ML18283B393

Responding to Letter of 3/16/1976, Letter Transmitting Final Response to IE Bulletins 76-02 and 76-03

ML18283B393
Person / Time
Site:	Browns Ferry
Issue date:	05/17/1976
From:	Gilleland J Tennessee Valley Authority
To:	Moseley N NRC/RGN-II
References
Download: ML18283B393 (10)

Text

o O1.UTIOy t 830 Power TENNESSEE VALLEY AUTHORITY Buildin CHATTANOOGA. TENNESSEE 37401 So "MA gg-o>

'~)S-19<~ May 17, 1976 Mr. Norman C. Moseley, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Region II Suite 818 230 Peachtree'Street, Mf.

Atlanta, Georgia 30303

Dear Mr. Moseley:

OFFICE OF INSPECTION AND ENFORCEMENT BULLETINS 76-02 AND 76-03 IE:II:NCM 50-259, -260, -296, -327, -328, -390, -391,

-438, -439 - BROMNS PERRY UNIT 3, SEQUOXAE, WATTS BAR, AND BELLEFONTE This is in further response to your March 16, 1976, letter which transmitted IE Bulletins 76-02 and 76-03. An interim response, J. E. Gilleland to N. C. Moseley, covering Browns Ferry units 1 and 2, was submitted on April 14, 1976. Fnclosed is our final response to IE Bulletins 76-02 and 76-03.

Very truly you s, v+ Pj~c/ l ~ J /~.~

J; ,. Gilleland Assistant Manager of f Power Enclosure An Equal Opportunity Employer

EHCLOSUIQ'.

XHSI.ECXXO~ AHD I:.HFOI:CI.,IEHT BUI.LEI.XH (XEB)

HOS. 76-02, PJ'LhY. COXL FAX'LUIXS AND 76-03, RELAY PALPUNC'1XO'AS rXHAL REI ORT Relays of the type described in XE Bu11.etin Nos. 76-02 and 76-03 are being utilized for Class 1E service at this facility. Repair or. replacement of these relays will be accomplished before unit staxtup.

I Se uo ah Docket Hos. 50-327 and 50-328 Relay" of the type described in XE Bulletin Ho. 76-02 axe being utilized for Class lE service at this facility. Repair or xeplacement of these will be accomPl~shed b~fore the PreoPexational test Ho relays oi the type described in XE Bulletin 76-03 axe being utilized fox Class lE sexvice at this facility.

watts Bar Docket Hos 50 390 and 50 391 Relays of; the type described in XE Bulletin Ho. 76-,02 are being utilized for Class 1E sexvice at this facility. Repair or xeplacement of these relays will be accomplished before the pxeoperational tests.

Ho relays of the type describ d in XE Bulletin 76-03 are being utilized fox Cla s IE service at this facility.

Bellefonte Docket Hos. 50-438 and 50-439 Relays of the type described in XE Bulletin Mos. 76-02 and 76-,03 are planned for use in Class lZ serv'e t this facility. The relays will be inspected fox thi" condition before insLallation at the site.

UiVITED STATES NUCLEAR REGULATORY COMMISSION REGION ll 230 PEACHTREE STREET, N. W. SUITE 818 ATLANTA,GEORGIA 30303 HAR 169 In Reply Refer To.

IE: II:NCM 50-438 50-327 50-439 50-328 50-259 50-390 50-260 50-391 50-296 Tennessee Valley Authority ATTN: Mr. J. E. Watson Manager of Power 818 Power Building Chattanooga, Tennessee 37401 Gentlemen:

The enclosed Bulletins Number 76-02 and 76-03 are forwarded to you for action as matters concerning possible generic problems relating to reactor safety systems and components.

Any questions regarding these bulletins should be directed to this office.

Sincerely, Norman .C. Moseley Director

Enclosures:

1. IEB 76-02, 3/12/76 Relay Coil Failures

2. IEB 76-03, 3/15/76 Relay Malfunctions

'pproval of NRC requirements for reports concerning possible generic .prdblems has been obtained under .44 U.S.C. 3152 from (GAO Approval B-180255(R0072), expires 7/31/77)

BULLETIN 76-02 RELAY COIL FAILURES GE TYPE HFA, HGA, HKA, EfA RELAYS DESCRIPTION OF CIRCUMSTANCES:

r A failure of a General Electric (GE) model 12 HFA 51A42H Relay occurred recently in a safety related circuit at the Turkey Point facility. The relay failed during reactor safeguards- systems testing. Earlier failures of a similar nature involving GE type HGA relays were reported from Florida Power and Light Company in 1973.

THE RELAY MANUFACTURER HAS DETERMINED THAT OPEN CIRCUIT COIL FAILURES OF THE RELAY MINDINGS HAD BEEN CAUSED BY CORROSION. Halogens from a class of nylon coil spools (or bobbins) plus humid conditions were attributed as the fundamental causes of the corrosion and resulting coil failure.

The relays identified by the manufacturer which may have this nylon spool include HFA, HGA, HKA, HMA relay types, made by GE 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 POMER REACTOR FACILITIES WITH AN OPERATING LICENSE OR

. CONSTRUCTION PERMIT:

If you have received the attached GE service letter, describe 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.

2. If you have not received the attached GE service letter, describe what action you plan to take if relays of the type and vintage described in the enclosed GE letter are in use or planned for use in safety related systems.

Reports for facilities with operating licenses should be submitted within 30 days after receipt of this bulletin, and reports for facilities,with construction permits should be submitted within 60 days after receipt of this bulletin. Your report should also include the date when the above actions were or will be completed.

Reports should be submitted to the Director of the NRC Regional Office and a copy should be forwarded to the NRC Office of Inspection and Enforce-ment, Division of Reactor Inspection Programs, Mashington, D. C. 20555.

ATTACHMENT:

Extract from General Electric Service Letter:

HFA, HGA, HMA RELAYS NYLON COIL BOBBINS

XP. Bulletin Number 76-02 Date: March 16, 1976

~

ATTACHMENT A A, HGA, HKA, }MA RELAYS NYLON COIL BOBBINS Xn 1954, a program was initiated to improve the mechanical and electrical properties of paper based spools used for HFA, HGA, HKA and HMA relay coils. Heat stabilized nylon was selected for the spool material because its temperature characteristics made it well suited for Class A coils, and the material provided the desired improvement in electrical and mechanical properties. Manufacturing of KQ. relays with the nylon spools started in 1955. After three years of successful experience, the change to nylon spools was implemented in HFA, HGA, and HKA 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 to determine the cause of the failures.

It was found from this investigation'that the heat stabilizing element of the nylon coil spool contained halogen ions which could be released over a period of time. When combined with moisture, the halogen ions form hydrocloric acid and copper salts which could cause the eventual open circuit failure of the coils.

The most significant contributing fact'or in the reported failures is high humidity. Other contributing factors are the small wire sizz used in 19fA relays and in DC relays, and the releas~ of halogen ions is accelerated by DC potential. Relay coils which are continuously energized are not subject to this phenomenon because the coil temperature is maintained considerably above ambient, thus minimizing the probability of moisture getting into the coils After the spool material was changed to nylon in 1955-58, a new material, Lexan, became available. Lexan has the desired chemical, mechanical and electrical characteristics for use in spools. The change to the use of Lexan for spools was started in 1964 and completed in 1968. 'he first relay changed was the EfA followed by the HGA and HFA. Black was chosen for the color of Lexan spools to make them distinguishable from the nylon.

Since the initial report of open circuited 19fA coils, the failures of auxiliary relays has been very limited. However, recently one customer reported an accumulation of 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 keeping with our procedure of informing you of potential problems, we are bringing this matter to your attention, even though the overall rate of failure continues to be extremely lowe (Paragraph deleted)

Xf you have applications of HFA, HGA, HKA, and EfA 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)

BULLETIN 76-03 Date: March 16, 1976 RELAY MALFUNCTIONS GE TYPE STD RELAYS DESCRIPTION OF CIRCUMSTANCES:

A malfunction of a General Electric (GE) Type 12STD15B5A Relay occurred recently in a safety related load center at Joseph M. Farley Station.

The relay malfunction was due to radio frequency interference from an activated transceiver. This malfunction tripped the circuit breakers to isolate the associated transformer which xesulted in the removal of the incoming power to the 600 volt load center. Three other users of these devices have reported STD relay malfunctions 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 in similar applications at BMR or PMR facilities. The relays involved 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, Philadelphia.

ACTION TO BE TAKEN BY LICENSEES AND PERMIT HOLDERS:

For all power reactor facilities with an operating license or con-struction permit:

If you have received the attached GE service letter, describe what action you have taken regarding the xecommended action to update your existing STD relays identified in the enclosed GE letter.

2. If you have not received the attached GE service letter, des-

'ribe what act'ion you plan to take if relays of the type=and model described in the enclosed GE letter are in use ox planned for use in safety related systems.

ACTION TO BE TAKEN BY LICENSEES AND PERMIT HOLDERS (continued)

Reports for facilities with operating licenses should be submitted within 30 days after receipt of this bulletin, and reports for faci-lities with construction permits should be submitted within 60 days after receipt of this bulletin. Your report should also include the date when the above actions were or will be completed.

Reports should be submitted to the Director of the NRC Regional Office and a copy should be forwarded to the NRC Office of Inspec-tion 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:

STD RELAYS TRANSFORMER DIFFERENTIAL RELAY

BULLETIN 76-03 ATTACHHENT A STD RELAYS TRANSFORMER DIFFERENTIAL RELAY 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 differential relays.

Three customers have reported that the zener diodes or the asso-ciated 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 overload-ing the circuit. There are several possible ca'uses of such isolated failures including the possibility of mishandling during test. Incor-rect STD relay trip outputs are associated with such a failure in this circuit. Tests have shown that, with these components touching, the STD relay is also vulnerable to misoperation on DC transients.

Because of these reported problems, it is suggested that the clearance between the two 1N3024 diode cases and other component lead clearances on the sense amplifier card be visually inspected during routine STD test or maintenance.

When the problem was initially reported, insulating tubing was added to the zener diode in our manufacturing process as a future safeguard to prevent possible short circuiting due to deformation of the zener diode leads. Subsequently, to further improve the STD relay, the sense amplifier card has been redesigned using a new printed circuit card with components arranged to preclude any possiblity 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 milliseconds 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 Surge Withstand Capability test. In addi-tion, a change in nameplate design makes the output contacts more visible.*

The new sense 'amplifier card is identified as II0108B9305 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 reflect 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 level from 20% harmonics.

These principles have been proven effective on over 35,000 G.E. har-

. monic restraint transformer differential relays, including those applied to., transformers with the new high permeability core steel.

A reduction in the level of harmonic restraint is not desirable, as it would degrade performance (desensitize the relay in detecting faults during energizing) with no offsetting benefit.

OLD MODEL NJHBER NEW MODEL NAKER KIT NUMBER 12STD15B1A 12STD15C3A ~

0152C9069 G1 12STD15B2A 12STD15C2A 0152C9069 G2 12STD15B3A 12STD15C3A 0152C9069 G3 12STD15B4A 12STD15C4A 0152C9069 G4 12STD15B5A 12STD15C5A 0152C9059 G5 12STD15B6A 12STD15C6A 0152C9069 G6 12STD16B1A 12STD16C3A 0152C9069 Gj 12STD16B2A 12STD16C4A 0152C9069 G8 12STD16B3A 12STD16C3A 0152C9060 G9 12STD1684A 12STD16C4A 0152C9069 G10

'12STD16B5A 12STD16C5A 0152C9069 G11 12STD16B6A 12STD16C6A 0152C9069 G12 12STD16B7A 12STD16C7A 0152C9069 G13 12STD17B1A 12STD17C2A 0152C9069 G14 12STD17B2A 12STD17C2A 0152C9069 G15 12STD18B1A 12STD18C2A 0152C9069 G16 12STD18B2A 12STD18C2A 0152C9069 G17 12STD18B3A 12STD18C3A 0152C9069 G18 12STD18B4A 12STD18C4A 0152C9069 G19 l2STD21B1A 12STD21C1A 0152C9069 G20 12STD25B1A 12STD25D2A 0152C9069 G21 12STD25B2A ,12STD25D2A 0152C9069 G22 12STD25C1A 12STD25E2A 0152C9069 G23 12STD25C2A 12STD25E2A 0152C9069 G24 12STD26B1A 12STD26C1A 0152C9069 G25 12STD28B1D 12STD28C1D 0152C9069 G26 12STD28B2D 12STD28C2D 0152C9069 G27 12STD29B1D 12STD29C1D 0152C9069 G28 12STD29B2D 12STD29C2D 0152C9069 G29