ML19351F978
| ML19351F978 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 02/17/1981 |
| From: | Walbridge W SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Reid R Office of Nuclear Reactor Regulation |
| References | |
| TAC-12746, NUDOCS 8102200670 | |
| Download: ML19351F978 (62) | |
Text
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e esuun SACRAMENTO MUNICIPAL UTILITY DISTRICT C 6201 s street Bu 15830, sacramento, California 95813; (916) 452-3211 February 17, 1981 Director of Nuclear Reactor Regulation Attention: Mr. Robert W. Reid, Chief Operating Reactors, Branch 4 U. S. Nuclear Regulatory Conmission Washington, D. C.
20555 Docket 50-312 Rancho Seco Nuclear Generating Station, Unit No.1 Adequacy of Station Electric Distribution System Voltage
References:
1.
William Gammill to All Power Reactor Licensees dated August 8, 1979 2.
Jahr J. Mattimoe to Robert W. Peid Letter dated August 1,1980 3.
R. W. Reid to John J. Mattiace Letter dated September 25, 1980
Dear Mr. Reid:
The infonnation you requested in Reference 3 is listed below:
NRC Request:
"To enable a complete evaluation, submit the calculated voltages for all low-voltage AC (less than 480 volts) Class lE " buses" or documentation which demonstrates that all low-voltage AC Class lE equipment will be operating within their required voltage ratings for each case analyzed.
Do those " buses" supply any instruments or control circuits required by GDC 13? If so, is all equipment capable of sustaining the analynd voltages without blowing fuses, overheating, etc., and without affecting tne equipment's ability to perform the required function?"
District Response:
The District has perfomed tests and calculacions on 120 VAC circuits required to mitigate the consequences of an accident. The specific instru-mentation and control circuits described in GDC 13 are supolied through the vital AC systems which are battery-backed and regulated within + 1 percent.
These circuits are, therefore, excluded from this analysis.
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Mr. Robert W. Reid Page 2 February 17, 1981 Special 72st Procedure (STP) Numbers 882 Rev.1, dated November 7, 1960 and STP 883, dated November 26, 1980, cover the testing of low-voltage AC devices. Calculation No. A.S.08.2.66 develops the maximum control circuit lengths allowable based on measured device voltage drops and compares existing circuit lengths to these maximums.
This decumentation demonstrates that all 120V AC equipment, except for size three starters,will function as required without blowing fuses, overheating, or affecting the equipment's ability to perform the required function. The size three starters will be replaced with equipment capable of operating at the expected voltages. The results of the test and calculations are sunt.arized in Response to Guideline 9 of the attachment.
NRC Request:
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Provide a description of the test that will be performed to verify the assumptions and computer program used in calculating the voltages contained in the report. When available submit the results of the test.
District Response:
The District will perform a test durir.g the refueling cutage expected to take place in mid-1982 to verify the assumptions and computer program used in tne analysis.
The test will be performed with the plant shutdown and with the available grid voltage. The nuclear service buses for Train "A" ar.d "B" will be fed from the offsite sources, loads added to them and the bus voltages recorded. The impedance of the loads that are being served during the test and the recorded switchyard voltage will be entered as data for a computer run. The calculated voltages w ll then be compared with the i
test results.
NRC Request:
Submit calculations that verify reactor operation at 218 kv can be permitted with no spurious trips of the undervoltage system.
District Response:
The District has performed calculations that verify that no sourious trips of the undervoltage system occur at 218 kv. The results of the analysis are discussed in the attachment, Response to Guideline 1.
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Mr. Robert W. Reid Page 3 Fet ruary 17, 1981 The attachment is Enclosure I, Part A & B, Revision 2 dated February 9,1981 of our submittal on adequacy of station electric distribution system vo! ages. All modifications are indicated by a "2" in the margin.
This supersedes Enclosure I, Part A & B of our August 1,1980 submittal.
If you have any questions, please do not hesi+ ate to contact me.
^incerely,
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Wm. C. Walbridge General Manager Attachments l
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Enclosure I SACRAMENTO MUNICIPAL UTILITY DISTRICT RANCHO SECO NUCLEAR GENERATING STATION, UNIT NO. 1 RESPONSE TO:
NUCLEAR REGULATORY COMMISSION REQUEST TO REVIEW THE ADEQUAiY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTAGES (LETTER FROM WILLIAM GA.TfILL TO POWER REACTOR LICENSEES DATED AUGUST 8, 1979) l l
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i Issued: October 17, 1979 Revision 1: August 1, 1980 e
i Revision 2: Febru wf 9, 1981 i
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ENCLOSURE I PART A GENERAL RESPONSE TO WILLIAM GAMMILL TO POWER REACTOR LICENSEES' LETTER DATED AUGUST 8, 1979 l
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The following is the revised text of the October 17, 1979 letter to William Gammill, NRC's Acting Assistant Director for Operating Reactors Projects, from John J. Mattimoe, SMUD's Assistant General Manager and Chief Engineer.
The August 8,1979, letter from the NRC to all Power Reactor Licensees (except Humbolt Bay) 'equested:
1.
A verification by analysir of the capacity and capability of Rancho Seco's offsite power system and the onsite electrical distribution system.
l 2.
A verification, by test, of the adequacy of Rancho Seco's offsite power system and the onsite electrical distribution system.
3.
A review of Rancho Seco's electrical power supply system to determine if there are any conditions which could result in the simultaneous or consequential loss of both required cir-cuits to the offsite network to deterzine if any potential exists for violation of GDC-17 in this regard.
Immediate remedial action and prompt notification of the Commission with written followup in the event of a violation or potential violation,f GDC-17 or voltage requirements of safety loads.
The responses to these requests are listed below:
1.
The analysis of Rancho Seco's offsite power system and the onsite electrical distribution system demonstrates that the District's existing systems are adequate. To achieve this adequacy, it was necessary to:
(i) change the loading sequence of the diesel generator room supply and exhaust fans from Block Two to Block Three; (ii) Change the setpoint on the inverse-time undervoltage relays to 3744V (90 percent of 4160V);
2 (iii) issue special orders to the plant operators to describe operator actions at degraded voltage conditions (Reference SO 5-79); and (iv) modify the control circuit for the control room air conditioning unit.
Subsequent analysis, taking into account proposed relay type changes and accuracy considerations discussed in Enclosure II, have determined that the modifications listed below should be implemented.
Set undervoltage relay dropout at 3771V (91 percent of 4160V).
a.
b.
Set overvoltage relay pickup at 4580V.
Limit plant operation if the switchyard voltage is less than c.
216kV.
d.
Block automatic condensate pump starting on a turbiae trip to assure that safety equipment terminal voltage does not dip below the minimum required.
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4 Modify the 120V ac control circuit of the upper dome air 3
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circulators to insure operation at minimum expected voltages.
Since the normal switchyard voltage range is 221kV to 239kV, neither the setpoints nor operational limits will be affected by normal voltage variations. The voltage dip during condensate pump starting, although undesired, does not prevent the safety equipment from performing their required functions since the dip is of a short duration.
A discussion of each modification it included in the response to guidelines contained in Enclosure I, Part B.
The applicable guideline for each modification is listed below:
Modification Reference Guideline 10 a
b 11 c
6, 9 and 10 1
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The above modifications insure the adequacy of the Rancho Seco offsite power system and the casite electrical distribation system to supply safety-related loads under the conditions described in Enclosure I, Part B.
The capacity of the transformers to continuously carry the expected load demand is illustrated in Sketches 2-7 of Enclosure I, Part B.
2.
The District's method of determining the adequacy of the offsite power system and onsite electrical system is based on a combination of test data and analysis.
The load data for the Class IE 4.16-kV system and safety motors greater than 60 hp was based on actual field measurements (under simulated accident conditions, if applicable). The impedance data for transformers was based on factory test results.
If test data was not available, the data used in the analysis was based on conservative engineering assumptions. Refer to Enclosure I, Part B Response to Guideline 13 for a discussion of the assumptions made in the analysis. The analytical results were obtained using a computer load flow program. The program has been checked to verify its accuracy.
It solves nodal admittance network equations by the accelerated Gauss-Seidel method.
This basic program has been checked by field test at the Duane Arnold Energy Center in April 1980.
2 The District's analysis of the offsite power system and the onsite electrical distribution system in Enclosure I, Part B illustrates the voltage conditions on the nuclear services buses immediately following i
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completion of automatic load sequencing due to safety features actuation under different plant configurations. The District will perform a field test during the refueling outage expected to take place in mid-1981 to verify tne assumptions and computer program used in this analysis.
The test will be performed with the plant shut down and with the available grid voltage at the time of the test. The nuclear services buses 2
for trains "A" and "B" will be fed from the offsite tource and the bus voltages recorded. The impedances of the loads thac are being served during the test and the recorded switchyard voltage will be entered as input data for a computer run.
The calculated voltages will then be compared with the test results.
3.
The District has completed a review of Rancho Seco's electrical power supply for compliance to GDC-17.
The cases analyzed indicated that the District's electrical power supply system is in cospliance with GDC-17.
For information on the analysis performed for compliance to GDC-17 refer to Enclosure I, Part C.
4 The District has implemented modifications (i), (ii), and (iii) which have changed the loading requence, changed the relay setpoint, and issued special orders. Modification (iv), involving the control room 2
air conditioner control circuit, will be completed during the present refueling outage. This will insure safe plant operation until modifications a through e are implemented during the April, 1982 planned outage.
Enclosure I, Part B is the District's response to the Guidelines contained in Enclosure 2 of William Gansill to Power Reactor Licensee's letter dated August 8, 1979.
Enclosure I, Part C is an evaluation of the District's offsite power supply system for compliance to GDC-17.
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ENCLOSURE I PART B RESPONSE TO GUIDELINES LISTED IN ENCLOSURE 2 NRC'S WILLIAM GA.T1ILL TO P0kIR REACTOR LICENSEES, LETTER DATED AUGUST 8, 1979 l
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Listed below is a response co each guideline listed in Enclosure 2 " Guidelines for Voltage Drop Calculations" of NRC's, William Gameill to Power Reactor Licensees, letter dated August 8, 1979.
GUIDELINE #1 Separate analyses should be performed assuming the power source to safety buses is (a) the unit auxiliary transformer; (b) the start-up transformer; and (c) other available connections to the offsite network one by one assuming the need for electric power is initiated by (1) an antici-pated transient (e.g., unit trip) or (2) an accident, whichever presents the largest load demand situation.
RESPONSE TO GUIDELINE B The Rancho Seco electricai power system is described by the attached single line diagram (Sketch 1).
The District's analysis was performed at 214kV switchyard voltage 2
and additionally for Case 3 at 218kV, assuming the power source for the safety buses was obtained with the following plant configurations.
(Case 1 is the normal operating configuration).
Case Description Reference Sketches LA Bus 4A on start-up transformer #1 2
1B Bus 4B on start-up transformer #2 3
2 Buses 4A and 4B on start-up transformer #1 4
3 Buses 4A and 4B on start-up transformer #2 5 & 8-14 & 15-22 l2 4A Bus 4A on start-up transformer #2 6
4B Bus 4B on start-up transformer #1 7
l2 Sketches 2-7 illustrate the 214kV minimum voltage steady-state condition immediately following completion of automstic load requencing due to safety features actuation. Starting conditions are illustrated for Case 3 only which, due to the heavy loading on start-up transformer 42, represents the lLaiting case. Sketches 8-13 illustrate the minimum system voltages occurring during automatic load sequencing and Sketch 14 illustrates the minimum system voltages that could oct1r should the largest 4.16-kV load, a condensate pump, be manually started af ter completion of automatic load sequencing. Sketch 15 is the steady-state condition after automatic load sequencing at 218kV and Sketches 16-21 illustri.te the 2
starting conditions at the 218kV level for Case 3.
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i The unit auxiliary transformers are not an available source for the safety buses as indicated by Sketch 1; the above cases are all the connections available to the safety buses from the offsite network.
The transient assumed in the analysis is a loss of coolant accident (LOCA) with the reactor at 100-percent power coincident with a turbine-generator trip and a safety features actuation signal (SFAS) to both redundant safety systems. This transient producci the maximum load on the start-up transformers.
A turbine-generator trip will place non-safety buses 6A and 6B on start-up transformer #1 and non-safety buses 4C, 4D, 4E1 and 4E2 on start-up transformer #2.
GUIDELINE #2 For multi-unit stations a separate analysis should be performed for each unit assuming (1) an accident in the unit being analyted and simultaneous shutdown of all other units at that station; or (2) an anti-cipated transient in the unit being analyzed (e.g., unit trip) and simul-taneous shutdown of all other units at that station, whichever presents the largest load demand situation.
RESPONSE TO GUIDELINE #2 This guideline is not applicable to Rancho Seco. Rancho Seco is a single unit station.
GUIDELINE #3 All actions the electric power system is designed to automatically initiate should be assumed to occur as designed (e.g., automatic bulk or sequential loading or automatic transfers of bulk loads from one transformer to another).
Included should be consideration of starting of large non-safety loads (e.g., condensate pumps).
RESPONSE TO GUIDELINE #3 The District's analysis assumed the following automatic actions occur coincident with the LOCA/ turbine-generator trip:
(a) Buses 6A and 6B transfer from unit auxiliary transformer #1 to start-up transformer #1.
(b) Buses 4C, 4D, 4E1 and 4E2 transfer from unit auxiliary transformer #2 to start-up transformer #2.
(c) Heater drain pumps trip due to loss of net positive suction head.
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(d) The safety buses are seque' tially 4caded. The loading n
sequence is indicated in Table 1.
Time zero is when the SFAS signal is received.
Large non-safety loads are not started coincident with the event.
Automatic starting of the condensate pump, for example, is blocked on a turbine trip.
GUIDELINE _#4 Mantal load shedding should not be assumed.
RESPONSE TO GUIDELINE #4 Manual load shedding was not assumed in the District's analysis.
GUIDELINE #5 For each event analyzed, the maximum load necessitated by the event and the mode of operation of plant at the time of event should be assumed in addition to all loads caused by expected automatic actions and manual actions permitted by administrative procedures.
RESPONSE TO GUIDELINE 95 The event the District analyzed provided the maximum load on the start-up transfor=ers.
The analysis assumed automatic starting of safety equipment due to an SFAS signal. The safety equipment automatic loading sequence is indicated in Table 1.
It was assumed that the train B auxiliary feedwater pump was manually started simultaneously with the automatically started Train A auxiliary feedwater pump during the fourth automatic sequential loading block. Manual starting is an action permitted by operating procedures.
GUIDELINE #6 The voltage at the terminals of each saf ety load should be calculated based on the above listed considerations and assumptions and based on the assumption that the grid voltage is at the " minimum expected value".
The " minimum expected value" should be selected based on the least of the following:
The minimum steady-stste voltage experienced at the connec-a.
tion to the offsite circuit.
b.
The minimum voltage expected at the connection to the off-site circuit due to the contingency plans which say result in reduced voltage from this grid.
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The minimum predicted grid voltage from grid stability c.
analysis (e.g., load flow studies).
In the report to NRC on this matter the licensee should state planned actions, including any proposed " Limiting Conditions for Operation" for Technical Specifications, in response to experiencing voltage at the connection to the offsite circuit which is less than the " minimum expected value".
A copy of the plant procedure in this regard should be provided.
RESPCNSE TG GUIDELINE #6 The " minimum expected value" of the grid voltage is 214kV and is based on the minimum steady-state voltage experienced at the connection to the offsite circuit. The value of the voltages at the safety buses and at the most distant (electrically) load during this condition is shown on Sketches 2 through 14 for the cases the District analyzed.
Refer to Attachment 1 of Enclosure II for a description of
" Limiting Conditions for Operation" being considered for inclusion in the Technical Specifications.
The District will modify operating procedures to incorporate the operating constraints described in Attachment 1 of Enclosure II when the proposed design, and proposed technical specifications are approved by the NRC and the relays described in Enclosure II are installed.
Special orders have been issued to the plant operators to described operator action at degraded voltage conditions when the switch-yard voltage is less than 216kV. The special order is available for review at Rancho Seco.
GUIDELINE #7 The voltage analysis should include documentation for each condition analyzed of the voltage at the input and output of each trans-former and at each intermediate bus between the connection to the offsite circuit and the terminals ei each safety load.
RESPONSE TO GUIDELINE #7 Sketches 2-14 indicate the voltages at each intermediate bus between the connection to the offsite circuit and the terminals of the safety loads with the lowest steady-state voltage.
GUIDELINE #8 The analysis should document the voltage setpoint and any inherent or adjustable (with nominal setting) time delay for relays which (1) initiate or execute autematic transfer of loads from one source to another; (2) initiate or execute automatic load shedding; or (3) initiate or execute automatic load sequencing.
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l RESPONSE TO GUIDELINE #8 The Dtttrict has overvoltage and undervoltage trip relays which will (1) initiate an automatic transfer of the safety buses from tne offsite power source to the diesels and (2) initiate automatic load shedding.
Automatic load sequencing is initiated by an SFAS signal anc not by the voltage relaying.
The setpoint for the undervoltage relay is documented in the response to Guideline #10.
The setpoint for the overvoltage relay is documented in the response to Guideline #11.
GUIDELINE #9 The calculated voltages at the terminals of each safety load should be compared with the required voltage range for normal operation and starting of that load. Any identified inadequacies of calculated voltage require immediate remedial action and notification of NRC.
RESPONSE TO GUIDELINE #9 The District compared the calculated terminal voltages to that required for normal operation and starting of each safety load. The analysis identified inadequacies. To correct the inadequacies, the folicw-ing modifications were implemented.
1.
Automatic sequential loading of the diesel-generator supply and exhaust fans was changed from Block 2 to Block 3 (Table 1).
This change assured that an acceptable level of terminal voltage would be available for all safety motors being started.
2.
Special order 5-79 was issued to describe operator actions when the switchyard voltage is less than 216kV.
The analysis demonstrated that for this voltage level, or higher, the terminal voltage at any safety motor would never be less than its minimum required starting voltage.
Subsequent analyses, taking into relay accuracy considerations discussed in Enclosure II, demonstrate that reactor operation can only be permitted down to 218kV. These analyses also assumed that automatic condensate pump starting is blocked on a turbine trip.
Only automatic starting is blocked, the pumps continue to operate if they have been running prior to the event; all studies conservatively assumed that the condensate pumps were running at normal operating load. Condensate pump starting concurrent with auto-matic starting of safety equipment could cause the safety equipment termi-nal voltage to dip below the minimum required voltage during the condensate pump starting interval.
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The justification for each type of load to operate at the calcu-lated voltages indicated on sketches 2 through 14 is given below. This analysis assumes that the modification blocking auto starting of the condensate pumps has been implemented.
Motors - The voltage data shown on sketches 2-7 show that some safety-related motors could be operating below the nominal 90 percent minimum steady-state voltage stipulated by NEMA MG 1.
Generally, the cotors operating below this voltage are driving loads that are less than their nameplate horsepower. The District has performed an analysis that indicates continuous operation at the voltage indicated is practrial with no net loss in motor life since the increased heating effects due to the reduced voltage are offset by the lighter than nameplate load. For excep-tions, where the motors are operating at a high load demand factor, motor life will be expended at a greater rate.
However, this increased rate is acceptable since the total life expended is negligible due to the limited time of operation anticipated at the reduced voltage level.
(E.g.: For a fully loaded motor with Class B insulation, the life expended during 4-hours of operation - actual duration of the degraded voltage condition experienced - at 85-percent voltage is equivalent to 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> of operation at 90-percent voltage *.)
The Diatrict's safety-related motors were qualified to start at 75 percent of rated voltage. Skatches 8-14 show that voltage above this value will be available during starting periods and the motors will start.
Motor-Operated Valves - Motor-operated valves are capable of operating properly down to at least 368V (.80 of 460V) which is below the minimum voltage calculat: i for the valve motors.
Batterv Chargers - The battery chargers were factory tested at 140VDC, wit.2 an input voltage of 432 volts (.94 of 460V).
rated load, 2 :
The District has performed additional tests to verify that the battery chargers can operate at the minimum calculated voltage of 387 volts (.84 of 460V).
Heat Tracing Svstem - The heat tracing system for the safety-related pipes, tanks and valves containing boric acid, and freeze protection for the Auxiliary Feedwater System have been examined. The systems consist of strip-type resistance heating tape, transformers and 2
l thermostats. Both systems have low temperature alarms in addition to the low voltage alarm for the boric acid heat tracing which will allow l
corrective action to be taken in the event that temperatures fall below l
acceptable levels during degraded voltage conditions.
- This analysis assumes that for each 10 C temperature rise, life is expended at twice the rate.
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MCC Control Circuits - The District has performed field tests on components within the control circuits of the MCC's.
Tests on auxiliary relays, latching relays, time delay relays, control power ransformers and contactors were made and compared to the minimum bus voltage of 397 volts, which corresponds to the minimum steady state condition at a 214kV switchyard voltage, following automatic load sequencing as shown in Sketch 5.
Calcula-tion No. A.5.08.2.66 includes maximum control cable lengths and minimum device pickup voltages which has shown adequate margin for operation of all devices with the exception of 120 volt Size 3 starter coils. Five circuits are fed f rom Size 3 starters, four of which control power to Upper Dome Air Circulator fan motors, Equipment No.'s. A-532A, B, C and D.
Analysis of the acceleration time and bus veitage prior to the T=3 second start signal for the High Pressure Injection Pump, Sketch 9, shows that the minimum bus voltage recovers to 420 volts which ensures the sequence starting of the dome fans. The fifth Size 3 starter feeds the Contral Room Emergency Air Conditioner / Heater Unit Equipment No. U-545.
All five size 3 starters will be re-equipped with 480 voit operating coils. This modification will eliminate the control transformer as a source of the regulation voltage drop which presently limits the Size 3 coil pickup voltage.
Test values for relays and contactors have confirmed that dropout 2
will not occur under minimum vottage conditions.
Diesel Engine Control Panel - The panel contains a water jacket temperature " keep warm" heater with a minimum alarm temperatura of 120 F which will allow corrective action to be taken in the event of below minimum temperatures at degraded voltage. The diesel panel contactors have been unavailable for testing during plant operation, but those with 120V ac ceils have been identified as the same type and model numbers as those that have been tested, thereby assuring proper operation under minimum voltage conditions.
Receptacle Circuits - Portable Class IE room exhaust fans are employed as backup in the event of switchgear room normal air conditioning system failure. The fans are manually switched directly on the 480 volt circuit and will start under minimum voltage conditions.
Control Devices Mounted Externally to MCC's - Motor starters for the Emergency Pump Room Air Cooler and the Emergency Siren which are located remotely from the motor control centers have been shown to be capable of operation at the minimum voltage.
Overcurrent Protection - The switchgear overcurrent protective devices have been analyzed to verify that tripping of safety-related loads will not occur. Analysis of MCC overload protection is still being performed.
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GUIDELINE #10 For each case evaluated the calculated voltages on each safety bus should be compared with the voltage-time settings for the undervoltage relays on these safety buses. Any identified inadequacies in undervoltage relay settings require immediate remedial action and notification of NRC.
RESPONSE TO GUIDELINE #10 In the October 17, 1979 analysis report, the District compared the voltage-time settings of the undervoltage relays with the voltage requirements of t.te safety equipment. This comparison identified a poten-tial inadequacy. The District changed the undervoltage relay setpoint from 85 to 90 percent of 4160V to correct the inadequacy.
Subsequent analyses, taking into account proposed undervoltage relay type changes and accuracy considerations to implement NRC's position 1 (see Enclosure II), ongoing pcwer system modifications and proposed modi-fications, indicate that an increase in the undervoltage relay setting to 3771V (0.91 of 4160V), which is equivalent to a switchyard voltage of 216 kV, is desirable.
With this setting and the switchyard at 214 kV the steady state voltages on the 4160 volt buses 4A and 43 will be less than the relay setpoint.
(Refer to Sketches 2 through 7 for steady state voltages). The analysis indicates that 214 kV is the minimum experienced voltage and the minimum voltage that the offsite power system is capable of supplying the onsite distribution system. However, the proposed relay setting is justifi-able when the +1 percent relay tolerance is considered. The table 121ow indicates the relay setpoint, dropout voltage limits based on the relay tolerance and the equivalent switchyard voltage.
4160 Volt Bus Switchyard Voltage Voltage l2 Maximum Dropout Voltage 3809 (.92 of 4160) 218 kV Setpoint 3771 (.91 of 4160) 216 kV l2 Minimum Dropout Voltage 3733 (.90 of 4160) 214 kV The proposed relay setpoint provides adequate protection for safety equipment since the minimum dropout voltage is equal to the minimum voltage the equipment is qualified to operate at.
The setpoint will not cause spurious inadvertent operation since the maximum dropout voltage is below the normal operating voltage range.
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GUIDELINE #11 To provide assurance that actions taken to assure adequate voltage levels for safety loads do not result in excessive voltage, assuming the maximum expected value of voltage at the connection to the offsite circuit, a determination should be made of the maximum voltage expected at the terminals of each safety load and its starting circuit.
If this voltage exceeds the maximum voltage rating of any item of safety equipment immediate remedial action is required and NRC shall be notified.
RESPONSE TO GUIDELINE #11 The District has performed a review of data on voltage in the Rancho Seco switchyard. Based on this review, the maximum expected switch-yard voltage is 23?xV. For the existing transformation ratios (Sketches 2-7) and assuming a no load condition, the maximum voltage on the 4.16-kV system is 4531 volta and on the 480-V system is 511 volts. These voltages are 2
equal to or less than the maximum voltage ratings of any safety equipment except the 460-V motors and motor-operated valves (MOV's).
An analysis for each type of safety-related equipment is listed below.
This analysis was based on the maximum steady-state voltage allowed (4626V) by the overvoltage protection relays since this voltage is higher than the maximum expected voltage and represents the permissible extreme.
1 Motors & Motor-Operated Valves - The 4160-volt motors are designed to operate at a maximum voltage of volts which is less than the maximum calculated voltage of 4626 volts (111 percent of 4160V). The 460-volt motors and motor-operated valves have a maximum voltage rating which is less than maximum calculated voltage of 521 volts (113 percent of 460V).
Operation of the motors and motor-operated valves at these voltages is acceptable for the following rersons:
l a.
Oper4cion at :Le maximum expected switchyard vo tage is an estreme cond,; ion that is only expected to occur on rare occasions and for short durations.
(Note - Operating time of MOV's during this condition is further limited by their inherent short-time operating duty.)
b.
The maximum calculated voltage condition conservatively assumes that there is absolutely no auxiliary load operating (i.e: no voltage drop) when the maximum expected switchyard voltage occurs.
c.
The maximum calculated voltage condition conservatively assumes operation at two-percent above the maximum expected voltage (i.e., it allows for relay inaccuracy).
d.
The motors and motor-operated valves will be operating at less than 110 percent of rated voltage when equipment opera-tica is initiated by an SFAF due to voltage drop in the electrical system.
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The maximum voltages calculated will produce a torque that e.
is only slightly greater than the torque that would be produced at the nominal maximum vcltage of 110 percent.
However, due to voltage drop during starting and operation of a motor, the maximum voltage at the terminals of the motor and the increase in torque will be reduced. The MOV circuits have minimal voltage drop during starting and operation.
Therefore, it is possible for the MOV's to produce a slightly greater torque than that produced at 110-percent voltage. However, operation of the MOV is limited by a torque switch. Therefore, the excessive torque is not applied to the valve and operation during the overvoltage condition is acceptable.
f.
The motor manufacturers contacted did not eapect any adverse effect to their equipment due to the slight overvoltage levels being considered. Operating instructions published by one motor manufacturer
- indicate the following character-istics for operation of their motors above rated voltage.
Percent of Full Load Percent of Full Load Percent Percent Temp.
Rated Voltage Efficiency Current Torque Rise 100 100 100 100 110 101.5-102 93 121
(-)3 to (-)4*C 120 100+
89 144
(-)5 to (-)5*C rom the above data, it is indicated that motors are not r
particularly sensitive to overvoltage. Efficiency at 120 percent voltage, for example, is even better than at rated voltage, g.
Overvoltsge alarm relaying is being added to the 480-V safety buses to alert the operator should an unusual over-voltage condition (greater than 110 percent of 460V) occur.
Battery Chargers - The battery chargers are qualified to operate at full load with a maximum input voltasa of 528 volts (114 percent of 460V) which is above the maximum calculated voltage of 521 volts.
- Installation, Operat'on and Care of " Duty Master" Nuclear Service Class IE Integral Horsepower Induction Motors, Reliance Electric Instruction Manual B-3645, December, 1977.
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=
~
=
i i
Heat Tracing _ System - The hea: tracing system for the safety-related pipes, tanks, and valves containing boric acid consists of strip type resistance heating tape, transformers and thermostats. All of this j
equipment should be capable of cperating at the maximum calculated voltage of 521 volts.
MCC Centrol Circuits - The centrol voltage for each 480-volt.MCC i
feeder circuit is obtained froa-a feeder line tap thrcugh a 460 to 120 vol:
j stepdewn cen. col power trans for=er with the =axi=um expected switchyard voltage of of 239 kV, this voltage will not be exceeded.
The maximum voltage rating for the most limiting ce=penent is 132 volts. The 430-volt 2
safety bus overvoltage alarm se: point corresponds to 132 volts en the unicaded seccadary of the control pcwer transfer =er.
In case the maxi =um calculated Overvoltage Relav Serroint voltage is exceeded the analysis indicates that the District's overvoltage relay should be set a 4580 volts (110 percent of 4160V) which, assu=ing a I
no load condi icn, corresponds to a =aximum of 112 percent of 460 volts en the 450-V system. This se: point is equivalent to a voltage of 2;2kV in the switchyard. With this se: point, the relay will protect the safety-related equipment. The relay is set a higher voltage than th. maximum expected voltage and will not cause spurious trips.
It has a definite L=e delay 3 secends and eperates OL series with an external time delay relay set at set at 0.5 seconds.
GUI2ELINE n12 Voltage-time settings for undervoltage relays shall be selected j -
so as to avoid spuricus separatica of safety buses frem offsite pcwer during plant startup, normal cperatien and shutdewn due to startup and/c cperation of electric leads.
RESPCNSE TO GUIDELINE #12 t
The se :ing for the undervoltage relay was selected to assure protection of the safety equipment as explained in the response to Guide-line #10. The setting selected avoids spuricus separation of the safety l
buses from offsite power during plant startup, nor=al operatica and shut-dcwn due to starting and/or cperation cf loads providing the switchyard voltage is above 216kV. This level is belew the 221-kV voltage defined as the normal minimum voltage for the switchyard.
GUIDELINE d13 l
I Analysis documentation should include a statement of the assump-i tiens for each case analyzed.
1 4
4 I
1 4
1 I.3-11 i
e
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,,,,_,,w,,.._,,,,.-,,,,.ne,,
,,.--mn._aw.,y,.-.-
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,,-m,.,,,,,,n,.,.,,
,-,,,,,,rg,
,e
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RESPONSE TO GUIDELINE #13 For the cases analyzed the District's assumptions have been included. The following statements describe the general assumptions used in the computer analysis.
The computer modeled running loads.nd motors as having a a.
constant volt-ampere characteristic.
b.
Starting motors are modeled as having a constant impedance characteristic.
c.
The load data for the non-Ci sss IE 4.16-kV system (and subsystems) and safety motors greater than 60 hp was based on actual field measurements (under simulated accident condi-tions, if applicable); for other loads, tield test data, manufacturers' data and t7pical motor / load data were utilized.
d.
Impedance data for transformers was based on the actual nameplate or test report data.
Impedance data for bus duct was based on manufacturers e.
published data.
3 f.
Impedance of cables was modeled for Class IE 4160-480V transformer primary and secondary cables, MCC feeders and worst-case loads. Other loads were lumped together at their supply point.
g.
Cable impedance was calculated based on the actual cable length pulled and cable type.
h.
The impedance of switching equipment (switchgear, breakers, etc.) is negligible and was not included.
I e
I.B-12
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y
-,-m--,%w-.
TABLE 1 NUCLEAR SERVICE BUS (EACH) ALTr0MATIC LOADING SEQUENCE ACC.
Offsite Power System Time Loading Sequence Quantity Sec.
Description Block 1 - Energize at:
0 + 0 see 1
0.9 Decay heat pump (low l
pressure inj.)
i 2
5.3 Reactor Building upper dome air circulators l
1 1
Motor control center (miscellaneous load) 0 + 3 sec*
1 0.7 Makeup pump (high pressure inj.)
I Block 2 - Energize at:
O + 16 sec 2
4.2 Reactor Building Emer-gency air cooler 1
0.6 Nuclear service cooling water pump Block 3 - Energize at:
l 0 + 26 see 1
0.6 Nuclear service raw water t
Pump 2
5.8 Diesel generator room supply and exhaust fans Block 4 - Energize at:
1 3
Auxiliary Feedwater Pump (Train A only) o + 36 sec Block 5 - Energize at:
0 + 300 see 1
0.5 Reactor Building spray system including pump
- Start of the make-up pump (high pressure inj.) is delayed 3 seconds to allow its bearing lube oil flow to get started.
I.B-13
SKI!;H 2 CASE 1 A' BUS 4A ON STARTUP TRANSFORMER NO.1 STEADY STATE AFTER SEQUENTIAL LOADING 214 KV SWITCHYARD VOLTAGE i
220 KV SWITCHYARD STA RTL'P TR ANS. N O.1 214 KV 1
221 - 12.47 - 6.3 KV p
TAP -130 KV t A
..1>
H WIN 0lNGY38.6 MV A y
4
.6 VA 5.6 MV A X
Y TO 6.9 KV BUSSES 6A & 68 TO CANAL PUMPING $UB 27 3 MVA 11.5 KV NUCLE AR SERVICE SUPPLY TRANSFORMER ti..ii ZZZZ 12.47-4.36 KV
' ' 7.5 M V A ESF SYSTEM 3.76MVA, 4160 V BUS 4A 3S22 V
(.34 0F 4160 VI STATION SERVICE
_i
_i_; T R A NS. X 34 A 3gj g y
(
_ _ _ _ 4160-480V MOTOR
(.34 0F 4160 VI
] ' ' TAP-1260V l
1 1.12 MVA J7MVA 440 V BUS 3A 421 V
(.310F 450 VI l
OTOR F 460 V1 480 V MCO 2A1 413 V (J10F 440 V)
'0I Y MOTOR (JS OF 460 V) i BOTES:
- 1. MOTORS CONNECTED TO A 3160V BUS ARE RATED 41SOV. THE 440V SYSTEM MOTORS ARE RATED 460V.
- 2. THE MOTORS SHOWN ARE ELECTRICALLY THE MOST OtSTANT MOTORS FROM THE BUSSES SHOWN. ALL OTHER MOTORS ON THESE BUSSES WILL OPERATE AT A VOLTAGE BETWEEN THAT 0F THE BUS, AND THAT OF THE MOST DISTANT MOTOR.
I.3-35 u.
SKETCH 3 CASE 1B BUS 4B ON STARTUP TRANSFORMER NO. 2 STEADY STATE AFTER SEQUENTIAL LOADING 214 KV SWITCHYARD VOLTAGE 220 KV SWITCHY ARD 214 KV H
STARTUP TRANSFORMER 40.2 ti 12 221 - 4.36-4.36 KV
_ _ J_' T_ _ _
TAP -230 KV
'Y' H WINDIN G - 42.6 MV A Y
Z Y WINDING - 24 MVA Z WINDING - 22.6 MVA TO 4160 V BUSSES 4E1 & 4E2 14.0 MVA
~ 14.1 MVA TO 4160 V BUSSES 4C & 40 3794 V ESF SYSTEM 4160 V BUS AB 3790 V (310F 4160 V)
STATION SE RVICE NN 4160-480 V MOTOR 3III Y
' ' TAP -4260 V
(.310F 4160 V 1.12 MVA 1#3 MVA o
l 480 V BUS 3B l
av l
L88 0F 460 V) 1 396 V MOTOR L36 0F 460 V) 480 V BUS 281 402 V L87 0F 460 V)
MOTOR 336 V L86 0F 460 V)
WOTES:
- 1. MOTORS CONNECTED TO A 4160V BUS ARE RATED 4160V. THE 480V SYSTEM MOTORS ARE RATED 460V.
- 2. THE MOTORS SHOWN ARE E8.ECTRICALLY THE MOST OISTANT MOTORS FROM THE BUSSES SHOWN ALL OTHER MOTORS ON THESE BUSSES WILL OPERATE AT A VOLTAGE BETWEEN THAT OF THE BUS, AND THAT CF THE MOST DISTANT MOTOR.
I,3-16 1
SKETCH I.
CASE 2 BUS 4A & 48 ON STARTUP TRANSFORMER NO.1 STEADY STATE AFTER SEQUENTIAL LOADING 214 KV SWITCHYARD VOLTAGE 220 KV SWITCNY ARD STARTUP T R ANS. N O.1 214 KV 221 - 12.47 KV H
TAP-230 KV ti..i; H WINDING - 38.6 MV A Q 'g X WINDING - 10 MVA 8.50 MVA X
Y Y WINDING - 34.6 MVA M63W M Su&H TO CAN AL PUndPING SUB 11.4 KV g gg WW NUCLEAR SERVICE rT-^-^i SUPPLY TR ANSFORMER
'T 12.47-4.36 KV 5.89 MVA 7.5 MV A o
4160 V BUS 4A ESF SYSTEM 4160 V BUS 48 3805 V 3801 V LS10F 4160 VI LS10F 4160 V) 3789 V LS10F 4160 VI STATION SERV.
STATION SERV. '
- T R ANS. X43A t_A; _i #
3793 V TR ANS. X438 MOTOR MOT 0p 4160 -480 V
--3 LSI 0F 4160 V) 4160 - 483 V r1-1 i ry 1
TAP - 4260 V TAP - 4260 V 1.12 MVA 1.12 MV A 37gyg 37 MVA o
480 V BUS 3A 480 V BUS 38 406 V 407V L88 0F 460 V)
L88 07 460 V) 399 V 087 0F 460V1 MOTOR MOTOR
,, y, 440 V MCO 2A1 480 V MCO 281 405 V 40E V L88 0F 440 V)
L88 0F 460 V) 399 V
$$fp4ggj MOTOR MOTOR iOTES:
- 1. MOTORS CONNECTED TO A 4150V BUS ARE RATED 4160V. THE 480V SYSTEM MOTORS ARE RATED 460V.
- 2. THE MOTORS SHOWN ARE ELECTRl: ALLY THE MOST DISTANT MOTORS FROM THE BUSSES SHOWN. ALL OTHER MOTORS ON THESE BUSSES WILL OPERATE AT A VOLTAGE BETWEEN THAT OF THE SUS. AND THAT OF THE MOST OISTANT MOTOR.
I.3-17
~v.-
.-w-
---a
---m n
SMH 5 CASE 3 8US 4A O 4B ON STARTUP TRANSFORMER NO. 2 STEADY STATE AFTER SEQUENTIAL LOADING 214 KV SWITCHYARD VOLTAGE 220 KV SWITCHY ARO 214 KV H
,y A,y y,
221 - 4.36-4.36 KV TAP-230 KV Y
Z H WINDING - 42.6 MVA TO 4160 V SUSSES 4E13 4E2 Y WINDING - 24 MVA 2 WINDING - 22.6 MVA 14.1 MVA 17.0 MV A TO 4160 V BUS 4C TO 41E0 V BUS 40 3745 V 3740 V I
ESF SYSTEM 4160V BUS 4A 4160 V BUS 48 3743 V 3737 V
(.90 0F 4160 V)
(.30 0F 4160 VI STATION SERV.
STATION SERV. W W TR ANS. X43B TRANS X43A 4160 - 480 V MOTOR 3731 V 4160 - 480 V MOTOR TAP - 4260 V
(.90 0F 4160 V)
TAP - 4260 V 1.12 MV A 1.12 MVA 3725 V J7 MVA
(.30 0F 4160 V) y,g 480 V BUS 3A 480 V BUS 38 ESV 399 V L37 0F 460 V)
(.37 0F 440 V) 83 MOTOR MOTOR W5 F 40 V) 391 V L85 0F 480 V) 480 V MCC 2A1 480 V MCC 281 398 V 397 V (J6 0F 460 V) 087 0F 460 V)
MOTOR MOTOR F 440 V)
BOTE 5 0F 440 V)
- 1. MOTOR 3 CONNECTED TO A 4180V BUS ARE RATE 0 4180V. THE 480V SYSTEM MOTORS ARE RATE 0 440V.
- 2. THE MOTORS SHOWN AMC ELECTRICALLY THE MOST OISTANT MOTORS FROM THE BUSSES SHOWN. ALL OTHER MOTORS ON THESE SUSSES WILL OPERATE AT A VOLTAGE BETWEEN THAT OF THE SUS, AND THAT
~
OF THE MOST DISTANT MOTOR.
7,3_tg
SKITCH 6 CASE 4A BUS 4A ON STARTUP TRANSFORMER NO. 2 STEADY STATE AFTER SEQUENTIAL LOADING 214 KV SWITCHYARD VOLTAGE 220 KV SWITCHYARD 214 KV H
STARTUP TR ANSFORMER NO 7 l
WW 221 - 4.36-4.36 KV mm mm TAP - 23O KV Y
Z H WINDING - 42.6 MVA Y WINDING - 24 MVA TO 4160 V BUSSES 4E1 & 4E2 Z WINDING - 22.8 MVA 14.1 MV A 13.5 MVA l
TO 4160 V BUS 4C TO 4160 V BUS 40 l
i asca v ESF SYSTEM l
4160 V BUS 4A l
3801 V LSI 0F 4160 V) j i
STATION SERV.
l TRANS X43A I
4160-480V WW i
TAP-4260 V T*
I' MOTOR l
1.12 MVA (J10F 4160 V)
J7 MVA 480 V BUS 3A 406 V LS8 0F 460 V) 400 V MOTOR L87 0F 460 V) 480 V MCC 2A1 l
WV L88 0F 480 V) 8 450 W BOTES:
- 1. MOTORS CONNECTED TO A 4150V EUS ARE RATED 4160V. THE 480V SYSTEM MOTORS ARE RATED 480V.
- 7. THE MOTO RS SHOWN ARE ELECTRICALLY THE MOST OlSTANT MOTORS FROM THE BUSSES SHOWN. ALL OTHER MOTORS ON THESE BUSSES WILL OPER ATE AT A VOLTAGE BETWEEN THAT OF THE BUS, AND THAT OF THE M OST OtSTANT WOTOR.
I.B-19 1
,w-
-+
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,-w
,-w.-s e-g 9
~e-
+-- ~ - - - - -
SKETCH 7 CASE 4B BUS 4B ON STARTUP TRANSFORMER NO.1 STEADY STATE AFTER SEQUENTIAL LOADING 214 KV SWITCHYARD VOLTAGE 220 KV SWITCHY ARD 214 KV STA RTUP TR ANS. N O.1 221 - 12.47-6.9 KV H
TAP - 230 KV ti _i; 86MVA M f; r1- ^
A r T' 'A g
X Y
Y WINDING - 34.6 MVA TO 6.9 KV BUSSES EA & 68 5.64 MVA TO CAN AL PUMPING SUB 27J MVA 11.47 KV NUCLEAR SERVICE LO W SUPPLY TRANSFORMER
&% 12.47 - 4.36 KV 7.5 MV A 3.83 MVA y
ESF SYSTEV 4160 V BUS 4B 3918 V LS4 0F 4160 V) 3906 V STATION SERV. ww TRANS X438 rTA MOTOR
~
4160-480 V TAP-4260 V 1.12 MVA 450 V BUS 38 419 V 0910F 480 V) 412 V LSO OF 460 V)
MOTOR 480 V MCC 281 418 y LS10F 480 V)
'7 412 V 50TE3.
MOTOR
- 1. MOTORS CONNECTED TO A 4180V BUS ARE RATED 4160V. THE 480V SYSTEM MOTORS ARE RATED 480V.
~
- 2. THE MOTORS SHOWN ARE ELECTRICALLYTHE MOST DISTANT MOTORS o
FROM THE BUSSES SHOWN. ALL OTHER MOTORS ON THESE BUSSES ~
WILL OPERATE AT A VOLTAGE BETWEEN THAT OF THE BUS, AND THAT OF THE M OST OlSTANT MOTOR.
P I.3-20 e6 wy w,
--,-w n
.~~y
-e 4
e
~
-m-e,e~
~ - - -
SKnCH 8 CASE 3 BUS 4A G 4B ON STARTUP TRANSFORMER NO. 2 VOLTAGE DURING BLOCK LOADING OF EMERGENCY BUSSES (BLOCK 1., T = 0 SEC.)
START DECAY HT REMOVAL PP, RE UPPER DOME FANS AND MISCELLANEOUS MCC LOADS 220 KV SWITCHY ARO 214 KV STARTUP TR ANSFORVER NO 2 H
221 - 4.36-4.36 KV TAP - 230 KV
&MMM N WINDING - 42.6 MV A TO 4160 V BUSSES 4E1 & 4E2 Y WINDING - 24 MVA y
Z Z WINDING - 22.6 MVA TO 4160 V BUS 4C TO 4160 V BUS 4t 3739V 3734 V' ESF SYSTEM 4160 V BUS 4A 4160 V BUS 48 3738V 373g y LSO OF 4160 V)
(.30 0F 4160 V) 3728 V (JO OF 4160 V)
STATION SERV.
(STARTING) 3735 V STATION SERV.
TR ANS. X43 A 4160 - 480 V Zz :
T (JO OF 4160 V)
%W g 1., 1, ri^
r ^'
TAP - 4260 V MOTOR I.ST A RTING) 4160 - 480 V v
MOTOR 1.12 MV A TAP - 4260 V 1.12 MV A 480 V SUS 3A 480 V SUS 38 338 V 395 V L37 0F 440 V)
La$ OF 460 VI l
l l
i 4:0 v MCC 2A1 aso V MCC 2s1 383 V N1V L85 0F 440 V)
(.35 0F 440 V) l 383 V 376 V MOTO R i.79 0F 480 V)
L22 0F 440 V) MOTOR (STARTING)
(STARTING) 50TES:
- 1. MOTORS CONNECTED TO A 4160V IUS ARE RATED 4160V. THE 440V SYSTEM MOTOR $ ARE RATE 0 440V.
- 2. THE MOTORS SHOWN ARE ELECTRICALLY THE MOST OISTANT MOTORS FROM THE BUSSES SHOWN. ALL OTHER MOTORS ON THESE BUSSES WILL QPERATE AT A VOLTAGE BETWEEN THAT OF THE BUS, AND THAT OF THE MOST OlSTANT MOTOR.
I.3-21
S!CTOH 9 C ASE 3 BUS 4A O 4e ON STARTOP TRANSFORMER NO. 2 VOLTAGE DURING BLOCK LOADING OF EMERGENCY BUSSES (BLOCK 1.,T = 3 SEC.)
START HP INJECTION PP,THE RB DOME FANS CONTINUE STARTING 220 KV SWITCHY ARD 214 KV STA1 TUP TR ANSFORMER NO 7 H
221 - 4.36-4.36 K V WW TAP - 230 KV
&%&M M WINDING -42.6 MVA TO 4160 V BUSSES 4E1 & 4E2 Y WINDING - 24 MV A y
~
Z Z WIN DIN G - 22.6 M VA TO 4160 V SUS 40 TO 4160 V SUS 4C
~
3667 V 3673 V I
~
ESF SYSTEM 4160 V SUS 48 4160 V BUS 4A 3672 /
3663 V L'8 0F 4160 V)
(.88 0F 4160 V)
LS8 0F 4160 V)
STATION SERV.
STATION SE RV.
(STARTIN G)
TR ANS. X43A 3667 V 4160 - 430 V L88 0F 4160 V)
TR ANS. X438 WW TAP.- 4260 V MOTOR (STARTING) 4160 4'O V rv--^-v' MOTOR TAP -4260 V 1.12 MVA 1.12 MV A 480 V 8US 38 480 V BUS 3A 393 V 402 V L 7 0F 480 V)
(.87 0F 480 V) l l
l l
480 V MCO 231 480 V MCO 2A1 387 V 389V (JS OF 440 V)
L87 0F 480 V) l ss8 V 381 V l
MOTOR
(.80 CF 480 V)
(.83 0F 460 V) MOTOP (STARTING)
(STARTING)
NOTES:
- 1. MOTORS CONNECTED TO A 4150V SUS ARE RATED 41EDV. THE 48CV SYSTEM MOTORS ARE RATED 440V.
- 2. THE MOTORS SHOWN ARE ELECTRICALLY THE MOST OlsTANT MOTO RS FROM THE SUSSES SHOWN. ALL OTHER WOTORS ON THESE BUSSES WILL OPER ATE AT A VOLTAGE BETWEEN THAT OF THE SUS, AND THAT O F TH E MOST OtSTANT MOTOR.
I.3-22
SKITCH 10 CASE 3 SUS 4A O 4B ON STARTUP TRANSFORMER NO. 2 VOLTAGE DURING BLOCK LOADING OF EMERGENCY BUSSES (8 LOCK 2., T = 16 SEC.)
START NUCLEAR SERVICE AIR COOLERS AND NUCLEAR SERVICE COOLING WATER PUMPS 220 KV SWITCHYAR.*
214 KV STARTUP TR AN0FORMER NO 2 H
221 - 4.36-4.36 KV W A' TAP - 230 KV l
N' Yi &
M N WINDING - 42.6 MVA TO 4160 V E.;SES 4E1 & 4E2 Y WINDING - 24 MV A y
2 2 WINDING - 22.6 MVA T0 4160 V BUS 4C TO 4160 V BUS 40 3732 V 3727 V ESF SYSTEM 4153 V BUS 4 A 4160 V BUS 48 3731V 3724 y L30 0F 4160 V)
LSO OF 4160 V) 3721 V ST ATION SERV.
(.30 0F 4160 V)
T R ANS. X43A 1728 V STATION SERV.
4160 - 480 V LSO OF 4160 V)
T R ANS. X425 WW 4160 - 480 V MOTOR TAP 4260 V MOTOR T AP - 4260 V 1.12 MVA 1.12 MV A 480 V BUS 3A 480 V SUS 3B 369V 366 V L30 0F 460 V)
LSO OF 460 V) 344 V L75 0F 460 V)
CSTARTING) l F 460 V)
MOTOR (STARTING)
M OT,0 R f
i r
i 440 V M00 2A1 480 V MCO 281 l
387 V 364 V I
L40 0F 460 V)
L75 0F 460 VI l
357 v nev L78 0F 460 VI MOTOR MOTOR L77 0F 440 V)
ECTES:
- 1. MOTORS CONNECTED TO A 4180V EUS ARE RATED 4160V. THE 480V SYSTEM MOTORS ARE MATED 460V.
- 2. THE MOTORS SHOWN ARE ELECTRICALLY THE MOST DISTANT MOTORS FROM THE BUSSES SHOWN. ALL OTHER MOTORS ON THESE SUSSES WILL OPERATE AT A VOLTAGE BETWEEN THAT OF THE SUS. AND THAT O F THE M OST DISTANT MOTOR.
I.3-23
.e, P"
er
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-y--.
+-
S12TCH 11 CASE 3 l
BUS 4A O 4B ON STARTUP TRANSFORMER NO. 2 VOLTAGE DURING BLOCK LOADING OF EMERGENCY BUSSES (BLOCK 3., T = 26 SEC.)
START THE NUCLEAR SERV RAW WATER PUMPS AND THE DIESEL.G5NERATOR ROOM VENT FANS 220 KV SWITCHYARO 214 KV STARTUP TRANSFORMER NO 2 H
221 - 4.36-4.36 KV WW TAP - 230 KV ri^-A&%
H WINDING - 42.6 UV A TO 4160 V BUSSES 4E1 & 4E2 Y WINDING - 24 MVA y
2 2 WINDING - 22.6 MV A TO 4160 V BUS 4D TO 4180 V BUS 4C 3685 V 3632 V ESF SYSTEM 4160 V BUS 48 4160 V BUS 4A J
3681 V 3630 V
(.88 0F 4160 V)
(.89 0F 4160 VI
,y
(.88 0F 4160 V)
STATION SERV.
(STARTING)
TE ANS. X43A 3656 V STATION SE RV.
4160 - 460 V
(.88 0F 4160 V)
T R ANS. X438 WW TAP - 4260 V MOTOR (STARTING) 4160 - 480 V mm UOTOR TAP -4260 V 1.12 MV A 1.12 MV A 480 V 8US ?S 480 V BUS 3A 382V 386 V
(.84 0F 460 V)
(.83 0F 460 V) 370 V
(.80 0F 460 V)
GTARTING) 389 V
(.80 0F 480 V)
MOTOR MOTOR STARTING) 480 V MCC 281 480 V MCC 2A1 381V 344 V
(.83 0F 460 V)
(.83 0F 440 V) d 374 Y 371 V
(.810F 440 V) MOTOR MOTOR l.310F 480 VI 50TES:
- 1. MOTORS CONNECTED TO A 4160V BUS ARE RATED 4160V. THE 480V SYSTEM MOTORS ARE RATED 460V.
- 2. THE MOTORS SHOW s ARE ELECTRICALLY THE MOST DISTANT MOTORS FROM THE BUSSES SHOWN. ALL 0THER MOTORS ON THESE BUSSES WILL OPERATE AT A VOLTAGE BETWEEN THAT OF THE BUS, AND THAT OF TdE M OST DICTANT MOTOR.
I.B-24
3 N 12 CASE 3 BUS 4A & 4B ON STARTUP TR ANSFORMER NO. 2 VOLTAGE DURING BLOCK LOAOING OF EMERGENCY BUSSES (BLOCK 4.,1 u 36 SEC.)
START AUX FEED WATER PUMPS 220 KV SWITCHY ARO 214 KV STARTUP TR ANSFO AMER NO 2 H
221 -4.36-4.36 KV WW TAP - 230 KV rv^^--i ii 1
^^vi H WINDING - 42.6 MV A TO 4160 V BUSSES 4E1 & 4E2 Y WINDING - 24 MVA y
2 Z WINCING - 22.6 MVA TO 4160 V BUS 4C TO 4160 V BUS 40 3556 V 2547V ESF SYSTEM 4160 V 8US 4A 4160 V RUS 4B
~
3553 V 3541 y L35 0F 4160 V)
(.85 0F 4160 V) 3491 V
(.84 0F 4160 V)
STATION SERV.
T R ANS. X43 A 3523 V STATION SE RV.
(STARTINGl 4160 - 430 V WN
(.85 0F 4160 V)
T R ANS. X438 WW TAP - 4260 V MOTOR (STARTING) 4160 - 480 V
&M MOTOR TAP -4260 V 1.12 MV A 1.12 MV A 480 V BUS 3A 480 V SUS 3B 384 V 380 V
(.84 0F 460 V)
(.83 0F 480 V) 312 V
(.810F 480 V) pgy L82 0F 480 VI MOTOR MOTOR 480 V MCC 2A1 480 V MCC 281 383 V 378 V L83 0F 460 VI (22 0F 480 V) 372 V 370 V L810F 460 VI MOTOR MOTOR LSO OF 480 V)
- 0TE3:
- 1. MOTORS CONNECTED TO A 4160V BUS ARE RATED 4160V. THE 480V SYSTEM MOTORS ARE RATED 460V.
- 2. THE MOTORS SHOWN ARE ELECTRICALLY THE MOST DISTANT MOTORS FROM THE SUSSES SHOWN. ALL OTHER MOTORS ON THESE BUSSES WILL OPER ATE AT A VOLTAGE BETWF.EN THAT OF THE BUS. AND THAT
-.i 0 F TH E M OS' OISTANT MOTOR.
'l I.3-25 I
CASE 3 SN 13 BUS 4A 0 4B ON STARTUP TRANSFORMER NO. 2 VOLTAGE DURING BLOCK LOADING OF EMERGENCY BUSSES (BLOCK 5., T = 300 SEC.)
START REACTOR BUILDING SPRAY PUMP i
220 KV SWITCHYARD 214 KV STARTUP TR ANSFORMER NO 2 j
H 221 -4.36-4.36 KV U_
- _U TAP - 230 KV
&M&%
H WIN 0 LNG - 42.6 MVA TO 4160 V BUSSES 4E1 & 4E2 Y WIN 0 LNG - 24 MV A y
Z Z WINDING - 22.6 MVA TO 4160 V BUS 4C TO 4160 V BUS 40 3639 V 3493 V
~
~
ESF SYSTEM 4160 V 8US 4 A 4160 V BUS 48 3638 V 3689 V LAS OF 4160 V)
LSS OF 4160 V) 3679 V 60 W RA S X4 A 3688 V STAT 10% SE RV.
4160 - 480 V DN LAS OF 4160 V)
TR ANS. X438 WW TAP - 4260 V MOTOR 4160 - 480 V
&M MOTOR 1.12 MV A TAP - 4260 V 1.12 MVA 480 V BUS 3A 480 V BUS 38 369 V 385 V L80 0F 440 V)
L79 0F 440 V) 363 V L77 0F 460 V)
MARTING) 357 V L78 0F 440 V)
)
MOTOR STARTING)
MOTOR j 480 V MCC 2A1 480 V McC 281 367 V 364 V L40 0F 440 V)
L79 0F 440 V) 3" Y M3V L77 0F 480 V) MOTOR MOTOR L77 OF 480 V)
MOTES:
- 1. MOTORS CONNECTED TO A 4160V BUS ARE RATED 4160V. THE 430V SYSTEM MOTOR $ ARE RATED 440V.
- 2. THE MOTORS SHOWN ARE ELECTRICALLY THE MOST OlSTANT WOTORS FROM THE BUSSES SHOWN. ALL OTHER MOTORS CN THESE BUSSES WILL OPERATE AT A VOLTAGE SETWEEN THAT OF THE BUS. AND THAT OF THE WOST OtSTANT MOTOR.
I.B-26 e-
,,-,-x-.....---_,----.,_,-.,,_,__...,-,.--_,_.,-w, s
.,,,-.-.,,-m,
SKE~Cli it.
CASE 3 BUS 4A & 4B ON STARTUP TRANSFORMER NO. 2 VOLTAGE DURING START OF C ENSATE PUMP 220 KV Sw"TCHY ARO 216 KV STARTUP TR ANSFOR*JEa NO 2 H
221 - 4.36-4.36 KV
,,--1, TAP - 230 KV rT v i & %
H WIN 0tNG - 42 6 MVA TO 4160 V BUSSES 4E1 & 4E2 Y WIN 0 LNG - 24 MV A y
I Z WINOING - 22.6 MVA T0 4t60 V SUS 4C T0 4160 V BUS 40 3462 V 3A43 V ESF SYSTEM 4160 V BUS 4 A 4160 V BUS 4B 3461 V 3A45 V L23 0F 4160 V)
(.83 0F 4160 V) 3432 V
(.12 0F 4160 V)
TRA.5'x43A 3A47 V STATION SE RV.
4160 - 480 V
(.83 0F 4160 V)
&P MOTOR TAP - 4250 V MOTCH TAP - 4260 V 1.12 MV A 1.12 M V A 480 V BUS 3A 480 V BUS 38 365 V 364 V L79 0F 480 V)
L79 0F 440 V) 355 V L77 0F 440 V) gy L74 0F 440 V)
MOTO R MOTOR 480 V WCO 2A1 480 V MCC 281 363 V 383 V L79 0F 480 V)
(.75 0F 480 V) l 355 V I
349 Y L77 0F 460 V) MOTOR MOTO R ( 7g op agg yj WOTES:
- 1. MOTORS CONNE0TED TO A 4160V SUS ARE RATED 4160V. THE 480V SYSTEM MOTO AS ARE RATE 0 460V.
i
- 2. THE WOTORS SHCWN ARE ELECTRICALLY THE MOST OISTANT WOTORS FROM THE BUSSES SHOWN. ALL OTHER MOTORS ON THESE BUSSES WILL OPERATE AT A VOLTAGE BETWEEN THAT OF THE BUS. AND THAT OF THE WOST OISTANT MOTOR.
- 3. CONOENSATE FUMP ST ARTING TIM E IS LESS TN AN 2 SECONOS.
I.3-27 l
~
Sketch 15 CASE 3 BUS 4A & 4B ON STARTUP TRANSFORMER NO. 2 STEADY STATE AFTER SEQUENTIAL LOADING 218 KV SWITCHYARD VOLTAGE 220 KV SWITCHY ARD 218 KV i
H ST A RTU P TR ANS. N O. 2 ww 221 - 4.36-4.36 KV r 1, ma, y c,
y TAP - 230 KV y
7 H WINDING - 42.6 MV A Y WINDING - 24 MV A TO 4160 V BUSSES 4E1 & 4E2 Z wtN0 LNG - 22.6 MV A 14.1 WV A 17.0 WV A o
TC 4160 V BUS 40 TO 41E0 V BUS AC 3824V 3829v ESF SYSTEM 4160 V BUS 48 4150v BUS 1 A
~
382iv 3627V
(.92 0F 4160 VI
(.92 0F 4160 vt STATION SERV. YzYI STATION SERV.
TR ANS. X43B TRANS X43A WW t a gg.,
4160 - 480 V MOTOR 4163 480 V MOTOR (".92 0F 4160 V)
T AP - 4260 V TAP 4260 V 1.12 MV A r
1.12 uv A 3EC9Y
.97 MV A 60 W 480 v BUS 3B 480 V EuS 3A 4C9V 409V
(.89 0F 460 VI
(.69 0F 4f0 VI MOTOR.SS F 460 V)
ActV l
(. S7 0F 460 VI l
480 V WCC 251 l
l 480 V MCC 2A1 40eV 4cTv
(.89 0F 460 V)
(.89 0F 460 vi i
MOTOR f
MOTOR 6 0F 460 V) 4CIV
( 37 0F 460 V) m0TES; l
- 1. WOTORS CONNE0TED TO A 4160V BUS APE RATED 4160V THE 480V SYSTEV MOTORS ARE RATED 460V.
f
- 2. THE MOTORS SHOWN ARE ELECTRICALLY THE MOST DISTANT MOTORS
"~
FROM THE BUSSES SHOWN. ALL OTHER MOTORS ON THESE BUSSES WILL OPERATE AT A VOLTAGE BETWEEN TMAT OF THE SUS, AND THAT OF THE MOST DISTANT MOTOR.
I.3-23
_ _ - - ~. -
Sketch 16 CASE 3 BUS 4A 8 08 ON STARTUP TRANSFORMER HO. 2 VOLTAGE DURING BLOCK L% DING OF EMERGENCY 80SSES (BLOCK t., Tm O SEC-)
START DECAY HT REMOVAL PP, RB UPPER DOME i
FANS ANO MISCELLANEOUS WCC LOADS 22D KV SWITCHY ARD 218V wb ST A RTUP T R A NS. N O. 2 221 - 4.36-4.36 KV
,y y 3
,y TAP - 230 KV Y
2 H WINDING - 42.6 MVA TO 4160 V BUSSES 4E1 & 4E2 Y WINDING - 24 MVA Z WINDING - 22.6 MVA TO 4160 V BUS AC TO 4160 V BUS 40
~
3867 V 3812 V ESF SYSTEM 4160 V BUS AB 4160V BUS 4A 3Sf6V -
3809V
(.92 0F 4160 VI
(.92 or 4160 v) 38G6V
(.91 CF 4160 V)
(STARTING)
STATION SERV. Yi/I STATION SERV. WW TR ANS. X43B TRANS X43A MOTOR (3813V Y
4160 - 480 V MOTOR 4160 - 480 V
.92 0F 4160 VI TAP - 4260 V TAP - 4260 V 1.12 MV A (STA R T IN G) 1.12 MVA 480 V BUS 3A 480 V BUS 3B 4C7 V 404V
( 86 0F 450 VI
(.88 0F 460 VI l
480 V VOC 2A1 480 V MCC 2B1 4Civ 4COv
(.57 0F 460 VI
(.87 0F 460 VI I
MOTOR WOTOR 81 F 460 V)
(. 83 0F 460 VI
- 1. WOTORS CONNECTED TO A 4160V BUS ARE RATED 4160V. THE 480V (STARTING)
SYSTEM WOTORS ARE R ATED 460V.
- 2. THE WOTORS SHOWN ARE ELECTRICALLY THE MOST DISTANT WOTORS FROM THE SUSSEL SHOWN. ALL OTHER MOTORS ON THESE BUSSES l
WILL OPER ATE AT A VOLTAGE BETWEEN THAT OF THE BUS, ANO THAT i
j OF THE WOST OIST ANT WOTOR.
g,3 29 m
Sketch 17 CASE 3 803 4A O CB ON STARTUP TRANSFORMER NO.2 VOLTAGE DURING BLOCK LOADING OF EMERGENCY SUSSES (BLOCX l., T= 3 SEC.)
START HP INJECTION PP, THE RB 00ME FANS CONTINUE STARTING 220 KV SWITCHY ARD 218KV H
221 - 4.36-4.36 KV
,1--3 7y- -,
1 y
TAP - 230 KV Y
Z H WINDING - 42.6 MVA Y WIN 0tNG - 24 MVA TO 4160 V BUSSES 4E1 & 4E2 Z WINDING - 22.6 MV A TO 4160 V BU',40 TO 4160 V BUS AC 3744V 3751V ESF SYSTEM 4160 V BUS AB 4160V BUS 4A 3740V 3734y 3749V
( 90 0F 4160 V)
(.90 CF 4160V)
(.90 0F 4160 V)
(STARTING)
STATION SERV.
STATION SERV.
TR ANS. X43B WW MOTOR TRANS X43A
^-
MOTOR (3744V 4160 - 480 V
'T' 4160 480 V
.90 0F 4160 V)
TAP - 4260 V TAP 4260 V 1.12 MV A (STAR TlNG) 1.12 MvA 480 V BUS 3B 480 V BUS 3A 408V 4iG V
(.89 0F 460 V)
(.99 0F 43 VI 480 V MCC 281 480 V MCO 2A1 4C6V 407V
(.88 0F 460 V)
(.89 0F 460 V) 37 MOTOR MOTOR 82 F 460 V)
(STARTING) sggy
~
NOTES:
(.85 0F 460 VI
- 1. MOTORS 00NNECTED TO A 4160V BUS ARE RATED 4160V. TH! 480V (STAR- ;NG)
SYSTEM W0 ORS ARE RATED 440V.
- 2. THE MOTO ds SHOWN ARE ELECTRICALLY THE WOST DISTANT MOTORS FROM THE BUSSES SHOWN. ALL OTHER MOTORS ON THESE BUSSES WILL OPERATE AT A VOLTAGE BETWEEN THAT OF THE BUS AND THAT OF THE MOST OtSTANT WCTO R.
._~
Sketch 18 CASE 3 SUS 4A O 48 ON STARTUP TRANSFORMER NO.2 VOLTAGE DURING BLOCK LOADING OF EMERGENCY BUSSES (BLOCMi ~2., T = 16 SEC.)
START NUCLEAR SERVICE AIR COOL 2RS AND NUCLEAR SERVICE COOLING WATER PUMPS 220 KV SwiTCHY ARO 2'8 KV H
ST A RTUP TR ANS. N O. 2 t_ajj_;
221 - 4.26-4.36 KV ry, 1 ir1 -
1 i TAP-230 KV Y
Z H WINDING - 42.6 MV A Y WINDING - 24 MVA TO 4160 V BUSSES 4E1 & *E2 Z WINDING - 22.6 MV A TO 4160 V BUS 40 TO 4160 V BUS 4C 3807V 38 2V ESF SYSTETA 416C V BUS 43 4160V BUS 4A 3803V 38ilV
(.91 0F 4150 V)
(.92 of 4160 VI 3800 V STATION SERV.
STATION SERV. DN T R ANS. X438 TRANS X43A WW 4160 - 480 V MOTOR MOTOR ( 807 V 4160 480 V
.92 0F 4160 VI T AP - 4260 V TAP - 4260 V 1.12 MV A 1.12 MV A 480 V BUS 3B 480 V BUS 3A 372 V i
l 377 V
(.810F 460 V)
L82 0F 460 VI 351V
(.76 CF 460 V)
(STARTING)
MOTOR l
78 0F 460V)
(STARTING) 480 V MCC 281 480 V MCC 2A1 373 V
~
376 V
(.810F 460 VI
(.82 0F 460 V)
MOTOR MOTOR (79 0F 460 VI 365V
(.79 0F 460 VI NOTES.
- 1. UOTORS CONNECTED TO A 4160V SUS ARE RATE 0 4160V. THE 480V SYSTEM MOTOR $ ARE RATE 0 460V.
- 2. THE MOTORS SHOWN ARE ELECTRICALLY THE MOST OISTANT MOTORS
" 3 FROM THE BUSSES SHOWN. ALL OTHER MOTORS ON THESE BUSSES WILL OPERATE AT A VOLTAGE BETWEEN THAT OF THE BUS. AND THAT 0F THE MOST OISTANT MOTOR.
g 1
Sketch 19 CASE 3 BUS 4A & 48 ON STARTUP TRANSFORMER NO.2 VOLTAGE DURING BLOCK LOADING OF EMERGENCY BUSSES (BLOCK 3., T= 26 SEC.)
START THE NUCLEAR SERV RAW WATE'A PUMPS AND THE DIESEL-GENERATOP ROOH '.'dNT FANS 227 FV SWITCHY A%
218 K V H
STARTUP TRANS NO. 2 t
i.m i;
221 - 4.36-4.36 KV ry y,
,y
,-3 TAP - 23C G Y
Z H WINDING - 42.6 MVA TO 4160 V BUSSES 4E1 & 4E2 Y WINDING - 24 MV A Z WINDING - 22.5 MV A TO 4160 V BUS 40 TO 4160 V BUS AC 3755V 3771v ESF SYSTEM 4160 V BUS 48 4160V sus'4A 376tv 3769V
(.90 0F 4160 V) 3728 y
(. 910F 4160 vi
(STARTING)
STATION SERV. NN STATION SERV.
TRANSX43A
,73 6 V 4160 - 480 V MOTOR P
4160 - 480 V MOTOR ("'90 0F 4160 VI TAP - 4260 V TAP - 4260 V IdTARTING) 1.12 MV A 1.12 MV A 480 V $US 28 480 V BUS 3A (395 v) 391V 379 V
(.85 0F 460 VI
(.86 0F 460 VI (STARTING)
MOTOR (3 82 0F 460 VI 480 V MCC 281 480 V MCC 2 A1 393 V 390 V
(.85 0F 460 VI
(.85 Or 460 VI is MOTOR {g.,tv OF 460 VI 283 V (563 0F 46: VI "UT E3'
- 1. MOTORS CONNECTED TO A 4160V BUS ARE RATED 4160V. THE 480V SYSTEM MOTORS ARE R AYE0 460v.
2 THE MOTO RS SHOWN ARE ELECTRICALLY THE MOST DISTANT MOTORS FROM THE BUSSES SHOWN. ALL OTHER MOTORS ON THESE tuSSES WILL OPER AT6 AT A VOLTAGE BETWEEN THAT OF THE BUS, AND THAT OF TME MOST DISTANT MOTOR.
I.3-32
Sketch 20 CASE 3 SUS 4A & 4B ON STARTUP TRANSFORMER NO. 2 VOLTAGE ~00 RING BLOCK LO ADING OF EMERGENCY SUSSES (SLOCK 4., T = _36; SEC.)
START AUX FEED WATER PUMPS 229 KV SWITCHY ARO 218 KV w
j STARTUP TRANS ha. 2 221 - 4.36-4.36 KV rY VirY vi TAP-230 KV Y
Z H WIN 0!NG - 42.6 MVA TO 4160 V BUSSES 4E1 & 4E2 Y WINDING - 24 MV A Z WINDING - 22.6 M ' A TO 4160 V BUS AD TO 4160 V BUS AC 3626 V 3634 V ESF SYSTEM 4160 V sus 4s 4160v ses4A 3619 V 3568 V 3631 V
(. 87 0F 4160 V)
(.86 OF 4160 V)
(.67 0F 4160 V)
(STARTING)
STATION SE RV.
STATION SERV.
MOTOR (3552 V 4160 - 480 v MOTOR TP 4160 - 480 V
.85 0F 4160 V)
TAP - 4260 V TAP - 4260 V (STAR TING) 1.12 MV A 1.12 MV A 440 V BUS 9 480 V BUS 3A 393 V 390V
(.96 0F 460 v)
(.85 0F 460 VI
(.83 OF 460 V)
MOTORfg8 MOTOR 480 V MCC 281 480 V MCC 2A1 388 V 392 V
(.84 0F 440 VI
(.85 0F 460 vi MOTOR MOTOR OF 440 VI 381V NOTES;
( 83 0F 460 VI
- 1. MOTJRS CONNECTED TO A 4160V SUS ARE RATE 0 4160V. THE 480V SY', TEM MOTORS ARE RATED 440v.
- 2. YHE MOTORS SHOWN ARE ELECTRICALLY THE MOST OISTANT MOTORS FROM THE BUSSES SHOWN. ALL OTHER MOTORS ON T'SE BUSSES WILL OPERATE AT A VOLTAGE BETWEEN THAT OF TH' ads, ANO THAT OF THE MOST OtSTANT MOTOR.
y.
Skatch 21 CASE 3 BUS 4A & 4B OtJ STARTUP TRANSFORMER NO. 2 VOLTAGE DURING BLOCK LOADING OF EMERGENCY SUSSES (BLOCK 5., T = 300 SEC.)
START REACTOR BUILDING SPRAY PUMP 22Q KV SwlTCHY ARD 218r(V
[A; STARTUP TRANS NO. 2 tj 221 - 4.36 4.36 KV rT 7 3 rT 1-i 1
TAP - 230 KV Y
Z H WINDING - 42.6 MV A Y W!NotNG - 24 MVA TO 4160 V BUSSES 4E1 & 4E2 2 WINDING - 22.6 MV A T0 4160 V BUS 40 T0 4160 V BUS 4C 3775 V 378iV ESF SYSTEM
'.160 V BUS 48 4160V BUS 4A
~
3771 V 3761V 3780 V
(.91 0 F 4160 V)
(.910F 4160 VI
(.90 OF 4160 V)
STATION SERV.
STATION SE RV.
T R ANS. X438 bb TRAN3 X43A W O_'
3770V 4160 - 480 v MOTOR 4160 - 480 V MOTOR
( 910F 4160 VI TAP - 4260 V T AP - 4260 V 1.12 MV A 1.12 MV A 480 V BUS 3B 480 V BUS 3A 374 V 377V
(. 810F 460 VI 361V
(.62 0F 460 V)
(.79 CF 460 V)
(STARTING) 65 OTOR
(.81 0F 460 V)
(.82 0F 460 VI OTOR MOTOR (
OF 460 VI 365V
(.79 0F 460 VI NOTES:
- 1. MOTORS CONNECTED TO A 4160V BUS ARE RATED 4160V. THE 480V SYSTEM MOTORS ARE R ATED 460V.
- 2. THE MOTORS SHOWN ARE ELECTRICALLY THE MOST DISTANT MOTORS FROM THE BUSSES SHOWN. ALL OTHER MOTORS ON THESE BUSSES WILL OPERATE AT A VOLTAGE BETWEEN THAT OF THE BUS, AND THAT OF THE MOST OISTANT MOTOR.
I.3-34
Sketch 22 CASE 3 SUS 4A & 43 CN STARTUP TRANSFORMER NO. 2 YOLTAGE DURING START OF CONDENSATE PUMP
)
228 KV SWITCHY ARD 215 < <
L4 Loi; STARTUP TRANS. NC 2 221 - 4.36-4.36 KV cc :n rf c,
TAP - 230 KV y
7 H WINDING - 42.6 WVA Y WINDING - 24 WV A TO 4160 V BUSSES 4Et & 4E2 Z Wf NOING - 22.6 WV A TO 4160 V BUS 40 TO 4160 V Bus 4C 3524 V 3536 v ESF SYSTEM 4160 V BUS 48 416CV BU34A 3521V 3536 V
( 85 0F 4160 V1 33gg y
(.65 0F 4160 VI
(.64 CF 4!60 V)
STATION SERV.
STAT 10N SERV.
TR ANS. X438 U"U TRANS x43A 4160 - 480 V WOTOR WOTOR (3522 V 4160 - 480 V
.65 0F 4160 V).
tap. 4260 V TAP 4260 V 1.12 W V A 1.12 WV A 480 V BUS 3B 480 V BUS 3A 373 V 37 ' V
(.810F 460 V) i
(.810F460VI i
40 TOR WOTOR p
365V
(.79 0F 460V1 480 V WC 2B1 480 V WCC 2A1 372 V 372 V
(.810F 460 V)
(.Sl0F46;VI 2"9 V MOTOR WOTOR {7S OF 460 VI u5v (y9 0F 460VI ES;
- 1. WOTORS CONNECTED TO A 4160v BUS ARE RATED 4160V. THE 480V SYSTEW WOTORS ARE RATE 0 460V.
- 2. THE WOTORS SHOWN ARE ELECTRICALLY THE WCST DISTANT WOTORS FROM THE BUSSES SHOWN. ALL OTHER WOTORS ON TkISE BUSSES wtLL OPE R ATE AT A VOLTAGE BETWEEN THAT OF THE BUS. AND THAT OF THE WOST DIST ANT WOTOR.
I.B-35
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b ENCLOSURE I PART C 1
Evaluation of the Rancho Seco Offsite Power System for Compliance to General Design Criterion 17 I
(Refer to-NRC Letter William Gammill to Power Reactor Licensees Dated August 8, 1979)
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The NRC's August 8, 1979, letter'to alb Reactor Licensees (except Humbolt Bay) requested the District "To review the electric power systems of your nuclear station to determine if there are any events or ccaditions which could result in the simulganeous or consequential loss of both required circuits to the offsite network to determine if any potential exists for violation of GDC 17 in this regard."
The District has completed a review of the electrical power system for Rancho Seco and has determined that the District's electrical power sapply system is in compliance with GDC-17.
The basis for this cona clusi,n is contained in what follows.
The power distribution system from the transmission network to the onsite safety related electrical distribution system consists of:
a.
Five everhead lines b.
Start-up transformers #1 and #2 and the nuclear service trans fo rme rs.
c.
Bus duct from the start-up transformers to the onsite safety related electrical distribution system.
d.
Protective relays, circuit breakers, control panels, batte-ries, and power and control cables associated with the operation of the distribution system.
The following assumptions were made by the District in determining events which could result in simultaneous or consequential loss of both required circuits.
(For a one line diagram of the Rancho Seco distribution system refer to Sketch 1.)
All switchyard breakers are closed and in service, a.
b.
All five lines that connect the switchyard to the transmission system are in service.
Safety Bus 4A is connected to start-up transformer #1.
c.
d.
Safety Bus 4B is connected to start-up transformer #2.
Only a single event or failure is assumed to occur unless e.
it could be demonstrated that the single event could lead to multiple failures.
Based on the following assumptions, the District has analyz s' the following events to determine if they could cause loss of both required CirCU ts.
I.C-1 n.-
e FIRE It is possible for a single fire either in a control cabinet, cable tray or conduit to involve the control circuits for all the circuit breakers required for both offsite sources. and cause the circuit breakers to trip. However, this loss of power would only be temporary since the required circuit breakers can be quickly closed manually without any elsc-trical power.
The District has minimized to the extent pracLical the likelihood of this event by:
1.
Using flame retardant cable for all cable between the plant and switchyard.
2.
Installing a fire detection and suppression system in the plant and switchyard where the circuits of concern are routed.
3 Providing a manual method of choosing the circuit breakers.
Therefore, this event is not a violation or potential violation of GDC-17.
SEISMIC EVENT A design basis earthquake may cause the loss of both offsite sources. However, the District has designed and located equipment so as to minimize to the extent practical the likelihood of loss of both required circuits during a seismic event by including a seismic load in the design of supports for equipment required to be in service te provide offsite power. Therefore, loss of both required offsite power sources during an earthquake is not a violation or potential violation of GDC-17.
RANDOM SINGLE FAILLTES The District has analyzed the power distribution system from the j
transmission system to the onsite safety electrical distribution system for single failures that can cause loss of both required offsite circuits. The l
review indicated that there are no single failures that can cause the loss l
of both required offsite sources. This analysis included the following items.
a.
Short circuits b.
Breaker failures I
c.
Switchyard battery failure d.
Relay failures l
e.
Transformer failures I
f f.
Lightning strikes l
I i
I.C-2 I
l
4 I
TOWER FAILURES The District has analyzed the transmission system for compliance with GDC-17 and determined that there is no single tower failure that could
.ause the loss of all offsite power. Therefore, failure of a transmission tewer is not a violation or potential violation of GDC-17.
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Enclosure II SACRAMENTO MUNICIPAL UTILITY DISTRICT RANCHO SECO NUCLEAR GENERATING ST/. TION, UNIT NO. I RESPONSE TO:
NUCLEAR REGULATORY COMMISSION REQUEST FOR INFORMATION REGARDING ENCLOSURE 1 0F NRC TO SMUD LETTER DATED JUNE 3, 1977 TITLED SAFETY EVALUATION AND STATEMENT OF STAFF POSITIONS RELATIVE TO THE EMERGENCY POWER SYSTEMS FOR OPERATING REACTORS I
I I
Issued: July 19, 1977 Revision 1: August 1, 1980 Revision 2: September 22, 1980 i
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Listed below is a response to each position listed in Enclosure 1
" Safety Evaluation and Statement of Staff Positions Relative to the Emergency Power Systems for Operating Reactors" of NRC's Robert W. Reid to J. J.
Mattimore, letter dated June 3, 1977.
POSITION 1:
SECOND LEVEL UNDER0 ROVER VOLTAGE PROTECTION WITH A TIME DELAY We require that a second level of voltage protection for the onsite power system be provided and that this second level of voltage protection shall satisfy the following criteria.
a)
The selection of voltage and time set points shall be determined from an analysis of the voltage requirement.s of the safety-related loads at all onstte system distribution levels; b)
The voltage protection shall include coincidence logic to preclude spurious trips of the offsite power sor.rce; j
c)
The time delay selected shall be based on the folleving conditions:
(1) The allowable time delay, inciuding nargin, shall not exceed the maximum time delay that is assumed in the FSAR accident analyses; (2) The time delay shall minimize the effect of short duration distribances from reducing the availability of the offsite power source (s); and (3) The allowable time duration of a degraded voltage condition at all distri.bution system levels shall not result in failure of safety systems or components; d)
The voltage monitors shall automatically initiate the disconnection of offsite power sources whenever the voltage set point and time delay limits have been exceede e)
The voltage monitors shall be designed to satisfy the requirements of IEEE Std. 279-1971, " Criteria for Protection Systems for Nuclear Power Generating Stations"; and f)
The Technical Specification shall include limiting condtions for operation, surveillance requirements, trip set points with minimum and maximum limits, and allowable values for the second-level voltage protection monitors.
RESPONSE TO POSITION 1 The recond level of voltage p otection for the onsite power z
system is not necessary since equivalent protection is afforded by a single inverse time-undervoltage relay type.
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b a)
The selection of voltage and time settings was determined by analysis of the voltage requirements of the safety-related loads. The undervoltage relay settings are analyzed in the response to Guideline #10 of Enclosure I.
The overvoltage relay settings are analyzed in the response to Guideline #1 of Enclosure I.
b)
A scheme incorpcrating coincidence logic is proposed to The preclude spurious trips of tae offsite power system.
circuit proposed is shown in Figure 1.
Three potential transformers will be used to monitor the bus voltage. Each potential transformer will monitor a different line-to-line voltage. Connected to the secondary of each potential transformer (PT) will be an undervoltage ::elay, overvoltage relay and a voltmeter.
The contacts from the undervoltage and overvol'tage relays are connected such that if either relay is removed, an alarm will be received in the control room on the plant annunciator and plant computer. A normally-closed contact from the overvoltage relay and a normally-opened contact from the undervoltage relay on the same PT are connected in series to operate an auxiliary relay (4AUL1, 4AUL2 and 4AUL3). The auxiliary relays are deenergized for either an undervoltage or evervoltage condition. The contacts from the auxiliary relays are arranged in a two-out-of-three logic. This logic string is used to operate an existing time delay energize-deenergize relay (62A). A time delay close (TDC) contact from this relay is used to initiate bus' load shedding t>d diesel starting in the existing scheme.
The 62B relay is a time delay on energizing relay that prevents an accidental bus unloading when the logic circuit is initially energized. The 125V de to terminals 7 and 8 on the overvoltage and undervoltage relays is the control i
power to the relays.
c)
The time delay setting was based on thefollowing conditions:
(1) The undervolt.ge relay will trip in less than one second on a complete loss of voltage (see Figure 2).
This, combined with the 62A relay definite time delay, is appreciably less-than 5-second maximum delay shown in the FSAR. Time requirements for overvoltage trip delay are not addressed in the FSAR.
(2) The time delays selected have been analyzed to verify that short-duration disturbances caused by motor starting and short circuits will not cause inadvertent disconnec-tion of the offsite power source.
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(3) The time duration that' a-degraded voltage condition is allowed to persist before tripping of the voltage relays has been analyzed to verify that failure of safety system or components will not occur.
d)
The voltage monitors will automatically initiate the discon-nection of offsite power sources whenever the voltage set-point and time delay limits have been exceeded.
e)
The voltage monitors were designed to satisfy the requirements of IEEE 279 except independence between channels of the same train is not provided.ince the sensing and protective action functions relate o-f to that train. However, independence is provided betvr 2 redundant portions of the safety systems (i.e.: between :.ain A and Train B) in accordance with the requirements for independence established in IEEE 603.
f)
Technical Specifications will be revised to include limiting conditions for operation, surveillance requirements, trip set points with maximum and minimum limits, and allowable values.
Refer to Attachment 1 for a descriptiva of the Technical Specification modifications being considered by the District.
POSITION 2:
INTERACTION OF ONSITE POWER SOURCES WITH LOAD SHED TE/TURE Ve require that the current system designs automatically prevent load shedding of the emergency buses once the onsite sources are supplying power to all sequenced loads on the emergency buses. The design shall also include the capability of the load shedding feature to be automatically reinstated if the onsite source supply breakers are tripped. The automatic bypass and reinsta:ement feature shall be verified during the periodic test-ing identified in Position 3.
In the event an adequate basis can be provided for retaining the load shed feature when laods are energized by the onsite power system, we will require that the setpoint value in the Technical Specifications, which is currently specified as "... equal to or greater than..." be amended to specify a value having maximum and minimum limits. The licensees' bases for the setpoints and limits selected must be documented.
RESPONSE TO POSITION 2 The existing Rancho Seco design complies with this position; consequently, no changes are necessary.
The existing scheme functions as follows:
1.
After exceeding the voltage setpoint a contact of the 62A relay closes energizing a set of load shedding relays.
II-3 e
i 2.
The load shedding relays perform the following functions:
A.
Trip the normal offsite supply breaker to the safety features 4160 volt buses.
B.
Trip the load breakers on the 4160 volt buses.
C.
Set up the load sequencing timing circuit.
D.
Start the emergency diesel generators.
3.
When the diesel driven generator reaches the required voltage, its circuit breaker will automatically close connecting it to the 4160 volt bus, and the step loading sequence will automatically commence if a safety features actuation signal exists.
4.
An auxiliary 'b" contact from the generator circuit breaker opens to disable the load shedding feature of the circuit.
Consequently, the voltage sensing relay cannot re-initiate the load shedding feature of the scheme so long as the generator circuit breaker remains closed.
5.
Should the generator circuit breaker be opened for any reason the load shedding and loading sequences would be re-initiated as described in Items 2 and 3 above.
POSITION 3: ONSITE POWER SOURCE TESTING We require that the Technical Specifications include a test requirement to demonstrate the full functional operability and independence of the onsite power sources at least once per 18 months during shutdown.
The Technical Specifications shall include a requirement for tests:
(1) simulating loss of offsite power in conjunction with a safety injection actuation signal; and (2) simulating interruption and subsequent reconnec-tion of onsite power sources to their respective buses. Proper operation shall be determined by:
l a)
Verifying that one loss of offsite power the emergency buses have been de-energized and that the loads have been shed from the emergency buses in accordance with design requirements.
b)
Verifying that on loss of offsite power the diesel generators start from ambient condition on the autostart signal, the emergency buses are energized with permanently connected loads, the autoconnected emergency loads are energized l
through the load sequencer, and the system operates for five minutes while the generators are loaded with the emergency loads.
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Verifying that on interruption of the onsite sources the loads are shed from emergency buses in accordance with design requirements and that subsequence loading of the onsite sources is through the load sequencer.
RESPONSE TO POSITION 3 Refer to Attachment 1 for a description of the Technical Specifi-q cation modifications being considered by the District.
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I FIGURE 2 UNDERVOLTAGE RELAY TIME-VOLTAGE CHARACTERISTIC TRIP SETTING 0.9065 12 g
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ATTACHMENT 1
,4 ATTACHMENT 1 TECHNICAL SPECIFICATION MODIFICATIONS The modifications described herein have been drafted in response to NRC positions and guidelines. They are being considered by the District for iaclusion in the Technicel Specifications and are submitted to the NRC for preliminary review. Jpon NRC approval of the voltage protection system modifications, a proposed Technical Specification ehtoge will be submitted for NRC approval.
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ATTAC M NT 1 3.
LIMITING CONDITIONS FOR OPERATION
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3.7 AUXILIARY ELECTRICAL, SYSTEMS Specification 3.7.1 The reactor shall not be brought critical unless the following conditions are met:
Add paragraph 3.7.1 (1) as follows:
I.
The switchyard voltage is 218 kV or above.
3.7.2 The reactor shall not remain critical unless all of the following requirements are satisfied.
Add paragraph 3.7.2 (H) as follows:
H.
If the switchyard voltage is below 218 kV for less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, no corrective ac. tion is required. After 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, if the voltage has not increased above 218 kV, both diesel generators will be started, connected to the nuclear service buses, and the startup transformers removed from the nuclear service buses. Switchyard voltage above 218 kV will allow unrestricted plant operation.
Ado paragraph 3.7.4 as follows:
3.7.4 The voltage protection system trip setting shall be as stated in Table 3.7.1.
Add paragraph 3.7.5 as follows:
3.7.5 Voltage Protection System Limiting Conditions A.
Startup and operation are not permitted unless the minimum requirements and action statements of Table 3.7.5 are met.
B.
In the event the number of protective channels falls below that listed in Table 3.7.5, the plant will be brougnt to a hot shutdown within 48 haurs.
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.D ATTACHMENT 1 Bases Add the following paragraph to Bases The voltage protection system is designed to isolate the nuclear service buses from ;ue startup transformers when the bus voltage exceeds the allowable operating limits of the equipment. The allowable operating range for the 4160-V nuclear service buses is 3731 to 4626 volts and 397 to 521 volts for the 480-V nuclear service buses. This corresponds to a switchyard voltage range of 214 to 244kV. This range of switchyard voltage encompasses the normal operating range of 221 to 239kV.
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TABLE 3.7.t VOLTAGE PROTECTION SYSTEM RELAY TRIP VALUES 1
1 Trip Valig Time Delay linite rvoltage (Note 1) 2 a.
Dropout 3771 1 38V 12s i 1.73 i
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75-percent of 4160V 3120 1 31V 1.9 i G.2s i
0 1.5 1 0.2s Complete loss c.
l Overvoltage 4580 1 46V 3.0 1 0.3s l2 4
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.w' TAHI.E 3.7.5 Minimum Total Number Channels Channels Action Functional IJnit of Channels to Trip OPERABI.E (Note 1) 11ndervoltage 3/Hus 2/ Bus 2
A Overvoltage 3/Hus 2/Hus 2
A Action Statements Action A -
With the number of OPERABLE channels one less than the Total Number of Channels operation may proceed provided both of the following conditions are satisfied:
The inoperable channel is placed in the trapped condition within one hour.
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The Minimum Channels OPERABI.E requirement is met; however, one additional channel may b.
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Note 1: The above table is not applicable when the plant is in cold shutdown.
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SURVEILLANCE STANDARDS 4.1 OPERATIONAL SAFETY REVIEW TABLE 4.1-1 INSTRUMENT SURVEILLANCE REQUIREMENTS Add item 48 to Table 4.1-1.
Channel Description Check Test Calibrate Remarks 48.
Voltage Protection S
Compare voltmeter readings a.
R b.
Ove rvolt age M
R c.
Time Delay M
R S = Each Shift M = Monthly R = Once during the refueling interval 4.6 EMERGENCY POWER SYSTEM PERIODIC TESTING Specification Substitute 4.6.2 with the following:
4.6.2 During each refueling interval, a test of the diesel generators and emergency start circuits shall be performed to verify that these emergency power sources and associated equipment are operable by:
A.
Simulating a loss of offsite power in conjunction with a safety injection actuation signal, and:
1)
Verifying deenergization of the nuclear services buses and operation of the load shedding circuitry.
2)
Verifying the diesel starts from ambient condition on the auto-start signal and energizes the nuclear services buses, and by verifying proper operation of the automatic load sequencing circuitry. The diesel generators will be operated for at least 5 minutes in this cer.dition.
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Verifying that on diesel-generator trip, the load shedding circuitry operates properly and the diesel restarts on the auto-start signal, and by verifying proper operation of the automatic load sequencing circuitry. The diesel generator will be cperated for at least 5 minutes in this condition.
B.
Load testing the diesel generators to SFAS capacity.
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