Part 21 Report - 1995-199
ACCESSION #: 9509080034
ABB
August 30, 1995
LD-95-039
Document Control Desk
U.S. Nuclear Regulatory Commission
Washington, D.C. 20555
Subject: Report of a Defect Pursuant to 10 CFR 21 in Palisades Nuclear
Power Plant Reactor Protection System
Dear Sir:
The purpose of this letter is to notify the Nuclear Regulatory Commission
of a "defect", as defined in 10 CFR 21 - "Reporting of Defects and
Noncompliance", in a Reactor Protection System (RPS) sub-component
provided by Combustion Engineering, Inc. (CE) to Consumers Power Company
for the Palisades Nuclear Power Plant. The defect was the presence of a
hardwired connection (i.e., a "jumper") in each of the four (4)
Containment High Pressure (CHP) trip logic circuits. This causes the RPS
to be unable to trip the reactor on a valid high containment pressure
signal.
An evaluation performed by CE has determined that this condition
represents a major degradation of safety-related equipment and a loss of
safety function necessary to mitigate the consequences of certain
accidents since all four (4) trip channels were disabled. In addition,
the conditions surrounding an initiating accident could be exacerbated
since the CHP trip signal, while failing to initiate a reactor trip,
would initiate several Engineered Safety Features (ESF) actions.
This condition was identified by CPCo, who in turn notified CE. CE
assisted CPCo personnel in correcting the identified problem and
returning the RPS, and specifically the CHP trip channels, to an operable
status. Having examined the nature of the problem, CE has no reason to
believe that this reportable condition applies to any other plant for
which CE designed the Nuclear Steam Supply System (NSSS).
ABB Combustion Engineering Nuclear Power
Combustion Engineering, Inc. P.O. Box 500 Telephone (203) 688-1911
1000 Prospect Fax (203) 285-5203
Hill Rd.
Windsor, CT 06095
Document Control Desk LD-95-039
August 30, 1995 Page 2
The Enclosure summarizes the information available to us at this time.
If you have any questions, please feel free to contact me or Mr. Chuck
Molnar of my staff at (203) 285-5205.
Very truly yours,
COMBUSTION ENGINEERING, INC.
Dr. Ian C. Rickard, Director
Operations Licensing
Enclosure: As stated
cc: K. Powers (CPCo)
R. S. Siudek (CE)
J. W. Davis (ABB Electro Mechanics)
Enclosure to LD-95-039
Page 1 of 2
ABB Combustion Engineering Nuclear Operations
10 CFR 21 Report of a Defect or Failure to Comply
The following information is provided pursuant to the requirements
identified in 10 CFR 21.21 (c)(4):
(i) Name and address of the individuals informing the Commission:
Dr. I. C. Rickard, Director
Operations Licensing
Combustion Engineering, Inc.
1000 Prospect Hill Road
Windsor, CT 06095-0500
(ii) Identification of the facility the activity or the basic
component supplied or such facility or such activity within the
United States which fails to comply or contains a defect.
The facility affected by this defect is the Consumers
Power Company (CPCo) Palisades Nuclear Power Plant
The basic component which is the subject of this report is
a sub-component of the Reactor Protection System (RPS) and
is identified as ABB Electro Mechanics Part No. 11247-
47003 Rev. A, "Trip Unit Bin & Interconnection Module
Assembly". The Trip Unit Interconnection Module Assembly
is located immediately behind the individual bistable and
auxiliary trip units, and serves as the interconnection
point for trip unit inputs and outputs. It is in this
assembly that trip unit inputs and outputs are routed to
the proper connectors to form the two (2) out of four (4)
trip logic, as well as providing trip annunciation,
sequence of events recording, and trip unit bypass and
test capability.
(iii) Identification of the firm constructing the facility or
supplying the basic component which fails to comply or contains
a defect.
Combustion Engineering, Inc. (CE) supplied the Trip Unit
Bin & Interconnection Module Assembly.
(iv) Nature of the defect or failure to comply and the safety hazard
which is created or could be created by such defect or failure
to comply:
The defect identified is a hardwired connection (i.e., a
"jumper") across the Slot 11 Containment High Pressure
(CHP) trip contacts. The presence of this jumper
precludes initiation of a reactor trip when a valid CHP
trip signal is received.
CE has determined that this "jumpered" condition
represents a major degradation of safety-related equipment
and a loss of safety function necessary to mitigate the
consequences of certain accidents since all four (4) trip
channels were disabled. In addition, the conditions
surrounding an initiating accident could be exacerbated
since the CHP trip signal, while failing to initiate a
reactor trip, would initiate several Engineered Safety
Features (ESF) actions. For example, on high containment
pressure the High and Low Pressure Safety Injection Pumps
receive start signals, Charging Pumps are started, and
Containment Isolation is initiated. The potential exists,
therefore, for ESF actions to take place without reactor
trip occurring while still operating at full power.
Moreover, the reactor operator will receive conflicting
reactor trip inputs. Specifically, receipt of a valid
containment high pressure trip signal will result in
annunciation of reactor trip on
Enclosure to LD-95-039
Page 2 of 2
that signal; however, power to the Control Rod Drive
Mechanisms (CRDMs) will not be interrupted and a reactor
trip will not occur. Consequently, the control rod "on-
bottom" light indication will not light. The reactor
operator would have to decide which trip input indication
being received is valid; resulting in the potential for
taking inappropriate corrective action(s).
(v) The date on which the information of such defect or failure to
comply was obtained:
The presence of a jumper across the Slot 11 CHP trip
contacts was identified by CPCo Palisades Nuclear Power
Plant personnel on or about July 28, 1995. CE was
informed of the situation by CPCo on July 30, 1995. CE
completed the 10 CFR 21 discovery phase of its internal
reporting procedure on August 3, 1995. The decision that
the deviation represented a defect which is reportable
under the provisions of 10CFR21 was finalized by the
Nuclear Safety Committee on August 28, 1995.
(vi) In the case of a basic component which contains a defect or
fails to comply, the number and location of all such components
in use at, supplied for, or being supplied for one or more
facilities or activities subject to the regulations in this
part.
CE provided new Interconnection Module Assemblies to CPCo
for the Palisades Nuclear Power Plant in 1992. To the
best of CE's knowledge, based on a poll of other CE
plants, the defect described above is only applicable to
these specific Interconnection Module Assemblies supplied
to the Palisades Nuclear Power Plant.
(vii) The corrective action which has been, is being, or will be
taken; the name of the individual or organization responsible
for the action; and the length of time that has been or will be
taken to complete the action:
The corrective action, which has been taken was to remove
the jumpers (by cutting through the circuit board
connections) in Slot 11 of the Interconnection Module
Assemblies in all four (4) RPS channels. Once the problem
was identified, the jumper connection on the
Interconnection Module was readily identified on both the
wire list and on the physical layout of the
Interconnection Module Turret Board Assembly. The
corrective action was supervised by CPCo personnel and
performed by ABB Electro Mechanics personnel at the
Palisades site in the presence of an engineer from CE
Instrumentation and Controls Engineering. CPCo personnel
performed post-correction action verification of jumper
removal. The matrix test procedure, which had originally
failed to detect the jumper, was modified to provide a
valid test. This modified procedure was run on all four
(4) RPS channels to verify that the jumper was no longer
present, and that the CHP trip function was operable
(i.e., that a reactor trip would be initiated, if
required).
A comprehensive test program was developed and conducted
to verify that all Interconnect Module inputs and outputs
were functional. This test program was further extended
to include verification of all RPS functions, whether
associated with the Trip Unit Interconnect Module or not.
This enhanced test program was performed by Palisades
personnel prior to plant startup. CE and Palisades
personnel worked together to derive the list of procedures
which must be performed to verify operability.
(viii) Any advice related to the defect or failure to comply about the
facility, activity, or basic component that has been, is being,
or will be given to purchasers or licensees:
CE plans to issue an Infobulletin to licensees of CE
designed NSSSs discussing the defect reported above.
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