Bulletin 88-03: Inadequate Latch Engagement in HFA Type Latching Relays Manufactured by General Electric (GE) Company
OMB No.: 31500011
NRCB 88-03
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555
March 10, 1988
NRC BULLETIN NO. 88-03: INADEQUATE LATCH ENGAGEMENT IN HFA TYPE
LATCHING RELAYS MANUFACTURED BY GENERAL
ELECTRIC (GE) COMPANY
Addressees:
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose:
The purpose of this bulletin is to request that licensees perform inspections
to ensure that all GE latching-type HFA relays installed in Class 1E (safety-
related) applications have adequate latch engagement and that those relays
which fail to meet acceptance criteria be repaired or replaced.
Description of Circumstances:
GE Meter and Control Business Department (MCBD) investigated a report dated
October 7, 1987 from their Nuclear Energy Business Operation that certain
latch-type relays supplied by GE with Certificates of Conformance, qualifying
them to the requirements of IEEE-323, "IEEE Standard for Qualifying Class 1E
Equipment for Nuclear Power Generating Stations," which includes IEEE-344,
"IEEE Recommended Practices for Seismic Qualification of Class 1E Equipment
for Nuclear Power Generating Stations," were malfunctioning. MCBD informed
the NRC of this problem in accordance with 10 CFR Part 21 on November 12, 1987
(attached) and sent a letter dated November 16, 1987 to all purchasers of HFA
151B, 154B, and 154E type latching relays who had specified Class 1E or
equivalent on their purchase order. Although GE reported that they have
informed all their customers who purchased the relays as Class 1E components,
there may be "Other Equipment Manufacturers" who purchased these relays as
commercial grade components and then installed them in panels and certified
them as Class 1E components on the basis of analysis. GE MCBD has halted
production of these relays pending resolution of this problem.
The NRC believes that the operability of all HFA 151B, HFA 154B and HFA 154E
relays with a manufacturing date code prior to November, 1987 has been brought
into question and therefore the relays should be inspected. Also, the
following
8803040062
. NRCB 88-03
March 10, 1988
Page 2 of 4
additional latching-type HFA relays which were not qualified to IEEE-323 by
GE, but which may have been qualified and used by "Other Equipment
Manufacturers" in Class 1E, (safety-related) applications may also be suspect:
Non-Century Series Century Series
Types HFA 54 HFA 154
HFA 74 HFA 174
HFA 51B HFA 151B
HFA 71B HFA 171B
In GE latching-type HFA relays, when the coil is energized, the armature
operates a latch which locks in the change in the state of the contacts and
holds them in that state once the relay is de-energized until such time that
the relay is mechanically or electrically reset. GE MCBD determined that when
the relay is energized, with the armature in the latched position, each leg of
the U-shaped latch should engage the top of the armature by the required
minimum of 1/32 inch. With less than 1/32 inch latch engagement, it is possi-
ble that the relay could unlatch prematurely. GE MCBD concluded that two
circumstances can cause latch engagement to be less than 1/32 inch:
(1) Insufficient clearance between the top of the relay armature and the top
of the moving contact carrier and, (2) Insufficient tension provided by the
formed leaf spring that rotates the latch to its fully engaged position, which
may permit the spring to relax before full engagement between the latch and
the armature is achieved.
Actions Requested:
Addressees should complete the actions described below for all latching-type
HFA relays in Class 1E (safety-related) applications no later than restart
following the next refueling outage scheduled to begin 30 days or more from
receipt of this bulletin.
1) In accordance with the GE recommendation contained in Attachment 1,
measure the distance between the top of the molded contact carrier and
the top of the relay armature. This distance should be a minimum of 1/32
inch.
2) In accordance with the GE recommendation contained in Attachment 1, with
the armature fully depressed against the pole piece, check to see if the
latch is fully rotated by pulling up on the latch assembly. If the latch
is fully rotated, there should be no motion of the latch, since the latch
should be held against the armature by spring tension.
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March 10, 1988
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3) Repair or replace any relay which fails the above inspections, such that
the relay satisfies the GE criteria.
4) Inspect all existing spare HFA relays as above. Future spares received
should be inspected prior to their installation if manufactured prior to
November 1, 1987.
Reporting Requirements:
Records of inspection and corrective actions in response to this bulletin
shall be documented and maintained in accordance with plant procedures for
Class 1E equipment. Any addressee who does not have HFA type latching relays
subject to this bulletin shall provide a letter to the NRC stating this fact
within 120 days of receipt of this bulletin. Addressees who do have HFA type
latching relays subject to this bulletin including those who have previously
responded to the GE SAL shall provide letters of confirmation of completion of
the inspections. These letters shall include the number of relays of each
type inspected, the number of relays of each type requiring corrective actions
due to item 1 under Actions Requested, and the number of relays of each type
requiring corrective actions due to item 2 under Actions Requested. These
letters of confirmation shall be submitted to the NRC within 30 days of com-
pletion of the inspections.
The letter of confirmation shall be submitted to the appropriate Regional
Administrator under oath or affirmation under the provisions of Section 182a,
Atomic Energy Act of 1954, as amended, including the provisions of 10 CFR
50.54(f). In addition, the original copy of the cover letter and a copy of
any attachment shall be transmitted to the U. S. Nuclear Regulatory
Commission, Document Control Desk, Washington, D.C. 20555, for reproduction
and distribution.
This request for information was approved by the Office of Management and
Budget under blanket clearance number 31500011. Comment on burden and
duplication should be directed to the Office of Management and Budget, Reports
Management, Room 3208, New Executive Office Building, Washington, D.C., 20503.
Although no specific request or requirement is intended, the following
information would be helpful to the NRC in evaluating the cost of implementing
this bulletin:
1. Staff time to perform the requested inspections and corrective actions.
2. Staff time to prepare the requested documentation.
3. Additional cost incurred as a result of the inspection findings (e.g.,
costs of corrective actions, costs of downtime).
. NRCB 88-03
March 10, 1988
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If you have any questions about this matter, please contact one of the techni-
cal contacts 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 Contacts: K. R. Naidu, NRR
(301) 492-9659
E. T. Baker, NRR
(301) 492-4783
Attachments:
1. GE letter dated November 12, 1987
2. List of Recently Issued NRC Bulletins
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