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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