ML20037B276
| ML20037B276 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 03/16/1976 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Brian Lee COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 8009100875 | |
| Download: ML20037B276 (1) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION l-REGION lli f
799 ROOSEVELT RO AD CLEN ELLYN, ILLINOIS ' 60j37 MAR 1 6 1976 ne'.
ca==a= wealth Ediaan Company Docket No. 50-10 AITMs Mr. Byron Ime, Jr.
Docket No. 50-237 Vice Freefdent Docket No. 50-249 P. O. Boa 767 Omicago, Tn4mais 60690
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pi The enclosed Bulletins No. 76-02 and No. 76-03 are forwarded I
J to you as a matter concerning a possible generic problem rslating to reacter safety systems and courponents.
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Any questions regarding this bellatin should be directed to e
"E-l this office.
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Siwarely,
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James C. Esppler j
Engional Director 9
Encierrures 1.
IEB 76-02, 3/16/76 2,
1E5 76-03, 3/16/76 l
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B. B. Stephensen j
Station Superintendent 1
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1 Central Files IE Files I
PDR Local PDR AO-Anthony Roisman, Esq.
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March 16, 1976 IE Bulletin No. 76-02 i
RELAY COIL FAILURES - GE TYPE HFA, HCA, HKA, HMA RELAYS DESCRIPTION OF CIRCUMSTANCES:
A failure of a General Electric (CE) model 12 HFA 51A42H Relay occurred recently in a safety related circuit at the Turkey Point facility.
The
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relay failed during reactor safeguards systems testing. Earlier failures l
l of a similar nature involving GE type HGA relays were reported from j
Flori,da Power and Light Company in 1973.
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The relay manufacturer has determined that open circuit coil failures of the relay windings had been caused by corrosion.
Halogens from a class of nylon coil spools (or bobbins) plus humid conditions were l
attributed as the fundamental causes of the corrosion and resulting l
coil failure.
i The relays identified by the manufacturer which may have this nylon spool include HFA, HGA, HKA, HMA relay types, made by CE prior to 1969, and they may be identified by a white, nylon coil spool.
Portions of a GE service letter containing information about these relays are attached to this bulletin.
Further instructions regarding repair procedures can be 'obtained from the GE Service Engineering Department, Philadelphia.
ACTION TO BE TAKEN BY LICENSEES AND PERMIT HOLDERS:
For all power reactor facilities with an operating license or construction permit:
I J
1.
If you have received the attached GE service letter, describe l
what action you have taken regarding replacement of the older style nylon coil bobbins with the recommended Lexan type bobbins in the types of relays identified in the enclosed GE letter.
l 2.
If you have not received the attached GE service letter, describe
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what action you plan to take if relays of the type and vintage l
described in the enclosed GE letter are in use or planned for use l
in safety related systems, l
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L tz IE Bulletin No. 76-02 March 16, 1976
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Reports for facilities with operating licenses'should be submitted i
within 30 days af ter receipt of this bulletin, and reports for
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facilities with construction permits should be submitted within Your report should also 60 days after receipt of this bulletin.
include the date when the above actions were or will be completed.
Reports should be submitted to the Director of the NRC Regional Of fice and a copy should be f orwarded to the NRC Of fice of Inspection and Enforcement, Division of Reactor Inspection Programs, Washington, D. C.
20555.
Approval of NRC requirements for reports concerning possible generic problems has been obtained under 44 U.S.C. 3152 from the U. S. General Accounting Office.
(GAO Approval B-180255(R0072), expires 7/31/77)
ATTACHMENT:
Extract from General Electric Service Letter:
HFA, HGA, HKA, HMA RELAYS NYLON COIL BOBBINS i
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Extract From Cencral Electric Service Letter 5
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IlFA, llGA,,llKA, llMA RELAYS NYLON COIL BOBBINS in 1954, a program was initiated to '-orove the mechan-
'ic,l and electrical properties of paper based spools used a
l for.l!FA, HGA,llKA and HMA relay coils.
Heat stabilized nylon was selected for the spool material because its tem-perature characteristics made it well suited for Class A coils, and the material provided the desired improvement in electrical and mechanical properties. Manufacturing of HMA relays with the nylon spools started in 1955.
After three years of successful experience, the change to nylon spools was impicmented in HFA, HGA, and IIKA relays in 1958.
In the mid 60's, a few failures of HMA coils utilizing the nylon spools for DC applications were reported.
As a result of these failures, an investigation was undertaken l
to determine the cause of the failures.
It was found from of the this invc'stigation that the heat stabilizing element nylon coil spool contained halogen ions which could bc j
released over a period of time. When combined with moisture, l
the halogen ions form hydrocloric acid and copper salts which I
l could cause the eventual open circuit failure of the coils.
I The most significant contributing factor in the reported failures is high humidity.
Other contributing factors are the small wire size used in HMA relays and in DC relays, and the release of halogen ions is accelerated by DC potential.
Relay coils which are continuously energized are not subject I
to this phenomenon because the coil temperature is maintained considerably above ambient, thus minimizing the probability of moisture getting into the coil.
i Attachment A Page 1 c.f : Pages
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9 After the spool material was ch3nged to nylon in 1955-58, a new material, Lexan, became avaliabic.
Lexan has the desired chemical, mechanical and electrical character-istics for use in spools. The change to the use of Lexan for spools was started in 1964 and completed "in 1968.
The first relay changed was the llMA followed by the HGA i
and HEA.
Black ~was chosen for the color of Lexan spools to make them distinguishable from the nylon.
Since the initial report of open circuited IEUi coils, the failures of auxiliary relays has been very limited..
l However, recently one customer reported an accumulation of I
open circuit failures of a significant number of HGA relays with nylon spools which were used in X-Y closing circuits of breakers. As a result of this recent report and in l
keeping with our procedure of informing you of potential l
problems, we are bringing this matter to your attention,
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even though the overall rate of failure continues to be extremely low.
l (Paragraph deleted) l If you have applications of HFA, HCA, HKA, and IBM relays in areas of high humidity, intermittent operation, DC power, and with white nylon spools, you may wish to consider replacing the coils or relays.
(Paragraph deleted) 1 I
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Attachment A Pagc 2 of : Pagcc f*
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he bp March 16, 1976 IE Bulletin No. 7 6-03
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RELAY MALFUNCTIONS - GE TYPE STD RELAYS DESCRIPTION OF CIRCUMSTANCES:
A malfunction of a General Electric (GE) Type 12STD15B5A Relay occurred i
recently in a safety related load center at Joseph M. Farley Station.
The relay malfunction was due to radio frequency interference from an This malfunction tripped the circuit breakers activated transceiver.
to isolate the associated transformer which resulted in the removal of the incoming power to the 600 volt load center. Three other users of these devices have reported STD relay malfuntions due to radio fre-quency interference. In addition, there have been several cases of failed shorted components on the STD relay amplifier card which resulted in relay malfunction. The STD type relay may be installed j
in similar applications at BWR or PWR facilities. The relays involved l
were initially marketed in 1968.
Portions of a GE service letter containing information about these relays are attached to this bulletin.
Further instructions regarding repair procedures can be obtained from the GE Service Engineering Department, l
Philadelphia.
I ACTION TO BE TAKEN BY LICENSEE AND PERMIT HOLDERS:
For all power reactor facilities with an operating license or construction permit:
1.
If you have received the attached GE service letter, describe what action you have taken regarding the recommended action to update your existing STD relays identified in the enclosed GE letter.
2.
I'f you have not received the attached GE service letter, describe what action you plan to take if relays of the type and model described in the enclosed GE letters are in use or planned for use in safety related systems.
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March 16, 1976 IE Bulletin No. 76-03 a
Reports for facilities with operating licenses should be submitted within 30 days af ter receipt of this bulletin, and reports for facilities with construction permits should be submitted within Your report should also 60 days after receipt of this bulletin.
include the date when the above actions were or will be completed.
Reports should be submitted to the Director of the NRC Regional E
Office and a copy should be forwarded to the NRC Of fice of Inspection and Enforcement, Division of Reactor Inspection 20555.
Programs, Washington, D. C.
Approval of NRC requirements for reports concerning possible generic problems has been obtained under 44 U.S.C. 3152 from the U. S. General Accounting Office.
(GAO Approval B-180255(R0072), expires 7/31/77)
ATTACHMENT:
Extract from General Electric Service Letter :
STD RELAYS TRANSFORMER DIFFERENTIAL RELAY 4
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Extract From General Elcetric Service-Letter
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STD RELAYS TRANSFORMER DIFFERENTIAL RELAY E
In line with our policy of keeping users informed of conditions which could possibly affect relay operation, the following information is provided on type STD transformer j
r differential relays.
Three customers have reported that the zoner diodes or the associated dropping resistors on the STD Sense Amplifier Card have failed shorted. The problem has been traced to two zener diodes whose, cases.have been physically touching, short circuiting one diode and overloading the circuit.
There are several possible causes of such isolated failures including the possibility of mishandling during test.
In-correct STD relay trip outputs are associated with such a failure in this circuit. Tests have shown that, with these
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components touching, the STD relay is also vulnerable to misoperation on DC transients.
Because of these reported problems, it is suggested that the cicarance between the two IN3024 diode cases and other component lead cicarances on the sense amplifier card be visually inspected during routine STD test or maintenance.
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Attachment A Page 1 of 3 pages e
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. IE Bulletin !!o. 76-03 When the problem was initially reported, insulating tubing was added to the zener diode in our manufacturing process as a future safeguard to prevent possibic short circuiting due to deformation of the zener diode 1 cads.
Subsequently, to further improve the STD rela', the sense y
amplifier card has been redesigned using a new printed circuit card with components arranged to preclude any possibility of short circuiting.
At the same time the card had been redesigned to improve the card layout, the STD dropout time was reduced to 32 milli-seconds and its radio frequency sensitivity was reduced significantly. Thus, an updated relay will pass the RFI and Fast Transient tests, and, of course, the standard IEEE In addition, a change in Surge Withstand Capability test.
nameplate design makes the output contacts more visible.*
The new sense amplifier card is identified as #0108B9305 G-4.
This new card will become a standard feature in all STD relays shipped after December 1, 1975. At that time the STD model numbers will be changed in accordance with the attached list to reficct these changes, and the new relay models will be automatically substituted on unfilled orders.
Existing STD relays now in service can be updated with a new amplifier card, associated dropping resistors and minor wiring changes.
- None of these design improvements affect the basic operating principles of the STD (operate on fundamental, restrain on all harmonics) nor do they change the restraint Icvel from 20%
These principles have been proven effective on harmonics.
over 35,000 G.E. harmonic restraint transformer differential relays, including those applied to transformers with the new high permeability core steel. A reduction in the IcVel of harmonic restraint is not desirabic, as it would degrade performance (desensitize the relay in detecting faults during energizing) with no of fsetting benefit.
I Attachment A Page 2 of 3 Pages O
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OLD MODEL NUMBER NEW MODEL NUMBER KIT NUMBER 12STD15BIA 12STD15C3A 0152C9069 G1 12STD15B2A 12STD15C2A 0152C9069 G2 12STD15B3A 12STD15C3A l0152C9069 G3 12STD15B4A 12STD15C4A 0152C9069 G4 12STD15BSA 12STD15C5A 0152C9069 G5 12STD15B6A 12STD15C6A 0152C9069 G6 12STD16BIA 12STD16C3A 0152C9069 G7 12STD16B2A 12STD16C4A 0152C9069 G8 12STD16B3A 12STD16C3A 0152C9069 G9 12STD16B4A 12STD16C4A 0152C9069 GIO 12STD16BSA 12STD16CSA 0152C9069 Gil 12STD16B6A 12STD16C6A 0152C9069 G12 12STD16B7A 12STD16C7A 0152C9069 G13 12STD17BIA 12STDl?C2A 0152C9069 G14 12STD17B2A 12STD17C2A 0152C9069 GIS 12STD18BlA 12STD18C2A 0152C9069 G16 12STD18B2A 12STD18C2A 0152C9069 G17 12STD18B3A 12STD18C3A 0152C9069 G18 12STD18B4A 12STD18C4A 0152C9069 G19 12STD21BIA 12STD21 CIA 0152C9069 G20 12STD25BIA 12STD25D2A 0152C9069 G21 12STD25B2A 12STD25D2A 0152C9069 G22 12STD25 CIA 12STD25C2A 0152C9069 G23 12STD25C2A 12STD25E2A 0152C9069 G24 12STD26BlA 12STD26 CIA 0152C9069 G25 12STD28 BID 12STD28CID 0152C9069 G26 12STD28B2D 12STD28C2D 0152C9069 G27 12STD29BlD 12STD29CID 0152C9069 G28 12STD29B2D 12STD29C2D 0152C9069 G29 Attachment A Page 3 of 3 Pcpes
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