Category:NRC Information Notice[Table view]The following query condition could not be considered due to this wiki's restrictions on query size or depth: <code> [[:Beaver Valley]] OR [[:Millstone]] OR [[:Hatch]] OR [[:Monticello]] OR [[:Calvert Cliffs]] OR [[:Dresden]] OR [[:Davis Besse]] OR [[:Peach Bottom]] OR [[:Browns Ferry]] OR [[:Salem]] OR [[:Oconee]] OR [[:Mcguire]] OR [[:Nine Mile Point]] OR [[:Palisades]] OR [[:Palo Verde]] OR [[:Perry]] OR [[:Indian Point]] OR [[:Fermi]] OR [[:Kewaunee]] OR [[:Catawba]] OR [[:Harris]] OR [[:Wolf Creek]] OR [[:Saint Lucie]] OR [[:Point Beach]] OR [[:Oyster Creek]] OR [[:Watts Bar]] OR [[:Hope Creek]] OR [[:Grand Gulf]] OR [[:Cooper]] OR [[:Sequoyah]] OR [[:Byron]] OR [[:Pilgrim]] OR [[:Arkansas Nuclear]] OR [[:Braidwood]] OR [[:Susquehanna]] OR [[:Summer]] OR [[:Prairie Island]] OR [[:Columbia]] OR [[:Seabrook]] OR [[:Brunswick]] OR [[:Surry]] OR [[:Limerick]] OR [[:North Anna]] OR [[:Turkey Point]] OR [[:River Bend]] OR [[:Vermont Yankee]] OR [[:Crystal River]] OR [[:Haddam Neck]] OR [[:Ginna]] OR [[:Diablo Canyon]] OR [[:Callaway]] OR [[:Vogtle]] OR [[:Waterford]] OR [[:Duane Arnold]] OR [[:Farley]] OR [[:Robinson]] OR [[:Clinton]] OR [[:South Texas]] OR [[:San Onofre]] OR [[:Cook]] OR [[:Comanche Peak]] OR [[:Yankee Rowe]] OR [[:Maine Yankee]] OR [[:Quad Cities]] OR [[:Humboldt Bay]] OR [[:La Crosse]] OR [[:Big Rock Point]] OR [[:Rancho Seco]] OR [[:Zion]] OR [[:Midland]] OR [[:Bellefonte]] OR [[:Fort Calhoun]] OR [[:FitzPatrick]] OR [[:McGuire]] OR [[:LaSalle]] OR [[:05000000]] OR [[:Zimmer]] OR [[:Fort Saint Vrain]] OR [[:Shoreham]] OR [[:Satsop]] OR [[:Trojan]] OR [[:Atlantic Nuclear Power Plant]] OR [[:Crane]] </code>.
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose
This information notice is being provided to alert addressees to potential
problems resulting from the mechanical failure of indicating-type fuses.
It is expected that recipients will review the information for applicability
to their facilities and consider actions, as appropriate, to avoid similar
problems.
However, suggestions contained in this information notice do not
constitute NRC requirements; therefore, no specific action or written response
is required.
Description of Circumstances
The Nuclear Regulatory Commission has been notified of four separate events in
the past two years related to the mechanical failure of indicating-type fuses.
The events occurred at McGuire Nuclear Station, Unit 1; Catawba, Unit 2; and
Sequoyah Nuclear Plant and are described herein.
On March 25, 1986, Duke Power Company's McGuire Nuclear Station, Unit 1, ex- perienced a reactor trip on a steam generator low-low level signal when the
mechanical failure of a Bussman FNA-type fuse caused a main feedwater contain- ment isolation valve to close.
McGuire personnel determined that the failure
was the result of the fuse element having pulled loose from the solder joint
inside the fuse.
The solder joint was found unbroken; the element wire had
pulled out of the solder joint. The licensee found that 8% of the spare fuses
in stock also had failed mechanically.
Previously, in December 1981 and
December 1985, the licensee had reported to the NRC the mechanical failures of
FNA-type fuses [Licensee Event Reports (LERs) 369-81-179 and 369-85-036].
On July 3, 1986, the NRC issued a Confirmation of Action Letter (CAL) to Duke
Power Company as a followup to an event at Catawba, Unit 2. In that event one
of the auxiliary feedwater trains failed to start during testing because of a
mechanically failed FNA-type fuse.
On July 7, 1986, Duke Power notified the
NRC of the preliminary results of a review of all safety-related circuits where
FNA-type fuses were used.
The review included the inspection of approximately
The inspection found 14 failed FNA-type fuses, 9 of which were
determined to have failed mechanically.
The inspection of the spare fuses
in the warehouse stock found an additional 11 mechanically failed fuses.
On October 29, 1986, the Tennessee Valley Authority (TVA) submitted a notifica- tion on Bussman MIS-5-type fuses to the NRC pursuant to the requirements of 10
CFR Part 21.
The Bussman MIS-5 actuating fuse consists of two very thin wires
in a sand-like filler.
One of the wires, which is approximately 96% silver, acts as a fuse link; the other, a nichrome alloy, acts as a retaining wire for
a spring-loaded actuator/indicator rod that is located at one end of the fuse
assembly.
In the notification TVA indicated that fuses at the Sequoyah Nuclear
Plant had exhibited partial actuation, not detectable in all cases by visual
examination, that was the result of the elongation of very thin wires.
The
elongation of these wires could significantly change the characteristics of the
fuse and its current-carrying characteristics.
This is particularly true if
the silver wire breaks but remains in contact with the elongated and unbroken
nichrome wire.
TVA contacted Bussman and established the resistance and
current values that could be used to conclusively test the operability of the
remaining fuses.
On July 20, 1987, TVA submitted an LER on Littlefuse Incorporated FLAS-5 type
fuses to the NRC (LER 327-87-030).
The LER noted that there had been two
separate Engineered Safety Feature actuations of the Sequoyah Nuclear Plant's
November xx, 1987 and TVA shows that the safety significance evaluation Is dependent on an
accurate root-cause determination. In the event of an indicating fuse failure, additional investigation, including internal examination of the fuse, may be
warranted if an electrical fault cannot be found.
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the technical
contact 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:
James C. Stewart, NRR
(301) 492-4644
Joseph J. Petrosino, NRR
(301) 492-4316 Attachment:
List of Recently Issued NRC Information Notices
IOiUS CONCURRENCES
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RPetrosino
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TechEd
11/04/87 Cal5 C/OGCB:DOEA:NRR
CHBerlinger
11/q/87 D/DOEA:NRR
CERossi
11/ /87
IN 87-XX
October xx, 1987
Page 2 of
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the technical
contact listed below or the Regional Administrator of the appropriate regional