ML17312B712
| ML17312B712 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 10/08/1997 |
| From: | Thomas K NRC (Affiliation Not Assigned) |
| To: | NRC (Affiliation Not Assigned) |
| References | |
| NUDOCS 9710140062 | |
| Download: ML17312B712 (68) | |
Text
ti LICENSEE:
FACILITY:
October 8, 1997 ~
Arizon
, ublic Service Company Palo Verde Nuclear Generating Station, Unit Nos.
- 1. 2, and 3
SUBJECT:
SUMMARY
OF MEETING HELD ON SEPTEMBER 16,
- 1997, TO DISCUSS PROPOSED TECHNICAL SPECIFICATION AMENDMENT DATED NOVEMBER 6,
- 1996, TO PROVIDE A METHOD TO RESPOND TO A SUSTAINED, DEGRADED SWITCHYARD VOLTAGE The NRC staff met with Arizona Public Service Company (APS) on September 16, 1997, at the NRC to discuss APS's November 6,
- 1996, request f'r a technical specification amendment to provide a method to respond to a sustained, degraded switchyard voltage at the Palo Verde Nuclear Generating Station.
A list of participants is contained in Attachment 1.
Attachment 2 contains the material distributed during the meeting.
During the meeting, APS discussed the contributors to a degraded switchyard voltage/double sequencing condition, actions taken to date to prevent a
degraded switchyard voltage/double sequencing condition, and proposed changes to the technical specifications for degraded switchyard voltage.
APS explained that administrative controls to protect the plant against a degraded switchyard voltage/double sequencing event is the appropriate permanent solution to this problem for the Palo Verde Nuclear Generating Station.
At the conclusion of the meeting, APS indicated that they would review the Final Safety Analysis Report to verify that it adequately describes the plant as it relates to degraded switchyard voltage and double sequencing.
In
- addition, APS indicated they would provide the staff with an analysis of the risk impact of'he proposed administrative controls and the basis for concluding that the Palo Verde Nuclear Generating Station will be operated in accordance with the regulations with the use of administrative controls as a
permanent solution to protect against double sequencing of safety related equipment.
The staff informed APS that as a result of the information provided during the
- meeting, a response to the staff's August 7,
- 1997, request was not needed.
Original Signed By Kristine M. Thomas, Project Manager Project Directorate IV-2 Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation Docket Nos.
STN 50-528, STN 50-529 and STN 50-530 Attachments:
- l. Attendance List
- 2. Handouts cc w/atts:
See next page 97iOi40062 97i008 PDR ADOCK 05000528 P
- See Previous Concurrence Document Name:
PV97192.MTS DISTRIBUTION:
Docket File PUBLIC PDIV-2 Reading KThomas
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LICENSEE:
FACILITY:
SUBJECT:
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 2055&4001 October 8,
1997 Arizona Public Service Company Palo Verde Nuclear Generating Station, Unit Nos.
1, 2.
and 3
SUMMARY
OF MEETING HELD ON SEPTEMBER 16.
- 1997, TO DISCUSS PROPOSED TECHNICAL SPECIFICATION AMENDMENT DATED NOVEMBER 6,
- 1996, TO PROVIDE A METHOD TO RESPOND TO A SUSTAINED.
DEGRADED SMITCHYARD VOLTAGE The NRC staff met with Arizona Public Service Company (APS) on September 16, 1997, at the NRC to discuss APS's November 6,
- 1996, request for a technical specification amendment to provide a method to respond to a sustained, degraded switchyard voltage at the Palo Verde Nuclear Generating Station.
A list of participants is contained in Attachment 1.
Attachment 2 contains the mater'ial distributed during the meeting.
During the meeting, APS discussed the contributors to a degraded switchyard voltage/double sequencing condition, actions taken to date to prevent a
degraded switchyard voltage/double sequencing condition, and proposed changes to the technical specifications for degraded switchyard voltage.
APS explained that administrative controls to protect the plant against a degraded switchyard voltage/double sequencing event is the appropriate permanent solution to this problem for the Palo Verde Nuclear Generating Station.
At the conclusion of the meeting, APS indicated that they would review the Final Safety Analysis Report to verify that it adequately describes the plant as it relates to degraded switchyard voltage and double sequencing.
In
- addition, APS indicated they would provide the staff with an analysis of the risk impact of the proposed administrative controls and the basis f'r concluding that the Palo Verde Nuclear Generating Station will be operated in accordance with the regulations with the use of administrative controls as a
, permanent solution to protect against double sequencing of safety related equipment.
The staft informed APS that as a result of the information provided during the meeting.
a response to the staff's August 7,
- 1997, request was not needed.
~ (A. III~~
Kristine M. Thomas, Project Manager Project Directorate IV-2 Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation Docket Nos.
STN 50-528, STN 50-529 and STN 50-530 Attachments:
1.
Attendance List 2.
Handouts cc w/atts:
See next page
l~
T f
t l
I
cc w/att:
Mr. Steve Olea Arizona Corporation Commission 1200 W. Washington Street Phoenix.
Arizona 85007 Douglas Kent Porter Senior Counsel Southern California Edison Company Law Department.
Generation Resources P.O.
Box 800 Rosemead.
California 91770 Senior Resident Inspector USNRC P. 0.
Box 40 Buckeye, Arizona 85326 Regional Administrator, Region IV U. S.
Nuclear Regulatory Commission Harris Tower 8 Payillion 611 Ryan Plaza Drive, Suite 400 Arlington, Texas 76011-8064
- Chairman, Board of Supervisors ATTN:
Chairman 301 W. Jefferson, 10th Floor
- Phoenix, Arizona 85003 Mr. Aubrey V. Godwin, Director Arizona Radiation Regulatory Agency 4814 South 40 Street
, Phoenix, Arizona 85040 Ms. Angela K. Krainik, Manager Nuclear Licensing Arizona Public Service Company P.O.
Box 52034 Phoenix.
Arizona 85072-2034 Mr. John C. Horne, Vice President Power Supply Palo Verde Services 2025 N. Third Street, Suite 220 Phoenix.
Arizona 85004 Mr. Robert Burt Los Angeles Department of Water 5 Power Southern California Public Power Authority 111 North Hope Street.
Room 1255-B Los Angeles, California 90051 Mr. David Summers Public Service Company of New Mexico 414 Silver SW, ¹0604 Albuquerque, New Mexico 87102 Mr. Robert D. Bledsoe Southern California Edison Company 14300 Mesa Road.
Drop D41-SONGS San Clemente, California 92672 Mr. Robert Henry Salt River Project 6504 East.Thomas Road Scottsdale.
Arizona 85251 Terry Bassham.
Esq.
General Counsel El Paso Electric Company 123 W. Mills El Paso, Texas 79901 Mr. James M. Levine Executive Vice President.
Nuclear Arizona Public Service Company Post Office Box 53999
- Phoenix, Arizona 85072-3999
V W
T
~ t J
j
Meetin with Arizona Public Service Com an Palo Verde Nuclear Generatin Station Attendance List Se tember 16 1997 Arizona Public Service Com an W. Ide S.
Bauer S. Kesler H. L'cake S..Burns NRC W.
Bateman J.
Calvo J.
Lazevnick D. Thatcher F. Orr K. Thomas Attachment 1
r
Palo Verde Nuclear Generating Station NRC Presentation September 16, 1997
'0
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,b
o Substandard Voltages e Double Sequencing e Technical Specification Operability i Completed Actions I Continuing Actions
'0
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Palo Verde Unit 1 Electrical Distribution System Simplified Single Line Diagram Switchyard 525KV U-3 Startup U-2 Startup 13.8,KV VEIL Main 13.8KV Common Load Unit Auxiliary common Load 13.8 KV 13.8 KV ESF FBT House Load House Load FBT ESF 4.16 KV 4.16 KV DVR 3J'~~~
480 V Emergency Diesel Generator DVR f~t 480 V
~s EngiVRIPNRR PresOÃllWRC0991~
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Palo Verde Offsite Power - Normal Operation
~
~
I Westwing 1 525 KVEast Bus Westwing 2 Kyrene North Gila Devers 525 KVWest Bus Unit 1 Start Up Transformer Unit2 Start Up Unit 3 Start Up Transformer 1$.8 KV ~~ Malo 1$gKV V utu Unit Common Aux Common Load Load 1$.8 KV 1$.8 KV 1$.8 KV 1$8 KV 1S.8 KV
~ryIes Matn 1$8KV
~uLu Untt Aux tsar KV 1$.8 Kv 1$S KV g~ M>>
1$mv flu Unit Aux 4.18 Kv House House Load Load 4.18 Kv House House Load Load 4.1e Kv ESF 4.18 Kv House House Load Load 4.18 KV ESF Emergency Olesel Y480 V Generator Emergency Diesel Generator Emergency Olesel Generator Unit1 Unit 2 Unit 3 xNr ancsrRlpwRR presoQsrwRcossrers
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1992
'1 993 1994ime ine 1995 1996 1997 0
~
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DJF JJ S
Subst dard Voltage Double S uencing Plant Modific tions Approved Temp T.S. Cha ge ain Interaction aluation PV Grid Volta e Study PV ngineering Grid Voltage Respon e Modeling
~ p
'e P
o a e ssues e Voltage Spread o Degraded Voltage Protection 0 Double Sequencing ITech Spec LCO for Offsite Power e Offsite Power Operability I Grid Voltage Study
r
o a e rea onri uors I High impedance Startup transformers I Large load transfer following plant trip I As-built distribution system loading more extreme than original design calculation assumptions w Two voltage transformation levels between switchyard and 4.16 kV Class 1E systems
~,
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Heavy station loading
@ min switchyard voltage SWITCHYARD Light station loading
@ max switch ard voltage 13.8 KVBUS "Zri<p+
4160 V BUS 480 V BUS 480 V LOAD
~49'+~
~. ~YN gF~..
i4'ji voltage increase due to boost at transformer voltage decrease due to impedance drop 70 80 90 100 110 Percent of nominal Bus voltage s ~VRIPWRR Pres099lWRCOQ91.ppl
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I Two conditions must occur simultaneously
~ Switchyard Voltage in the lower end of original operating range (i.e. 95'/o 98'/o)
~ Startup Transformers loaded near capacity of 70 MVa I Calculation Results
~ Unacceptable voltage levels for some safety related equipment
~ Degraded Voltage Relays could trip
li
'I
SWITCHYARD 13.8 KVBUS 4160 V BUS 480 V BUS 480 V LOAD gy
, ~m-
~
yah. M~-&p'.Lpg, o At 95% Switchyard voltage and heavy distribution system loading i DVRs may actuate o Minimum load voltages too low 70'0
'0 100 110 Res ~VRIPWRR PresOQ9iNRCOQpl.ppt Percent of nominal Bus voltage qEilg
0 0
~ I
anuar om ensaor casu re SWITCH YARD 13.8 KVBUS 4160 v BUS 480 V BUS
~>4@4" g$'p~f i WDL."
7P4k P~PQ g'>~>'ry$
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Pgfj I Limitminimum switchyar voltage to 100'/o t Narrower than desired range for long-term operation 0
DVR's won't actuate in restricted switchyard voltage range 480 V LOAD 70 80 90 100 I Adequate voltage for all iso safety related equipment Percent of nominal Bus voltage s EngiVklPWkk PreaO991NkCN91.0PI
0 I
ou e
e uencin Pre Accident Voltage Voltage Drop due to LoadlGeneration changes
%Accident Analysis criteria could be exceeded
~ V IEquipment could misoperate DVR tolerance band DVR starts timing and actuates after time delay, Loads resequence onto EDG.
0'
cions a en t Restrict switchyard normal operating range I Implemented LCO/Admin Controls I Replaced DVR's with more accurate relays I Revised Class 1E transformer tap settings I Upgraded Unit 1 Switchyard voltage meter o Unit 1 Control Room Low Voltage alarm I Trip of WRF load on SIAS and Low Voltage o Replaced Class 1E Control Power Transformers e Relocated CEDM Fan Sequence Step t Replaced Class 1E Control Circuit Contactors
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e Uie o Offsite Power is INOPERABLE if:
~... any condition that renders offsite power unavailable for safe shutdown and emergency requirements.
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)0 Highest actuation voltage (-91.4%)
Setpoint (90%)
0 Ifactuated, loss of offsite power occurs 0 Offsite power is inoperable ifan accident or unit trip would cause actuation
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100'/
98'/
94'/
96'/
N O N Q CO GO O CU < CO 00 O CV rt (0.00 O N < (0 CG I
CV N bl Q PI P) 0) P) P) P) seconds gyral
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inimum era in oae onsi erin Minimum allowable voltage tO lU o
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)0 0 Voltage must be kept above "minimum allowable" to ensure operability of offsite source 0 Requires tech spec administrative controls
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o a e an e
ue o as us rans er 100%
98%
96%
94'/0 N D CU < (0 00 C) P4 < (0 00 D CU rf (0 00 D R < CO 00
~~~~~CUM&M&P)P)P) P)C9 seconds
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enera in nl 100'/o 98%
96%
h,V3 94'/o
&C)&rt CDOOC)&N(DOOC)CVN(DoOneq~cOoO I
~~~ ~~Pd&&P4&P)P)P)P)e) seconds
t
si e ower onsi erin LCQ 0 Reflected to switchyard establishes minimum switchyard voltage d2 6$
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6$
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)~7Yp~z'%~ytg I Consistent with TS 3.8.1.1.f and g
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a niu eo
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t Onsite load flow/voltage regulation calculation I Models entire 3-phase system to load equipment terminals I Models steady-state and motor starting scenarios
t J
a niu eO w Grid load flow calculation I Models over 10,000 buses in WSCC region
~ Software
>Originally used WSCC /PS
) Transitioning to GE PSLF I Responsibility
~ APS Transmission Planning department
~ Developing PVNGS Engineering expertise
I
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tl a c 0 e SSurn ionS t One Palo Verde unit on line I Maximum house loads in all three PVNGS units i Heavy transmission system loading 1 One 525 kV line out of service I Operating PVNGS unit trips
h
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re i
e era in an e
104%
102%
6$
100%
V 98%
Generator 44'-w~~4i 44<<W
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~+<~cB~jjk$+~~~P~j capability
~,.ex gg,i 3~)~& tp Generator minimum voltage pirb Al'4+
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Grid physical operating constraints Load equipment minimum voltage Load equipment maximum voltage 960/
-600
-500 400
-300
-200
-100 0
100 200 300 400 500 600 Net MVARS per PVNGS Unit s ~VRIPVIRR Pre&QQ1WRC0991.ppl
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Is oI Ica erain an e
104%
102%
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V
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-600
-500 Q00
-300
-200
-100 0
100 200 300 400 500 600 Net MVARS per PVNGS Unit V<<ss ~VRIPVSRR PrsslOSS<<VSRQS9<<SSR
ensi ivi o
o re-ri era in on iions I Multiple PVNGS units on line
~ Switchyard voltage regulated by operating unit(s)
~ Single unit trip results in minimal hV3 I One PVNGS unit on line
~ If bucking, unit trip causes voltage increase
~ If boosting, unit trip causes voltage decrease
~ Load flow calc used to determine magnitude of AV3
f'
~
f d
'P IP
(
(
I Maintain switchyard voltage range
~ Voltage monitored and alarmed
> Unit 1 Control Room
> Energy Control Center i Established LCO/Actions
~ Action statements for inoperable switchyard voltage
) Complete actions in 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />
> Clariries action applicability and LCO compliance i Operating experience shows sustained low switchyard voltage infrequent and short duration
0 J,
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y F
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wic ar oa e<
Frequency of Occurrence 0 1995
~ Feb
~ Jul
~ Oct i 1996
~ July
~ Aug I 1997
~ Aug 2.50 minutes 518.0 kV (98.67'lo) 0.16 minutes 523.6 kV (99.73%)
3.00 minutes 523.5 kV (99.71'lo) 0.18 minutes 521.9 kV (99.40'lo) 6.00 minutes 523.9 kV (99.79%)
0.02 minutes 523.7 kV (99.75'lo)
.C i
~'
e, C
on inuin nves i a ions e Reduce U1 LCO equal to U2 8 3
~ Credit WRF tripping circuit
~ Update Tech Spec t Reduce LCO for all three units
~ Increase operating flexibility
~ Refine hV3 value based on grid calc results
~ Update Tech Spec I IEEE panel discussion on degraded voltage protection (11/97 in Albuquerque)
Il 4 1 f
C
I Maintain switchyard voltage range
~ Voltage monitored and alarmed
) Unit 1 Control Room
> Energy Control Center t Established LCO/Actions
~ Action statements for inoperable switchyard voltage
) Complete actions in 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />
) Clarifies action applicability and LCO compliance
h o e Jh wg Agt ri I
I 1