Information Notice 1998-21, Potential Deficiency of Electrical Cable/Connection Systems
K>
K-;
'J_1
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555-0001
June 4, 1998
NRC INFORMATION NOTICE 98-21: POTENTIAL DEFICIENCY OF ELECTRICAL
CABLEICONNECTION SYSTEMS
Addressees
All holders of operating licenses for nuclear power reactors, except those licensees who have
permanently ceased operations and have certified that fuel has been permanently removed
from the reactor vessel.
Purose
The U.S. Nuclear Regulatory Commission (NRC) is issuing this Information notice to alert
addressees to a potential deficiency relating to environmental qualification of electrical
cable/connection systems. It is expected that recipients will review the information for
applicability to their facilities and consider actions, as appropriate. However, suggestions
contained in this information notice are not NRC requirements; therefore, no specific action or
written response to this notice is required.
Description of Circumstances
Sandia National Laboratories (SNL), under contract to NRC, tested electrical cable connections
to assess their accident performance If they were aged more slowly (i.e., at lower temperatures
and radiation dose rates) than in typical industry qualification tests and to investigate the
performance of connections aged to a nominal 60-year life. The results of this testing are
contained in the report NUREG/CR-6412, "Aging and Loss-of-Coolant Accident (LOCA) Testing
of Electrical Connections," January 1998 (Accession Number 9803180097). Electrical
connection test specimens consisting of conduit seals, connectors, and splices were chosen on
the basis of their usage In commercial nuclear power plants. The test program generally
followed the guidance provided In the Institute of Electrical and Electronics Engineers (IEEE)
Standard 323-1974, "IEEE Standard for Qualifying Class 1E Equipment for Nuclear Power
Generating Stations," and IEEE Standard 383-1974, "IEEE Standard for Type Test of Class IE
Electric Cables, Field Splices, and Connections for Nuclear Power Generating Stations.*
Test program specimens consisted of 10 different electrical connection types: three types of
conduit seals, two types of cable-to-device connectors, three types of cable-to-cable
connectors, and two types of In-line splices. Environmental exposure for the test specimens
consisted of two phases. The first phase consisted of simultaneous thermal and radiation
R
980129 P6 o
IN 98-21 June 4, 1998 aging for 6 months at 99 OC (210 OF) and a total radiation dose of 200 kGy (20 Mrad) at a dose
rate of 45.6 Gy/hr (4.56 krad/hr); the thermal exposure is equivalent to 60 years at 55 OC (131
'F) for an activation energy of 1.15 eV. The subsequent phase was a LOCA simulation that
consisted of an accident irradiation exposure at a dose rate of 3 kGy/hr (300 kradlhr) for an
accident dose of 1,000 kGy (100 Mrad) sequentially followed by a simulated accident steam
exposure. The simulated accident steam exposure test profile generally followed the typical
test profile contained in IEEE Standard 323-1974. During the simulated steam exposure test, the connections were energized at approximately 110 Vdc, 0 mA, to allow for online
measurement of insulation resistance (IR). Following the steam exposure test, which did not
include chemical spray, SNL performed several types of electrical measurements.
Post-steam
exposure measurements performed on the test specimens included dry IR, submerged IR, dry
alternating current (ac) dielectric withstand, and submerged ac dielectric withstand.
Five of the 10 cable connection types did not pass a post-LOCA, submerged, ac dielectric
withstand test. These types were the Conax Buffalo, Rosemount, Patel/EGS quick disconnect, Amphenol coaxial, and Litton-VEAM. In addition, all of the Conax Buffalo electrical conduit seal
assembly cable connection conductors and approximately half of the Litton-VEAM connector
and the Amphenol coaxial cable connection conductors did not pass a dry ac dielectric
withstand test. The Conax Buffalo conduit seal assembly conductors had low IR values and the
two non-grounded conductors repeatedly blew 1-ampere fuses when energized at 110 Vdc.
Approximately one-third of the Lftton-VEAM connector and all four Amphenol coaxial cable
connector conductors had IR values below 107 ohms. The list of electrical cable connection
types included in the test program and the test results from the NUREGICR-6412 report are
provided in Attachment 1.
SNL has performed similar testing of electrical cables to determine the minimum insulation
thickness necessary for cable functional performance and long-term aging degradation of
cables. Results from these testing programs were provided In NRC Information Notice (IN) 92-
81, 'Potential Deficiency of Electrical Cables with Bonded Hypalon Jackets," dated December
11, 1992, and IN 93-33, "Potential Deficiency of Certain Class 1 E Instrumentation and Control
Cables," dated April 28, 1993.
Discussion
The SNL test results provided in NUREGICR-6412 raised potential Issues relating to the long- term environmental qualification of electrical cable/connections that did not pass a dry ac
dielectric withstand test, a submerged ac dielectric withstand test, or exhibited very low or
marginal IR values. The staff reviewed the test data contained in the report and noted that
some of the tested cable/connections exhibited low or marginal IR values as early as 3 days
after the start of the simulated LOCA test exposure. It was also noted that Rockbestos Firewall
Ill cross-linked polyethylene multiconductor and Rockbestos coaxial cables were Installed by
SNL on connection test specimens that were supplied to SNL without a length of cable.
IN 98-21 June 4, 1998 Using these two nuclear-qualified cable types that were previously tested to the equivalent of 60
years helped to ensure that the testing isolated the effects of aging on the cable connections.
The aging research study sponsored by the NRC and performed by SNL Included searches of
licensee event reports (LERs) to Identify and review those LERs that contained Information
relating to cable connection aging. The results of these searches and reviews are provided in
NUREG/CR-5461, Aging of Cables, Connections, and Electrical Penetration Assemblies Used
in Nuclear Power Plants." In NUREG/CR-5461, SNL reported that electrical cable connections
are highly reliable devices under normal plant operating conditions, and they exhibited no
evidence of significant increases in failure rate under normal operating conditions with aging.
However, NUREGICR-5461 also reports that many of the causes of failures of electrical cable
connections In accident conditions would not be detected during normal operations because of
the absence of high temperatures and humidities, and that the expected most important failure
mode is shorting or reduced electrical Isolation. These conclusions are consistent with the
recorded test data results obtained during the electrical cable connection testing In that there
was no significant degradation in the measured insulation resistances of the test specimens
during the aging and accident irradiation exposures.
In addition, NUREG/CR-6412 reports post-test examination results for the tested cable
connection specimens. One primary reported result is that the jackets of a large fraction of the
cables attached to the connections were cracked and would allow ingress of moisture Into the
cable, which could then migrate Into the connection. Specifically, the jackets of the EGS
conduit seal cables were not sealed. The jackets of the NAMCO EC 210 connector cables
were split open and extensively cracked. Jackets over the Kapton-Insulated conductors for the
Conax Buffalo conduit seal cables were not sealed. The jackets of the Okonite tape splice and
Litton-VEAM connector cables were split open and cracked all the way around. For the EGS
Grayboot connector cable, the jacket was split open and was also not sealed. Generally, the
main function of a cable jacket is to protect the insulation during Installation. The SNL test
results, however, indicate that cable jacket integrity may be important in preventing moisture
intrusion at connections. Another post-test examination result was that the behavior of the
Conax Buffalo conduct seal conductors was produced by degraded Kapton-Insulated cable
leads. Post-test examination results for the behavior of the Litton-VEAM connector revealed
that the O-ring seals were brittle and had experienced compression set, which thereby reduced
their sealing ability and allowed moisture to enter the connector body. No explanation for the
behavior of the Amphenol coaxial connector or the Rosemount 353C conduit seal was Identified
during the post-test examination. Reported results also Indicate that the test results for a
particular connection type should be evaluated while considering the specific application and
set of environmental conditions. However, In certain nuclear power plant circuit applications, degradation or failure of electrical cable/connection systems during and/or following
design-basis events can significantly affect the functional performance of safety-related
equipment.
y-I
IN 98-21 June 4, 1998 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 Reactor Regulation (NRR) project manager.
fa~k W. Roe, Acting Director
'-ision of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical Contacts:
Frank S. Ashe, NRR
301-415-2785 E-mail: fsa@nrc.gov
Satish K. Aggarwal, RES
301-415-6005 E-mail: ska~nrc.gov
John R. Tappert, NRR
301-415-1167 E-mail: jrt@nrc.gov
Attachments:
1.
"Tested Electrical Cable Connections and Reported Test Results"
2.
List of Recently Issued NRC Information Notices r-- A-TMCd, ,4g V, 1p Lu d -
J
-
t
Tested Electrical Cable Connections and Reported Test Resuts
Electrical Connection
Connection Type
Number of Connection
Number of Connection
Number of Connection Type
Type Conductors that
Type Conductors that
Conductors with Insulation
Failed Submerged AC
Failed Dry AC Dielectric
Resistance Values Below
Dielectric Withstand Test
Withstand Test
10' Ohms During Steam
Exoosure Test
Conax Buffalo Electrmc
ConduitSeal
4 of 4 failed
4 of 4 failed
4 of 4
Conductor Seal Assembly
Patel/EGS Conduit Seal
Conduit Seal
passed
passed
passed
Rosemount 353C Conduit
Conduit Seal
3 of 6 failed
passed
passed
Seal
Narnco EC210 Y2" Series
Cable-to-Device
passed
passed
passed
Connector
Patel/EGS Y2"Quick
Cable-to-Device
5 of 6 failed
passed
passed
Disconnect
Connector
Amphenol 82- Cable-to-Cable Connector
4 of 4 failed
2 of 4 failed
4 of 4
816/16100/34500 Coa.dal
Connector
EGS GB-I Grayboot
Cable-to-Cable Connector
passed
passed
passed
Connector
Litton-VEAM CIR0I/CIRO6 Cable-to-Cable Connector
6 of 6 failed
2 of 6 failed
2 of 6 Okonite T-95/No.35 Tape
In-Line Splice
passed
passed
passed
Splice
.
Raycheem NPKC-3-31A
In-Line Splice
passed
passed
passed
Splice Kit
pa-
- denotes no repod abnonalfles
0O 0
rt
0
M 0 '0
CO I.-
'0
cr
' Attachment 2 IN 98-21
June 4,1998 LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issuance
Issued to
98-20
Problems with Emergencv
6/4/98
All holders of operatina licenses
preparedness Respiratory
Protection Programs
for nuclear power reactor;
non-power reactors;
all fuel cycle and material
licensees require to have an
NRC-approval emergency plan
98-19
98-18
98-17
98-16
Shaft Binding in General Electric
Type SBM Control Switches
Recent Contamination Incidences
Resulting from Failure to Perform
Adequate Surveys
Federal Bureau of Investigations
(FBI) Awareness of National
Security Issues and Responses
(ANSIR) Program
Inadequate Operational Checks
of Alarm Ratemeters
Intergrity of Operator Licensing
Examinations
Undocumented Changes to
Non-Power Reactor Safety
System Wiring
6/3/98
5/13/98
5/7/98
4/30/98
4/20/98
4120/98
All holders of operating licenses
for nuclear power reactors
Part 35 Medical Licensees
All U.S. Nuclear Regulatory
Commission fuel cycle and power
and non-power reactor licensees
All Industrial Radiography
Licensees
All holder of operating licenses
for nuclear power reactors except
those that have permanently
ceased operations and have
certified that fuel has been
permanently removed from the
reactor vessel
All holders of operating licenses
or construction permits for test
research reactors
98-15
98-14 OL = Operating License
CP = Construction Permit
IN 98-21 June 4, 1998 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 Reactor Regulation (NRR) project manager.
Jack W. Roe, Acting Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical Contacts:
Frank S. Ashe, NRR
301-415-2785 E-mail: fsainrc.gov
Satish K. Aggarwal, RES
301-415-6005 E-mail: ska@nrc.gov
John R. Tappert, NRR
301-415-1167 E-mail: jrt@nrc.gov
Attachments:
1. "Tested Electrical Cable Connections and Reported Test Results"
2.
List of Recently Issued NRC Information Notices
Document name: S:\\DRPMSEC\\98-21.IN
- SEE PREVIOUS CONCURRENCES
To receive copy, indicate: "C" = Copy w/o attachment; "A" = Copy w/attachment; "N" = None.
NO MARK = NO COPY!
OFC_[ EELE
}EMMEBE
SJ
SCEE:DE]IIEfMEB:RESf
SECY:EELB:DE
NAME
- FAshe:ahc
JSKAggarwal
- PSGill
- DFThatcher
- MEMayfeld
i
DATE
1l07 j10/08197
10107197
10107197
1010W97
051
98 OFC
IC:EELB:DE
l
AD:DE
PECB:DRPM
l
S:PECB
Cl
PECB
AD:DRPM
Xl
NAME
- JACalvo
GCLainas'
JRTapperr
RLDennig*
JStolz*
JWRoe'
DATE
10/20/97
05105198
05/20/98
05/20/98
05122/98
05/28/98
OFFICIAL RECORD COPY
IN 98-XX
May xx, 1998 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 Reactor Regulation (NRR) project manager.
Jack W. Roe, Acting Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical Contacts:
Frank S. Ashe, NRR
301-415-2785 E-mail: fsa@nrc.gov
Satish K. Aggarwal, RES
301-415-6005 E-mail: ska~nrc.gov
John R. Tappert, NRR
301-415-1167 E-mail: jrt@nrc.gov
Attachments:
1. "Tested Electrical Cable Connections and Reported Test Results"
2.
List of Recently Issued NRC Information Notices
Document name: G:\\JRT\\A20
- SEE PREVIOUS CONCURRENCES
To receive copy, indicate: "C" = Copy w/o attachment; A" = Copy w/attachment; "N" = None.
NO MARK= NO COPYI
OFC
EELB:DE
EMMEB:RES
SC:EELB:DE
SC:EELB:DE
l
C:EMMEB:RES
SECY:EELB:DE
NAME
FSAshe:ahc
SKAggarwal
- PSGiII
DFThatcher
_
MEMayfeld I
DATE
10106/97
10/08197
10/07/97
10107/97
10/08197
051 /98 OFC
C:EELB:DE
AD:DE
PECB:DRPM
l
SC:PECB
lI
1l[
NAME
IJACalvo
GCLainaL
JRTappert*
RLDennig
Ij
DATE
10/20197
05105198
05120/98
05/20/98
0a8
05 O\\8
OFFICIAL RECORD COPY
IN 98-XX
May xx, 1998 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 Reactor Regulation (NRR) project manager.
Jack W. Roe, Acting Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical Contacts:
Frank S. Ashe, NRR
301-415-2785 E-mail: fsainrc.gov
Satish K. Aggarwal, RES
301-415-6005 E-mail: ska@nrc.gov
John R. Tappert, NRR
301-415-1167 E-mail: jrt~nrc.gov
Attachments:
1. "Tested Electrical Cable Connections and Reported Test Results"
2.
List of Recently Issued NRC Information Notices
Document name: G:\\JRT\\A20
- SEE PREVIOUS CONCURRENCES
To receive copy, indicate: "C" = Copy w/o attachment; "A" = Copy w/attachment; "N" = None.
NO MARK = NO COPY!
OFC
EELB:DE
EMMEB:RES
SC:EELB:
1C:EELB:D
l
C:EMMEB:RES
SECY:EELB:D
NAME
- FSAshe:ahc
- SKAggarwal
- PSG111
- DFThatcher
IMEMayfield
DATE
10/06/97
10/08197
10/07197
10107/97
10/08/97
051
/98 OFC
C.EELB.DE
AD:DE
I
PECB:DRPM
CPK
1 DDP
OC_
_
NAME
- JACalvo
GCLainas*
JRTappert
A
nnig
JWRoe
DATE
10/20/97
05105/98
0
98
/
98
.
OFFICIA. RECORD COPY
IN 98-XX
XXX, 1998 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 Reactor Regulation (NRR) project manager.
Jack W. Roe, Acting Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical Contacts:
Frank S. Ashe, NRR
(301) 415-2785 E-Mail: fsa@nrc.gov
Satish K. Aggarwal, RES
(301) 415-6005 E-Mail: ska@nrc.gov
John R. Tappert, NRR
(301) 415-1167 E-Mail: jrt@nrc.gov
Attachments:
1. "Tested Electrical Cable Connections and Reported Test Results"
2.
List of Recently Issued NRC Information Notices
Document name: G:\\SHAREDA20
- SEE PREVIOUS CONCURRENCES
To receive copy, indicate: "C" = Copy w/o attachment; "A' = Copy w/attachment; "N" =
None. NO MARK = NO COPY!
OFC
EELB:DE
EMMEB:RES
SC:EELB:DE
l
SC:EELB:DE
l
C:EMMEB:RES
SECY:EELB:DE
NAME
FSAshe:ahc fSKAggarwal
PSGill
j
1DFThatcher
- MEMayfield
l
DATE
10/06/97
10108/97
10/07/97
10/07/97
10108/97 l
/98 OFC
C:EELB:DE
- DE
\\'5 PECB:DRPM
l
C:PECB:DRPM
l
AD:DRPM
l
NAME
'JACalvo
_
as
JRTappert
RLDennig
JWRoe
DATE
10120197
=51
98
051 /98
051 /98
OFFICIAL RECORD COPY
IN 97-XX
XXX, 1997 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 Reactor Regulation (NRR) project manager.
Jack W. Roe, Acting Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical Contacts: Frank S. Ashe, NRR
(301) 415-2785 E-Mail: fsaenrc.gov
Satish K Aggarwal, RES
(301) 415-6005 E-Mail: ska~nrc.gov
John R. Tappert, NRR
(301) 415-1167 E-Mail: jrt@nrc.gov
Attachments:
1. "Tested Electrical Cable Connections and Reported Test Results"
2. List of Recently Issued NRC Information Notices
Document Name: G:ISHAREDIA20-WPD
To receive copy. kidicate: "CE a CoDy wo attachment WA"
= Coov wlattachment "N" = None. NO MARK = NO COPY1
-
OFFICE
EELB:DE
EMMEB:RES-
C/EMMEB:RES 1SCEELB:DE
SC/EELB:DE
L4 NAME
FSAshe:nkw
e
M.
SKAggarwlA'
MEMayfiell/o4 PGiII
DFThatch5aV
DATE
106b/97
108 /97
1 0t)97
______
_0__
1_1
_7_97 OFFICE
SECY/EELE
IEB:DE
ADDE
l
PECB:DRPM
CPECB:DRPM
NAME
JACalvo
GCLainas
JRTappert
IRLDennig
DATE
10bz197
10/ /97
10/ /97
101 /97
11 //97 OFFICE
D/DRPM
II
NAME
JRoe
DATE
10/ /97
41
14 too
OFFICIAL RECORD COPY