Part 21 Report - 1995-174
ACCESSION #: 9507260097
SCE
Southern California Edison Company
P. O. Box 128
SAN CLEMENTE, CALIFORNIA 92674-0128
RICHARD M. ROSENBLUM TELEPHONE
VICE PRESIDENT 714-368-1460
July 21, 1995
U. S. Nuclear Regulatory Commission
Document Control Desk
Washington, D.C. 20555
Dear Sir:
Subject: Part 21 Report, Potter & Brumfield (P&B) MDR Relays
San Onofre Nuclear Generating Station, Units 2 and 3
Reference: P&B Letter of June 28, 1995 to SCE and other affected
companies; "MDR Relays With Potentially Damaged Internal
Contact Arms"
This letter provides notification to the NRC concerning a defect found in
P&B Model 5095 Motor Driven Relays (MDR). Since the vendor supplies
these relays as commercial grade items and they are dedicated for Nuclear
Service by SCE, this letter provides Edison's 10 CFR Part 21 report on
the subject. The referenced letter provides P&B customer notification of
possible improper reassembly of several different models of P&B relays.
The improper reassembly involves internally damaged (bent) contact arms
that could adversely effect relay interrupt capability, dielectric
capability, reliability and life expectancy. The problem is potentially
applicable to any MDR relay returned to P&B for rework or disassembly
between March, 1993 and March, 1995.
The vendor/manufacturer findings are based on inspection and testing of
several P&B Model 5095 MDR relays conducted at the SCE Commercial Grade
Inspection (CGI) Laboratory on June 5-6, 1995. The defective contact
arms could prevent the proper opening or closing of certain relay
contacts and thus cause the relay to malfunction in a safety-related
application depending on the design use of the relay. The enclosure to
this letter provides the information available to SCE concerning the
defect as specified by 10 CFR Part 21 reporting requirements.
If you have any further questions, please contact me.
Sincerely,
R. M. Rosenblum
Vice President, Engineering & Technical Services
Enclosure
cc: L. J. Callan, Regional Administrator, NRC Region IV
A. B. Beach, Director, Division of Reactor Projects, Region IV
K. E. Perkins, Jr., Director, Walnut Creek Field Office, NRC Region
IV
J. A. Sloan, NRC, Senior Resident Inspector, San Onofre Units 2 and
3
M. B. Fields, NRC Project Manager, San Onofre Units 2 and 3
SCE
ENCLOSURE
10 CFR Part 21 Report on P&B MDR Relays
1. Name & address of notifier:
R. M. Rosenblum
Vice President, Engineering & Technical Services
Southern California Edison
Box 128
San Clemente, CA 92672
2. Facility name:
San Onofre Nuclear Generating Station, Units 2 & 3
3. Component supplier
Potter & Brumfield Inc. (A Siemens Co.)
Chapel Hill Road
Marion, KY 42064
4. Nature of defect:
During initial commercial grade dedication of thirty-three Model
5095 MDR relays, excess epoxy was discovered in and around the
stators of nine test sample relays. The entire batch of thirty-
three relays (including ten which had been destructively tested at
SONGS) were hand-carried back to the P&B factory in Marion, Kentucky
for rework in November of 1993. Following clean-up of the epoxy and
reassembly of the twenty-three operable relays, normal testing was
performed on each relay at the factory. Four relays failed the
factory test and were not accepted by the attendant SONGS engineer.
One of the nineteen relays returned to SONGS failed the coil
resistance check during acceptance testing and was rejected for
safety related use. Seven of the remaining eighteen relays were
subsequently installed in safety related systems at Units 2 and 3.
Six went into the containment pressure sensing isolation lines at
both units and one into the charging pump to regenerative heat
exchanger isolation valve at Unit 3. Nine relays underwent
destructively testing and two remain in stock under quarantine.
SCE
Disassembly and close inspection of nine of the eighteen reworked
Model 5095 P&B MDR relays at the San Onofre CGI Lab revealed some
bent contact arms in the relays. There are fourteen contact arms
per relay and between three and seven arms were bent in each relay.
It was determined that these arms had been bent during reassembly of
the relays at P&B in November of 1993. Extensive testing and
examination of thirty-six P&B MDR relays has shown the defective
contact arms were restricted to the factory reworked relays.
The bent arms could conceivably cause a contact to fail to open or
close whenever it changed state or have inadequate interrupt
capability because of an improper gap opening. Such failures could,
in turn, cause or prevent the proper operation of safety related
equipment depending on how the relay was designed into the system.
5. Date defect discovered:
June 28, 1995, when P&B issued a notification letter to all MDR
relay users that had returned relays for factory rework during the
time frame of March, 1993 to March, 1995. The reassembly defect
occurred at the new Marion facility following the P&B move from
Princeton, Indiana.
6. Component location:
Seven of eighteen returned relays were subsequently installed in
safety-related systems of the SONGS plants. Three in Unit 2 (2HV-
0352C, 2HV-0352D & 2HY9200) and four in Unit 3 (3HV-0352A, B, C &
D).
The most limiting application for these seven MDR relays is in the
control circuits of Valcor solenoid valves which isolate containment
pressure transmitter sensing lines at Units 2 & 3. The solenoid
valves are normally open and remain open during accident conditions
inside the containment. These valves are only required to close in
order to isolate a sensing line failure or loss of pressure boundary
in the transmitter.
7. Corrective actions:
The two spare Model 5095 relays have been quarantined and the seven
installed relays will be replaced per NCR 95030035 at the earliest
opportunity following procurement of replacements. The next
production run for this type of relay is scheduled for late August
1995. SCE will send an engineer familiar with past MDR relay
problems to the Marion facility to oversee assembly and testing of
the relays as part of the procurement package.
SCE
8. Other pertinent information:
The seven installed P&B MDR relays at SONGS remain operable as
highlighted in NCR 95030035. That evaluation is based on positive
dedication testing response, system design use, successful
installation post-maintenance testing and past operating experience
with other relays used in this type application.
POWER REACTOR EVENT NUMBER: 29096
FACILITY: SAN ONOFRE REGION: 4 NOTIFICATION DATE: 07/21/95
UNIT: [ ] [2] [3] STATE: CA NOTIFICATION TIME: 20:45 [ET]
RX TYPE: [1] W-3-LP, [2] CE, [3] CE EVENT DATE: 07/21/95
EVENT TIME: 00:00 [PDT]
NRC NOTIFIED BY: RILEY LAST UPDATE DATE: 07/21/95
HQ OPS OFFICER: TIM McGINTY
NOTIFICATIONS
EMERGENCY CLASS: NOT APPLICABLE
10 CFR SECTION:
CCCC 21.21 UNSPECIFIED PARAGRAPH
UNIT SCRAM CODE RX CRIT INIT PWR INIT RX MODE CURR PWR CURR RX
MODE
2 N Y 100 POWER OPERATION 100 POWER OPERATION
3 N Y 83 POWER OPERATION 83 POWER OPERATION
EVENT TEXT
SAN ONOFRE PROVIDED A PART 21 REPORT REGARDING POTTER & BRUMFIELD
(P&B)
MODEL-5095 MOTOR-DRIVEN RELAYS (MDR). SAN ONOFRE WAS NOTIFIED BY
P&B OF
POSSIBLE IMPROPER RE-ASSEMBLY OF SEVERAL DIFFERENT MODELS OF P&B
RELAYS.
THE IMPROPER RE-ASSEMBLY INVOLVES INTERNALLY DAMAGED (BENT)
CONTACT ARMS
THAT COULD ADVERSELY EFFECT RELAY INTERRUPT CAPABILITY, DIELECTRIC
CAPABILITY, RELIABILITY, AND LIFE EXPECTANCY. THE PROBLEM IS
POTENTIALLY
APPLICABLE TO ANY MDR RELAY RETURNED TO P&B FOR REWORK OR
DISASSEMBLY
BETWEEN MARCH 1993 AND MARCH 1995.
POTTER & BRUMFIELD INC. (A SEIMENS CO.) IS LOCATED IN MARION, KY. SEVEN
OF EIGHTEEN RELAYS RETURNED FROM P&B TO SONGS WERE SUBSEQUENTLY
INSTALLED
IN SAFETY-RELATED SYSTEMS OF THE SONGS PLANTS. THE MOST LIMITING
APPLICATION OF THESE SEVEN MDR RELAYS IS IN THE CONTROL CIRCUITS OF
VALCOR SOLENOID VALVES WHICH ISOLATE CONTAINMENT PRESSURE
TRANSMITTER
SENSING LINES AT UNITS 2 AND 3. THE SOLENOID VALVES ARE NORMALLY
OPEN
AND REMAIN OPEN DURING ACCIDENT CONDITIONS INSIDE THE CONTAINMENT.
THESE
VALVES ARE ONLY REQUIRED TO CLOSE IN ORDER TO ISOLATE A SENSING LINE
FAILURE OR LOSS OF PRESSURE BOUNDARY IN THE TRANSMITTER. THE SEVEN
INSTALLED RELAYS WILL BE REPLACED AT THE EARLIEST OPPORTUNITY
FOLLOWING
PROCUREMENT OF REPLACEMENTS. THE SEVEN INSTALLED P&B MDR RELAYS
AT SONGS
REMAIN OPERABLE AT THIS TIME BASED ON POSITIVE DEDICATION TESTING
RESPONSE, SYSTEM DESIGN USE, SUCCESSFUL INSTALLATION
POST-MAINTENANCE
TESTING, AND PAST OPERATING EXPERIENCE WITH OTHER RELAYS USED IN THIS
TYPE APPLICATION.
THE HOO FORWARDED THE PART 21 NOTIFICATION TO VERN HODGE.
*** END OF DOCUMENT ***
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Page Last Reviewed/Updated Wednesday, March 24, 2021