ML20116L600

Part 21 Rept Documenting Event 24505 Re GE Ak Circuit breaker,RMS-9 Trip Devices W/Instantaneous Trip Adjustment. Installation of RMS-9 W/Instantaneous Function Discontinued

ML20116L600
Person / Time
Site:	Browns Ferry
Issue date:	10/27/1992
From:	Andrews T TENNESSEE VALLEY AUTHORITY
To:	Ridgell E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
REF-PT21-92 NUDOCS 9211190026
Download: ML20116L600 (2)

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POWER REACTOR EVENT NUMBER: 24505 FACILITY: BROWNS FERRY REGION: 2 NOTIFICATION DATE: 10/27/92 UNIT: [1] (2) (3) STATE: AL RX TYPE: (I) GE-4,(2) GE-4,[3] GE-4 NOTIFICATION TIME: 08:24 (ET)

EVENT DATE: 10/27/92 EVENT TIME? 00:00(CST)

HRC NOTIFIED BY: EARL RIDGELL LAST UPDATE DATE: 10/27/92 HQ OPS OFFICER: THOMAS ANDREWS NOTIFICATIONS EHERGENCY CLASS: NOT APPLICABLE 10 CFR SECTION:

CCCC 21.21 UNSPECIFIED PARAGRAPH UNIT SCRAM CODE RX CRIT INIT PWR INIT RX MODE CURR PWR CURR RX MODE

\

1 N N O REFUELING 0 REFUELING 2 N Y 89 POWER OPERATION 89 POWEF. OPERATION 3 N N O REFUELING 0 REFUELING EVENT TEXT THE FOLLOWING INFORMATION WAS RECEIVED VIA FACSIMILE.

COMPONENT OR SYSTEM IDENTIFICATION:

GENERAL ELECT 2IC AE CIRCUIT BREAKER, RMS-9 TRIP DEVICES WITH 15sTANTANEOUS TRIP ADJUSTMENT SUPPLIER:

GENERAL ELECTRIC (GE) CORPORATION NATURE OF DEFECT OR NONCOMPLIANCE AND CAUSE:

THE 480 VOLT DISTRIBUTION SYSTEM AT BROWNS FERRY HAS EXPERIENCED EXTREMELY SHORT DURATION, HIGH AMPLITUDE CURRENT TRANSIENTS THAT WILL CAUSE THE RMS-9 UNIT TO TRIP. THE RMS-9 TRIP DEVICE WAS CERTIFIED BY GE AS SUITABLE REPLACEMENT FOR THE EC TRIP UNITS THAT WERE PREV.IOUSLY INSTALLED IN GE AK CIRCUIT BREAKERS. PER GE, TO PREVENT SPURIOUS TRIPS, A HOLD-OFF CIRCUIT ENSURES THAT THE FAULT CONDITION PERSISTS FOR A SUFFICIENT DURATION TO INSURE THAT A TRIP SIGNAL WITH DURATION OF OVER 300 MICRO SECONDS FOR THE RMS-9 TO INITIATE AN INSTANTANEOUS TRIP SIGNAL. HOWEVER, SUBSEQUENT TESTING DEMONSTRATED THAT THE RMS-9 UNIT WILL TRIP IN RESPONSE TO A 100 MICRO SECOND PULSE WIDTH IF THE CURRENT VALUE IS SUFFICIENTLY ABOVE THE INSTANTANEOUS SETPOINT.

EXTEND OF SAFETY HAZARD:

TENNESSEE VALLLY AUTHORITY HAD INSTALLED A LIMITED NUMBER (6) OF GE AK CIRCUIT BREAKERS WITH RMS-9 TRIP DEVICES IN THE 480 VOLT DISTRIBUTION SYSTEM FOR UNITS 1 AND 3 AND HAD PLANNED TO INSTALL THESE BREAKERS THROUGHOUT THE 480 VOLT DISTRIBUTION SYSTEM FOR ALL THREE UNITS. THE OPERABILITY OF THE INSTALLED CIRCUIT BREAKERS HAS-BEEN EVALUATED AND-n n n n3(Continued on next page) n j 9211190026 921027 '

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FRCILITY: BROWNS FERRY PAGE / 2 OF EVENT NUMBER: 24505 DETERMINED TO HAVE NO ADVERSE EFFECT ON PLANT OPERATION. HAD THE RMS-9 CONVERSION BEEN COMPLETED PRIOR TO DISCOVERY OF THIS DEVIATION, AN ELECTRICAL SYSTEM DISTURBANCE COULD HAVE RESULTED IN TRIPPING OF THE SAFETY RELATED MOTORS RECEIVING MOTIVE POWER FROM ONE 480 VOLT SHUTDOWN BOARD WHILF A SINGLE FAILURE COULD HAVE DISABLED THE REMAINING DIVISION'S BOARD, RESULTING IN THE LOSS OF BOTH DIVISION I AND DIVISION II MOTORS 7ED FROM-THE 4 80 VOLT SHUTDOWN BOARDS. .

DATE WHICH INFORMATION OF DEFECT OR NONCOMPLIANCE WAS OBTAINED:

OCTOBER 16, 1992.

NUMPER OF IDENTICAL COMPONENTS IN USE OR SUPPLIED:

SIX INSTALLED, TWENTY-THREE IN WAREHOUSE.

LOCATION OF INSTALLED COMPONENTS:

480 VOLT SHUTDOWN BOARDS 1A (COMPT. 3D - UNIT 1 I&D BUS A AND COMPT. 5A -

CONTROL AIR COMPxiSSOR A), 1B (COMPT. 3D - UNIT 1 I&C BUS B), 2A (COMPT. 5A

- CONTROL AIR COMPRESSOR D), 3A (COMPT. 2B - UNIT 3 I&C BUS A) AND 3B.

(COMPT. 5B - UNIT 3 I&C BUS B).

CORRECTIVE ACTION AND RECURRENCE CONTROL TAKEN OR TO BE TAKEN:

DISCONTINUED INSTALLATION OF RMS-9 WITH INSTANTANEOUS TRIP FUNCTION.

EXPECTED COMPLETION DATE:

TO BE DETERMINED.

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