Information Notice No. 95-52

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 UNITED STATES

 NUCLEAR REGULATORY COMMISSION

 OFFICE OF NUCLEAR REACTOR REGULATION

 WASHINGTON, D.C. 20555-0001

 November 14, 1995

NRC INFORMATION NOTICE 95-52: FIRE ENDURANCE TEST RESULTS FOR

 ELECTRICAL RACEWAY FIRE BARRIER SYSTEMS

 CONSTRUCTED FROM 3M COMPANY INTERAM FIRE

 BARRIER MATERIALS 

Addressees

All holders of operating licenses or construction permits for

nuclear power reactors.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this

information notice to inform addressees of the results of recent

fire endurance tests for electrical raceway fire barrier systems

constructed from 3M Company Interam fire barrier materials. It

is expected that recipients will review the information for

applicability to their facilities and consider this information,

as appropriate, in their review of Interam fire barriers.

Background

On April 20, May 17, and July 7, 1995, the NRC staff visited

Omega Point Laboratories (OPL), San Antonio, Texas, to witness

full-scale fire endurance tests for electrical raceway fire

barrier systems constructed from 3M Company Interam fire barrier

materials. These tests were sponsored by Peak Seals Corporation

(Peak Seals). Peak Seals informed the NRC staff that the test

specimens included in this test program were intended to

represent generic Interam fire barrier systems and that these

test programs were conducted in accordance with Generic Letter

(GL) 86-10, Supplement 1, "Fire Endurance Test Acceptance

Criteria for Fire Barrier Systems Used To Separate Redundant Safe

Shutdown Trains Within the Same Fire Area." The following

information is based on observations made by the NRC staff who

witnessed these fire tests. The NRC staff has not reviewed the

test reports.

Description of Circumstances

1-Hour Fire Endurance Tests

The first test assembly included nominal 24-inch and 6-inch-wide

steel cable trays; 1-inch, 2-inch, 3-inch, and 5-inch-diameter

steel conduits; a 2-inch diameter air drop; each was arranged in

a U-shaped configuration; and a 12-inch by 12-inch by 8-inch

steel junction box. With regard to the 2-inch-diameter steel

conduit, the junction box was installed in one of its vertical

runs and the 2-inch diameter air drop was installed in the other. 

These test specimens did not include cable fill and were

supported by a common trapeze 

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support. They were protected with three layers of Interam E53A

fire barrier mat material. Each layer was 7.6 mm [0.3 inch]

thick.

On April 20, 1995, OPL subjected the test assembly to the test

fire specified in American Society for Testing and Materials

(ASTM) Standard E-119, "Fire Test of Building Construction and

Materials," for 1 hour. After the fire exposure, the test

specimens were subjected to a fog-nozzle hose stream test. The

24-inch-wide cable tray; the 3-inch-, 2-inch-, and 1-inchdiameter conduits; and the air drop exceeded the temperature rise

acceptance criteria of GL 86-10, Supplement 1, near the end of

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Information Notice No. 95-52

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the 1-hour fire exposure. None of the barriers burned through

during the fire exposure nor were they breached by the hose

stream. Table 1 (see Attachment 1) summarizes the test specimen

and fire barrier configurations and the results of the

April 20, 1995, test. 

The second test assembly included a 24-inch-wide steel cable

tray, 1-inch- and 5-inch-diameter steel conduits, and a 2-inchdiameter air drop. These test specimens did not contain cables

and were protected with three layers of Interam E54A fire barrier

mat material. Each layer was 10 mm [0.4 inch] thick.

On May 17, 1995, OPL subjected the test assembly to the test fire

specified in ASTM Standard E-119 for 1 hour. After the fire

exposure, it subjected the test specimens to a fog-nozzle hose

stream test. These 1-hour test specimens met the acceptance

criteria of Supplement 1 to GL 86-10. Table 2 (see Attachment 1)

summarizes the test specimen and fire barrier configurations and

the results of the May 17, 1995, test. 

3-Hour Fire Endurance Test

The third test assembly included nominal 24-inch- and 6-inch-wide

steel cable trays; nominal 1-inch-, 3-inch-, and 5-inch-diameter

steel conduits; a 2-inch-diameter air drop; each was arranged in

a U-shaped configuration; and a nominal 12-inch by 12-inch by

8-inch steel junction box. The cable trays were filled with a

single layer of mix cables. The cable trays, the 1-inch- and 

3-inch-diameter steel conduits, and the air drop were protected

with five layers of Interam E54A fire barrier mat material. The

5-inch-diameter conduit and the junction box were protected with

six layers of Interam E54A fire barrier mat material. Each layer

was 10 mm [0.4 inch] thick. 

On July 7, 1995, OPL subjected the test assembly to the test fire

specified in ASTM Standard E-119 for 3 hours. After the fire

exposure, it subjected the test specimens to a fog-nozzle hose

stream test. The barriers did not burn through during the fire

exposure, nor were they breached by the hose stream. There was

no visible damage to the test specimen cables. However, all of

the test specimens exceeded the temperature rise acceptance

criteria of GL 86-10, Supplement 1. Table 3 (see Attachment 1)

summarizes the test specimen and fire barrier configurations and

the results of the July 7, 1995 test. 

Discussion

Section 50.48 of Title 10 of the Code of Federal Regulations

requires that each operating nuclear power plant must have a fire

protection plan that 

 IN 95-52

 November 14, 1995

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satisfies General Design Criterion (GDC) 3 of Appendix A to 10

CFR Part 50. Fire protection features required to satisfy GDC 3

include features to ensure that one train of systems necessary to

achieve and maintain shutdown conditions is free of fire damage. 

One means of satisfying this requirement is to separate one safe

shutdown train from its redundant train with a fire-rated

barrier. The level of fire resistance required of the barrier, 1

hour or 3 hours, depends on the other fire protection features in

the fire area.

The NRC issued guidance on acceptable methods of satisfying the

regulatory requirements of GDC 3 in Branch Technical Position

(BTP) Auxiliary and Power Conversion Systems Branch (APCSB)

9.5-1, "Guidelines for Fire Protection for Nuclear Power Plants";

Appendix A to BTP APCSB 9.5-1; BTP Chemical Engineering Branch

(CMEB) 9.5-1, "Fire Protection for Nuclear Power Plants"; and

GL 86-10, "Implementation of Fire Protection Requirements." 

These guidance documents state that the fire resistance ratings

of fire barriers should be established in accordance with

National Fire Protection Association (NFPA) Standard 251,

"Standard Methods of Fire Tests of Building Construction and

Materials" (1975), by subjecting a representative test specimen

to a standard fire exposure.

On March 25, 1994, the NRC issued Supplement 1 to GL 86-10 to

(1) clarify the applicability of the test acceptance criteria in

GL 86-10 to raceway fire barrier systems, (2) specify a set of

fire endurance test acceptance criteria that are acceptable for

demonstrating that fire barrier systems can perform the required

fire-resistive function and maintain the protected safe shutdown

train free of fire damage, (3) specify acceptable options for

hose stream testing, and (4) specify criteria for cable

functionality testing when a deviation is necessary, such as when

the fire barrier temperature rise criteria are exceeded or the

test specimen cables sustain visible damage. These positions are

incorporated by the NRC staff in its review and evaluation of the

adequacy of fire endurance tests and fire barrier systems

proposed by licensees or applicants to satisfy existing NRC fire

protection rules and regulations. 

Some temperatures observed during the tests exceeded the maximum
Information Notice No. 95-52

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allowable temperature acceptance criteria of Supplement 1 to GL

86-10. In accordance with this supplement, an engineering

evaluation could be performed to determine the acceptability of

an in-plant Interam fire barrier that was bounded by a deviating

test specimen configuration. Information about such evaluations

can be found in Enclosure 2 of Supplement 1 to GL 86-10. By

letter dated August 7, 1995 [accession number 9509050173 ], Peak

Seals submitted to the NRC staff additional documentation

relating to the thermal performance of the 3-hour fire barrier

test specimens for information.

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This information notice requires no specific action or written

response. If you have any questions about the information in

this notice, please contact one of the technical contacts listed

below or the appropriate Office of Nuclear Regulation (NRR)

project manager.

 /s/'d by DMCrutchfield

 Dennis M. Crutchfield, Director

 Division of Reactor Program Management

 Office of Nuclear Reactor Regulation

Technical contacts: Patrick M. Madden, NRR

 (301) 415-2854

 Amarjit Singh, NRR

 (301) 415-1237

Attachments:

1. Tables 1, 2, and 3, Summaries of Endurance Tests [see WordPerfect file ]

2. List of Recently Issued NRC Information Notices