ML17201Q401
| ML17201Q401 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 04/03/1989 |
| From: | Siegal B Office of Nuclear Reactor Regulation |
| To: | Muller D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8904120488 | |
| Download: ML17201Q401 (28) | |
Text
MEMORANDUM TO:
FROM:
SUBJECT:
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555
. Apri 1 3, 1989 Daniel R. Muller, Director Project Directorate III-2 Division of Reactor Projects III, IV, V, and Special Projects Byron L. Siegel, Project Manager Project Directorate III-2 Division of Reactor Projects III, IV, V, and Special Projects
SUMMARY
OF MEETING ~!ITH COMMONWEALTH EDISON tOMPANY.
TO DISCUSS 4KV UNDERVOLTAGE SETPOINTS FOR DRESDEN UNITS 2 AND 3 A meeting was held on March 20, 1989 at the USNRC office located at One White*
Flint North in Rockville, Maryland with Conunonwealth Edison Company (CECo). A list of meeting attendees is contained in Enclosure 1.
The purpose of the meeting was to discuss the proposed change to the 4KV undervoltage trip setpoints contained in the proposed Technical Specification (TS) amendment submitted by CECo in a letter dated March 28, 1989 for Dresden Units 2 and 3.
CECo requested the change because it was discovered that the current undervoltage setpoints in the TS are not consistent with the field settings on the undervo ltage re lays. The basis for the acceptability of the proposed TS change was presented by CECo during the meeting and a copy of the handouts is contained in Enclosure 2.
After CECo's presentation, the staff caucused and determined that*th~ proposed amendment for Dresden was acceptable provided CECo convnitted to the following actions:
/
- 1.
Develop a procedure for-all the CECo plants for the operators to manually disconnect offsite power if the undervoltage is less than 75% of the bus voltage for longer than one minute.
- 2.
Re-confirm for Dresden that only two systems needed for safe shutdown are operating prior to the occurrence of a degraded voltage condition (evaluation should include all safety related equipment, down to 120V, connected to bus that would be subjected to the low voltage).
- CECo tentatively agreed to the staff's prC1posed actions pending -further plant and corporative management approval and stated that within one week a formal response would be provided.
Enclosures:
As statE:d cc: See next page
~ (,'1~roject Manager roject Directorate III-2 Division of Reactor Projects Ill, IV, V, and Special Projects
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April 3, 1989 *
- 2. -
CECo tentatively agreed to the staff's proposed actions pending further plant and corporative management approval and stated that within one week a formal response would be provided.
Enclosures:
As stated cc: See next page DISTRIBUTION r.centr-a-LtiJe::J
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ENCLOSURE 1 MARCH 20 1 1989-MEETING BETWEEN-CECO &-NRC TO DISCUSS-4KV UNDERVOLTAGE SETPOINT ISSUE NAME AFFILIATION John Si lady CE Co NLA Nick Kalivianakis CE Co Production Jack Brunner CECo* Dresden Mark Kluge CE Co BWR Eng.
Suheil Z. Haddad S&L Elect. Analytical Div.
George P. Wagner CE Co Production Services Ashok Thadan1 NRC SAD Thomas J. Kovach CE Co Licensing Manager Dennis Galle CE Co V.P. BWR Operations William L. Forney NRC Reg.III, Deputy Dir.,DRP Byron Siegel NRC Dresden Project Manager Gary M. Holahan NRC Director DRSP Faust Rosa NRC SELB Dom Tondi NRC SELB Fred Burrows NRC SELB D. R. Muller NRC NRR/PDIII-2
Mr. Henry E. Bliss Conmonwealth Edison Company cc:
Michael I. Miller, Esq.
Sidley and Austin One First National Plaza Chicago, Illinois 60603 Mr. J. Eenigenburg.
Plant Superintendent Dresden Nuclear Power Station Rura.1 Route #1 Morris, Illinois 60450 U. S. Nuclear Regulatory ColTlllission Resident Inspectors Office Dresden Station
- Rural Route #1 Morris, Illinois 60450 Chainnan Board of Supervisors of Grundy County Grundy County Courthouse Morris, Illinois 60450 Regional Administrator Nuclear Regulatory Commission, Region III 799 Roosevelt Road, Bldg. #4 Gl~n Ellyn, Illinois 60137 Mr. Michael E. Parker, Chief Division of Engineering Illinois Department of Nuclear Safety 1035 Outer Park Drive, 5th Floor Sprillgfield, Illinois 62704 Dresden Nuclear Power Station Units 2 and 3
- TRIP SETPOINT DRESDEN UNITS 2 AND 3,
COMMONWEALTH EDISON - NRC
~V1EETING ROCKVILLE, MARYLAND
- MARCH 20, 1989.
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AGENDA SUBJECT PRESENTER' OPENING REMARKS D.P.GALLE DEFINITIONS J. A. SILADV HISTORY,
J. A. SILADV PURPOSE OF 1ST AND 2ND LEVEL J. A. SILADV UNDERVOLTAGE TRIPS RESPONSE TO NRC QUESTIONS J. *D. BRUNNER CONCLUSIONS J." A. SILADV OVERVIEW D. P. GALLE.
NRC-2
CECO 4 KV UNDERVOLTAGE TERMINOLOGY LEVEL "FIRST'
- *sECOND*
- CALLED *FIRST*
LEVEL BECAUSE THEY WERE THE FIRST AS PART OF ORIGINAL DESIGN
- CALLED *SECOND.
LEVEL BECAUSE THEY WERE ADDED LATER (EARLY 19BO'S)
NRC-IA TECH SPEC TERM LOSS OF VOLTAGE RELAYS DEGRADED VOLTAGE RELAYS TYPICAL VALUE t¥70%
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DRESDEN 4 KV UNDERVOLTAGE SETTINGS LEVEL VOLTS o/o I..
NORMAL OPERATION 4160 100%
SECOND LEVEL
~ 3708
~ 89% *
(CURRENT TECH SPEC &
. ACTUAL)
FIRST LEVEL
? 3092
. ~ 74%
(CURRENT TECH SPEC)
FIRST LEVEL 2930 ! 5%
707!
(ACTUAL & PROPOSED TECH SPEC)
- 1.N TODAYS' DISCUSSION, WILL REFER TO AS *90%
NRC-IB
GENERAL BACKGROUND - HISTORY *
- ORIGINAL DRESDEN DESIGN BASIS
- INCLUDED ONLY FIRST LEVEL TO DETECT LOSS OF OFFSITE POWER
- SETTING NOT INCLUDED. IN TECH SPECS
- LATE 1970'S -
EARLY 1980'S
- NRC LETTERS TO ALL LICENSEES ON NEED FOR SECOND LEVEL (8/77)
- NRC LETTER TO ALL LICENSEES REQUESTING STUDY OF ADEQUACY OF ELECTRICAL DISTRIBUTION SYSTEM (8/79)
- SUBMITTED DRESDEN STUDY (11/79)
- COMMITTED TO ADD SECOND *LEVEL FOR DEGRADED VOLTAQE (8/80)
- NRC SER ISSUED ON DRESDEN STUDY (10/81)
- SUBMITTED PROPOSED AMENDMENT ADDING SECOND LEVEL WITH 5 MINUTE DELAY, AS WELL AS FIRST LEVEL SETPOINT (3/82)
- NRC *SER ISSUED ON DRESDEN REVISED UNDERVOLTAGE SCHEME
. AND TECH SPECS (5/82)
NRC-.CA
HISTORY HOW THE INCORRECT SETPOINT MS PLACED INTO TECH SP.
1982
. LEVEL UV. MODIFICATION AND TECH SPEC CHANGE
- TECH SPEC ON-SITE REVIEW (OSR) PREPARED BY TECH STAFF ENGINEER WHO USED INCORRECT FIRST LEVEL OF 3092 BASED ON 3255 -
5%
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HISTORY DISCOVERY OF PROBLEM {MARCH 1988)
- REVIEW INCLUDED COMPARISON TO TECH SPEC AND CEco*s OPERATIONAL ANALYSIS DEPARTMENT*s CALIBRATION RECORIOS *
- DISCOVERED DIFFERENCES BETWEEN CURRENT TRIP VALUE (
THE TECH SPEC VALUE
- PROMPTLY NOTIFIED NRR. AND. R-111
- REQUESTED AND RECEIVED WAIVER NRC-4C
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PURPOSE OF 4KV UNDERVOLTAGE RELAY TRIPS.
- 1ST LEVEL:
TO DETECT LOSS OF OFFSITE POWER
(,.., 70"-)
- 2ND LEVEL:
TO DETECT DEGRADED VOLTAGE AS *
(,_ 90"-)
DETERMINED BY LOAD ANALYSIS *
- BOTH LEVELS:
TO TRANSFER SAFETY BUSES TO ONSITE POWER (DIESEL GENERATORS) i NRC-ac
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SECOND LEVEL 5 MINUTE TRIP DELAY ii APPLICABLE ONLY FOR NON-LOCA SITUATIONS:
- TO ALLOW OPERATOR SUFFICIENT TIME TO ATTEMPT VOLTAGE RESTORATION
- TO MINIMIZE UNNECESSARY TRANSFER OF EQUIPMENT FROM OFFSITE POWIER
- TO AVOID UNNECESSARY DUTY ON DIESEL GENERATOR
- BYPASSED WHENEVER_ LOCA SIGNALS. ARE PRESENT (HIGH DRYWELL PRESSURE OR LOW LOW WATER LEVEL WITH LOW REACTOR PRESSURE) SO THAT *ONLY THE INHERENT 7 SECOND DELAY OCCURS NRC-3D
NRC QUESTION #1
- WHAT IS THE EFFECT ON EQUIPMENT OF OPERATION AT 87%
RATED VOLTAGE FOR FIVE MINUTES?
- ASSUMING THIS OCCURRED, THE EQUIPMENT WOULD EXPERIENCE NO PERMANENT DAMAGE
./ FOR MOTORS, BASED ON DRESDEN MOTOR STUDY DATED 9/20/88
./ FOR OTHER EQUIPMENT, (E.Q. RELAYS, BATTERY CHARQERS ETC.) DRAW LESS CURRENT UNDER DEGRADED VOLT.ABES
- HOWEVER, THIS CONDITION IS NOT A CREDIBLE SCENARIO
./ 7177 AND 11/79 SUBMITTALS TO NRC INDICATED LOWEST EXPECTED TRANSIENT VOLTAGE WOULD BE 81.5% OF NOMINAL VOLTAGE. LOWEST STr=ADY STATE VOLTAGE WOULD BE 88%.
./ LASALLE YIELDS SIMILAR NOMINAL
- CONFORMANCE TO BTP PSB-1
./ APPENDIX DESCRIBES COMPLIANCE NRC-#1
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NRC QUESTION #2
- CAN MOTORS BE RESTARTED FOLLOWING OVERCURRENT TRIPS BY OPERATION AT 87~ VOLTAGE?
- EXAMPLE
- CONCLUSION VOLTAGE:
CURRENT:
TRIPS:
TEMP RISE:
87~
NOMINAL 185~ NOMINAL 80 SECONDS
~ 80 DEGREES C MOTOR COULD BE STARTED WITH NO TIME DELAY ASSUMING ADEQUATE BUS VOLTAGE IS RESTORED
- CON.SEQUENCES FOR TRIPPED MOTORS, LOCKED OUT RELAYS MUST BE RESET
- WHAT ARE CONSEQUENCES OF MOTORS TRIPPING 'PRIOR TO OR DURING AN ACCIDENT?
- .EXTREMELY LOW PROBABILITY J ASSUMES SEVERELY DEGRADED OFFSITE POWER FOR A SUSTAINED PERIOD FOLLOWED BY A DBA CONCURRENT WITH ECCS PUMPS SURVEILLANCE NRC-#2
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NRC QUESTION #2 (CONT'D)
- EXTREMELY LOW PROBABILITY
,/ ALSO ASSUMES SEVERELY DEGRADED OFFSITE POWER FOR A SUSTAINED PERIOD FOLLOWED BY A TRANSIENT
,/ ALL SYSTEMS CREDITED IN FSAR TRANSIENT ANALYSES ARE DC INITIATED AND THEREFORE MOTOR TRIPS HAVE NO EFFECT (E.G. ISOLATION CONDENSER, RELIEF VALVES, HPCI)
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I NRC QUESTION #3
- WHAT IS THE CONCERN ABOUT RAISING UNDERVOLTAGE RELAY SETPOINT TO 75% OF RATED VOLTAGE?
- RAISING SETPOINT PRESENTS THESE CONCERNS:
./ INCREASE PROBABILITY OF TRANSFER TO THE DIESEL GENERATORS
./ INCREASE PROBABILITY *OF UNIT TRIPS*
./ INCREASE PROBABILITY.OF MOTOR TRIPS IF ON DIESEL GENERATORS
./ DELAY IN LOCA RESPONSE DUE TO RELAY RESET CHARACTERISTICS NRC*#3 (CONT'D)
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I NRC QUESTION #3' (CONT'D)
- ANSWERS TO OTHER RELATED QUESTIONS
- LOADS HAVE BEEN ADDED BUT NO VOLTAQE CHANGES OF CONSEQUENCE HAVE RESULTED
- EFFECT OF LOAD ADDITIONS ARE ADDRESSED AT TIME LOAD IS ADDED.BASED ON ANALYSIS OR ENGINEERING JUDGEMENT
- POTENTIAL MODIFICATIONS DO NOT MITIGATE THE FIRST TWO CECO CONCERNS NRC-#3A l
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- WHAT ARE *THE LOWEST ALLOMBLE STARTING AND RUNNING MOTOR VOLTAGES?
- TYPICAL RATINGS
./ STARTING!
ANSI:.
85% MOTOR VOLTAGE. RATING CECO:
NORMALLY SPECIFIED AS 75*85%
MOTOR VOLTAGE RATING!
./ RUNNING!
ANSI:
75% MOTOR VOLTAGE RATINQ FOR ONE MINUTE
- LARQE MOTORS ARE ONLY STARTED SIMULTANEOUSLY DURINQ A LOCA AND WHEN THE BUS VOLTAGE IS ABOVE 90%
- DURING A LOCA, IF BUS VOLTAGE IS LESS THAN 90%, WE TRANSFER TO THE DIESEL GENERATORS AND THEN LOAD THE MOTORS SEQUENTIALLY NRC-#-4 r
NRC QUESTION #5
- HOW MS STAFF INFORMED THAT THE TECHNICAL SPECIFICATIONS LISTED TAP VALUES RATHER THAN TRIP SETTINGS?
- CECO DID NOT INTEND TO GIVE THE IMPRESSION THAT
. THE STAFF MS INFORMED OR COULD HAVE KNOWN THAT THE 1982 TECHNICAL SPECIFICATION TRIP LEVEL SETTINGS WERE THE TAP SETTING VALUES.
NRC-#&
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- c CECO CONCLUSIONS
- DRESDEN 1st AND 2nd LEVEL RELAYS FULFILL
- INTENDED FUNCTION AND COMPLY WITH DESIGN. BASIS AND
. STANDARDS
- FSAR QUESTIONS AND ANSWERS ON LASALLE AND BYRON/BRAIDWOOD HAVE SATISFACTORILY ADDRESSED THE SAME ISSUES AS D~SCUSSED TODAY NRC-9
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CECO CONCLUSIONS (CONT'D)
- HAVE APPLIED THE SAME PROTECTION METHODOLOGY AT NEW CECO SITES CURRENT TECH SPEC ALLOWABLE SETTINGS EIRSI LEVEL SECOND LEVEL NON-LOCA LOCA STATION VOLTS
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VOLTS
~ DELAY*
DELAY DRESDEN
?3092
?74
?3708
?89
~5 MIN
-1 SEC LASALLE DIV. I/II 2625*
-63
'3814**
-92
-5 MIN
-10 SEC DIV. Ill 2870*
-69 3814** s MIN
-10 SEC BYRON
~2730
?69
~3728
?90 310 SEC
-10 SEC BRDWD
~2730
~69
?3728
?90 310 SEC
-10 SEC
+ 10% of set point
- !: 2% of setpoint
- % 0 f 4 1 6 0 VO It S NRC-9A-T
CECO CONCLUSIONS (CONT'D)
- CURRENT CONFIQURATION ADDRESSES SEVERLY DEQRADED VOLTAQES (BETWEEN FIRST AND SECOND LEVELS)
- CHARACTERISTICS OF THE OFFSITE POWER SYSTEM ESSENTIALLY PRECLUDE OPERATION IN THIS RANQE
- SECOND LEVEL DELAY (5 MIN) IS BYPASSED IF LOCA SIQNAL PRESENT: TRIPS WITHIN 7 SECONDS
- THERMAL OVERLOAD TRIPS ALSO PROTECT. MOTORS FOR NON*LOCA EVENTS WITH DEQRADED VOLTAQE IN THIS RANQE
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CECO CONCLUSIONS* (CONT'D)
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- NO NET IMPROVEMENT IN. PLANT SAFETY IF FIRST LEVEL RELAY SETPOINT IS CHANGED FROM 70% TO 76%
- MODIFICATIONS DO NOT RESOLVE ALL CECO CONCERNS PRESENTED BY A SETPOINT CHANGE NRC-IC
~-------
,-,I APPENDIX
REGULATORY HISTORY JUNE 77 CECO RESPONSE I
POSITION U2CICKEil1a-1a M6I 12 BEB
~Bl-l.I UL-'£ ll I
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- 2nd LEVEL UV WILL PROVIDE COMPLY SAME W/TIME DELM RELMB
- SETPOINTS COMPLY MME SAME FROM VOLmaE ANALYSIS
- ~- <o *I' **
- COINCIDENT COMPLY COMPLY SAME LOBIC
- TIME DELAY PROVIDED SET-COMPLY TWO TIME AIOID8 TRANSi-
. POINTS (IN-
. (SAME REVIEWER DELAYS; ENT DISTURBAN-CORRECT SET-.
FOR and LEVEL
-LONGER CES DOES NOT TINBS);
AND VOLT.ABE THAN MOTOR EXCEED F8AR SEPARATELY ANALYSIS START VOLTAGE ANALYSIS, DOES PROVIDED 1979 10/81 SER)
DIP TRANSIENT NOT DAM.ABE VOLT.ABE ANALYSIS
-NO DAM.ABE TO SAFETY EQUIP-W/CORRECT PERMANENTLY MENT DURIN6 SETPOINT CONNECTED DE&RADED (IEIN-7904 AND 1E LOADS IF VOLmaE NAC LETTER)
OPERATOR FAILS TO RESTORE VOLTA BE
REGULATORY HISTORY JUNE 77 CECO RESPONSE POSITION UM~KEil1a-1a NAY aa SER
- AUTOMATICALLY COMPLY COMPLY DISCONNECTS OFF-SITE SOURCE
COMPLY
- COMPLY
- TECH SPECS PROVIDED TECH ACCEPTED SPECS CECO POSITION
- LOAD SHED COMPLY (2nd COMPLY PREVlENTED WHEN LEVEL '2.W.l:)
DIESEL ON BUS
- ONSITE POWER DESCRIBED ACCEPTED TESTI NB EVERY TESTINB CECO 11 MONTHS POSITION
- RC*IOB psB-1 JULY 11 SANE SANE SANE PREVENT LOAD SHED DURINB SE-QUENCING, REIN-STAI" E UPON CON-PLETION. LOAD SHED CAN BE RETAINED DURING SEQUENCING IF 1*t LEVEL SET-POI NT HAS MAX I NIN LIMITS WITH*
BASIS VOLTABE LEVELS OPTIMIZED BASED ON ANAL'IBIS
-SANE AS 1171 ANALYSIS
-VERIFIED BY MEASUREMENT
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