Information Notice No. 82-54: Westinghouse NBFD Relay Failures in Reactor Protection Systems
SINNS No.: 6835
IN 82-54
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D. C. 20555
December 27, 1982
Information Notice No. 82-54: WESTINGHOUSE NBFD RELAY FAILURES IN
REACTOR PROTECTION SYSTEMS
Addressees:
All holders of a nuclear power reactor operating license (OL) or
construction permit (CP).
Purpose:
This information notice is provided as an early notification of a
potentially significant problem pertaining to a certain "batch" of
Westinghouse (W) NBFD relays used in the reactor protection system and
engineered safeguards systems. This problem may affect both PWR and BWR
facilities. The Nuclear Regulatory Commission (NRC) staff is reviewing the
problem and its effects. If the evaluation so indicates, the NRC may request
further licensee action. In the interim, we expect the addressees of this
information notice to review the information herein for applicability to
their facilities and to take appropriate actions. No specific action or
response is required at this time.
Description of Circumstances:
Wisconsin Electric Power Company (WEPC) issued Licensee Event Report 82-
026/OIT-0 on December 7, 1982, notifying the NRC that replacement relays and
coils for W NBFD relays installed at Point Beach Unit 1 have experienced a
higher-than-expected failure rate following post-installation tests.
According to the licensee, failure was attributed to coil filler epoxy which
flows during service into the plunger cavity, inhibiting or preventing the
relay from moving to a de-energized position after power is removed. The
relays had been replaced to correct deficiencies discussed in IE Information
Notice 82-02.
After reviewing the above problem, Westinghouse has issued a technical data
letter via an electronic mailgram to all sites having a W Resident Engineer,
and has made telephone contact with those W PWRs that do not have a
permanent W Resident Engineer. An extract from the latest version of this
technical data letter is attached for your information and appropriate use.
The technical data letter discusses the problem and provides inspection and
test methods for verifying operability of normally energized and
de-energized NBFD relay applications in safety-related systems. The
technical data letter recommends that after completing the initial
inspection/test of all NBFD relays received after October 29, 1981, these
normally energized relays be retested weekly until the "sticking" problem is
resolved. The technical data letter also provides the relay coil style
number to facilitate identification of the potentially affected relays.
8208190275
.
IN 82-54
December 27, 1992
Page 2 of 2
Since the NBFD relay is not unique to W PWR power plants, the problem may
also exist at other nuclear power plants. Therefore, we advise all nuclear
plants to review their safety-related systems to ascertain whether NBFD
relays received after October 21, 1981 have been installed, or are being
held as spare parts.
If you have any questions regarding these matters, please contact the
administrator of the appropriate Regional Office or this office.
Edward L. Jordan, Director
Division of Engineering & Quality Assurance
Office of Inspection and Enforcement
Technical Contact: V. D. Thomas
301-492-4755
Attachments:
1. Extract from Westinghouse Technical Letter
2. List of Recently Issued IE Information Notices
.
Attachment 1
IN 82-54
December 27, 1982
Page 1 of 2
EXTRACT FROM WESTINGHOUSE TECHNICAL DATA LETTER "NBFD RELAYS" DATED
DECEMBER 9, 1982.
ALL PLANTS WITH NBFD RELAYS IN I&C PROTECTION SYSTEM
The following information is provided as a recommendation from Westinghouse
as to a representative procedure which may be conducted to assure proper
operation of certain NBFD relays. You may have additional information
concerning previous operational history of the subject relays coupled with
comparable testing programs that are already implemented and would provide
you sufficient assurance of proper operations. Response time testing of the
relays which you may have included in your test program would also provide
important information to support your evaluation of the performance of these
relays.
Whichever choice you make with regard to testing of these relays, please
forward the test data and program information to Westinghouse for our
information during our continuing review of this problem. We will keep you
advised of our progress and the outcome of our evaluation.
Recent information indicates that there is a possibility of sluggish
operation of NBFD relays when they are de-energized. The following are
Westinghouse interim recommendations pending final resolution of this
possible problem with the NBFD relay coils. They apply to all plants having:
1. Installed NBFD relay coils bearing style No. 1293C51G01
2. Installed NBFD relay coils received after October 29, 1981: or
3. Installed NBFD relay coil whose vintage cannot be identified.
Previous information or instructions provided concerning this potential
problem with NBFD relays is superseded by this notice.
IMMEDIATE ACTION
Perform a complete test of the reactor trip system in accordance with
surveillance test procedures to confirm operability of normally energized
NBFD relays which open the reactor trip breakers or which provide power
level permissive signaling such as P-7.
At that step in the procedure where the relay is de-energized, manually
depress and release the contact block actuation buttons several times. The
movement should be positive, free and unrestricted. Any abnormal resistance
during depression of the buttons or sluggish non-snapping return of the
buttons upon release should be considered evidence that the plunger is
binding. In such cases refer to the CORRECTIVE ACTION section of this
notice. In conjunction
.
Attachment 1
IN 82-54
December 27, 1982
Page 2 of 2
with the relay functional tests, all relay cabinets should be visually
examined for indications within the rack of molten or soft epoxy flowing out
of the relay housings. All normally energized reactor trip and permissive
relays in this system must be tested.
During this interim period, all tests on these relays should be conducted
weekly.
Normally de-energized NBFD relays associated with initiation of safeguards
should be manually tested and visually examined as described above, but with
proper coordination with plant operators to block actuation of the final
device where necessary. The weekly tests on normally energized relays should
not be required for the safeguards normally de-energized relays. However, in
the event that the normally de-energized relays are energized for an
extended period of time, the possibility exists for the plunger to bind and
prevent smooth, quick return to the de-energized mode. Station operators
should be alerted to the potential need for manual intervention should a
safeguards relay bind up and fail to return to the de-energized state.
In the event that battery equalizing is necessary during this interim
period, the tests of the normally energized reactor trip and permissive
relays should be conducted immediately following the battery equalization
cycle.
CORRECTIVE ACTION
Any relay coil found to have sluggish or restricted plunger travel or any
evidence of uncured epoxy must be replaced. Before installing any
replacement coil with style #1293C51G01, the coil should be oven heated at
no less than 200 degrees Fahrenheit for no less than 2 hours and visually
inspected for evidence of flow of the black filler epoxy. The coil bore
should also be carefully inspected. After installation of oven heated coils
into the relay assembly, electrical and manual tests should be conducted
periodically to confirm proper operation.
All suspect coils may be returned to Westinghouse for replacement.
Westinghouse plans to test our current stock for use in replacing previously
shipped suspect coils.
Page Last Reviewed/Updated Tuesday, March 09, 2021
Page Last Reviewed/Updated Tuesday, March 09, 2021