Information Notice 1988-27, Deficient Electrical Terminations Identified in Safety-Related Components
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555
May 18, 1988 NRC INFORMATION NOTICE NO. 88-27: DEFICIENT ELECTRICAL TERMINATIONS
IDENTIFIED IN SAFETY-RELATED COMPONENTS
Addressees
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose
This information notice is being provided to alert addressees of deficiencies
identified in electrical terminations in safety-related components. It is ex- pected 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 do not constitute
NRC requirements; therefore, no specific action or written response is required.
Description of Circumstances
The Nuclear Regulatory Commission (NRC) has been notified of several recently
identified deficiencies in electrical terminations in safety-related components
that, if they had remained uncorrected, would have jeopardized the ability of
these components to perform their intended safety function. These deficiencies
were identified at River Bend Station, Unit 1; Shoreham Nuclear Power Station;
Vermont Yankee Nuclear Power Station; and Oyster Creek, Unit 1.
River Bend Station, Unit 1
On January 19, 1988, the Gulf States Utility Company (GSU) submitted a notifica- tion to the NRC, pursuant to 10 CFR Part ?1, regarding oversized motor operator
termination lugs in three main steam shutoff valves and two feedwater isolation
valves.
GSU reported that during functional testina of a main steam shutoff
valve on December 7, 1987, the valve motor operator experienced a high current
surge, which tripped its motor overload heater and prevented the valve from
fully closing. During GSU's investigation, two motor leads were found burned
and separated from the lugs. A third lug was easily pulled from the motor lead
by GSU personnel after they removed the heat shrink insulation. The lugs were
found to be oversized for the motor lead conductors. In addition, during mainte- nance on a feedwater isolation valve, a lug on one motor lead was found to be
8852C
at
IN 88-27 May 18, 1988 oversized for the conductor and not crimped.
These lugs were manufactured by
Thomas & Betts. They were marked "T&B Navy 23-30 E-611 and were sized for use
with a #5-#6 AWG conductor. The actual motor leads were #10 AWG stranded
conductors.
Further investigation by GSU personnel found that both valves used Llmitorque
SMB-4 motor operators with terminal blocks that had one-ouarter-inch diameter
terminal screws. The lugs were the correct size for the one-quarter-inch screw, but not for the conductor. All SMB-4 operators used in safety-related applica- tions were inspected by the licensee to determine lug size. Ten SMB-4 operators
were inspected, and five were found with oversized lugs that were deemed unre- liable by the licensee, although they passed their surveillance requirements.
GSU personnel replaced the defective lugs with correctly sized lugs. GSU is
also revising its procedures for inspecting Limitorque motor operators when they
are received to include inspection of lug size on the motor leads to prevent re- currence of this condition, since the defective wire lugs were contained in valve
operators supplied by the Limitorque Corporation during the construction of River
Bend Station.
In a separate 10 CFR Part 21 notification dated December 23, 1987, GSU reported
that several defective terminations were identified in electrical heater panels
supplied by NUTHERM International, Inc. The defective wire terminations were
in heater panel circuits of the fuel storage building engineered safety feature
charcoal filters. The deficiency involved improper stripping of conductors that
resulted in insulation under the termination lugs. This insulation inhibited a
good connection and Jeopardized the ability of the filters to perform their
function. GSU reported that it had notified NUTHERM International of the defect.
Shoreham Nuclear Power Station
On October 19, 1987, the Long Island Lighting Company (LILCO) submitted a
notification to the NRC pursuant to 10 CFR Part 21 regarding inadequately
crimped termination lugs discovered at the Shoreham Nuclear Power Station.
The subject lugs, which were manufactured by AMP Special Industries, were
installed in control wiring in 4160-volt switchgear equipment manufactured
by the General Electric Company (GE).
The licensee discovered that many of
the GE-installed termination lugs were inadequately crimped to the control
wires and, in some cases, the lugs could be removed by hand.
When LILCO
personnel inspected these lugs in equipment supplied by GE, they found that
of approximately 1400 lugs installed by GE, 42% had to be replaced.
GE determined that its personnel had deviated from the crimp process described
in their installation procedures during the manufacture of the equipment.
There- fore, the insulation around the control wires was not properly stripped before
beinq inserted into the AMP lugs and an AMP crimper was not used as required.
GE also determined that this problem was limited to equipment supplied to
IN 88-27 May 18, 1988 Shoreham and Salem.
GE stated that it had notified both facilities of the
problem and that its personnel had been requalified on the proper crimping
procedures to preclude any further similar incidents.
Vermont Yankee Nuclear Power Station
On September 28, 1987, Vermont Yankee Nuclear Power Station (Vermont Yankee)
personnel were conducting pre-startup operability tests on the residual heat
removal (RHR) pumps and core spray pumps.
During the operability tests, the
"B" RHR pump motor experienced severe arcing problems and was quickly secured, preventing damage to the motor windings.
Vermont Yankee personnel investigated the problem and found that the arcing
resulted from a failed AMP motor lead to power lead termination lug. Motor
lead and power lead termination lugs were subsequently Inspected on three other
RHR pumps and core spray pumps fitted with AMP lugs. Termination lugs manu- factured by Thomas & Betts (TABR
that are used on RHR service water pumps and
station service water pumps also were inspected. These inspections identified
evidence of cracking of varying severity on seven AMP motor lead termination
lugs; however, no cracks were found on power lead terminations.
Little or no
cracking was identified on terminations manufactured by T&B. The AMP motor
lead termination lugs were of the ring tongue type, #2 AWG, model #35184, manufactured by AMP Special Industries. The terminations were supplied in
conjunction with the motors by GE.
Several of the cracked lugs were discovered by direct visual inspection, while
the remainder were identified using IOX magnification and/or dye penetrant
testing. During inspection of the lugs, it appeared that the manufacturer's
stamping on the throat of the lug contributed to the observed cracking because
a shallow "AMP" die stamp was found at the throat section of the lug. A stamp
(a numeral 1, 2, or 3) on the opposite side of the throat, believed to be a
phase indication, was also suspected of being a contributor.
The cracking
identified on these luqs was ultimately attributed to excessive bending during
maintenance activities, with the manufacturer's stamping providing pre-stressed
flaws for crack initiation and propagation.
The small cramped work space inside
the motor terminal housings, coupled with the rigidity of the required Raychem
splices, contributed to fatiguing the lugs during maintenance activities.
Oyster Creek, Unit 1
GPU Nuclear Corporation (GPUNC) submitted Licensee Event Report (LER) 219-87-011, Revision 1, to the NRC on May 4, 1987, regarding deficient electrical terminations
at Oyster Creek, Unit 1. GPUNC reported that on February 10, 1987, an electrical
technician who was verifying proper wiring connections inadvertently moved a wiring
harness in a control room panel. This movement disconnected the "A" feedwater
flow rate signal wire and initiated a sequence of events that resulted in a
IN 88-27 May 18, 1988 turbine trip and an anticipatory scram. On February 26, 1987, an electrical
technician, performing an Inspection of wire terminations In response to the
previous event, disturbed a wire that caused the automatic closure of the main
steam isolation valves.
The GPUNC investigation determined that the cause of the first event was in- sufficient procedural controls over wire termination practices. The wire
terminations used in the control room panel were compression-type terminations, which capture wires under a metal plate compressed by a screw, rather than
lug-type terminations. GPUNC personnel found that different size wires were
used in the same termination and that sometimes the plate in the compression
terminations was removed when wires were too large to fit under the plate. The
GPUNC investigation also found terminations with cracked or broken pressure
plates, as well as wires that were unlabeled, unterminated, and uninsulated.
Furthermore, GPUNC personnel discovered that.when new cables were pulled to
support modification work, existifng wire terminations were stressed by the new
wires that lay on top of the original wiring.
The second event was attributed to faulty wire installation, either during
plant construction or during subsequent maintenance.
Inspection of the wire
termination showed that the screw used to fasten the wire was loose. Movement
of this wire caused four relays to deenergize, resulting in automatic closure
of the main steam isolation valves.
GPUNC personnel identified and corrected a total of 123 deficient terminations, both compression-type and lug-type. GPUNC has revised its Installation Speci- fications for wire terminations and Quality Assurance Procedures for inspecting
wire terminations to ensure and verify proper electrical terminations. These
revisions will ensure that an adequate structural integrity of the termination
exists, require that a post-modification and maintenance tug test be performed, and eliminate the practice of terminating two wires with significant cauqe
differences in compression-type terminations unless it Is endorsed by the
termination manufacturer.
In addition, GPUNC Indicated that It was in the
process of Identifying those terminations that are frequently accessed for
surveillance and maintenance purposes and will install test connections to
minimize movement and stress on the terminations.
Discussion:
These examples emphasize the need to carefully monitor the receipt, Instal- lation, and maintenance of safety-related components with respect to their
cable or wire terminations.
Licensees may wish to review their current receipt, installation, and maintenance procedures to assure that proper ouality controls
and measures exist to preclude such events as those discussed above.
IN 88-27 May 18, 1988 No specific action or written response is required by this information
If you have any questions about this matter, please contact one of the
contacts listed below or the Regional Administrator of the appropriate
office.
notice.
technical
regional
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contacts:
Jaime
(301)
Guillen, NRP
492-1153
Carl S. Schulten, NRR
(301) 492-1192 Attachment:
List of Recently Issued NRC Information Notices
Attachment
May 18, 1988 LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issuance
Issued to
85-35,
Supplement 1
Failure of Air Check
Valves to Seat
5/17/88
All holders of OLs
or CPs for nuclear
power reactors.
88-26
88-25
88-24
88-23 Falsified Pre-Employment
Screening Records
Minimum Edge Distance for
Expansion Anchor Rolts
Failures of Air-Operated
Valves Affecting Safety-
Related Systems
Potential for Gas Binding
of High-Pressure Safety
Injection Pumps During a
Loss-of-Coolant Accident
Disposal of Sludge from
Onsite Sewage Treatment
Facilities at Nuclear
Power Stations
Inadvertent Criticality
Events at Oskarshamn
and at U.S. Nuclear
Power Plants
Unauthorized Individuals
Manipulating Controls and
Performing Control Room
Activities
5/16/88
5/16/88
5/13/88
5/12/88
5/12/88
5/9/88
5/5/88
All holders of OLs
or CPs for nuclear
power reactors and
all major fuel
facility licensees.
All holders of OLs
or CPs for nuclear
power reactors.
All holders of OLs
or CPs for nuclear
power reactors.
All holders of OLs
or CPs for PVWRs.
All holders of OL.s
or CPs for nuclear
power reactors.
All holders of OLs
or CPs for nuclear
power reactors.
All holders of OLs
or CPs for nuclear
power, test and
research reactors, and all licensed
operators.
88-22
88-21
88-20
OL = Operating License
CP = Construction Permit
IN 88-27 May 18, 1988 No specific action or written response is required by this information
If you have any questions about this matter, please contact one of the
contacts listed below or the Regional Administrator of the appropriate
office.
noti ce.
technical
regional
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contacts:
Jaime Guillen, NRR
(301) 492-1153
Carl S. Schulten, NRR
(301) 492-1192 Attachment:
List of Recently Issued NRC Information Notices
Initially transmitted by memorandum dated November 20, 1987, to C. H. Berlinger
from W. D. Lanning
- SEE PREVIOUS CONCURRENCES
05//V88
- C/OGCB:[OEA:NRR *PPMB:ARM
- DRP:RI
CHBerlinger
TechEd
WFKane
05/10/88
02/29/88
03/ /88
- OGCB:DOEA:NRR *OEAB:DOEA:NRR*SC/OEAB:DOEA:NRR
JGuillen
CSchulten
PWBaranowsky
03/02/88
03/03/88
03/03/88
- D/DEST:NRR
LCShao
04/13/88
- C/EAB:DOEA:
WDLanning
03/31/88
- SAD/DEST:NRR
AThadani
04/12/88 NRR*C/SELB:DEST:NRR
FRosa
03/21/88
IN 88-XX
May xx, 1988 No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the technical
contact listed below or the Regional Administrator of the appropriate regional
office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Jainme Guillen, NRR
(301) 492-1153
Carl S. Schulten, NRR
(301) 492-1192 Attachment:
List of Recently Issued NRC Information Notices
Initially transmitted by memorandum dated November 20, 1987, to C. H. Berlinger
from W. D. Lanning
- SEE PREVIOUS CONCURRENCES
D/DOEA:NRR
CERossl
05/ /88 C
/OGCB:DOEA:NRR *PPMB:ARM
- DRP:RI
CHBerlinger
TechEd
WFKane
05/10/88
02/29/88
03/ /88
- OGCB:DOEA:NRR *OEAB:DOEA:NRR*SC/OEAB:DOEA:NRR
JGuillen
CSchulten
PWBaranowsky
03/02/88
03/03/88
03/03/88
- D/DEST:NRR
- SAD/DEST:NRR
LCShao
AThadani
04/13/88
04/12/88
- C/EAB:DOEA:NRR*C/SELB:DEST:NRR
WDLanning
FRosa
03/31/88
03/21/88
IN 88-XX
March xx, 1988 No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the technical
contact listed below or the Regional Administrator of the appropriate regional
office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Jaime Guillen, NRR
(301) 492-1153
Carl S. Schulten, NRR
(301) 492-1192 Attachment:
List of Recently Issued NRC Information Notices
Initially transmitted by memorandum dated November 20, 1987, to C. H. Berlinger
from W. D. Lanning
- SEE PREVIOUS CONCURRENCES
D/DOEA:NRR
CERossi
03/ /88 C/OGCB:DOEA:NRR
CHBerlinger
03/ /88
- OGCB:DOEA:NRR
JGuillen
03/02/88
- PPMB:ARM
DRI
TechEd
WFKane
02/29/88
03/ /88 '
- OEAB:DOEA:NRR*SC/OEAB:DOEA:NRR
CSchulten
PWBaranowsky
03/03/88
03/03/88
.:NRR
FRosa
03/21/88
IN 88-XX
March xx, 1988 No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the technical
contact listed below or the Regional Administrator of the appropriate regional
office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Jaime Guillen, NRR
(301) 492-1153
Carl S. Schulten, NRR
(301) 492-1192 Attachment:
List of Recently Issued NRC Information Notices
Initially transmitted by memorandum dated November
from W. D. Lanning
20, 1987, to C. H. Berlinger
- SEE PREVIOUS CONCURRENCES
JGui len
03/X 88 DR :
WF
ne
/
/88 OEA P9E- :NRR
Cs
03 5 /88
- PPMB:ARM
TechEd
02/29/88 D/DOEA:NRR
CERossi
03/ /88
^~
Piar~'ows ky
0313 /88 C/OGCB:DOEA:NRR
CHBerlinger
4&03/4v/88 C/SELB: OSw RR
FRosa V
03/2#/88
IN 88-XX
February xx, 1988 No specific action or written response is required by this infonmation notice.
If you have any questions about this matter, please contact the technical
contact listed below or the Regional Administrator of the appropriate regional
office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Jaime Guillen, NRR
(301) 492-1153 Attachment:
List of Recently Issued NRC Information Notices
Initially transmitted by memorandum dated November
from W. D. Lanning
20, 1987, to C. H. Berlinger
D/DOEA:NRR
CERossi
02/ /88 C/SELB:DEST:NRR
FRosa
02/ /8F
C/OGCB:DOEA:NRR
CHBerlinger
021 /88 DRP:RI
WFKane
02/ /88 OGCB:DOEA:NRR
JGuillen
02/ /88 OEAB:DOEA:NRR
CSchulten
02/ /88 PPMB:ARM
TechEd 42?
02/a2/88