ML20237F016
| ML20237F016 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 12/23/1987 |
| From: | Maine Yankee |
| To: | |
| Shared Package | |
| ML20237E999 | List: |
| References | |
| MYC-430, MYC-430-R01, MYC-430-R1, NUDOCS 8712290308 | |
| Download: ML20237F016 (14) | |
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MaineYankee MYC-430, Rev. 1 Page 1 of 14 l
MYC-430 u
Revision 1 Maine Yankee Auxiliary. Power System Voltage Study t-P.
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MaineYankee MYC-430, Rev. 1 Page 2 of 14 TABLE OF CONTENTS Pace TABLE OF C0NTENTS.................................................
2 1.0 PROBLEM DESCRIPTION...............................................
3 2.0 METHOD OF S0LUTION................................................
3 3.0 COMPUTER H0 DEL....................................................
4 4.0 ASSUMPTIONS.......................................................
4 5.0 INPUT DATA........................................................
5 6.0 CASE DESCRIPTIONS................
7 7.0 VOLTAGE LIMITS....................................................
8 8.0 RESULTS.............................
9
9.0 CONCLUSION
13
10.0 REFERENCES
13 APPENDICES I.1 Voltage Study Output for Case 1 (Suroweic)............
100 Pages I.2 Vol tage Study Output for Cas e 2 (Surowei c)............
204 Pages I.3 Voltage Study Output for Case 3 (Suroweic)............
44 Pages II.1 Voltage Study Output for Case 1 (Mason)...............
100 Pages II.2 Voltage Study Output for Case 2 (Mason)...............
204 Pages II.3 Voltage Study Output for Case 3 (Mason)...............
44 Pages III Bus Loading Tab 1es....................................
32 Pages IV Cable Data............................................
1 Page V
T ra n s fo rm e r D a t a......................................
17 Pages VI Motor Data............................................
21 Pages VII Figures...............................................
2 Pages VIII Case Study Input Data.................................
18 Pages IX.1 Summary of DAPPER Case Studies (Suroweic).............
3 Pages IX.2 Summary of DAPPER Case Studies (Mason)................
3 Pages X
Miscellaneous Information.............................
6 Pages XI Central Maine Power Load Flow Information.............
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MaineYankee HYC-430, Rev. 1 Page 3 of 14 1.0 PROBLEM DESCRIPTION Criterion 17 of 10CFR50, Appendix A. " General Design Criteria for Nuclear Power Plants," states in part that:
An on-site electric power. system and an off-site power system shall be provided to permit functioning of structures, systems, and components important to safety. The safety function of each system (assuming the other system is not functioning) shall be to provide sufficient capacity and capability to assure that (1) specified acceptable fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded as a result of anticipated operational occurrences and (2) the core is cooled and containment integrity and other vital functions maintained in the event of postulated accidents.
Regarding the off-site power system, Section 8.2.3 of the Maine Yankee Final. Safety Analysis Report (FSAR) states that "Either of the two 115 kV incoming lines are independently capable of supplying the plant auxiliary power requirectents."
The purpose of thi.s calculation is to provide a detailed assessment of voltages throughout the Maine Yankee Auxiliary Power System for various operational scenarios in order to reconfirm that the requirements of GDC-17 and FSAR Section 8.2.3 are still satisfied. Voltages will be obtained down to the 480 V Motor Control Center (MCC) level and beyond j
u as required.
2.0 METHOQ_QF_SQLUI1QN A computer program package known as DAPPER (Distribution Analysis for Power Planning Evaluation and Planning) will be employed to analyze the plant's Auxiliary Power System voltages.. The DAPPER Voltage Drop and l
Load Flow Analysis Program (VDSTUDY) calculates the voltage drop on each feeder, bus voltage at each load bus, and power flow through balanced three-phase power systems.
Power losses in each feeder and total system
. power losses are also calculated.
The DAPPER programs have been used by Stone & Webster for short circuit studies at both the Yankee and Maine Yankee plants and for a voltage study at the Yankee plant. Validation of DAPPER for the above studies 4
was provided by Stone & Webster by satisfactorily benchmarking DAPPER against their mainframe load flow program.
Further validation was performed by comparing actual field data from the Yankee plant with the information predicted by DAPPER.
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MaineYankee HYC-430, Rev. 1 Page 4 of 14 3.0 COMPUTER MODEL The computer model of the Auxiliary Power System used for this calculation is shown in Figure VII-1 in Appendix VII.
This model is essentially the same as the one used by Stone & Hebster for the short-circuit studies, References (g) and (h). As shown in Figure VII-1, all switchgear buses and motor control centers, as well as certain plant loads (motors, distribution panels, etc.), have a unique Bus Record Number (BRN).
DAPPER uses these BRNs to determine how the power system network is configured. Data in the output report also utilizes these BRNs.
Certain Motor-Operated Valves (MOVs) have also been assigned BRNs in order to determine the voltage at the motor terminals, Reference (j).
4.0 ASSUMPTIONS (1)
The values used for rated loads are the nameplate values indicated on the latest issue (see Section 10.0) of the one-line diagrams, unless otherwise noted.
(2)
The kVA rating of motors less than or equal to 10 hp in size is enual to their hp rating. A power factor of 0.00 was assumed for motors of this size.
(3)
Distribution panels, heaters, heat tracing panels, and lighting panels are normally assumed to be loaded to 50% of their supply transformer, or rated load if no transformer is used.
During light load conditions, no heating or heat tracing loads are inrluded in the bus loading values.
(4)
Battery chargers are fully loaded except for the light load case which assumes 10% loading.
(5)
Loads with transfer switches are only included in their normal configuration.
(6)
The efficiency of 90% used for motors rated between 10 hp and 50 hp was taken from Reference (e), Figure 33 (Page 3-47).
A copy of Figure 33 is included in Appendix X, " Miscellaneous Information."
(7)
Motor efficiencies and power factors for motors rated 50 hp and greater are taken from actual motor data sheets. Copies of the i
motor data sheets are included in Appendix VI.
(8)
The power factor of 0.87 used for motors rated between 10 hp and 50 hp was taken from Reference (e), Figure 35 (Page 3-48).
A copy l
of Figure 35 is included in Appendix X, " Miscellaneous Information."
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MaineYankee MYC-430, Rev. 1 Page 5 of 14 (9)
Loading data for the reactor coolant pumps and the main feedwater pumps _were taken from Stone & Hebster Calculation 11550-10. A summary data sheet and a copy of Stone & Hebster Calculation 11550-10 are provided in Appendix X, " Miscellaneous Information."
(10) Motor starting loads are treated as constant impedance loads.
(11) 4160/480 V unit substation transformers X-507, X-608, X-309, X-311, X-313, X-410, X-412, X-414 are assumed to be at their nominal tap setting.
(12) Motor starting power factors for large motors rated 350 hp and up are taken from Figure 8 on Page 2-30 of Reference (e).
A copy of Figure 8 is included in Appendix X, " Miscellaneous Information."
(13) A motor starting power factor of 0.60 is assumed for H0Vs.
This is a conservative value derived from Figure 8 on Page 2-30 of Reference (e).
(14) The Staff Building load on Bus 3 is assumed to be 375 kVA at 0.90 PF (507. of transformer rating).
(15)
Load values are roundad to the nearest whole nemoer before input into the computer program.
(16) MOVs are not included in the Bus Loading Tables of Appendix III because they are small intermittent loads and are adequately covered by the conservative assumptions used for other loads.
5.0 1RP111616 5.1 Loadina Data The Bus Loading Tables in Appendix III were used to determine the auxiliary power system loading for the various cases described in Section 6.0.
The Bus Loading Tables provide a record of the basis for the values for " Heavy Load," " Starting Load," and " Light Load".
Each load on each bus has been reviewed to determine the applicable scenario (s) to arrive at the worst case loading.
Conservative diversity factors have been applied to certain loads, as appropriate.
Appendix VIII provides the actual "Special Bus Loads" and "End-Use Loads" values used as input to each case study on DAPPER.
5.2 Cable Data The cable impedances established in References (g) and (h),
Stone & Webster Short-Circuit Calculations E-2 and E-5, have also 9222L-SDE
MaineYankee HYC-430, Rev. 1 Page 6 of 14 been used in this calculation. The portion of each DAPPER output report (Appendices I.1 - I.3 and II.1 - II.3) entitled " FEEDER DATA" contains the cable data used by DAPPER.
Appendix IV contains Table IV-1, " Summary of Feeder Cable Data,"
as well as any additional information for the various types of cables included in this calculation which were not addressed by References (g) and (h).
5.3 Transformer Data The transformer data established in References (g) and (h) have been used in this calculation. Appendix V contains data for the various transformers included in this calculation.
5.4 Motor Data Appendix VI contains copies of motor data sheets from specifications or equipment identification cards for all 6.9 kV and 4.16 kV motors examined in this calculation. Motor data-sheets are also provided for several of the larger 480 V motors.
5.5 J15 kV Switchyard Voltaaes Two 115 kV transmission lines, one from Mason Station and one from Suroweic Substation supply the Maine Yankee 115 kV syltchyard. As shown on Figure VII-2 in Appendix VII, both Mason and Suroweic are extensively interconnected with the 115 kV and 345 kV transmission netvork in the New England area.
Each station has a 345 kV/115 kV automatic load tap-changing autotransformer which maintains station voltage at approximately 122 kV for Mason and 121 kV for Suroweic.
Normally, both 115 kV lines are in service with Mason supporting loads on the Suroweic line. Consequeritly, thn " worst case" loading condition for the Mason line is not when it is independently supplying Maine' Yankee, but when it is also supporting Suroweic line loads.
The 115 kV system is under the control of Central Maine Power Company (CMP); as such, CMP was requested to provide the Maine Yankee switchyard voltage for each case under evaluation.
In order to provide station load data to CMP, each case study was evaluated by DAPPER with a switchyard voltage of 118 kV.
The use of 118 kV provides satisfactory results because most of the plant load consists of constant kVA load.
Constant kVA loads are relatively unaffected by voltage changes within their normal 101.
voltage tolerance.
The load values provided by us to CMP, as well as the resulting 115 kV switchyard voltages calculated by CMP, are found in Appendix XI.
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Mainehkee MYC-430, Rev. 1 Page 7 of 14 6.0 CASE DESCRIPTIONS To meet the purpose of this calculation, three basic study cases were developed.
Each case represents a specific auxiliary power system-loading condition or sequence of conditions which must be evaluated.
The following descriptions provide the conditions specified for each case:
Case 1 simulates the voltage levels caused by a simultaneous plant trip and transfer of the plant's auxiliary power system load to Reserve Station Service Transformers X-14 and X-16.
Case 1 has been subdivided into Case 1A which represents the step load addition to the 115 kV system, and Case IB which is the same situation less than one minute later after the LTC transformer at Mason or Suroweic has adjusted to compensate for the voltage drop.
Case 2 simulates the voltage levels caused by a simultaneous plant trip, start of safety-related equipment, and transfer of the plant's auxiliary power system load to Reserve Station Service Transformers X-14 and X-16.
Case 2 has been subdivided into:
Case 2A simulates voltage resulting from the step load addition to the 115 kV system.
Case 2B simulates the voltage levels a few seconds later, after the 4 kV motors have started.
Case 2C simulates the voltage levels an additional few seconds later after all safety-related loads are running.
Case 2D is less than one minute later, after the LTC transformer at Mason or Suroweic has adjusted to compensate for the voltage drop.
Case 3 simulates the voltage levels associated with minimum load steady-state conditions while power is being supplied by the Reserve Station Service Transformer X-14.
This case is examined to determine if any overvoltages exist.
In order to reconfirm the statement in-FSAR Section 8.2.3 that either of the two incoming 115 kV lines are independently capable of supplying the plant auxiliary power system requirements, the three cases described above must be evaluated for the worst case loading on each the Suroweic and Mason line.
Except for the light load condition, the " worst case" loading for the Mason line is when both lines are in service because the Mason line normally supports load (Topham and Bath Substations) on the Suroweic line.
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MaineYankee MYC-430, Rev. 1 Page 8 of'14
'7.0-VOLTAGE LIMITS ~
'7;l Motors and Contactors Table 7-1. provides operating voltage limits for the various motors and contactors in the auxiliary power system.
For motors, the.
110%~11mit specified by NEMA standards is used except for the 4000 volt safety-related motors which were specified to start at -
75% of rated voltage.
For contactor pickup and dropout voltages, manufacturer?s data was used.
TABLE 7-1
-Motor and Contactor Voltaae Requirements Maximum Minimum Minimum Operating Operating Starting Voltage Voltage Voltage (volts)
(volts)
(volts) 1101.yolt System 6600 volt motors 7260 5940 5910 116 0 {31t Svster, 4000 volt notors -
4400 3600 3600 4000 volt motors 4400 3600-3000 (safety reltited)
_4fELYQ1LSylifLm j
460 volt motors 506 414 414 460 volt contactors 506 414 370 (contactor pickup) j 322 (contactor dropout).
7.2 Undervoltaae Relav Setooints
.l Table 7-2 provides the setpoints for the various relays associated with the Auxiliary Power System. The setpoints in Table 7-2 were 1
taken from Reference (1).
I i
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MaineYankee MYC-430, Rev. 1 Page 9 of 14 TABLE 7-2 Undervoltaae Relav Settinos Function Relav Tvoe Setooint Loss of.ll5 kV Alarm Instantaneous 4050 50 V (Hith Time Delay) for_ 10 seconds 6.9 kV Bus 1 and Bus 2 Induction Disc 5580 V Undervoltage Trip / Alarm 4.16 kV Bus 3 and Bus 4 Induction Disc 3255 V Undervoltage Trip / Alarm 4.16 kV Bus 5 and Bus 6 Induction Disc 3255 V Undervoltage Trip / Alarm 4.16 kV Bus 5 and Bus 6 Instantaneous 3820 140 V Undervoltage Trip / Alarm (With Time Delay) for 10 seconds (Second Level) 8.0 RESULTS l
THe DAPPER output reports are provided in Appendices I.1-I-3 and II.1-II.3 for Surowelc and Mason, respectively.
The bus voltages contained in the DAPPER output reports were extracted and tabulated in Appendix IX.1 for Suroweic and Appendix IX.2 for Mason.
These voltages were then compared with the voltage limits specified in Section 7.0.
8.1 Suroweic Line 1
Table 8.1 provides a summary of the Suroweic line's capability to meet its intended function.
In general, the Suroweic line is Dat capable of supporting the Maine Yankee plant loads evaluated under Case 1 and Case 2.
Case 3, however, provides satisfactory results.
l 1
1 1
1 L
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MaineYankee MYC-430, Rev. 1 Page 10 of 14 TABLE 8.1 Summary of Suroweic Line Caoability Eauioment Case 1 Case 2 Case 3 6.9 kV Motors Acceptable Acceptable Acceptable (Note 1)
(Note 1) 4.16 kV Safety-Related Motors Acceptable Unacceptable Acceptable (Note 1)
(Note 5) 4.16 kV Nonsafety-Related Motors Acceptable Acceptable Acceptable (Note 1)
(Note 1) 480 V Safety-Related Motors Unacceptable Unacceptable Acceptable (Note 2)
(Note 2) 480 V Nonsafety-Related Motors Unacceptable Unacceptable Acceptable (Note 3)
(Note 3) 480 V Safety-Related Contactors Acceptable Acceptable Acceptable (Note 4) 480 V Nonsafety-Related Contactors Acceptable Acceptable Acceptable k
(Note 4) 1 Loss of 115 kV Alarm Actuatloa Yes Yes No 6.9 kV Bus 1, Bus 2 Undervoltage No No No Trip / Alarm Actuation 4.16 kV Bus 3, Bus 4 Undervoltage No No No Trip / Alarm Actuation 4.16 kV Bus 5, Bus 6 Undervoltage No No No Trip / Alarm Actuation 4.16 kV Bus 5, Bus 6, Undervoltage No No No Trip / Alarm Actuation (Second Level)
NOTES 1.
Voltages are initially unacceptable, but recover to an acceptable level after the LTC transformer operates (less than one minute). Overall, the condition is deemed acceptable.
2.
Voltage on the 480 V safety-related buses does not recover to an acceptable tevel, even after the LTC transformer has operated.
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MaineYankee MYC-430,.Rev. 1 Page 11 of 14 NOTES FROM TABLE 8-1 (Continued) u 3.
Voltage on most of the nonsafety-related buses does not recover to an acceptable level, even after.the LTC transformer has operated.
- Furthermore the voltages that do recover only recover to marginally acceptable levels.
4.
All contactors covered under this case were previously energized and will remain in that condition.
5.
Voltage levels sufficient to start the 4.16 kV safety-related motors, but voltage'does not recover.to an acceptable level until the LTC transformer operates (less than one minute).
Since there is a possibility of actuating the motor overcurrent relays due to prolonged starting current, this condition is unacceptable, i
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MaineYankee MYC-430, Rev. 1 Page 12 of 14 8.2:
Mason Line Table 8.2 provides an evaluation of the Mason.line's capability to meet its intended function. The Mason line voltage study data demonstrates that it.11 capable of supporting the Maine Yankee plant loads evaluated under Cases 1, 2, and 3.
TABLE 8.2 Summary of Mason Line Canability Eauioment Case 1 Case 2 Case 3 6.9 kV Motors Acceptable Acceptable Acceptable 4.16 kV Safety-Related Motors Acceptable Acceptable Acceptable 4.16 kV Nonsafety-Related Motors Acceptable Acceptable Acceptable 480 V Safety-Related Motors Acceptable Acceptable Acceptable 480 V Nonsafety-Related Motors Acceptable Acceptable Acceptable 480 V Safety.Related Contactors Acceptable Acceptable Acceptable 1
480 V Nonsafety-Related Contactors Acceptable Acceptable Acceptable Loss of 115 kV Alarm Actuation No No No l
6.9 kV Eus 1, Bus 2 Undervoltage No No No Trip / Alarm Actuation
(
4.16 kV Bus 3, Bus 4 Undervoltage No No No I
Trip / Alarm Actuation 4.16 kV Bus 5, Bus 6 Undervoltage No No No Trip / Alarm Actuation 4.16 kV Bus 5, Bus 6, Undervoltage No No No i
Trip / Alarm Actuation J
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MaineYankee MYC-430, Rev. 1 Page 13 of 14
9.0 CONCLUSION
The calculation has provided a detailed assessment of voltages throughout the Maine Yankee Auxiliary Power System.
The conclusion reached is that the FSAR's statement that "Either of the two 115 kV incoming lines are independently capable of supplying the plant auxiliary power requirements" is no longer valid under certain loading conditions.
The calculation demonstrates that while the Mason line is capable of supplying the plant's auxiliary power requirements, the Suroweic line is not under worst case conditions.
10.0 REFERENCES
(a)
YAEC Report No. 1204, " Auxiliary Power System Voltage Study for Maine Yankee Atomic Power System," dated February 28, 1980.
(b)
Calculation MYC-430 (Revision 0), " Auxiliary Power System Voltage Study - Maine Yankee," dated October 25, 1983.
(c)
Maine Yankee Final Safety Analysis Report (FSAR).
(d)
The followiag Maine Yankee Electrical Drawings:
Drawing Revision Number Number Title FE-1A 11 Main One-Line Diagram FE-1C 3
115 kV One Line Diagram FE-1D 3
6900 V Bases 1 c.nd L FE-1E 12 4.16 kV Buses 5 and 6 FE-1F 6
4.16 kV Buses 3 and 4 FE-1H 14 480 V Bus 7-10 FE-1J 12 480 V Bus 11-14 FE-1K 14 480 V MCC 110, 120, 13A, and 14A t
l FE-1L 22 480 V MCC 7A, 8A, and 138 FE-1H 22 480 V MCC 78, 781, 88, and 8B1 FE-1N 11 480 V MCC 9A, 10A, and 11E FE-1P (Sh. 1) 17 480 V MCC 98, 118, and 11C FE-1P (Sh. 2) 0 480 V MCC 981 l
FE-lO 19 480 V MCC 11A, 12A., and 14B l
FE-lR 12 480 V MCC 108, 128, 12C, and 12E (e)
" Motor Application and Maintenance Handbook," Robert H. Smeaton, McGraw-Hill Book Company, 1969.
(f)
IEEE Standard 399-1980, "IEEE Recommended Practice for Power System Analysis" (IEEE Brown Book).
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MaineYankee MYC-430,'Rev. 1 Page 14 of'.14 (g).
Stone & Webster. Calculation E-2, Revision 2, "Short Circuit Study of the-
. Auxiliary Station Service Electrical System."
(h)
Stone & Hebster Calculation E-5, Revision 2, " Medium Voltage Switchgear
..Short Circuit Study."
-(i)
Memo, MYP 86-1136. F. D. Baxter to R.
P.' Shone, " Procedural Response'to Low Voltage Alarms," December 22, 1986.
(j)
Service Request M-86-208, " Determine the Expected Available Voltage at-Each MOV Required for IEB 85-03 for the Design Condition.
. k).
Service Request M-85-181'
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