UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS

WASHINGTON D.C. 20555-0001

April 1, 2005

INFORMATION NOTICE 2005-07: RESULTS OF HEMYC ELECTRICAL RACEWAY FIRE

BARRIER SYSTEM FULL SCALE FIRE TESTING

ADDRESSEES

All holders of operating licenses for nuclear power reactors, except those who have

permanently ceased operations and have certified that fuel has been permanently removed

from the reactor vessel, and fuel facilities licensees.

PURPOSE

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

addressees of the results of Hemyc electrical raceway fire barrier system (ERFBS) full-scale fire

tests. The Hemyc ERFBS did not perform for one hour as designed because shrinkage of the

Hemyc ERFBS occurred during the testing. It is expected that recipients will review the

information for applicability to their facilities and consider actions as appropriate to avoid similar

problems. However, suggestions contained in this information notice are not NRC

requirements; therefore, no specific action or written response is required. 

BACKGROUND

The Hemyc ERFBS, manufactured by Promatec, Inc., has been installed at nuclear power

plants (NPPs) to protect circuits in accordance with regulatory requirements (Reference 1) and

plant-specific commitments.

As a result of fire protection inspections, unresolved items (URIs) were opened at some nuclear

power stations due to questions raised regarding the fire resistance capability of the Hemyc

ERFBS (Reference 2). The Office of Nuclear Reactor Regulation (NRR) performed a review of

the Hemyc ERFBS (Reference 3) and requested the NRC’s Office of Nuclear Regulatory

Research (RES) to perform confirmatory testing of this ERFBS. RES performed the testing at

the Omega Point Laboratories in Elmendorf, Texas. 

DISCUSSION

This information notice describes the results of the investigation of the fire resistance capability

of the Hemyc ERFBS (Attachment 1). The NRC performed two ASTM E 119 furnace tests on a

number of cable raceway types that are protected by the Hemyc ERFBS (with and without air

gaps) in accordance with the Hemyc ERFBS test plan (see ADAMS Accession No.

ML043210141 for a preliminary version of the test plan). The test plan provides 

ML050890089
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a detailed discussion of the assemblies and the thermocouple positions. The Hemyc ERFBS

tests were performed for a period of 60-minutes each, followed by a hose stream test and posttest visual inspection of the ERFBS.

A bare No. 8 stranded copper conductor, instrumented with thermocouples every 6 inches along

its length, was routed through each of the conduit and cable tray test specimens. Additional

thermocouples were mechanically attached to the outer surfaces of the conduit test specimens

and along the length of both side rails of the cable tray test specimens at 6-inch intervals. All

results in Attachment 1 refer to the additional thermocouples attached to the outer surfaces of

the conduits and cable trays unless otherwise stated. 

Shrinkage of the Outer Covering

The Hemyc ERFBS is constructed of Hemyc mats consisting of Kaowool insulation inside an

outer covering of Siltemp high-temperature fabric. The mats are machine-stitched at the factory

to fit each electrical raceway installation. Hemyc mats that are directly wrapped around the

electrical raceway use 2-inch-thick Kaowool. Hemyc mats that are installed over spaced frames

to provide a 2-inch air gap between the Hemyc and the electrical raceway (for cable tray

protection) use 11⁄2-inch-thick Kaowool. 

While Siltemp is a frequently used descriptor for the outer covering, and thus is used generically

in this information notice, the material originally known as Siltemp is not now available

commercially. The Promatec vendor manual references either Siltemp, Refrasil, or Alpha 600

as equivalent materials for the outer covering of the Hemyc ERFBS mats. This testing used the

Refrasil brand fabric. The term “Siltemp” is most commonly used in the nuclear industry to

describe the outer covering fabric of the Hemyc ERFBS mats. The NRC’s preliminary testing

indicates that the material density, thickness, and fabric weave are identical for both Siltemp

and Refrasil. 

During the fire testing, the outer layer of Siltemp consistently showed thermal shrinkage and

change of color from tan to white. This shrinkage led to some gaps opening between the

Hemyc ERFBS mats. NRC’s preliminary findings indicate that the color change and shrinkage

of both Siltemp and Refrasil materials are spatially uniform. Based on preliminary testing both

Siltemp and Refrasil shrink approximately 8 percent during the ASTM E 119 furnace exposure. 

Opening of the Joints

This testing examined the four most common methods of joining the Hemyc material into a

complete ERFBS: (1) using stitched joints, (2) using minimum 6-inch collars over a joint,

(3) using minimum 2-inch overlapping of the mats, and (4) using through bolts with fender

washers. The Siltemp shrinkage led to the opening of each of the joint systems, which exposed

the assembly (conduit, cable tray, junction box, air drop cable) to the furnace environment. For

method (1), the shrinkage led to the seams being torn open. For method (2), the mats also

experienced shrinkage, causing openings in the Hemyc ERFBS. It appeared that the 6-inch

collar contracted and moved with one side of the material. For method (3), the 2-inch

overlapping joints also opened. For method (4), the through-bolting of the Hemyc mats on the

cable tray designs using the 2-inch air gap appeared to provide the most robust resistance to

Siltemp shrinkage. However, due to this rigid fixed mounting of the Hemyc mats, the Siltemp 
IN 2005-07

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experienced tearing of the machine sewn seams and tearing of the Siltemp fabric. All but one

assembly (conduit or cable tray) experienced temperatures capable of damaging plant cables

(Reference 4). 

Supports and Intervening Item Protection

With only the 3-inch thick Kaowool protection on supports as required by the vendor manual, the

single point temperature rise of 325 o

F was exceeded in 13 to 32 minutes. To prevent

corruption of the thermal measurement data for the raceways because of potential thermal

short-circuiting from structural supports, this program did not test the raceway and the structural

supports together. Intervening metallic items would also be expected to permit the same

temperature rise.

Significance of Results

The significance of the test results is that the Hemyc ERFBS did not perform for one hour as

designed. Observations made during the testing, such as mat shrinkage and thermal shorts

through the support protection, were not identified during previous testing of the material. 

Consequently, the Hemyc ERFBS does not provide the level of protection expected for a rated

1-hour fire barrier. 

CONTACT 

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

questions about this matter to the technical contact(s) listed below or the appropriate NRR 

project manager.

/RA/

Patrick L. Hiland, Chief

Reactor Operations Branch

Division of Inspection Program Management

Office of Nuclear Reactor Regulation

Technical Contact: Daniel Frumkin, NRR/DSSA

301-415-2280

E-mail: dxf1@nrc.gov

Attachment 1: Hemyc 1-Hour Fire-Rated Test Results

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

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

1. Title 10 of the Code of Federal Regulations, Part 50, Appendix R, Section III.G.2 

2. NRC Inspection Report 50-400/1999-13 (ADAMS Accession No. ML003685341); NRC

Inspection Reports 50-369/2000-09 and 50-370/2000-09 (ADAMS Accession No.

ML003778709)

3. NRR Response to Task Interface Agreement (TIA) 99-028, “Shearon Harris Nuclear Power

Plant, Unit 1 - Resolution of Pilot Fire Protection Inspection Fire Barrier Qualification Issues,”

dated August 1, 2000 (ADAMS Accession No. ML003736721)

4. Inspection Manual Chapter 0609, Appendix F, Fire Protection Significance Determination

Process, Attachment 7, page F7-2
Hemyc 1-Hour Fire-Rated Test Results

Conduit , Supports & Junction Box

Raceway

Time to 

)Tave > 250oF

(minutes)

Time to

Single Point

)T > 325oF

(minutes)

Max. Temp.

Bare #8

@ 1 hour1

(oF)

1" Conduit (1E)(Empty)

46 42 1013 

1" Conduit (1F)1.02 lb./linear foot (lin.ft.) Cable Fill

44 34 1177 

2 1⁄2 " Conduit (1C)(Empty)

48 41 709 

2 1⁄2 " Conduit (1D)5.85 lb./lin.ft. Cable Fill

51 38 446 

4" Conduit (1A)(Empty)

49 33 865 

4" Conduit (1B)14.84 lb./lin.ft. Cable Fill

57 43 199 

Junction Box18” x 24” x 8”

17 15 NA 

Unistrut Support3 NA 22 - 32 NA 

2" Tube Steel Support3 NA 13 - 25 NA 
Hemyc 1-Hour Fire-Rated Test Results

Cable Tray, Junction Box, & Airdrop

Raceway

Right Side

Tray Rail 

)Tave >

250oF

(minutes)

Right Side

Tray Rail

Single Point

)T > 325oF

(minutes)

Left Side

Tray Rail 

)Tave >

250oF

(minutes)

Left Side

Tray Rail

Single Point

)T > 325oF

(minutes)

Bare #8 

)Tave >

250oF

(minutes)

Bare #8

Single Point

)T > 325oF

(minutes)

@ 

12" Cable Tray Empty,(2A) Direct Attachment

36 34 27 18 32 32 

12" Cable Tray Empty,(2B) 2" Air Gap

37 35 38 35 33 34 

36" Cable Tray Empty,(2C) Direct Attachment

41 39 34 33 35 35 

36" Cable Tray Empty,(2D) 2" Air Gap

32 31 33 32 28 27 

Air Drop, (2E)Direct Attachment

NA NA NA NA 35 32 

Air Drop, (2F)2" Air Gap

NA NA NA NA 32 28 

18” x24” x 8”JunctionBox,(2G)Direct Attachment withBands 4

31 32 NA NA NA NA 
Notes: 1. The temperatures recorded on the Bare No. 8 conductor may not be indicative of the actual temperature 

for two reasons. First, to insure the integrity of the thermocouple’s jacket and insulation during installatioBare No. 8 conductor was located in the center of the cable; therefore it may not have been exposed to temperature within the conduit. The second reason was that the joints opened during the testing, produon the interior of the raceway that may or may not have been picked up by the Bare No. 8 conductor.

2. All Hemyc ERFBSs experienced some thermal shrinkage of the outer Siltemp covering. As a result, som

exposed the conduits or cable trays to the furnace environment at various points during the test.

3. The time provided for the structural supports was determined to be the time when the single point tempe

exceeded 325 oF at a distance 3 inches into the Hemyc insulation protecting the structural steel. Three 

minimum structural support protection recommended in the vendor manual.

4. The junction box average temperature is the average across all thermocouples mounted on the outside 

The single-point temperature is also measured on the external surface of the junction box.