Information Notice 2019-10, Failures Reported in Eaton/Cutler Hammer A200 and Freedom Series Contactors
| ML19294A196 | |
| Person / Time | |
|---|---|
| Issue date: | 12/04/2019 |
| From: | Chris Miller NRC/NRR/DRO |
| To: | |
| References | |
| IN-19-010 | |
| Download: ML19294A196 (5) | |
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
OFFICE OF NEW REACTORS
WASHINGTON, DC 20555
December 4, 2019
NRC INFORMATION NOTICE 2019-10: FAILURES REPORTED IN EATON/CUTLER HAMMER
A200 AND FREEDOM SERIES
CONTACT
ORS
ADDRESSEES
All holders of an operating license or construction permit for a nuclear power reactor under Title 10
of the Code of Federal Regulations (10 CFR) Part 50, Domestic Licensing of Production and
Utilization Facilities, except those that have permanently ceased operations and have certified that
fuel has been permanently removed from the reactor vessel.
All holders of and applicants for a combined license under 10 CFR Part 52, Licenses, Certifications, and Approvals for Nuclear Power Plants.
PURPOSE
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to inform
addressees of operating experience with regard to failures of Eaton/Cutler Hammer A200 and
Freedom series contactors.
These contactors are widely used throughout the nuclear industry in various applications, many of
which are safety related. Under certain conditions, these contactors may stick closed, preventing
the contactors from performing their safety function. The NRC expects that recipients will review
the information in this IN for applicability to their facilities and consider actions, as appropriate, to
avoid similar problems. INs may not impose new requirements, and nothing in this IN should be
interpreted to require specific action.
DESCRIPTION OF CIRCUMSTANCES
The NRC has received multiple reports1,2 of instances of Eaton/Cutler Hammer contactors sticking
shut when power is removed, as shown in the table below. In addition, while not formally reported
to the NRC, nuclear suppliers have also received information about additional failures.
1 AZZ Nuclear, Part 21 Report No. P21-02082019, Initial Notification of potential 10 CFR Part 21, EATON A200
Series Starters/Contactors, February 8, 2019 (Agencywide Documents Access and Management System
(ADAMS) Accession No. ML19053A499).
2 Curtiss-Wright Corporation/QualTech NP, Notification of 10 CFR Part 21 on Eaton/Cutler Hammer A200 series
Starters (& Contactors), December 18, 2015 (ADAMS Accession No. ML15357A042). Contactor
Type
- of Installed
Failures
Mfg. Date
Range
Failure
Dates
Plant
Vendor
A200 Series
8
5/2008-12/2012
2008-2015 Diablo Canyon
Curtis Wright
A200 Series
7
2011-2015*
2017-2019 Susquehanna
AZZ/NLI
Freedom Series
6
2016-2017
2018 LaSalle
- The manufacture date for one of the failed contactors is unknown.
These contactors are commercially manufactured components that have been dedicated for
safety-related use. Many of the A200 series contactors were originally supplied by Westinghouse
and installed in Westinghouse-manufactured motor control centers. Westinghouse and other
third-party suppliers have also supplied Eaton/Cutler Hammer A200 and Freedom series contactors
as replacements for both Westinghouse and non-Westinghouse original equipment.
Recently, failed contactors from LaSalle County Station and Susquehanna Steam Electric Station
were returned to their respective supplying vendors, Westinghouse and AZZ/NLI, for examination.
Both Westinghouse and AZZ/NLI performed root cause evaluations of the failed devices. Through
its commercial relationship with the commercial manufacturer Eaton/Cutler Hammer, Westinghouse
was able to perform an extensive examination of the overall root cause of this issue. Although the
AZZ/NLI root cause analysis was limited to the specific returned components, both evaluations
came to similar conclusions.
In its letter to the NRC dated September 24, 2019, Westinghouse provided a copy of its Nuclear
Safety Advisory Letter (NSAL)-19-2, Revision 0, Contactors Failing to Release/Open When
De-energized, dated August 28, 2019 (ADAMS Accession No. ML19269B709), that it had sent to
all its nuclear-related customers about this issue. The results of the AZZ/NLI evaluation are
summarized in its evaluation under 10 CFR Part 21, Reporting of Defects and Noncompliance, dated August 29, 2019, and, in general, are in agreement with the Westinghouse conclusions.
As multiple suppliers may have provided these contactors to facilities, this IN summarizes the
Westinghouse NSAL and the AZZ/NLI 10 CFR Part 21 report below.
DISCUSSION
Previous failures of A200 series contactors had been attributed to certain materials used in the
manufacturing process and were thought to be limited to certain manufacture date codes.
However, more extensive analysis performed on returned sticking contactors that had manufacture
date codes outside of the range thought to be affected has revealed the existence of an additional
failure mechanism. Consequently, it is now believed that contactors under all manufacture date
codes are potentially susceptible to the failure mechanism as described below.
The failure analysis of the returned contactors by Westinghouse and Eaton/Cutler Hammer
identified a contaminant on the magnet and armature pole faces consistent with the breakdown of
an organic material. The material emanates from the laminations of the contactor core and
armature and is part of the original equipment design. It does not result from any recent design
changes or from the manufacturing process itself. As part of an extent-of-condition review, Westinghouse tested more than 100 Freedom and A200 series contactors of various sizes under
specific temperatures, voltages, and durations to replicate the failure mode. Westinghouse has
confirmed that under the right conditions, the organic-based nonmetallic material can leach out and migrate to the mating surface of the core and armature. Once migration to the pole-face surface
occurs, the material degrades from heat, moisture, and oxygen, and causes the contactors to stick.
Factors that contribute to and accelerate the failure mode include the following:
temperature
-
type of coil installedlow-voltage drop-out coils produce higher temperatures
-
voltage applied to coilhigher voltage drives much higher temperatures
-
environmenthigher ambient temperatures
time
-
energized durationlack of cycling for extended periods of time
The following contactor series showed signs of sticking during the Westinghouse extent-of-condition
testing:
A200, Sizes 1-4
Freedom, Sizes 2-4
While this same material may be used in other Eaton manufactured components such as D15, AR,
and BF Relays, there have been no reports of similar failures and Westinghouse testing has shown
that these components are not susceptible to the previously described failure mechanism.
In its NSAL, Westinghouse indicated that Eaton/Cutler Hammer is planning to change the laminate
coating material used in the manufacture of the commercial contactors. The date the manufacturer
will implement the design change is currently unknown.
Freedom and A200 series contactors, Sizes 1-4, are used in many different safety-related and
non-safety-related applications; however, Westinghouse has determined that this potential failure
mode is limited to components used in continuously energized applications. Operation at high
ambient temperatures or high control voltages, or both, for an extended period increases the
potential for a failure. Components used in momentary applications are not susceptible to this
failure mode. Also, if continuously energized applications have been energized for a cumulative
total of 1 year or more and have been successfully cycled, Westinghouse data suggests they may
no longer be susceptible to this failure mode; however, testing done by AZZ/NLI on one contactor
taken from the Susquehanna Nuclear Station tends to conflict with that conclusion as that contactor
had been energized for over 1 year, had been successfully cycled, and then stuck closed.
For the affected contactors, the safety significance of this issue will vary based upon site-specific
and application-specific conditions. Factors that would impact the safety significance include
whether and how quickly loads are able to be deenergized locally through the manual opening of
the breaker at the motor control center cubicle and whether the specific contactor is relied upon to
open to perform automatic load shedding during certain accident scenarios.
In its NSAL, Westinghouse has recommended the following actions:
Freedom and A200 series continuously energized contactors that have not been cycled
since the original installation should be cycled at the earliest available opportunity. *
Any A200 or Freedom series contactors that fail to open should be replaced with contactors
manufactured with the new material.
Although not in the NSAL specifically, Westinghouse has also recommended in recent webinars
that its customers replace continuously energized contactors that are in critical applications that
have had less than 1 year of cumulative service, regardless of whether or not they fail to open.
Westinghouse has indicated that it is implementing changes to its dedication procedures to ensure
that all subsequently procured contactors are suitable for their safety-related applications and will
be of the new material design.
Related NRC Generic Communications
None
CONTACT
This IN requires no specific action or written response. Please direct any questions about this
matter to the technical contact listed below.
/RA/
Division of Reactor Oversight
Office of Nuclear Reactor Regulation
Technical Contacts:
Jeffrey Jacobson, NRR/DRO
301-415-2977 E-mail: jeffrey.jacobson@nrc.gov
Kerri Kavanagh, NRR/DRO
301-415-3743 E-mail: kerri.kavanagh@nrc.gov
Note: NRC generic communications may be found on the NRC public Web site, http://www.nrc.gov, under NRC Library, Document Collections.
OFFICE
NRR/DRO/IQVB
QTE
NRR/DRO/IQVB/BC
NRR/DRO/IOEB/PM
NAME
JJacobson
JDougherty
PPrescott for
KKavanagh
BBenney
DATE
11/12/19
10/23/19
11/13/19
11/21/19 OFFICE
NRR/DRO/IOEB/LA
NRR/DRO/IOEB/BC
NRR/DRO/D
NAME
IBetts
LRegner
CMiller
DATE
11/25/19
11/27/19
12/4/19