ML19209B600
| ML19209B600 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 10/05/1979 |
| From: | Goodwin C PORTLAND GENERAL ELECTRIC CO. |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7910100208 | |
| Download: ML19209B600 (35) | |
Text
r
=f r-c October 5, 1979 Trojan Nuclear Plant Docket 50-344 License NPF-1 Director of Nuclear Reactor Regulation AITN:
Mr. A. Schwencer, Chief Operating Reactors Branch #1 Division of Operating Reactors U.S. Nuclear Regulatory Commission Washington, D. C. 20555
Dear Sir:
In the NRR Generic Letter of August 6, 1979, you requested, as a follow-up to Information Uctice 79-04, information on the effects of potential degraded voltage conditions. The analyses provided in the attachment were performed by Bechtel Power Corporation in response to this request.
These analyses examine the potential for overloading due to transfers of either safety or nonsafety loads and the potential for starting transient problems.
In addition, vc have reviewed Section 8.0 of the FSAR for any inconsistencies with the voltage conditions or degree of reliability to be found on the grid today. This included a review of the electric power system considering the requirements of GDC-17.
This review and our conclusions involving the system as a whole are also summarized in the attachment.
Sincerely, C. Goodwin, Jr.
Assistant Vice President Thermal Plant Operation and Maintenance CG/JCL/4kk9A12 Attachment c:
Mr. Lynn Frank, Director Oh g State of Oregon Department of Energy g
126 085 Mr. R. H. Engelken, Director Nuclear Regulatory Commission Region
- TNP: GOV REL F:NRC Chrono,PGE to h1R 7 910100do 8
e t
t Guestion Are safety loads protected from undervoltage conditions without causing voltages in excess of maximum voltage ratings of safety loads and without causing spurious separations of safety buses from off-site power? Assuming all on-site sources of AC power are not available, determine if the off-site power system and on-site distribution system is of sufficient capacity and capability to automatically start as well as operate all required safety loads within their required voltage ratings in the event of (1) an antici-pated transient (such as unit trip); or (2) an accident (such as a LOCA) regardless of other actions the electric power system is designed to automatically initiate and without the need for manual shedding of any r
electric loads.
Thirteen guidelines for voltage drop calculations should be observed.
Response
Portland General Electric has analytically determined that the of f-site power system and the on-site distribution system at the Trojan Nuclear Plant is of suf ficient capacity and capability to autcmatically start as well as operate all required safety loads.
Safety loads are protected from under-voltage conditions without causing voltages in excess of maximum voltage ratings of safety loads and without causing spurious separations of safety buses from off-site power.
I.
Discussion A detailed description of the analyses follows in Section II of this response. Assumptions for the analyses are shown in Table 1-1.
Inter-pretation and implementation of the NRC guidelines is provided in Section II-C and detailed description of the various study cases is provided in Section II-D.
Criteria for minimum and maximum acceptable 4160-V and 480-V nominal safety load starting and dropout voltages are 1126 086
provided in Table 1-2.
Existing undervoltage relays (and setpoints) that could conceivably initiate spurious separation of safety buses from otf-sit power are listed in Table 1-3.
Comparison of these setpoints (Table 1-3) and the minimum and maximum voltage criteria (Table 1-2) with the results of the study cases (Table 1 through 11) supports the conclusion that the off-site power system and on-site distribution system is of sufficient capacity and capability.
I!
Descriution of Calculations A.
On site Electric System As discussed in Section 8.1.2 of the FSAR, the plant normal and preferred power supplies are obtained from trans formers connected through the isolated phase bus to the 22-kV gent.ator leads and to each switching station 230-kV bus, res pec t ively.
The unit auxiliary transformer (normal source) which is located outdoors next to the Turbine Building has a 22-kV primary and a 12.47-kV double secondary winding with each secondary winding connected t.o circuit breakers in separate 12.47-kV switchgear.
The 230- to 12.47-kV startup transformers (preferred source) are located in the switching station and are also connected to the 12.47-kV switchgear assemblies through circuit breakers.
As can be seen from FSAR Figure 8.3-1 (attached), each startup transformer is connected to only one 12.47-kV bus.
This configuration is very different from the Arkansas Nuclear One (ANO) configuration as described in the NRR letter. Trojan is a single unit plant with off-site power supplied by two startup transformers which are completely independent (except for the 230-kV grid). There is no shared autotransformer supplying these startup transformers.
There is no shared backup transformer as is the case at ANO.
I126 08/
a The 12.47-kV system is split into two load groups and supplies principally the condensate, reactor coolant and circulating water pumps and the 4.16-kV system buses through the unit substation stepdown transformers.
In addition to the unit stbstation trans-formers, the 4.16-kV Engineered Safety Features (ESP) buses each have a diesel-engine generator connected to automatically start and supply power in the event that power from the 12.47-kV bus (normal or preferred source) fails.
The 4.16-kV system is split into four buses.
Each 12.47-kV bus supplies two 4.16-kV buses (one serving redundant safety-related loads and the other nonsafety-related loads).
This division in plant load is shown on FSAR Figure 8.3-1.
The 4.16-kV buses supply both plant auxiliary and ESF 480-V buses through stepdown transformers.
The 480-V buses in turn feed the 120/208-V instrument ac system, the 120-V preferred instrument ac system and battery charders for the 125-V de system.
B.
Description of Analyses The H1 12.47-kV bus and its associated loads represent the " half" of the plant distribution system (including one redundant train of safety-related loads) with the largest connected load.
Since the redundant safety-related loads on the H1 bus are essentially identical to those on the H2 bus and since each bus is conected to its own startup transformers, computerized voltage drop calcula-tions were performed examining the voltage profile of only the H1 and associated buses under various conditions of loading and
~
grid voltage, as dictated by the 13 guidelines attached to the NRR letter.
The computer program employed for these calculations is specifi-cally designed for use in power plant voltage calculations and utilizes nodal-admittance network equations with the accelerated Gauss-Seidel iterative solution.
The program allows direct input 1126 088
of simple impedances, transformer data, cable data, running load data, starting load data and generator controlled bus data with all required conversion to a common MVA and voltage base accomplished within the program.
The output vol' ges are automatically converted to any desired voltage base.
In addition, a diagnostic check on input data is performed and error messages are printed when data inconsistencies are encountered.
C.
Compliance with Guidelines for Voltage Drop Calculations The guidelines were complied with as follows:
1.
Separate analyses should be performed assuming the pcwer sontce to safety bases is \\a) the unit auxiliary transformer;
\\b) the stattip ttansf armer; and \\c) other available connection to the of fsite netcork one by one assuming the need for electtic power is initiated by \\1) an anticipated ttansient
\\e.g., unit trip) or \\2) an accident, ahichever presents the latgest load demand situation.
Guideline 1 is met by studying the following cases:
a.
The grid at 236 kV and plant load being fed thro' the unit auxiliary transformer with:
a.1 Normal plant loads plus all DBA loads (Study Case 1).
b.
The grid at 236 kV and plant loads being fed through the startup transformer (nominal tap) with; b.1 Normal plant loads (Study Case 8).
b.2 Normal plant loads plus starting and loading of each DBA load (Study Case 3).
1126 089
b.3 Normal plant loads less the circulating water pump plus all DBA loads, plus starting and loading of the circulating water pump (Study Case 5).
c.
The grid at 240-kV and plant loads being fed through the unit auxiliary transformers with:
c.1 Normal plant loads plus all DBA loads (Study Case 2).
d.
With the grid at 240 kV and plant loads being fed through the startup transformer (nominal tap) with:
d.1 Normal plant loads (Study Case 9).
d.2 Normal planc loads plus starting and loading of each DBA load (Study Case 4).
d.3 Normal plant loads less the circulating water pump plus all DBA loads, plus starting and loading of the circulating water pump (Study Case 6).
d.4 Normal loads plus trip the reactor coolant pumps (Study Case 7).
d.5 Plant shutdown loads being fed through the startup transformer (+2.5% tap) (Study case 10).
Study Cases 7, 8, and 9 assume an anticipated transient (unit trip) has occurred.
Study Cases 1, 2, 3, 4, 5, and 6 assume an accident condition has occurred.
Study Case 10 assumes a normal plant shutdown condition and starting of all DBA loads to check for possible over-voltages.
1126 090
f 2.
For maltL-unit stations a sepatate analysis should be perfarmed for each unit assuming (1) an accident in the unit being analyzed and simultaneous shutdown of all other unit', at that station; or (2) an anticipated transient in d e utit being analyzed (e.g., unit trip) and simultaneous shutdown of all other units at that sta. tion, ahichever presents the largest load demand situation.
Guideline 2 is not applicaule to Trojan.
3.
All actions the electric power system is designed to automatically initiate should be assumed to occa.t as designed (e.g., automatic bulk or sequential bading or automa. tic Ltansfers of bulk loads from one ttansformer to another). Included should be conside.tation of starting of large non-safety loads (e.g., condensate pusnps).
Guideline 3 is satisfied by assuming that all normal plant loads except the circulating water pump are on, all DBA loads are on, and the operator starts the circulating water pump.
Starting this pump represents starting of the single largest (6500 hp) nonsafety-related load.
4.
Vanual load shedding should not be assumed.
Guideline 4 is satisfiad by not assuming any manual load shedding.
5.
For each event analyzed, the maximum load necessitated by the event and the made of operation of the plant at the time of the event should be assumed in addition to all loads caused by expected automatic actions and manual actions permitted by administrative procedures.
I126 091
All case studies involvilg DBA loads assume automatic addition of these loads via the DBA sequencer.
Since operation of the DBA sequencer will automatically load all the required safety equipment onto the bus, operator action would not contribute any additional plant loads of any significance.
The only operator action that could contribute to signifi-cantly changed loads would be manual shedding of the reactor coolant pumps following a safety injection.
Since this load shedding could conceivably result in overvoltages at the safety-related motor terminals, Study Case 7 (Table 7) was run which shows that unacceptable voltages do not occur.
6.
The voltage at he terminals of each safety load should be calculated based on the above listed conside.~ations and assumptions and based on de assumption dat de grid voltage is at the " minimum expected value". The " minimum expected value" should be selected based :n the least of the following:
1.
The minimum steady-state voltage experienced at the connection to the offsite circuit.
b.
The minimum voltage expected at the connection to n e of fsite circuit due to contingency plans which may A
't in reduced voltage from this grid.
c.
The minimum predicted grid voltage from grid stability 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 Opetation" for Technical Specifications, in i126 092
response to experiencing voltage at the connection to the of f-siti circuit which is less than the " minimum expected value." A copy of the plant procedute in this regard should be provided.
Steady-state grid voltage, as measured at the Trojan switching station, is expected to range from 236 kV to 240 kV.
Case studies developed in this analysis are based on these two extremes. To determine the minimum steady-state voltage actually experienced at the Trojan switching station, plant hourly logs were reviewed to detcrmine the lowest value recorded on any hour during the last six months of 1978.
(This period w.ss selected as most likely to yield conservative (low) voltages; Trojan was off-line daring this period.
The lowest value was found to be 235 kV.
This voltage was reached only twice. These results corroborated the general analytical assumption of 236 kV for the minimum voltage, but indicated the need for some analysis at a slightly lower value.
With respect to guideline 6(b), no contingency plans for manipulating the bulk power system in the Trojan vicinity could be identified which would result in reduced grid voltage.
As suggested by guideline 6(c), a grid stability analysis was performed using the Western Systems Coordinating Council (WSCC) load flow program, assuming Trojan to be off line as it would be following a plant trip.
Results of the study show that, at 100% PGE system load, the grid voltage will dip to 236 kV at the Trojan switching station.
This further corroborates the minimum grid voltage used in the case studies.
I126 OL93
Scenarios involving combinations of line outages and transformer failures outside of the Trojan of f-site power supply components (startup transformers, switching station and four 230-kV transmission lines) were not considered due to the historic stability exhibited by the Pacific Northwest grid system.
Since the historical minimum voltage observed during the last half of 1978 was slightly less than considered in the study case, a conservative grid system voltage of 232 kV was assumed and analyzed with acceptable results as shown on Table 11.
7.
The voltage analysis should include documentation for each condition analyzed, of the voltage at the input and output of each Ltansf armer and at each intermediate bus betaten the connection to the of fsite circuit and the terminals of each safety load.
Guideline 7 is satisfied by attached Tables 1 through 10.
8.
The analysis should document the voltage setpoint and any inherent or adjustable (with nom ~nal setting) time delay for relays uhich (1) initia,te or execute automatic ttansfer of loads from one source to another; \\2) initiate or execute automatic load shedding; or (3) initiate at execute automatic load sequencing.
Guideline 8 is satisfied by attached Table 1-3.
9.
The calculated voltages a,t the terminals of each safety load should be competed with the tequired voltage range fot normal opetation and statting of that load. Any identified inadequacies of calculated voltage require immediate remedial action and notification of NRC.
Guideline 9 is satisfied by attached Table 1-2.
I126 094
e
- 10. For each case cuatuated the calculated voltages on each safety bus should be compa,ted 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 notifica. tion of NRC.
Guideline 10 is satisfied with no inadequacies in the undervoltage relay settings found.
11.
To provide assurance that actions taken to assare adequate voltage levels for safety loads do not result in excessive voltage, assuming the maximum expected value of voltage at the connection to the of fsite 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 Y ~ shall be notified.
Guide. 9 11 is satisfied by not requiring any manual act ions to reduce load.
- 12. Voltage-time settings for undervoltage relays sha,tt be selected so as to avoid spwtious sepa,tation of safety bases from offsite power during plant startup, normat operation and shutdown due to sta,ttup and/or opera, tion of electric loads.
Guideline 12 is satisfied by confirmation chat the under-voltage relay voltage time settings will not cause spurious separation of safety buses from of fsite power under the conditions listed in the guideline.
13.
Analysi.s documenta. tion should include a statement of the assumptions for each case analyzed.
1 1 2 6 O. L, g Guideline 13 is satisfied by attached Table 1-1.
D.
Description of Study Cares The assumptions utilized for all cases are listed in Table 1-1.
A comparison between the calculated safety bus voltages and the required voltage ranges and/or the voltage time settings for existing voltage releys can be made by referring to the appli-cable case table (Tables 1 through 10) and Tables 1-2 and/or 1-3 re s pect ive ly.
The cases studied are discussed in detail below:
Case 1 - Minimum electric grid system voltage with normal plant auxiliary loads being supplied from the Unit Auxiliary Transformer during an accident condition.
At power, the normal source for plant auxiliaries (nonsafety-related and safety-related) is the main generator through the unit auxiliary transformer (UAT). After a reactor trip and a subsequent turbine trip, station power is provided through the startup transformers (SUT) from the offsite power source.
The generator has a 30-second delayed trip after a reactor trip, and during this 30-second delay, the plant auxiliaries will remain tied to the UAT.
Design Basis Accident (DBA) loads would begin sequencing on the UAT if an accident condition occurred in the 30-second time frame (
Reference:
Trojan FSAR Section 8.3).
To be conservative, this case analyzes the plant dis tribut ion supplied through the UAT with normal plant auxiliaries on and sequential loading of the DBA equipment under the minimum grid voltage condition of 236 kV.
The calculated voltages at each safety related bus, transformer, and certain motor terminal voltages are shown on Table 1.
~
l126 0'16
Case 2 - Maximum electric grid system voltage with normal plant auxiliary loads being supplied from the Unit Auxiliary Transformer during an accident condition.
This case has the same conditions as Case 1, except the electric grid system voltage is set at a maximum (240 kV).
The results are shown on Table 2.
Case 3 - Minimum electric grid system voltage with normal plant auxiliaries being supplied from the startup transformer during an accident condition.
This case analyzes the condition where the plant is at
,100% power, the unit trip occurs, and the normal plant auxiliary load is automatically transferred to the startup transformer with the DBA equipment sequentially loaded onto the startup transformer.
The grid system voltage is at the minimum level of 236 kV.
The results are shown on Table 3.
Case 4 - Maximum electric grid system vol. age with normal plant auxiliaries being supplied from the startup transformer during an accident condition.
This case has the same conditions as Case 3, except the electric grid system voltage is at the maximum value of 240 kV.
Results are shown on Table 4.
Case 5 - Minimum electric grid system voltage with normal plant auxiliary loads, all the DBA loads running, and the starting of a large nonsafety load (circulating water pump) supplied from the startup transformer.
This case follows Guideline 3 which includes the starting of a large nonsafety load under the worst conditions.
This case 1126 097
considers that the plant is at 100% power, the plant trips, and the normal plant load is automatically transferred to the SUT with the DBA loads sequentially loaded onto the SUT.
After the last DBA load has been started, the circulating water pump (6500 hp, the largest plant motor) trips and the operator restarts it.
This case represents the largest load demand of any of the cases analyzed.
The results are shown on Table 5.
Case 6 - Maximum electric grid system voltage with normal plant auxiliary loads, all the DBA loads running, and the starting of the circulating water pump supplied from the startup transformer.
This case has the same conditions as Case 5, except that the maximum grid voltage of 240 kV is utilized.
The results are shown on teh..e 6.
Case 7 - Maximum electric grid system voltage with normal plant auxiliary minus the reactor coolant pumps supplied from the starti.p transformer following a unit trip.
After the plant trip, the normal plant auxiliary loads are transferred to the SUT's.
This case considers the condition where the operator then trips the reactor coolant pumps in accordance with his administrative procedures.
It is considered in order to determine if an excessive voltage would exist on the safety equipment with the grid system voltage at maximum.
The results, shown on Table 7, indicate that the safety equipment voltages are within their allowable range as listed on Table 1-2.
I126 098
Case 8 - Minimum electric grid system voltage with plant auxiliary loads being supplied from the startup transformer folic'ing a unit trip.
This case analyzes the condition where following a plant trip, the normal plant auxiliary load is automatically transferred to the startup transformer with the grid voltage at the expected minimum of 236 kV.
No accident loads are loaded on the SUT for this case.
The results are shown on Table 8.
Case 9 - Maximum electric grid system voltage with normal plant auxiliary loads being supplied from the startup trans-formers following a unit trip.
This case is identical to Case 8, except thac the expected grid system voltage is at a maximum of 240 kV.
The results are shown on Table 9.
Case 10 - Maximum electric grid system voltage with normal plant auxiliaries during plant shutdown and being supplied from the startup transformers.
This case analyzes the situation where the plant has been brought to a cold shutdown conditica (Mode 5) and determines whether an overvoltage could exist ca the safety-related equipment.
It is assumed that the startup transformer taps are changed from normal (plant operating tap) to the +2.5 tap (plant shutdown tap) before reaching the Mode 5 condition. The voltages on the safety equipment were found to be within the required operating voltage ranges as shown on Table 10.
I126 099
4 Question Inform the NRC of any required sequential loading of any portion of the off-site power system or the on-site distribution system which is needed to assure that power provided to all safety loads is within the required voltage limits for the safety loads.
Resporise The only sequential loading required occurs automatically through the DBA sequencers. No other manual sequential loading is required.
1126 100
QuestiCn Verify by test the adequuuy af the on-site distribution of power from the off-site circuits to assure that the analyses are valid. Provide (1) a description of the method for performina this verification; and (2) the test results.
Response
The bus loads used by the camputer program for Cases 1 through 10 are based on worst case (ie, very conservative) running loads which are higher than those experienced during normal plant operation and consequently result in calculated bas voltages lower than would be expected during plant operation.
Voltage, current, and power factor measurements were taken on buses H1, Al, AS, B01, B03, B21, B23, and B25, and on the service water booster pump P-148A and P-148C feeders with the plant operational at 100% capacity.
This data was converted into actual bus loads and a special computer case was run based on supplying the plant auxiliaries through the UAT using the measured bus loads and the measured grid system voltage.
To determine the degree of conservation inherent in the calculations of Cases 1 through 10 due to the high assumed loading, a second computer case was run based on the same grid system voltage and the bus loading used in the study cases.
The measured bus voltages and the calculated bus voltages from these two caces are shown below:
Measured Calculated Bus Voltages Calculated Bus Voltages Bus Bus Voltage (Measured Bus Loading (
(Study Case Bus Loading)
Isophase 22.46 kV 22.46 kV 22.46 kV H1 12.5 12.132 12.001 H2 12.18 12.148 Al 4.14 4.116 4.052 AS 3.909 4.115 4.051 B01
.476
.476
.458 B03
.476 477
.466 B21
.477
.476
.457 B23
.477
.476
.457 14
- [) j l
B25
.477
.477
.465 I
U i
P148A
.470
.470
.451 P148C
.470
.472 460
As can be seen, based on measured bus loads, the computer model predicted the bus voltage within 5% on the 4.16-kV and 1% on the 480-V buses.
This close correlation between measured and predicted bus voltages verifies the program methodology for the ten case studies.
The conservatism in Cases 1 through 10 is documented by comparing the predicted bus voltages u:ing the study case bus loads with the measured bus voltages. Under the study case bus loading, the computer predicted bus voltages for the 480-V system were at least 2% and up to 4% lower than the measured values.
The calculated voltage on the 4160-V ESF bus is 2% lower than the measured value.
Thus, bus voltages predicted in the ten case studies are lower than actual bus voltages would be under the study conditions.
Ii26 i02
Question Revi ew the electric power systems of your nuclear station to determine if there are events or conditions which could result in simultaneous or con-sequential loss of both required circuits to the off-site network to determine if any potential exists for violation of GDC-17 in this regard.
Response
GDC-17 requires the electric power from the transmission network to the on-site electric distribution system to be supplied by two physically independent circuits designed and located so as to minimize to the extent practical the likelihood of their simultaneous failure under operating and postulated accident and environmental conditions.
Trojan is connected to the regional transmission network by two 230-kV circuits extending south to the Portland area and two 230-kV circuits extending north to the Longview area.
These two connections are on separate rights-of-way except for about one mile adjacent to the plant (where the distances between redundant towers of the physically independent circuits are greater than the tower height) and terminate in the Trojan switching station. Power is taken into the plant through two startup transformers as previously described. The four transmission lines, the Trojan switching station and the two startup transformers constitute the of f-site power supply.
The off-site power supply is divided into two indepe. dent sources: one startup trans former, one 230-kV circuit to the Portland area, and one 230-kV circuit to the Longview area.
High-speed clearing of faults and selective reclosing assure maximum avail-ability of power.
System stability studies show that no system instability will result from the loss of the Trojan plant, and that a sudden system load drop will not adversely affect the Trojan plant or the connected electric system.
As designed, the off-site power source does not violate GDC-17 requirement to provide two physically independent circuits designed and located to assure a reliable of f-site power source for the Trojan plant.
I126 103 RAY /rg/3kwSS.33Al
Table 1-1 Assumptions for the Voltage Study Cases 1.
The cases utilizing a minimum grid voltage will use the 236kV figure for the expected minimum grid voltage.
2.
The cases utilizing a maximum grid voltage will use the 240kV figure for the expected maximum grid voltage.
3.
The cases involving the startup transformer (SUT) will assume that the tap setting is on the nominal tap "C" when the plant is running.
4.
The cases involving the unit auxiliary transformer (UAT) will assume that the tap setting is on the nominal tap "D" when the plant is running.
5.
For all cases the cable impedance is only taken in account from SUT to 12kV Bus, UAT to 12kV Bus, UST to 4kV Bus, 4kV Bus to load center transformer, service water pump, charging pump, safety injection pump, containment spray pump, RHR pump, service water booster pump, containment air coolers, and diesel generator room ventilation fan.
6.
In all cases, except for case 7 and 10, it is assumed that the operator does not trip the Reactor Coolant Pumps and Heater Drain Pumps after a plant trip.
7.
The normal plant auxiliary is considered as listed below.
Ecuipment Operating Equipment Not Operating a.
Heater Drain Pump a.
Fire Pump b.
Reactor Coolant Pumps b.
CRDM (loss during plant trip) c.
Condensate Pump c.
Containment Spray Pump d.
Circulating Water Pump d.
Charging Pump' e.
Service Water Pump e.
Safety Injection Pump f.
Component Cooling Pump f.
RHR Pump g.
PDP Charging Pump g.
Room Fans for above Pumps i.
All loads on '.ue MCC's and load centers are assumed running except as listed.
8.
In cases 5 and 6, the largest non safety-related load is the Circulating Water Pump (6500 H.P.) and is not considered as part of the normal plant auxiliary load.
9.
In case 10, the shutdown condition,a survey of the loads on the MCC's, LC's, and switchgear was done to determine what was operating.
10.
In case 10, the tap setting is +2.5 on the startup trans-former during plant shutdown (Mode 5).
BQ-18 26 10/1
Table 1-2 Required Voltage Ranges for Safety Motors and Controllers
- 4.00 kV ?.ctors a.
Minimum Operating Voltage:
4.0 - 10% = 3.60 kV b.
Maximum Operating Voltage:
4.0 + 10% = 4.40 kV c.
For starting, the minimum motor terminal voltage is 70% of the rated voltage (4 kV) or 2.8 kV.
- 460 V Motors a.
Minimum Operating Voltage:
460 - 10% = 414 Volt b.
Maximum Operating Voltage:
460 + 10% = 506 Volt c.
For starting, the minimum motor terminal voltage is 70% of the rated voltage (460kV) or 322V.
480 V MCC Controllers a.
Minimum Bus Voltage for size 1, 2, 3, 4 Contactor Pickup
- 420 Volt b.
Minimum Bus Voltage for Contactor Dropout 1.
Size 1
- 178 Volt 2.
Size 2
- 178 Volt 3.
Size 3
- 221 Volt
~'
4.
Size 4
- 264 Volt y
~ <,..?',
.o it'-
t 'i:.
.,f.'
- Motor Nominal Rating
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d
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' ;e f.
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J
- i.
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Table 1-3 Exi'. ting Undervoltage Relay Setpoints for Relays on the 12kV and 4kV Buses Relay Setpoints for 12kV Bus There are three UV relays utilized on the 12.47kV buses.
1.
227-1(H1), 227-2(H2) set at 70% dropout = 8.4kV.
227-1 and 227-2 trip all 12.47kV loads (except RCP's) after 2 sec. time delay and trip the reactor for power greater than 10% with no time delay.
Setpoint was chosen such that potential transients on the grid system and voltage drop due to starting of large motors would not cause spurious trips.
2.
227-3(HI), 227-4(H2) set at 30% dropout = 3.6kV.
These undervoltage relays are connected to 12kV bus PT's to function as permissives to allow closing either the UAT or the SUT breakers on the 12kV bus in absence of synchronism.
3.
227-5(Hl), 227-6(H2) set at 10.4kV.
These relays are a permissive for fast transfer from UAT to SUT following a generator trip.
Setpoint was chosen such that the bus potential would be adequate to start ESF loads through SUT.
Relay Setpoints for the 4kV Buses There are two undervoltage relays utilized on the safety-related 4kV busas.
227-1(A1) and 227-2(A2) set at 2.56kv.
These relays are connected to 4kV safety-related bus PT's and trip all the 4kV safety bus loads, except the Class 1E load centers.
BQ-18 1126 106
Table 1 Case #: 1 Grid Voltage:
236kV Offsite Power Source:
Unit Auxiliary Transformer Load:
Normal plant auxiliaries running and DBA Loads sequentially loading (tharging Pump,. Safety Injection Pump, Containment Spray, and RHR Pump )
Bus Calculated Voltages (kV)
Designation Normal Load with NormaJ. Ioaa anc Nom.al Load,CCP and No maf U -~AnA ~
Charging Pung CCP,with Safety SIP,with Containnen. CCP, SIP, CSP, wit?
Startina Iniection Starting e~ ay Pu-o Startinc PHR Startinc 230kV Switchyard 236 236 236 236 12.47kV Bus H1 11.704 11.747 11.684 11.719 Unit Substation trans. Secorriary 3.993 4.021 3.977 4.003 4.16kV Bus Al 3.988 4.016 3.972 3.998 Servi Water Pt=p on Bus Al 3.991 Containment Spray
, Pu::p on Bus Al 3.995 Cc"ponent Cooling 3.995 Water Pump on Bus A.
Ciarging Pump on Bus Al 3.994 i SI Pumo on Bus Al 3.996 i
RHR Pu::p on Bus Al {
3.987 480V IC Bus B01 l
.437
.441
.435
.439 Contaunent Air
.432 Cooler on Bus B01 480V IC Bus B03
.445
.449
.443
.446 lContainmentAir I
i Cooler on Bus B03
{
441 480V FCC Bus B21 l
.437 8
i
- Servio3 Water Boosts r
.431 Pumo (on Bus B21) i f 480V SCC Bus B23
.437 l
t lD.G.FanonBusB23l
.432
, 480V SCC Bus B25
.446 -
Service Water Boost r Pu:Tp on Bus B25
.441 1126 lu/
Table 2 Case #:
2 Grid Voltage:
240 kV Offsite Power Source:
Unit Auxiliary Transformer Load:
Normal plant auxiliaries running and DBA Loads sequentially loading Charging Pump., Safety Injection Pump, Containment. Spray, and RHR Pump Required Voltage Ranges: See Table 1-1 Calculated Voltages (kV) cus Designation Normal Tmd with brmal Ioad and Wrmal Icad,p and,Nomal Icad and Charging Pu p IP,with Safety SIP,with Contaimenm, SIP, CSP,with l Starting rajec*ien c*,r+i m enray Pm S*,r+ina otm q*,r+4 7
?
l 230kV Switchyard 240 240 240 240 l
12.47kV Bus H1 11.933 11.977 11.913 11.951 Unit substation 4.074 4.103 4.059 4.086 trans. Secondarr i
4.16kV Bus Al 4.069 4.099 4.053 4.081 wrvice nater xtw l
cn Bus Al 4.074 l
Pump on Bus Al 4.078 Caponent (boling l
4.078 Water P9mo on Bus AJ Charging P 3 on Bus Al 4.078 SI Pung on Bus Al 4.078 PER Pump on Bus Al 4.070 i
~
400V IC Bus B01 0.447 0.451 0.445 0.449 contamment atr Cooler on Bus B01 0.442 480V If Bus B03 0.455 0.459 0.453 0.456 Contalnut iur Cooler on Bus B03 0.451 480V ECC Bus B21 0.447 Service Water Boost < r Pmp (on Bus B21) 0.441 480V'.NC Bus B23 0.447 D.G. Fan on Bus B23l 0.442 4
480V IE Bus 25 0.456 Service Water Boostct 0.451 Ptrno m g,,, ec; 1126 108
Tabic 3 Case #:
3 Grid Voltage:
236kV Offsite Power Source: Startup Transformer Load:
Normal plant auxiliaries running and DBA Loads sequentially loading (Charcjing Pump, Safety Injection Pump, Containment Spray, and RHR' Pump) r Bus Designation Calculated Voltages (kV)
Normal Irad wita Iormlj. Ioad 2:n Normal Irad Normal Icas anu Charging Pump CCP,with Safety SIP, with Co'CCP and ntaire:at. CCP, SIP, CSP, witi st rtino Iniection Starting g,ay P m Star *ino RHP Startinc p
230kV Switchyard 236 236 236 236 12.47kV Bus H1 11.555 11.602 11.534 11.570 Unit Substation trans. SeccMarv 3.939 3.969 3.923 3.949 4.16kV Bus Al 3.934 3.965 3.918 3.944 i
Service Water Ptr:p 3.937 on Bus Al l Containment Spray J lPumponBusAl 3.940 l
Ccrpenent Cooling 3.940 Water Pu:m on Busf.
f W
3.940 Bus Al l
3.941 SI Pu:m en Bus Al l
RHR Pt: p on Bus Al,
3.933 480V If Bus B01 i
0.432 t
0.431 0.434 0.429 Contal:raent Air 0.425 Cooler cn Bus B01 0.440 480V If Bus B03 0.439 0.443 0.437 Containment Air 0.435 Cooler on Bus B03 6
480V MCC Bus B21 0.430 Scrvice Water Booste r 0.424 Ptrp (en Bus B21) 480V FCC Bus B23 l,-.,
0.429 D.G.FancnBus323!
0.425 l
480V M r Bus B25
{
0.439
- ServiceWaterBoostj 0.434 r
l PLrp on Bus B25 i
II26 109
Table 4 Case #: 4 Grid Voltage:
240kV Offsite Power Source: Startuo Transformer
- Load:
Normaf plant auxiliaries running and DBA Loads sequentially loading (Chargi.ng Pump, Safety Injection Pump, Containment Spray, and RHR Pump )
Bus Calculated Voltages (kV)
Designatica No mal loac wita
- b mal load anQ Noc.al Loac,CCP and 24rmal 5 55:
Garging Pwp CCP,with Safety.
en,ay o,m Starina PHP Startina SIP,with Containmen.CCP, SIP, CSP,witl Startina Iniection Starting 23CkV Switchyard 240 240 240 240 12.47kV Bus H1 11.787 11.835 11.767 11.804 Unit Substation trans. Secondary 4.021 4.051 4.006 4.033 4.16kV Bus A1 4.316 4.047 4.000 4.028 Servi Water Pump on Bus Al 4.021 Contairment Spray 4.024 Pump cn Bus Al Cceponent Cooling Water Pu:ro on Bus A.
4.025 Charging Pmp cn Bus Al 4.024 SI Pump on Bus Al 4.025 FHR Pt.:p on Bus Al 4.017 480V IC Bus 301
,44 1
.444
.439
.442 Contal: rent Air Cooler cn Bus 301
.435 480V If Bus B03 r
.449
.452
.447
.450 Contamment Air Cooler on Bus B03
.445
'480V t{r Bus B21
.440 Service Water Boosts r Pumo (cn Bus B21)
,444 1
480V brC Bus B23
{
.440 t
D.G.FanenBusB23l
.435 i
480V drC Bus B25
,449 i Service Water Bcostt'r l Pump on Bus 325
{
,444 1126 ilC
Table 5 Case #
- 5 Grid Voltage : 236 kV Offsite Ibwer Source : Startup Transfonner Ioad
- lbcnal plant auxiliaries and DBA Icads running (Charging Pump, Safety Injection Pump, Containment Spray and RHR Pump) with the starting of large non-safety load.
Calculated Voltages (kV) l l
Bus l lbrmal loads with all l Normal loads with all Asignatien l IBA Ioads and Circulat-1 IEA Icads and G7 all I ing Water Punp Starting I running i
i 230kV Switchyard i
236.00 l
236.000 i
i 12.47kV Bus H1 1
10.072 l
11.676 I
I Unit Substation l
I trans. secondary l
3.442 l
4.022 I
i 4.16 kV Bus Al I
3.437 1
4.019 I
l Service Water l
l Pump on Bus Al 1
3.430 1
4.012 l
l Punp on Bus Al I
3.434 l
4.015 i
l Ccmponent Ccoling l
I Water Pumo on Bus Al 1
3.434 1
4.015 I
i Charging Punp On Bus Al l 3.433 l-4.015 i
SI Pump on Bus Al l
3.435 I
4.016 i
RHR Pump on Bus Al I
3.435 1
4.016 I
I 480 TC Bus B01 1
0.369 l
0.441 I
.I Containment Air l
l Cooler on Bus B01 1
0.361 1
0.431 I
i 480V IC Bus B03 1
0.379 I
0.449 i
i Containment Air l
l Cooler on Bus B03 1
0.373 1
0.443 1
1 480V MCC Bus B21 1
0.367 1
0.436 i
i Service Water Boos-l l
ter Pump (on Bus B21) 1 0.360 1
0.431 1
1 480V MCC Bus B23 1
0.367 1
0.436 l
1
~
D.G. Fan on Bus B23 1
0.?61 1
0.432 l
I 480V MCC Bus B25 1
0.378 1
0.448 l
I l126 Ill Service Water Booster l
1 Pu::p on Bus B25 l
0.372 l_
0.443
Table 6 Case #
- 6 Grid Voltage : 240 kV Offsite Power Source : Startup Transforrer Ioad
- Ibrmal pla% auxiliaries and DBA Ioads (Charging Pump, Safety Injection Pump, Containment Spray and RHR Pump) running aM Circulatirg Water Pump Startirg Calculated Voltages (kV)
I i
Bus I !brmal loads with all l tbtmal loads with all Designation l EBA Ioads aM Circulat-l EUA Ioads and gip all l ing Water Pump Starting i running i
i 230kV Switchyard I
240 1
240 l
i 12.47kV Bus H1 l
10.274 l
11.913 i
i Unit substation l
I trans. secondary l
3.515 I
4.108 1
1 4.16 kV Bus Al l
3.511 1
4.104 I
I Service Water l
i Pump on Bus Al 1
3.503 l
4.098 I
I Pump on Bus Al 1
3.507 l
4.101 1
I Crsonent Coolirg l
l W4.cer Pump on Bus Al I
3.508 1
4.101 I
i Charging Pu:@ On Bus Al I 3.507 I
4.101 i
i SI Purp on Bus Al 1
3.508 I
4.102 l
I RHR Ptmp on Bus _Al l
3.508 1
4.102 I
l 480 If Bus B01 l
.378 l
.451 I
I containment Air l
l Cooler on Bus B01 I
.371 I
.445 i
I 480V If Bus D03 l
.388 l
.459 I
l Containment Air l
l Cooler on Bus B03 1
.382 i
.454 I
l 480V MCC Bus B21 I
.377 l
.450 I
I Service Water Boos-l l
ter Pump (on Bus B21)
I
.370 l
.444 1
l 480V MCC Bus B23 i
.376 I
.450 i
i D.G. Fan on Bus B23 I
.371 I
.445 l
l 480V MCC Bus B25 l
.387 I
.459 I
I Service Water Boostec l
l Pump on Bus B25 l
.381 I
.454 1126 112
Table 7 Case #
- 7 Grid Voltage : 240 kV Offsite Ibwer Source : Startup Transformer Irad
- Normal plant auxiliaries running and Reactor Coolant Pumps tripped under no accident condition Calculated Voltages (kV)
I i
Bus l Normal loads running l
Designation I and RCP's tripped l
l l
l 1
230kV Switchyard l
240.00 l
i l
12.47kV Bus H1 1
12.292 l
l l
Unit Substation i
I trans. yecondary l
4.257 l
l l
4.16 kV Bus Al l
4.256 I
I I
l Pump on Bus Al 1
1 I
l Pump on Bus Al 1
l I
I Ccznponent Cooling l
l Water Pumo on Bus Al 1
l 1
l Charging Pump On Bus Al 1 1
I i
SI Pump on Bus Al 1
l 1
RHR Pump on Bus Al 1
1 I
I 480 If Bus B01 0.4'O I
I l
Containment Air I
l Cooler on Bus B01 l
l I
I 480V If Bus B03 1
0.477 l
l 1
Containment Air l
l Cooler on Bus B03 l
l i
1 480V MCC Bus B21 1
l I
I Service Water Bom-l I
ter Pump (on Bus B21) 1 I
l I
480V MCC Bus B23 1
1 1
i D.G. Fan on Bus B23 l
1 I
I 480V MCC Bus B25 l
1 I
I Service Water Booster l
l Pump on Bus B25 l
l 1126 113
Table 8 Case #
- 8 Grid Voltage : 236 kV Offsite Power Source : Startup Transformer Ioad
- Normal plant auxiliaries running and no DBA Icads Calculated Voltages (kV)
I Bus I Normal loads running and l Designation l
no DBA Icads l
l l
1 230kV Switchyard l
236.00 l
I i
12.47kV Bus H1 1
11.738 l
1 i
Unit Substation 1
i trans. secondary I
4.060 l
l 1
4.16 kV Bus Al l
4.058 l
l 1
l Pump on Bus Al 1
i i
l Pump on Bus Al 1
1 I
I Canponent Cooling l
I Water Pump on Bus Al l
l I
1 Charging Pump On Bus Al l l
l SI Pumo on Bus Al 1
1 I
i RHR Pump on Bus Al I
I I
480 If Bus B01 1
0.446 i
l I
Containment Air l
l Cooler on Bus B01 1
I I
I 480V IC Bus B03 1
0.454 l
l Containment Air l
l Cooler on Bus B03 1
l 1
1 480V MCC Bus B21 l
1 I
I Service Water Boos-l 1
ter Pump (on Bus B21) 1 l
I I
480V MCC Bus B23 l
l I
I D.G. Fan on Bus B23 1
I l
I 480V MCC Bus B25 l
1 I
Service Water Booster l
l Pumo on Bus B25 l
l 1126 114
Table 9 Case #
- 9 Grid Voltage : 24r kV Offsite Ibwer Source : Startup Transformer Load
- tbrmal plant auxiliaries running and no DBA Loads Calculated Voltages (kV)
I i
Bus l Normal loads running and l Designation l
no DBA Loads l
l 1
I I
230kV Switchyard l
240.00 l
l I
12.47kV Bus H1 1
11.973 l
l l
Unit Substation i
l trans. secondary l
4.144 l
l 1
4.16 kV Bus Al I
4.142 l
l 1
l Pump on Bus Al 1
1 I
l Pump on Bus Al 1
1 I
I Canponent Cooling l
l Water Pump on Bus Al 1
1 I
I Chargina Pump On Bus Al l l
l SI Pump on Bus Al 1
I l
i RHR Pump on Bus Al l
l l
l 480 If Bus B01 1
0.456 l
l Containment Air l
l Cooler on Bus B01 1
l l
l 480V If Bus B03 1
0.464 l
l l
Containment Air l
l Cooler on Bus B03 l
l 1
I 480V MCC Bus B21 1
l I
I Service Water Boos-l l
ter Pump (on Bus B21) 1 I
l i
480V MCC Bus B23 1
1 I
I D.G. Fan on Bus B23 l
1 i
l 480V MCC Bus B25 l
l 1
i Service Water Booster l
l Pump on Bus B25 l
l 1126 115
Table 10 Case #
- 10 Grid Voltage : 240 kV Offsite Ibwer Source : Star *4 Transformer Icad
- Plant shutdown auxiliaries running Calculated Voltages (kV) l Bus l Normal loads running and Designation l
no DBA Icads i
I 230kV Switchyard l
240.00 1
12.47kV Bus H1 l
12.381 i
Unit Substation I
trans. secondary I
4.317 I
4.16 kV Bus Al l
4.315 i
Pump on Bus Al 4.309 i
Contaiment Spray l
Pump on Bus Al 1
l Cmponent Cooling l
Water Pimp on Bus Al 1
Charging Pt=o On Bus Al 1 I
SI Ptmo on Bus Al 1
l RHR Puro on Bus Al l
l 480 If Bus B01 1
0.483 i
Containment Air l
Cooler on Bus B01 l
l 480V If Bus B03 1
0.491 i
Contaiment Air l
Cooler on Bus B03 1
l 480V MCC Bus B21 1
0.483 i
Service Water Boos-l ter Pump (on Bus B21) l 1
480V MCC Bus B23 1
0.483 i
D.G. Fan on Bus B23 1
1 480V MCC Bus B25 1
0.491 1
Service Water Booster i
Pump on Bus B25 1
1126 116
TABLE 11 Of fsite Power Source: Startup Transformer Load: Normal plant auxiliaries running and last DBA Load loading Bus Calculated Voltages (kV)
Designation 230 kV Switchyard 236 232 12.4 kV Bus H1 11.570 11.334 Unit Substation trans. Secondary 3.949 3.866 4.16 kV Sus Al 3.944 3.860 480V LC Bus B01 0.432 0.421 480V LC Bus B03 0.440 0.430 480V MCC Bus B21 0.430 0.421 480V MCC Bus B23 0.429 0.421 1126 117
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