ML20003E394
| ML20003E394 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 03/30/1981 |
| From: | Nichols T SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8104030327 | |
| Download: ML20003E394 (6) | |
Text
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I SOUTH CAROLINA ELECTRIC a GAS COMPANY POST OFFICE 30m 734 CotuMaiA, south CAROLINA 29218 T.c.Nicwots Ja.
March 30, 1981
%ct Persectnv a.o Gaoup tacevveys Nucktaa Oneations Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Subj ec t: Virgil C. Summer Nuclear Station Docket No. 50/395 SER Item 1.7.14
Dear Mr. Denton:
In the Safety Evaluation Report (SER) confirmatory issue 1.7.14 required the applicant to provide an analysis to demonstrate that at no time during sequencing of safety loads on diesel generators will the starting voltage at the 460 volt level go below 80 percent of the rated voltage. The attached marked n FSAR Section 8.3 provides that analysis.
These pages will be included in the next FSAR Amendment.
This should provide you with sufficient information to resolve this item. If you have any questions, please let us know.
Very truly yours,
'T. C. Nichols, Jr.
RBC:TCN:pj.
Attachment CC:
Mr. V. C. Summer w/att.
Mr. G. H. Fischer w/att.
Mr. T. C. Nichols, Jr. w/att.
Mr. C. A.' Price 'w/a tt.
Mr. D. A. Nauman w/att.
Mr. W. A. Williams, Jr. w/att.
Mr.-R. B. Clary w/att.
Mr. A. R.'Koon w/att.
Mr. A. A. Smith w/att.
~
Mr.'H. N. Cyrus w/att.
Mr. J. B. Knotts, Jr. w/att.
Mr. J. L. Skolds w/att.
-Mr.'B. A. Bursey w/att.
Mr. 0. S. Bradham w/att.
.ISEG-
-NPCF/Whitaker-File-PRS 810'40803*1
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Engineered Safety Features Motor Starting Torque Motors are designed for across the line starting.
ESF motors rated g'
6900 volts.*re capable of accelerating the driven equipment to rated speu 70 percent of the motor nameplate vol tage.
ESF motors rated 460 volts are capable of accelerating the driven equipment to rated speed at 80 percent of rated voltage". Motor f.
characteristics are such that ' starting current is minimized having normal torque and positive operation of driven equipnent is assured.
The motors are designed to operate at 1 10 percent of s
rated voltage, 1 5 percent of rated frequency or a combined varia-1 tion in vol tage and fre.luency of 1 10' percent of absolute values, provided.that frequency variation-does not exceed 1 5 percent of rated frequency.
Calculations based.on the diesel generator factory test dsta indi-cate that.the motor terminal voltage during starting will not go below 90 percent of the rated voltage for 6,)900 volt motors or N.
( Rsice +a A ppe.~ J N 8 E,
- below 82 percent for '460 volt motorsA The motor terminal voltage
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for the 6900 volt motors was calculated using the diesel generator N.
voltage regulation for starting of a 1750 Hp motor.
The motor terminal voltage'for the a60 volt motors was ralculated using the
' diesel generator voltage regulation for starting a 500 Hp motor and 22 considering the-voltage drop,through'the'7200/480 volt iransfor-mers.
The~ actual largest system motors are 900 Hp and 350 Hp for the 7200 volt and 480 volt systems respectively.
These' voltage
-levels are well above those allowed by Regu]atory cuide 1.9.
The adequacy of_ buss voltagefregulation during motor starting is con-firmed during, the preoperaticinal. testing program.-
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- 3.1
' Motor Insulation:
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Motor insulation -is' a minimuin of Class B outside' the-reactor e-f.
building and Class F inside1.the reactor building. The insulation temperature rating-is' greater;than,the sum.'of the motor temperature rise ~and the ambient temperature at the~ motor. location.
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8.3 ~ -AMENDMENT EE hy 1931 "W
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APPENDIX 8E Analysis of the Voltage Drops on the ESP System when Starting a 6900 or 460 Volt Motor with the ?iesel Generator as the Source 8E.1 Criteria The criteria was to determine (1) the voltage at the terminals of the Isrgest safety related 6900 and 460 volt motors when they are started and (2) the l
voltage at the other Safety Related buses during the same period. The power source was considered to be the diesel generator with the safety injection signal loads operating on the buses.
8E.2 Background The 6900 volt charging / safety injection (CH/SI) pump motors' and the 460 volt service water booster pump (SWHP) motors are the largest safety related motors for their respected voltages. Therefore, their characteristics were used in the - calculations.
The diesel generator factory acceptance test load simulation curves were used 4
to. determine voltage drops at the diesel generator terminals during motor starting.
The largest motor started during the simulated test was 1250 horsepower as compared i
to the 900 horsepower charging / safety injection pump. The test load used for l
-evaluation of the 350 horsepower service water booster pump motor was a 500 horseposer motor. The loads on the diesel generator at the time of starting these test motors was 2980KW for the 1250 HP motor and 3GC0 KW for the 500 Hp motor. In the actual loading sequence the Cd/SI. pump motor is part of the initial load block on the diesel generator.- So, the diesel is unloaded before starting the CH/SI pump motor.
Thus, the diesel terminal voltages calculated for starting the CH/SI pump is conservative. At the time of starting the SWHP motor the diesel generator has a i
f 3235 KW load on it.-
Thus, the load on the diesel generator when starting the 500 hp motor approximates the actual load on the diesel. generator when the SWBP motor is
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started, and the test motor size is conservative with respect to the SWBP motor.
As described in-Section 8D.3, the safety injection signal load is the largest load to be applied to Jthe ESF system buses at any one time. Thus, this load was used as the running load on the buses.
1:
f 8E.3 Method
.The percent voltage on the buses was determined by calculdting the per unit impedance of the. running loads, starting motors, motor feeder cable and transformers.
These per unit values' wereireduced to an' equivalent system impedance.
-tae percent of the diesel generator terminal. voltage on the IDA bus was then
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. determined by the impedance ratio of the diesel cable impedance to the system impedance as illustrated on-the following page.
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Diesel ess Generator
% of Diesel Terminal Voltage on Bus -
100 (
System Impendance
__)
[
(Cable Impendance + System Impendance
)
Feeder Cable
(
Impendance Equivalent System
(
Impendance
~The percent of rated voltage at the bus was then determined by multiplying the diesel terminal voltage in percent of rated times the percent of diesel terminal voltage on the bus as illustrated below:
% Voltage IDA = (diesel terminal voltage in %) (% of diesel terminal voltage in IDA)
The above method was then used to determine the percent of rated voltage at each of the buses during motor starting.
The percent of rated voltage at the starting motor terminals was determined using similar techniques.
8E.4 Conclusion Considering the diesel generator as the power source, the calculated voltage at the terminals of the 6900 volt CH/SI pump motor and 460 volt SWBP motor is above the minimum design starting voltage as mentioned in Section 6.3.1.1.4.2 and listed below:
Design Starting Calculated Motor Voltage Limits Terminal Voltage 6.9 CH/SI pump Motor 70%
90.7%
460 SWBP Motor 80%
81.77%
Since other safety related motors are smaller than the CH/SI pump motor and the SWBP motor for their respective voltage levels, the motor terminal voltage during the start. >g of all safety related motors will be above the design starting voltage for these motors.
(In the specific case of the 79.90 percent voltage calculated for motor control center XMCIDA2Z during the starting of the 6900 volt CH/SI pump motor the bus voltage is still above the design starting voltage of 80%
of 460 volts for the motors on this bus.)
Tables 8K-1 and 2 list the calculated voltages of the ESF system buses and the motor terminals.
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TABLE 8E-1 Calculated Voltage Level of ESF System Buses and Motor Terminals with a Diesel Generator as the Source and Starting the 6900 Volt Charging / Safety Injection Pump Motor.
Condi tions :
Initial Voltage:
7200 (Diesel Terminals)
Initial Load:
2980KW Power Source:
Diesel Generator Motor:
Charging / Safety Injection Pump Motor (6900 Volt)
Resultant Voltage Levels:
Percent of ESF System Points Voltages Nominal Bus Voltage Diesel Generator 6282 87.25 7200 Volt Bus IDA 6271 87.10 6900 Volt CH/SI Pump 6264 90.79 of motor nominal rating 480 Volt Bus IDA1 399.69 83.27 480 Volt Bus IDA2 387.64 80.76 480 Volt MCC IDA2Z 383.52 79.90 (83.4)1 7200 Volt Bus IEA 6264 87.01 480 Volt MCC IEA1X 414.24 86.3 (1) 83.4 percent of nominal motor voltage (460V).
TABLE 8E-2 Calculated Voltage Level of ESF Syster. Buses and Motor Terminals with a Diesel Generator as the Source and Starting the 460 Volt Service Water Booster Pump Motor Conditions:
Initial Voltage:
7200 (Diesel Termincl)
Initial Load:
3000KW Power Source:
Diesel Generator Motor:
Service Rater Booster Pump Motor (460 Volt)
Resultant Voltage Levels Percent of ESF System Points Voltate Nominal Bus Voltage _
Diesel Generator 6579 91.38 7200 Volt Bus IDA 6539 90.82 483 Volt Bus 1DAl 389.95 81.24 460 Volt SWBP Motor 376.14 81.77 of motor nominal rating 480 Volt Bus IDA2 404.2 84.21 480 Volt Bus IDA2Z 399.88 83.31 7200 Volt Bus IEA 6534 90.76 480 Volt Bus lEAlX 432.09 90.02