ML20245G641

Summary of Operating Reactors Events Meeting 89-23 on 890614.On 890607,multiple Electrical Distribution Sys Problems Occurred at Oconee,Units 1,2 & 3.On 890610,unit Power Signal Caused Scram

ML20245G641
Person / Time
Site:	Salem, Oconee, 05000000
Issue date:	06/15/1989
From:	Lanning W Office of Nuclear Reactor Regulation
To:	Rossi C Office of Nuclear Reactor Regulation
References
OREM-89-023, OREM-89-23, NUDOCS 8906290207
Download: ML20245G641 (12)

Text

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Charles E. Rossi, Director  ?

MEMORANDUM FOR:

Division of Operational Events Assessment i

FROM: Wayne D. Lanning, Chief Events Assessment Branch Division of Operational Events Assessment 1 i

SUBJECT:

THE OPERATING REACTORS EVENTS MEETING June 14, 1989 - MEETING 89-23 On June 14, 1989, an Operating Reactors Events meeting (89-23) was held to j brief senior managers from NRR, AE00, RES, Commission Staff, and Regional j Offices on events which occurred since our last meeting on June 7, 1989.

The list of attendees is included as Enclosure 1.

The events discussed and the significant elements of these events are presented in Enclosure 2. A summary of reactor scrams for the week ending 06/11/89 is presented in Enclosure 3. Three significant events were identified for input into tne NRC performance indicator program.

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Wayne D. Lanning, Chief Events Assessment Branch Division of Operational Events Assessment

Enclosures:

As stated cc w/ Encl.:

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,8 #o UNITED STATES

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t; ..:: E WASHINGTON, D. C. 20555 JUN 151989 MEMORANDUM FOR: Charles E. Rossi, Director Division of Operational Events Assessment FROM: Wayne 0. Lanning, Chief i Events Assessment Branch i Division of Operational Events Assessment

SUBJECT:

THE OPERATING REACTORS EVENTS MEETINC June 14, 1989 - MEETING 89-23 On June 14, 1989,'an Operating Reactors Events meeting.(89-23) was held to brief senior managers from NRR, AE00, RES, Commission Staff, and Regional "

Offices on events which occurred since our last meeting on June 7, 1989.

The list of attendees is included as Enclosure 1.

The events' discussed and the significant elements of these events are presented in Enclosure 2. A. summary o'f reactor scrams for the week ending 06/11/89 is presented in Enclosure 3. Three significant evcnts were identified for input into the NRC performance indicator program.

M #

Wayne D.'Lanning, Chief Events Assessment Branch Division of Operational Events Assessment

Enclosures:

As stated cc w/ Encl.:

See Next Page l

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. ENCLOSURE 1 4

i LIST OF ATTENDEES

- OPERATING REACTORS EVENTS BRIEFING (89-23)

June 14, 1989 i NAME ORGANIZATION NAME ORGANIZATION E. Rossi- NRR/DOEA J. Guttmann SECY-

- F.' Rosa NRR/SELB . D. Hood NRR/P02-3

- L.-Wiens NRR/PD2 R. Kendall NRR/00EA D. Matthews =NRR/PD2-3 M. Harper AEOD/DSP J.:Donohewi NRR/ADSF D. Trimble OCM/JRC A. Munno NRR/00EA n. Grann NRR/DRIS R;'Perfetti' OE D. Tondi NRR/SELB P. Baranowsky NRR/00EA. M. Reardon NRR/00EA D

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l ENCLOSURE 2 s

j b OPERATING REACTORS EVENTS ERIEFING 89-23 .

EVENTS ASSESSMENT BRANCH LOCATION: 12B-11, WHITE FLINT WEDNESDAY, JUNE 14, 1989, 11:00 A.M.

. OCONEE UNITS 1, 2, 3 MULTIPLE ELECTLCAL DISTRIBUTION SYSTEM PROBLEMS t

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Lt 89-23 OCONEE UNITS"1,2 3 MULTIPLE: ELECTRICAL DISTRIBUTION SYSTEM PROBLEMS L JUNE 7, 1989

[ ' PROBLEM

.WITH ONE OF:THE TWO STANDBY POWER-SOURCES OUT OF SERVICE, A LOCA IN ONE UNIT CONCURRENT.WITH A LOSS OF 0FFSITE POWER AND A SINGLE FAILURE COULD RESULT IN THE LOSS OF ALL 4.16KVAC EMERGENCY POWER' TO THE LOCA UNIT.

CAUSE-0 '" EMERGENCY POWER SWITCHING LOGIC" (EPSL) DESIGN CAN FALSELY SENSE AVAILABILITY OF STANDBY POWER, ALTHOUGH THE POWER FEED FROM THE STANDBY BUS IS UNAVAILABLE, AND Jo PLANT. TECHNICAL SPECIFICATIONS. ALLOW CONTINUOUS REACTOR POWER OPERATION WITH ONLY ONE OF THE TWO STANDBY SOURCES IN SERVICE.

SAFETY SIGNIFICANCE o UNANALYZED CONDITION OUTSI'DE THE PLANT DESIGN' BASIS.

o MULTIPLE EVENTS (12) HAVE BEEN REPORTED CURING THE PAST 18 MONTHS CONCERNING ELECTRICAL DISTRIBUTION SYSTEM PROBLEMS AT OCONEE. MANY OF THE EVENTS INVOLVE EPSL DESIGN PROBLEMS..

DISEDSSION o THE OCONEE ELECTRICAL DISTRIBUTION SYSTEM DESIGN IS UNIQUE (N0 EMERGENCY DIESEL GENERATORS; THE MAIN FEEDER BUSES ARE INTERCONNECTED VIA DOWNSTREAM SWITCHGEAR) o GIVEN A LOCA (MAIN GENERATCR TRIP) AND A LOSS OF 0FFSITE POWER (230KV SWITCHYARD), Tile EPSL WILL TRANSFER POWER TO THE MAIN FEEDER BUSES (MFB) FROM THE STANDBY SOURCE.

o WITH ONE OF THE TWO STANDBY SOURCES OUT OF SERVICE, A SINGLE FAILURE OF THE MFB SUPPLY BREAKER FROM THE REMAINING STANDBY SOURCE WOULD RESULT IN THE LOSS OF POWER TO THE MFBs.

CONTACT: R. KENDALL SIGEVENT YES

REFERENCE:

10 CFR 50.72 #15805

~

OCONEE UNITS 1, 2, 3 89-23

. I o IN ADDITION, THE RETRANSFER TO STARTUP LOGIC (RSL) PORTION OF THE EPSL WOULD BE DISABLED (THE RSL WOULD SENSL POWER TO THE STANDBY BUS, PREVENTING AUTOMATIC TRANSFER OF POWER TO THE MFBs FROM THE STARTUP TRANSFORMER AFTER 230KV SWITCHYARD POWER HAS BEEN RESTORED BY THE KE0 WEE OVERHEAD FEED).

o CORRECTIVE ACTIONS ARE TO MODIFY TECHNICA~L SPECIFICATIONS TO REQUIRE BOTH STANDBY SOURCES TO BE OPERABLE DURING REACTOR POWER OPERATION. THE CCONEE UNITS WILL ENTER A 72 HOUR LCO SHOULD ONE OF THE STANDBY SOURCES BECOME INOPERABLE.

o OTFER ITEMS INVOLVING ELECTRICAL DISTRIBUTION SYSTEM PROBLEMS AT OLONEE HAVE INCLUDED:

1. CONTROL CIRCUITRY FOR BREAKERS SK1 8 SK2 AND THE EPSL SHARE COMMON FUSES (REMOVING THE FUSES TO PERFORM MAINTENANCE ON THE BREAKERS DISABLES PART OF THE EPSL).

2. DISCOVERED THAT THE CAPACITY OF THE 100KV STANDBY SOURCE WAS NOT ADEGUATE FOR CERTAIN LOCA AND LOSS OF POWER SCENARIOS (DUE TO ADDITI0N OF MOTOR DRIVEN AFW PUMPS).

3. DISCOVERED A SINGLE FAILURE THAT COULD DEFEAT THE EPSL j FUNCTION (FAILURE OF A SINGLE RELAY COULD PREVENT CLOSURE 0F BREAKERS E1 & E2 FOLLOWING A MAIN GENERATOR TRIF / LOCK 0UT; HOWEVER, THE EPSL WOULD SENSE POWER BEING AVAILABLE AT THE STARTUP TRANSFORMER, PREVENTING AUTOMATIC TRANSFER TO THE

' STANDBY SOURCE).

O SCME OF THE ITEMS INVOLVED PROGRAMMATIC ASPECTS OF THE ELECTRICAL DISTRIBUTION SYSTEM, INCLUDING ADEQUACY OF OPERATING, MAINTENANCE, SURVEILLANCE AND TEST PROCEDURES, AND ADECUACY OF DESIGN. BASIS l DOCUMENTATION.  ;

FOLLOWUP o THE LICENSEE HAS DEVELOPED A DESIGN BASIS DOCUMENTATION PROGRAM THAT WILL BE COMPLETED FOR THE EPSL'BY THE END.0F 1989.

O lhE LICENSEE WILL PERFORM A SELF' INITIATED TECHNICAL AUDIT (SITA) 0F THE EPSL (INCLUDES INTERFACING SYSTEMS / EQUIPMENT; SIMILAR IN SCOPE TO A SSFI; SCHEDULED FOR COMPLETION BY THE END OF 1989).

o NRR (PDII-3, EAB, ESB), RGN II, AND AE0D TO MEET WITH THE LICENSEE TO DISCUSS THE ABOVE PROGRAMS. ESB TO EVALUATE ADECUACY OF CORRECTIVE ACTIONS.

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L EMERGENCY POWER SWITCHING LOGIC "EPSL" l

1. MAIN FEEDER BUS (MFB) MONITOR PANELS Function is to restore. power to the MFBs within 31 seconds for non-LOCA loss of power events.-

2. EPSL Same function, but within 11 seconds for loss of power in conjunction with a LOCA.'

3. RETRANSFER TO STARTUP LOGIC (RSL)

Senses EPSL transfer of power to the MFB from the standby source (2), and if power is subsequently lost for >10 secpnds, retransfers the MFBs back to the startup transformer (if power has since t,ecome available).

For RSL actuation, the following must occur in sequence:

• LOP + LOCA.

_EPSL MFB transfer to standby sources (UST from 230kV switchyard.is unavailable).

Restoration of 230kV switchyard (emergency power).

Loss of staridby source for >10 seconds.

• Then RSL will retransfer the MFBs back to the UST.

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)No;- 1-14/B9 :

' PERFORMANCE IN31CATOR3 SIGNIFICANT EVENTS ENCLOSURE 3 kNAME EVENT EVENT DESCRIPT10N' GTR S16MIFICANCE DATE

$0N 't . 06/01/89 REBUILT INBOARD AND DUTB0ARD SEALS FAILED ON A 1 POTENTIAL FOR OR ACTUAL DEERADAT10N RECIRCULATION PUMP. DF PRIMARY COOLANT PEE!SURE BOUNDARY UY! 02/26/E9 TEMP IN EXCESS OF 330 DE6REES F NERE CALCULATED TO HAVE O POTENTIAL FOR OR ACTUAL DEGRADATION EIISTED IN THE UPPER PCRTION OF THE DRYNELL. THE REGICM - 0F SAFETY-RELATED EQU1FMENT.

INVOLVED CONTAINS APFR0! 73 SAFETY-RELATED CABLES AND 35 SNUBBERS. EG TEMP FOR THE CABLES LS 195 DEGREES F, FOR

$NUBBERS 300 DE6REES F.

' STONE 1 03/22/89 THE LICENSEE REC 06NIZED THAT A HIGH ENERGY LINE BREAK 0 PDTENTIAL FOR OR ACTUAL DEGRADATION INSIDE CONTAINMENT COULD CAUSE DE6RADATION OF CONTAINMENTOF CONTAINMENT OR SAFETY-RELATED INTE6RITY. THE RBCCN SYSTEM NOULD NOT REMAIN A CLOSED STRUCTURES SYSTEM.

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5 e stEACTOR SCRAM

SUMMARY

WEEK ENDING 06/11/89 l

1. PLANT SPECIFIC DATA DATE SITE UNIT POWER SIGNAL CAUSE COMPLI- YTD YTD YTD CATIONS AB0VE BELOW TOTAL 15% 15%

06/10/89 SALEM 2 100 M EDUIPMENT ND 4 1 5 O

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NdTES'

1. PLANT SPsCIFIC DATA BASED ON INITIAL REVIEW OF 50.72 REPORTS FOR THE WEEK OF INTEREST. PERIOD IS HICNIGHT SUNDAY THROUCH MIDNIGHT SUNDAY. SCRAMS ARE DEFINED AS REACTOR PROTECTIVE ACTUATIONS WHICH RESULT IN R0D MOTION, AND EXCLUDE PLANNED TESTS OR SCRAMS AS PART OF PLANNED SHUTDOWN IN ACCORDANCE WITH A PLANT PROCEDURE. THERE ARE 111 REACTORS HOLDING AN OPERATING LICENSE.

2. COMPLICATIbHS:-REC 0VERYCOMPLICATEDBYEQUIPMENTFAILURESOR PERSONNEL' ERRORS UNRELATED TD CAUSE OF SCRAM.

3. PERSONNEL RELATED PROBLEMS INCLUDE HUMAN ERROR, PROCEDURAL DEFICIENCIES, AND MANUAL' STEAM GENERATOR LEVEL CONTROL-PRUBLEMS..

4. "0THER" INCLUDES AUTOMATIC SCRAMS ATTRIBUTED TO ENVIRONMENTAL -

CAUSES (LIGHTNING), SYSTEM DESIGN, OR UNKNOWN CAUSE.

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