Information Notice 2005-07, Results of Hemyc Electrical Raceway Fire Barrier System Full Scale Fire Testing
| ML050890089 | |
| Person / Time | |
|---|---|
| Issue date: | 04/01/2005 |
| From: | Hiland P NRC/NRR/DIPM/IROB |
| To: | |
| frumkin d, 415-2280, NRR/DSSA/SAPLB | |
| References | |
| IN-05-007 | |
| Download: ML050890089 (8) | |
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
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 NRCs 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
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 post- test 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 NRCs
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. NRCs 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 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 oF 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. 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 oF 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.
ADAMS ACCESSION #: ML050890089 OFFICE
DSSA:SPLB
Tech Editor
DSSA:SPLB
BC:DSSA:/SPLB
D:DSSA
NAME
DFrumkin
PKleene
SWeerakkody
JHannon
SBlack
DATE
04/01/2005
04/01/2005
04/01/2005
04/01/2005
/ /2005 OFFICE
OES:IROB:DIPM
A:SC:OES:IROB:DIPM
C:IROB:DIPM
NAME
RPierson
CVHodge
EJBenner /RLaura for/
PLHiland
DATE
04/01/2005
04/01/2005
04/01/2005
04/01/2005
OFFICIAL RECORD COPY
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.
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
IN 2005-07 Attachment 1 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)
Joint Opening2
Yes/No
1" Conduit (1E)
(Empty)
46
42
1013 Yes
1" Conduit (1F)
1.02 lb./linear foot (lin.ft.) Cable Fill
44
34
1177 Yes
2 1/2 " Conduit (1C)
(Empty)
48
41
709 Yes
2 1/2 " Conduit (1D)
5.85 lb./lin.ft. Cable Fill
51
38
446 Yes
4" Conduit (1A)
(Empty)
49
33
865 Yes
4" Conduit (1B)
14.84 lb./lin.ft. Cable Fill
57
43
199 Yes
Junction Box
18 x 24 x 8
17
15 NA
Yes
Unistrut Support3
NA
22 - 32 NA
NA
2" Tube Steel Support3 NA
13 - 25 NA
NA
IN 2005-07 Attachment 1 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)
Bare #8 Max.
Temp.
@ 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />
(oF)
Joint
Opening2 Yes/No
12" Cable Tray Empty,
(2A) Direct Attachment
36
34
27
18
32
32
1260
Yes
12" Cable Tray Empty,
(2B) 2" Air Gap
37
35
38
35
33
34
1002 Yes
36" Cable Tray Empty,
(2C) Direct Attachment
41
39
34
33
35
35
1330
Yes
36" Cable Tray Empty,
(2D) 2" Air Gap
32
31
33
32
28
27
1117 Yes
Air Drop, (2E)
Direct Attachment
NA
NA
NA
NA
35
32
1712 Yes
Air Drop, (2F)
2" Air Gap
NA
NA
NA
NA
32
28
1411 Yes
18 x24 x 8Junction
Box,(2G)
Direct Attachment with
Bands 4
31
32 NA
NA
NA
NA
NA
Yes
IN 2005-07 Attachment 1 Notes:
1.
The temperatures recorded on the Bare No. 8 conductor may not be indicative of the actual temperature inside the assembly
for two reasons. First, to insure the integrity of the thermocouples jacket and insulation during installation, the instrumented
Bare No. 8 conductor was located in the center of the cable; therefore it may not have been exposed to the highest
temperature within the conduit. The second reason was that the joints opened during the testing, producing local hot spots
on 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, some joints opened and
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 temperature rise (T )
exceeded 325 oF at a distance 3 inches into the Hemyc insulation protecting the structural steel. Three inches is the
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 of the boxs surface.
The single-point temperature is also measured on the external surface of the junction box.