

configurations. (See recommendations below.) Neither the plant-specific nor

the programmatic weaknesses caused concerns that the penetration seals

installed in the plants would not accomplish their fire protection function.

NUREG-1552 E-2
Fire Barrier Penetration Seals

The Commissioners - 3 -

On the basis of its review and assessment of available information, including

the "Report on the Reassessment of the NRC Fire.Protection Program" that had

been conducted by NRR, the review of fire barrier penetration seals that had

been conducted by the Office for Analysis and Evaluation of Operational Data

(AEOD), reports that had been prepared by Sandia National Laboratories on the

population of fire barrier types installed in nuclear power plants and

penetration seal aging, and the other documents referenced in its assessment

report, the staff concluded that the penetration seal programs in industry

remain satisfactory. The staff found neither plant-specific problems nor

generic problems of safety significance.

The staff expects that plant-specific deficiencies will occasionally be found

during future licensee surveillances and NRC inspections. However, licensees

know what potential fire barrier penetration seal problems to look for during

surveillance inspections; industry consensus fire test standards are available

and are followed; and fire test results and qualified fire-resistant seal

materials and designs are available. Therefore, licensees have the means to

correct problems as they are found, and staff oversight will continue to

ensure corrections on a case-by-case basis. In addition, the multiple layers

of protection provided by the fire protection defense in depth concept provide

reasonable assurance that penetration seal deficiencies will not present an

undue risk to public health and safety. Finally, the staff concluded that

actions it had taken in 1988 to address potential penetration seal problems

increased industry awareness of such problems and resulted in more thorough

surveillances, maintenance, and corrective actions. These actions together

with continued licensee upkeep of existing penetration seal programs and

continued NRC inspections are adequate to maintain public health and safety.

On the basis of the results of its second technical assessment the staff will:

(1) revise the NRC fire protection guidance documents to reflect the current

National Fire Protection Association position on testing laboratories;

(2) delete the noncombustibility criterion for penetration seal materials fromthe NRC fire protection regulation and review guidance; (3) develop guidance

for comparing fire-tested penetration seal configurations to as-built

configurations; and (4) issue an Information Notice that summarizes this

Commission paper and states that the attached technical assessment is

available in the public document room.

The Fire Protection Engineering Section of NRR conducted the technical

assessment documented in the report. The Special Inspection Branch of NRR and

Brookhaven National Laboratory helped with the reactor and vendor inspections.

Staff of NRR, AEOD, the Office of Nuclear Material Safety and Safeguards

(NMSS), Region I, Region II, Region III, and Region IV conducted a peer review

of the assessment report. An Independent Management Review Panel that was

chaired by NRR and represented by NMSS and the Office of Nuclear Regulatory

Research conducted a final review of this report.

The staff of the Fire Protection Engineering Section made presentations on

fire barrier penetration seals and this assessment at the International

Conference on Fire Protection and Prevention in Nuclear Facilities, Barcelona,

E-3 NJNUREG- 1552
Fire Barrier Penetration Seals

The Commissioners - 4 -

Spain (December 5-7, 1994); the Nuclear Energy Institute Fire Protection

Forum, St. Petersburg, Florida (January 29, 1996); and NRC Regulatory

Information Conferences (May 1994 and April 1996). On March 7, 1996, the

staff of the Fire Protection Engineering Section presented the results of this

technical assessment to the Advisory Committee on Reactor Safeguards, Fire

Protection Subcommittee.

The technical assessment report addresses concerns identified in outstanding

penetration seal allegations. The staff will use the assessment report as the

basis to close these allegations. The staff will also provide copies of the

assessment report to cognizant technical staff. This completes the staff

actions on its technical assessment of nuclear power plant fire barrier

penetration seal programs.

e~sM.TTa or , xecutive Director

for Operations

Attachment: As stated

DISTRIBUTION:

Commissioners

OGC

OCAA

OIG

OPA

OCA

ACRS

ASLBP

REGIONS

EDO

SECY

NUREG-1552 E-4
NRC FORM 335 U.S. NUCLEAR REGULATORY COMMISSION 1 REPORT NUMBER

(2-89) (Assigned by NRC, Add Vol., Supp., Rev.,

NRCM 1102, and Addendum Numbers, if any.)

3201.3202 BIBLIOGRAPHIC DATA SHEET

(See instructions on the reverse)

2. TITLE AND SUBTITLE NUREG-1552

Fire Barrier Penetration Seals in Nuclear Power Plants

3. DATE REPORT PUBLISHED

MONTH YEAR

July 1996

4. FIN OR GRANT NUMBER

5. AUTHOR(S) 6. TYPE OF REPORT

C.S. Bajwa and K.S. West Technical

7. PERIOD COVERED (Inclusive Dates)

8. PERFORMING ORGANIZATION - NAME AND ADDRESS (IfNRC, provide Division, Office or Region, U.S. Nuclear Regulatory Commission, and mailing address; if contractor,

provide name and mailing address.)

Division of Systems Safety Analysis

Office of Nuclear Reactor Regulation

U.S. Nuclear Regulatory Commission

Washington, DC 20555-0001

9. SPONSO RI NG ORGAN IZATIO N - NAME AN D ADDRESS (if NRC, type 'Same as above,; if contractor, provide NRC Division, Office or Region, U. S. Nuclear Regulatory Commission,

and mailing address.)

Same as above

10. SUPPLEMENTARY NOTES

11. ABSTRACT (200 words or less)

Nuclear power plants are divided into separate fire areas by fire-rated structural barriers. Fire-rated penetration seals are

installed to seal certain openings in these barriers. The seals maintain the fire-resistive integrity of the barriers and provide

reasonable assurance that a fire will be confined to the area in which it started. The U.S. Nuclear Regulatory Commission

conducted a comprehensive technical assessment of penetration seals toaddress reports of potential problems, to determine

if there were any problems of safety significance, and to determine if NRC requirements, review guidance, and inspection

procedures are adequate. The staff did not find plant-specific problems of safety significance or concerns with generic

implications. The staff concluded that the general condition of penetration seal programs in industry is satisfactory. The staff

also concluded that actions it had taken in 1988 and 1994 to address potential penetration seal problems increased industry

awareness of such problems and resulted in more thorough surveillances, maintenance, and corrective actions. These

previous staff actions, together with continued licensee upkeep of existing penetration seal programs and continued NRC

inspections, are adequate to maintain public health and safety.

12. KEY WORDS/DESCRIPTORS (List words or phrases that will assist researchers in locating the report.) 13. AVAILABILITY STATEMENT

Fire Barrier Penetration Seals unlimited

Silicone Foam 14. SECURITY CLASSIFICATION

Fire Barriers (This Page)

unclassified

(This Report)

unclassified

15. NUMBER OF PAGES

16. PRICE

NRC FORM 335 (2-89) This form was electronically produced by Elite Federal Forms, Inc.


Federal Recycling Program

NUKELi-lbbZ FIRE BARRIER PENETRATION SEALS IN NUCLEAR POWER PLANTS JULY 1996

UNITED STATES

NUCLEAR REGULATORY COMMISSION

WASHINGTON, DC 20555-0001

OFFICIAL BUSINESS

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