Information Notice 1993-87, Fuse Problems with Westinghouse 7300 Printed Circuit Cards
.
-UNITED
STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555
November 4, 1993 NRC INFORMATION NOTICE 93-87:
FUSE PROBLEMS WITH WESTINGHOUSE 7300 PRINTED
CIRCUIT CARDS
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 alert addressees to recent failures of Westinghouse 7300 printed
circuit cards related to the use of incorrect fuses.
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.
Description of Circumstances
On April 29, 1992, at the Catawba Nuclear Station, a capacitor failed in a
Westinghouse type NAL printed circuit card. The card was used in the control
circuit for the reactor coolant system power operated relief valves (PORVs).
The fault resulted in the loss of the PORV automatic operation function on two
of the three PORVs (although operation in the manual mode was not affected),
and no alarm was initiated to alert the operator to the card failure.
The
licensee, Duke Power Company, found that the card was protected with a
5.0 ampere (A) fuse, rather than the specified 0.5 A fuse.
Had the correct
fuse been installed, it would have cleared the fault and generated an alarm.
On April 5, 1993, at the V.C. Summer Nuclear Power Station, a fuse blew in a
type NAC card in the component cooling water system. The card was used for
annunciation and safety-related automatic action for low surge tank level.
The 0.63 A fuse blew with a card load of about 1.0 A, which is within the
normal range if all of the card outputs are energized. Thus the blown fuse
was the cause of the card failure, rather than a protective response to
another fault. The licensee, South Carolina Electric & Gas Company, found
that most type NAC cards have a 2.0 A fuse, but the installed card had the
0.63 A fuse specified in an outdated drawing (Revision 6).
Discussion
Type NAL signal comparator cards are used extensively in the Westinghouse 7300
series solid state protection system and process control cabinets.
Type NAC
signal comparator cards are not used in the solid state protection system, but
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November 4, 1993 are used in the process control cabinets, particularly where Westinghouse
provided balance-of-plant control equipment.
Catawba personnel inspected the 7300 circuit cards in both units and in the
warehouse stock (approximately 1000 cards) and found 150 discrepancies in fuse
size, compared with the values specified in the instruction book.
Most
discrepancies were small (e.g., 0.5 A required vs. 1.0 A installed), but 27 of
the MA and MB fuses on type NAL cards were found to be 5.0 A fuses, rather
than the specified 0.5 A fuses.
After the Catawba inspection, Westinghouse
prepared a list of correct fuse values for the various 7300 series card types.
The list was subsequently issued by Westinghouse to all customers early in
1993 as Infogram IG 93001.
The Westinghouse drawing for a circuit card may contain several groups and
typically has undergone several revisions. Westinghouse provides each
licensee with an instruction book for each card type, which includes the
schematic diagram and bill of material for the drawing revision in effect at
that time.
(The Catawba manual for the NAL card type, for example, is dated
September 1976.)
When a licensee returns a failed card for repair, Westinghouse routinely updates the card to the then-current drawing revision.
The documentation provided typically identifies that an update was performed, and identifies the new part numbers, but does not otherwise describe the new
parts.
Thus the licensee is advised that the card was changed, but does not
know the values or other details of any new parts. Although such changes are
relatively minor, they can affect component values.
The Catawba inspection found nine card types wtth discrepant fuse values:
NAL, NCD, NCH, NCT, NLP, NMA, NRA, NSA, and NSC.
The Infogram identified six
of these types as experiencing drawing revisions that included fuse changes.
The reason for the discrepant 5.0 A fuses on NAL cards at Catawba is not
clear, but Catawba sends cards to the vendor rather than repairing onsite.
The type NAC card that failed at Summer used a fuse specified only for an
outdated revision of the card.
According to Westinghouse, at drawing
Revision 5, fuse M121 had a value of 2.0 A and would not protect certain
lower-rated components on the card.
Accordingly, Revision 6 was generated to
change to a 0.6 A fuse that would protect all of the components. At the same
time, Revision 7 was initiated to upgrade component ratings and return the
fuse value to 2.0 A. These changes took place in late 1973, whereas the
Summer cards were not shipped until May 1978.
Westinghouse Infogram IG 93001
specifies the "correct" fuse values for the seven revisions.
However, it does
not warn that in Revision 5 the fuse may not protect board-mounted components, or that the Revision 6 card may experience a blown fuse during normal plant
operation.
IN 93-87 November 4, 1993 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.
orig /s/'d by BKGrimes
Brian K. Grimes, Director
Division of Operating Reactor Support
Office of Nuclear Reactor Regulation
Technical contacts:
George T. MacDonald, RII
(404) 331-5576 Richard C. Wilson,
(301) 504-3220
Attachment:
List of Recently Issued NRC Information Notices
- See previous concurrences
- VIB:DRIL
RWilson
09/01/93
- DRS:RII
AGibson
09/08/93
- DRS:RII
GMacdonald
09/01/93
- DRIL:NRR
CRossi
09/20/93
- VIB:DRIL
GCwal ina
09/01/93
- TechEd
09/07/93
- VIB:DRIL
LNorrholm
09/02/93
- OGCB: DORS
TJKim
09/28/93
- PD2-1:NRR
SBajwa
09/13/93
- OGCB:DORS
GMarcus
10/01/93
- PD2-.3: NRR
DMatthews
09/08//
lp/i-979
OFFICIAL RECORD COPY
Document Name:
93-87.IN
'
IN 93-XX
October XX, 1993 Revision 7 was initiated to upgrade component ratings and return the fuse
value to 2.0 A. These changes took place in late 1973, whereas the Summer
cards were not shipped until May 1978.
Westinghouse Infogram IG 93001
specifies the 'correct" fuse values for the seven revisions. It does not warn
that in Revision 5 the fuse may not protect board-mounted components, or that
the Revision 6 card may experience a blown fuse during normal plant operation.
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.
Brian K. Grimes, Director
Division of Operating Reactor Support
Office of Nuclear Reactor Regulation
Technical contacts:
George T. MacDonald, RII
(404) 331-5576
Richard C. Wilson, NRR
(301) 504-3220
Attachment:
List of Recently Issued NRC Information Notices
- See previous concurrences
- VIB:DRIL
RWilson
09/01/93
- DRS:RII
AGibson
09/08/93
- DRS:RII
GMacdonald
09/01/93
- DRIL:NRR
CRossi
09/20/93
- VIB:DRIL
GCwal ina
09/01/93
- TechEd
09/07/93
- VIB:DRIL
LNorrholm
09/02/93
- PD2-1:NRR
SBajwa
09/13/93
- OGCB:DORS j%
B:DORS
TJKim
tGMarcus
09/28/93
1/93
- PD2-3:NRR
DMatthews
09/08/93 DORS:NRR
BGrimes
09/ /93
OFFICIAL RECORD COPY
Document Name:WFUSE.IN
'1Z
IN 93-XX
September XX, 1993 Revision 7 was initiated to upgrade component ratings and return the fuse
value to 2.0 A. These changes took place in late 1973, whereas the Summer
cards were not shipped until May 1978. Westinghouse Infogram IG 93001 specifies the correct fuse values for the seven revisions.
It does not warn
that in Revision 5 the fuse may not protect board-mounted components, or that
the Revision 6 card may experience a blown fuse during normal plant operation.
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.
Brian K. Grimes, Director
Division of Operating Reactor Support
Office of Nuclear Reactor Regulation
Technical contacts:
George T. MacDonald, Region II
(404) 331-5576
Richard C. Wilson, NRR
(301) 504-3220
Attachment:
List of Recently Issued NRC Information Notices
- See previous concurrences
PD2 .NRR
SB iwa
atthews
09/3 /93
09/g /93 VIB:DRIL
RWilson
09/01/93
, IN
. I-I
AGIbson
09/c?/93 DRS:RII
GMacdonald
09/01/93 VIB:DRIL
GCwalina
09/01/93 DRI jNRR
TechEd
C09/479
09/o7/93 VIB:DRIL
LNorrholm
09/02/93 OGCB:D4RS
TJK0 m
e
09,A2/93 OGCB:DORS
GMarcus
09/ /93 DORS:NRR
BGrimes
09/ /93
OFFICIAL RECORD COPY
Document Name:WFUSE.IN
-1i
IN 93-XX
September XX, 1993
value to 2.0 A. These changes took place in late 1973, whereas the Summer
cards were not shipped until May 1978. Westinghouse Infogram IG 93001 specifies the "correct" fuse values for the seven revisions. It does not warn
that in Revision 5 the fuse may not protect board-mounted components, or that
the Revision 6 card may experience a blown fuse during normal plant operation.
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.
Brian K. Grimes, Director
Division of Operating Reactor Support
Office of Nuclear Reactor Regulation
Technical contacts:
George S. MacDonald, Region II
(404) 331-5576
Richard C. Wilson, NRR
(301) 504-3220
Attachment:
List of Recently Issued NRC Information Notices
OFFICE
VIB/DRIL
REGION IInal
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BC VhV
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TECHED
NAME
RWILSON
GMACDONALD
GA
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DATE
9 /93
9/ 1/93
9/1 /93
9/
9/ /93 lCOPY
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YES
YES
NO
NO
OFFICE
D/DRS/RII
D/DRIL/NRR
BC/OGC/DORS
D/DORS
NAME
AFGIBSON
CEROSSI
GMARCUS
BKGRIMES
DATE
9/ /93
9/ /93
9/ /93
9/ /93 l
COPY
YES
NO
YES
NO
YES
NO
YES
NO
Y
-
-
.ar..TLr*I
OFFICIAL RECORD COPY
Document Name:WFUSE-IN
.
~IN
93-87 November 4, 1993 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.
Brian K. Grimes, Director
Division of Operating Reactor Support
Office of Nuclear Reactor Regulation
Technical contacts: George T. MacDonald, RII
(404) 331-5576
Richard C. Wilson, NRR
(301) 504-3220
Attachment:
List of Recently Issued NRC Information Notices
I
Attachment
November 4, 1993
Page I of I
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LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issuance
Issued to
93-86 Identification of Iso-
10/29/93
All holders of OLs or CPs
topes in the Production
for test and research
and Shipment of Byproduct
reactors.
Material at Non-power
Reactors
)385 Problems with X-Relays
10/20/93
All holders of OLs or CPs
in DB- and DHB-Type
for nuclear power reactors.
Circuit Breakers Manu- factured by Westinghouse
93-84 Determination of Westing-
10/20/93
All holders of OLs or CPs
house Reactor Coolant
for pressurized water
Pump Seal Failure
reactors (PWRs).
93-83 Potential Loss of Spent
10/07/93
All holders of OLs or CPs
Fuel Pool Cooling
for boiling water reactors
Following A Loss of
(BWRs)
Coolant Accident (LOCA)
93-82 Recent Fuel and Core
10/12/93
All holders of OLs or CPs
Performance Problems in
for nuclear power reactors
Operating Reactors
and all NRC-approved fuel
suppliers.
93-81 Implementation of
10/12/93
All holders of OLs or CPs
Engineering Expertise
for nuclear power reactors.
on Shift
93-80
Implementation of the
10/08/93
All byproduct, source, and
Revised 10 CFR Part 20
licensees.
93-79 Core Shroud Cracking at
09/30/93
All holders of operating
Beltllne Region Welds
licenses or construction
in Boiling-Water Reactors
permits for boiling-water
reactors (BWRs).
93-78 Inoperable Safety Systems
10/04/93
All holders of OLs or CPs
At A Non-Power Reactor
for test and research
reactors.
OL - Operating License
Construction Permit
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