ML20040A753

Summary of 811218 Meeting W/Util in Bethesda,Md Re Licensee Plans for Providing Second Level Degraded Voltage Protection.List of Attendees,Meeting Agenda & Meeting Matl Encl

ML20040A753
Person / Time
Site:	Pilgrim
Issue date:	01/05/1982
From:	Eccleston K Office of Nuclear Reactor Regulation
To:	Ippolito T Office of Nuclear Reactor Regulation
References
NUDOCS 8201220048
Download: ML20040A753 (15)

Text

_ _ _ _ _

a RECEIVED JAN 5 - 1962 t.

JAN 6 1982*- '9 Docket No. 50-293 nummuw m '

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MEMORAllDUf1 FOR: Thomas A. Ippolito, Chief Operating Reactors Branch #2 s

e, Division of Licensing 4

FROM:

Kenneth T. Eccleston, Project Manager Operating Reactors Branch f2 Division of Licensing

SUBJECT:

fleeting Sumary - Boston Edison Company 4:00 PM, December 18, 1981 (Pilgrim I)

A meeting was held on December 18, 1981 to discuss the licensee's plans for providing second level degraded grid voltage protection at Pilgrim Nuclear Power Station Unit 1 (PNPS-1).

By letter dated October 26, 1981, Boston Edison (BEco) proposed relying on cperator action in lieu of automatic equipment to provide second 'ievel degraded grid voltage protection on the unit auxiliary transformer. The licensee stated that automatic second level degraded grid voltage protection is presently installed on the startup transfomer. BECo noted that the operator has no voltage control on the startup transfomer, but can control unit auxiliary transformer voltages at the of systm dispatcher's request. Hence, the licensee maintained that althogh second level protection is necessary on the startup transformer, it is not needed on the unit aux transfomer.

Boston Edison presented their arguments as to why they believe an automatic disconr.ect is less ' safe' than reliance on operator action. They maintained that an auto disconnect could lead to a cascading effect with a resultant loss of the entire grid.

Degraded grid voltage procedures exist for Pilgrim I which instruct the operator to take corrective action upon a degraded grid voltage event.

These procedures instruct the operator to manually start the diesel generators and power the safety related buses from the diesel generators at 93% voltage.

According to the licensee, ample time would exist during such an event to allow the operator to correctly analyze the event and perform the actions necessary to safely recover from it.

Concern was expressed by the NRC over the possibility for equipment damage as a result of trying to synchronize the diesels onto the system under these circumstances. The NRC noted that the parallel operations of diesel generators (as proposed by the licensee) may render them vulnerable to coninon mode failure. This concern is based on both operating experience and analvtical wnsiocrapions, j

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2-General Design Criterion 17 requires that onsite electrical power systems have sufficient independence to perform their safety functions assuming a single failure. Safety Guide 6 describes an acceptable degree of independence between redundant standby (onsite) power sources and between their distribution systems.

The licensee will provide additional infomation to include detailed procedures to be followed in event of a degraded grid condition and necessary drawings, photos, etc. which can be readily correlated with information in the operating procedures.

The NRC will review this additional information to detemine the suitability of reliance on operator action (in event of a degraded grid condition) in lieu of automatic equipment on the unit auxiliary transformer at Pilgrim I.

The licensee's submittal will demonstrate the manner in which compliance with GDC 17 is assured. After completion of its review, the NRC will advise the licensee as to the acceptability of the licensee position. is the meeting agenda and Enclosure 2 is a list of meeting a ttendees. Enclosure 3 is a copy of the material presented by the licensee at the meeting.

ORIGINAL SIGNED BY Kenneth T. Eccleston, Project Manager Operating Peactors Branch #2 Division of Licensing

Enclosures:

As stated cc: See next page a

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P Meeting Summary Distribution Docket File NRr PDR Local PDR ORB #2 Reading J. 01shinski J. Heltemes B. Grimes T. Ippolito Project Manager OELD IE (3)

S. Norris ACRS (10)

NRC Participants NSIC TERA Regional Administrator cc: Licensee with short cc list B. D. Liau l

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Mr. A. Victor Morisi Boston Edison Company cc:

Mr. Richard D. Machon Pilgrim Station Manager Boston Edison Company RFD #1, Rocky Hill Road Plymouth, Massachusetts 02360 Henry Herrmann, Esquire Massachusetts Wildlife Federation 151 Tremont Street Boston, Massachusetts 02111 Plymouth Public Library North Street Plymouth, Massachusetts 02360 Resident Inspector c/o U. S. NRC P. O. Box 867 Plymouth, Massachusetts 02360 l

Ms. JoAnn Shatwell Office of the Attorney General l

Environmental Protection Division I

1 Ashburton Place I

19th Floor Boston, Massachusetts 02108 l

Ronald C. Haynes Regional Administrator, Region I U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406 e

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Enclosura 1 Boston Edison Company December 18, 1981 - 4:00 P.M.

1.

Second Level Degraded Grid Voltage Protection a.

Reliance on operator action in lieu of automatic operation b.

Time necessary for operator action compared to time for degraded grid voltage condition resulting in equipment damage c.

Degraded voltage occurrence - sequence and timing to result in different severity levels of grid voltage d.

Time allowed in analysis for operator action e.

Effects of degraded voltage conditions on control room indications and possible operator inability to correctly diagnose degraded voltage event f.

Control room layout and location of necessary indication in control

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12/18/81 BECo Meeting - 4:00 P.M.

DEGRADED GRID V0LTAGE Name

_C_o, Function o

George MeHugh, Jr.

BECo Nuclear Energy Deputy Mgr.

John S. Collins BECo Nuclear Eng. Sr. Eng.

R. Prevatte NRC PSB Edward L. Cobb BECo Principal Operations Eng.

Robert V. Atkins BECo Sr. Elec. Eng. Nuc. Eng.

John Pawlak BEco Power Systems Group Leader Nuc. Org.

Jim Klapproth GE Licensing M. Srinivasan NRC PSB J. E. Knight NRC PSB T. A. Ippolito NRC DL M. Chiramal NRC AE0D Bill Deacon BECo Nuclear Operations Support Manager (Acting)

Ken Eccleston NRC NRR - Pilgrim PM Jim Keyes BECo BECo Peter M. Kahler BECo Licensing Bob Butler BECo N. Engineering Mgr.

D. Tondi NRC Human Factors W. G. Kennedy NRC Human Factors (Procedures)

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o DEG'RADED VOLTAGE ISSUE PRESENTATION OUTLINE l

0 CHRONOLOGICAL BACKGROUND & DEFINITION OF THE ISSUE l

o ACCEPTANCE CRITERIA l

o DESIGN AND OPERATOR ACTION FEATURES o

DESIGN EVALUATION - CRITIQUE D

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DEGRADED VOLTAGE-RELAYING CHRONOLOGY ACTION DATE l

MILLSTONE Il INCIDENT JULY 5, 1976 1

MILLSTONE " LOAD SHEDDING" JULY 21, 1976 l

NRC LET.TER REQUESTING REVIEW AUGUST 13, 1976 BECO VOLTAGE STUDY COMPLETE OCTOBER 28, 1976 BECO COMMITMENT TO INSTALL NOVEMBER 15, 1976 DEGRADED VOLTAGE RELAYS NRC POSITION LETTER REQUIRING JUNE 3, 1977 SECOND LEVEL UNDERVOLTAGE PROTECTION BECO U.'V'.

RELAYS INSTALLED-MONITORING NOVEMBER 1977 ARKANSAS NUCLEAR ONE INCIDENT SEPTEMBER 16, 1978 NRC 12/81 O

ACCEPTANCE CRITERIA o

MINIMIZE POTENTIAL FOR DAMAGE TO SAFETY-RELATED LOADS CAUSED BY SUSTAINED DEGRADED VOLTAGE I

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MINIMIZE POTENTIAL FOR LOSS OF POWER SUPPLY TO THE SAFETY-RELATED BUSES l

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n DD/ICF TABLE-UNDERVOLTAGE REL AYS DEVICE PdDEMRIPTIOM 1 RIP M T PC'NT' F UNC T ION 34Sxv 7

34SKV ST AR TUP

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TRIPS S34 STARTS DIESEL-LINE LINE I

T RANSFORLEF l.1 SEC, GE tl SHEdIN iil AT E LOAD d

127-@"l' Dif4G IN CONJUNCTIOP.

15 T LE VEL 3094 E TS_- WIIH LOCA SIGNAL Ji gNCERVDLTAGE 18SEC.

ELAY 34 5 SWITCHYARD 35 7 g

STARTUP H

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TO SsuTDp.WN 827A 504 [rNhEW SAuE AS ABOVE UNDERVOLTAGE

= 9.2 SEC.

TRANS t

RELAY n

BUS TRIPS 505, TRIPS ALL 8OO S aw 127-AS UN TME MOTORS ON AS BUS UNIT AUXILIARY TRA N SF.

STARTUP Et*

8US LARM AT THE A

TRANSF.

127A-AS DEGRADED 38SO VOLTS COf4 TROL ROON

[ TM WW WW OLTAGE RELAY

= 92 SEC.

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SHUTDOWN OVOLTS 127-sOOA gSfOR l.1 SEC.

TRIPS 501 3 04

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SOS-UNIT AUXILIARY TRANSFORMER BREAKER l

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SO9-DIESEL GENERATOR BREAKER SAFETY RELATED 2b a

2 NOTES:

1. SINGLE LINE VOLTAGE MONITORING DIAGRAM AND y

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DEVICE TABLE ARE SHOWN FOR SAFETY REL ATED BUS AS, t

2. THIS DIAGRAM 15 REPEATED FOR SAFETY RELATED l

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p BUS AG.

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VM FIGURE i SINGLE LINE AND VOLTAGE MONiiORING DIAGRAM FOR TY PICAL 41 GOV SAFETY RELATED AC POWER#

DIS TRIBU TION SYSTEM FOR PILGRIM STATION 1 a..

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DESIGN'& 0P$RATOR' ACTION FEATURES SUPPLY TO MINIMUM SAFETY-RELATED VOLTAGE BUSES LEVEL CRITERIA FEATURES START-UP 90%

o AUTO TRIP AT 90%

1 TRANSFORMER (3745 V)

(3745 V) in 9.25 SEC.

(GENERATOR NORMALLY o AUTO TRANSFER TO 0FF LINE)

D/G UNIT AUX NONE o FAST TRANSFER FROM TRANSFORMER UNIT AUX TO STARTUP (SCRAM)

TRANSFORMER UNIT AUX 90%

o AUTO VOLTAGE TRANSFORMER (3745 V)

REGULATOR ON MAIN (GENERATOR ON LINE-GENERATOR NORMAL OPERATING MODE) o OPERATOR ACTION T0:

o ATTEMPT TO CORRECT THE SITUATION o MANUALLY TRANSFER TO D/G AT 93%

(3850 V) i

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4.16KV BUS "A" S 4.16KV 0F START-UP XFMR VOLTAGE RELAYS (TYPICAL FOR AG BUS)

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RELAYS 182 SEE SNETO! (2) FOR 2: FOUR ITE UNDERVOLTAGE RELAYS 127A-504 SElTING 8 FUNCTION (SECOND LE'EL) 1 THRU 4 3:

Two GE PAV UNDERVOLTAGE P.ELAYS 182 SEE SKETCH (3) FOR

.7A-A5 SETTING 8 FUNCTION 4: The ITE UND LTAGE RELAYS (SEC0t!D LEVE 182 R.P.S. "A" EACK UP SCP#1 VALVE LOGIC (TYPICAL FOR R.RS, "B" LOGIC):.

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7-d VALVE [{j i g SA-K22A RELAY l

SPARE CONTACT To TRIP A505 UNIT Aux BKr y

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T.D. PER T!fE -

4.16KV Lf0EPNOLTAGE tvoLTAGE CURVE

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G VOLTS =1.1 SEC.

VOLTS < 73 127-504 TRIPS BPK FROM START-UP XFMR. TO BUS A5 E.

1 (A504) 4.16KV Ut0ERVOLTAGE p

VOLTS < 75" 127-504 2

INTERLOCKS BRK FR0r1 START-UP XFl(r TO bus A5 (A504)

PREVENTS THE CORE SPRAY SYS "A" TO START (BY PASSED IF BUS "A" VOLTAGE IS FOPFAL) 4.16KV DEGRADED VOLTAGE VOLTS 43750V 127A-504 1

9.2 PREVENTS THE RHR SYS "A" TO START SEC h (BY PASSED IF BUS "A" VOLTAGE IS E! ort %L) 4.16kV DEGPADED VOLTAGE b

5 SEC DILAY Put? "A" VOLTS 43750 127A-504 10 SEC DELAY PUMP "C" 2

9,'h STARTS DIESEL A SEC (WIm DRKS A504 8 A505 OPEN) 4.1EKV DEGRADED VOLTAGE VOLTS < 3750 127A-504 T.D 3

9.2 INITIATES "A5" Bus LOAD SPEDDIt!G SEC (WI E ECCS SIGNAL 3 A505 OPErd 4.16KV DEGRADED VOLTAGE n

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VOLTS 4 3750 127A-504 T.D 4

9.2 SEC LEGEND:

} = TIME DELAY

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LOW VOLTAGE L0k! VOLTAGE n

VOLTS < 3850 -127A-A5 U

9.2 g

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A5 LOW VOLTAGE A! M i SEC v

y L0k' VOLTAGE b

VOLTS s 3850 127A-A5 9.2 SEC LOSS OF VOLTAGE TRIPS CONTROL ROD DRIVE PUMP "A" (A502)

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TRIPS RHR PUMP "A" (A503)

TRIPS UNIT Aux. XFMR. FEEDER BRl(

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(A505) 4 TRIPS RHR PUMP "C" LOSS OF VOLTAGE (A506)

VOLTS < 25% 127-A5 1

TRIPS CORE SPPAY Pure "A" (A507)

LOSS OF VOLTAGE VOLTS < 25% 127-A5 I-

'1 2

INTERLOCKS PJiR PUMP "A" FROM STARTING (A503)

It!TERLOCKS PHR PUMP "C" FROM ST RTING (A505)

INTERLOCKS CORE SPRAY PUMP "A" FROM STAR (A507) erreu 2

SANTY SUGGESTE D RM OR OBSEROATION PROCEDURE g

FOR UNDFRVOLTAGC Al ARLA CONDITION CHECK 34SKV AS AND AG VOLTMETERS SYSTEM 332KV SAFETY BUSES <.3850V YES LOW NO VOLTAGE ATTEMPT TO CONTINUE TO CORRECT BY MONI TOR GEN EXCITAT ION BUS VOLTAGE ALERT PNPS E L ECT RICAL LOW NO EN GI N E ER VOLTAGE g

'.A 1IYES SHORT TERM PROBLEM START DtESEL GENERATORS CONTACT SY STEM OBSERVE RAPID DECAY REuVEC ONDITIO SAFETY BUSES <3740V SCRAM NIT LONG 1 f TERM (MANUAL)

SYNCH DIESEL

• DROOP' b

A D CL SE ODE OPEN UNIT -

AUX BREAKERS TO SAFETY BUSES BEGIN SHUTDOWN PROCEDURE, HOT SHUTDOWN IN 4 HOURS MONITOR BEGIN BtShbtTA RhEDURE COR ECT (VOIMPROVEtAENT)

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] [NO COLD SHUT DOWN LOGIC DIAGRAM FOR OPERATOR ACTIONS DURING A l OW VOI TAGF CONDITION WITH RNPS GENERATOR f

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