Part 21 Report - 1998-372

LICENSEE: ILLINOIS POWER CO. SITE: CLINTON 1 EN NUMBER:34330 DOCKET: 05000461 EVENT DATE: 03-14-98 RX TYPE: BWR EVENT TIME: : VENDORS: GE-6 NOTIFY DATE: 06-03-98 EMERGENCY CLASS: N/A REGION: 3 STATE: IL TIME: 10:25 OPS OFFICER: LEIGH TROCINE 10 CFR SECTION: CCCC 21.21 UNSPECIFIED PARAGRAPH UNIT SCRAM RX INIT INITIAL MODE CURR CURRENT MODE CODE CRIT PWR PWR 1 N N 0 COLD SHUTDOWN 0 COLD SHUTDOWN NOTIFICATION IN ACCORDANCE WITH 10 CFR PART 21 - RMX-TYPE KEPCO, INC., POWER SUPPLY FAILURES (REFER TO EVENT #33710 FOR ADDITIONAL INFORMATION.) THE FOLLOWING TEXT IS A PORTION OF A FACSIMILE RECEIVED FROM THE LICENSEE: "ON FEBRUARY 13, 1998, A NUCLEAR SYSTEMS [PROTECTION] SYSTEM [(NSPS)] 12-VOLT DIRECT CURRENT [(VDC)] POWER SUPPLY FAILED CAUSING THE DIVISION II NSPS INVERTER TO REVERSE TRANSFER TO THE BYPASS TRANSFORMER WHICH WAS OUT OF SERVICE FOR MAINTENANCE. THIS RESULTED IN A LOSS OF SHUTDOWN COOLING AS DESCRIBED IN NRC EVENT [NUMBER 33710 AND LICENSEE EVENT REPORT NUMBER 98-003-01]. THE CAUSE OF THE POWER SUPPLY FAILURE WAS AN INADEQUATELY DESIGNED OUTPUT TRANSISTOR PAIR COMBINED WITH DEGRADED CAPACITORS." "THE COMPONENT INVOLVED IN THIS REPORT IS A 12-VDC POWER SUPPLY, MODEL NUMBER RMX12-D-20993, [WHICH WAS] SUPPLIED TO CLINTON POWER STATION. THIS CONDITION WAS ALSO IDENTIFIED TO EFFECT MODEL NUMBERS RMX24-D-20804 AND RMT001-AA-20995. THE POWER SUPPLY WAS MANUFACTURED BY KEPCO, [INC.], AND [IT] WAS PURCHASED BY GENERAL ELECTRIC (GE) AS A NON-SAFETY-RELATED COMPONENT." "THE SUPPLIER PROVIDED MARGINALLY RATED OUTPUT TRANSISTORS IN THE POWER SUPPLY. THESE TRANSISTORS, AGGRAVATED BY DEGRADATION OF THEIR ELECTROLYTIC FILTER CAPACITORS, FAILED, PRODUCING A PHASE-TO-PHASE SHORT ON THE NSPS BUS. THE LARGE CURRENT DRAW CAUSED THE INVERTER TO REVERSE TRANSFER AS DESIGNED TO CLEAR THIS FAULT. SINCE THE ALTERNATE SOURCE WAS UNAVAILABLE, THE CONDITION RESULTED IN A LOSS OF POWER TO THE NSPS BUS LOADS WHICH INCLUDED THE PRIMARY VALVE FOR THE SHUTDOWN COOLING MODE AT THE TIME OF THE EVENT. THE LOSS OF POWER TO THE VALVE CAUSED THE VALVE TO CLOSE AND SHUT OFF SHUTDOWN COOLING. IN ADDITION, GE PARTS LIST DRAWING [NUMBER] 169C8805 IDENTIFIES THE POWER SUPPLY AS NON-SAFETY RELATED, AND [CLINTON] PURCHASED THE POWER SUPPLIES AS NON-SAFETY-RELATED. HOWEVER, BASED ON THE APPLICATION OF THE POWER SUPPLIES AND GE SPECIFICATION [NUMBER] 22A7822, REVISION 1, THE POWER SUPPLIES SHOULD BE CLASSIFIED AS SAFETY RELATED. SUBSEQUENTLY, [CLINTON] HAS REVISED THE MASTER EQUIPMENT LIST TO CHANGE THE CLASSIFICATION OF THE POWER SUPPLIES." "[THE LICENSEE] IDENTIFIED ON MARCH 12, 1998, THAT THE POWER SUPPLY FAILURE DURING STARTUP OF THE DIVISION [II] NSPS BYPASS TRANSFORMER ON FEBRUARY 13, 1998, MAY HAVE CAUSED THE INVERTER TO REVERSE TRANSFER. SUBSEQUENTLY, ON MARCH 14, 1998, THE RESULTS OF THE FAILURE ANALYSIS PERFORMED BY INTEGRATED RESOURCES, INC., CONFIRMED THAT THE POWER SUPPLY FAILURE WAS THE CAUSE OF THE REVERSE TRANSFER. THE OUTPUT TRANSISTORS WERE UNDERRATED AND ARE, THEREFORE, REPORTABLE UNDER 10 CFR [PART] 21." "RMX-TYPE KEPCO, INC., POWER SUPPLIES ARE IN USE AT [CLINTON] FOR ALL [4] DIVISIONS OF NSPS (16 TOTAL), NEUTRON MONITORING SYSTEM (24 TOTAL), AND THE DISPLAY CONTROL SYSTEM (2 TOTAL). CURRENTLY, [CLINTON] IS EVALUATING THE IMPACT ON ALL KEPCO SUPPLIED RMX-TYPE POWER SUPPLIES." "[THE LICENSEE PLANS TO] REPLACE THE OUTPUT TRANSISTORS AND DEGRADED CAPACITORS, DUE TO PREMATURE AGING, IN KEPCO RMX-TYPE POWER SUPPLIES." "[THE LICENSEE] RECOMMENDS EVALUATION OF RMX-TYPE POWER SUPPLIES MANUFACTURED BY KEPCO, INC., FOR CONDITIONS SIMILAR TO THOSE DESCRIBED IN THIS REPORT."

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