ML20011D756
| ML20011D756 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 07/01/1989 |
| From: | CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | |
| Shared Package | |
| ML20011D723 | List: |
| References | |
| NUDOCS 8912280369 | |
| Download: ML20011D756 (50) | |
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TABLE OF CONTENTS i
CHAPTER 8 - ELECTRIC POWER
8.1 INTRODUCTION
i 8.1.1 0FFSITE POWER SYSTEMS 8.1.2 ONSITE AC POWER SYSTEMS 8.1.3 ONSITE DC POWER SYSTEM 8 8.2 0FFSITE POWER SYSTEMS 8.2.1 FUNCTIONAL DESIGN DESCRIPTION 8.2.1.1 138 kV Line 8.2.1.2 46 kV Line 8.2.1.3 Cenerator Feed 8.2.1.4 Station Power Voltage Regulation 8.2.2 0FFSITE POWER FREQUENCY DECAY 8.2.3 DISTRIBUTION SYSTEM VOLTAGES AND DECRADED CRID PROTECTION 8.2.3.1 Evaluation 8.2.3.2 Maximum and Minimum Voltage Analysis
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8.2.3.3 Actions to Alleviate Undervoltages
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8.2.3.4 Diesel Cenerator Operation 8.2.3.5 Degraded Crid Protection 8.2.3.6 Conclusions 8.3 ONSITE AC POWER SYSTEM 8.3.1 FUNCTIONAL DESIGN DESCRIPTION 8.3.2 2400 VAC BUS 8.3.2.1 Description l
8.3.2.2 240 VAC Switchgear Protective Relaying 8.3.3 480 VAC BUSES 8.3.3.1 Description 8.3.3.2 480 VAC Bus Protective Relaying 8.3.4 EMERGENCY DIESEL CENERATOR 8.3.4.1 Description 8.3.4.2 Operation 8.3.4.3 Instrumentation and Relaying 8.3.4.4 Diesel Engine Start Time 8.3.4.5 Testing Requirements 8.3.5 STANDBY DIESEL GENERATOR 8.3.5.1 Description and Operation 8.3.5.2 Instrumentation and Relaying (v
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HIO689-0253A-BX01 8912280369 891222
,F,'DR ADOCK 05000155 PDC
8.4 ONSITE DC POWER SYSTEM 8.4.1 STATION BATTERY SYSTEM 8.4.1.1 Function / Description 8.4.1.2 Station Battery Load Profile 8.4.1.3 Station Battery Testina Requirements 8.4.1.4 DC Power System Bus Monitoring 8.4.2 ALTERNATE SHUTDOWW BATTERY SYSTEM 8.4.2.1 Punc tion /De script ion 8.4.2.2 Alternate Shutdown Battery Load Profile 8.4.2.3 Alternate Shutdown Battery Testing Requirements 8.4.2.4 Alternate Shutdown Battery System Monitoring 8.4.3 RDS UNINTERRUPTIBLE POWER SUPPLIES 8.4.3.1 Function / Description 8.4.3.2 UPS Battery Load Profiles 8.4.3.3 UPS Battery System Testing Requirements 8.4.3.4 UPS System Bus Monitoring 8.4.4 DIESEL STARTING SYSTEMS 8.4.4.1 Function / Description 8.4.4.2 Battery Loading and Test Requirements 8.4.4.3 Diesel Starting System Monitoring 8.b ELECTRICAL PENETRATIONS O
M10689-0253A-Bx01
8.1 INTRODUCTION
8.1.1 OFFSITE POWER SYSTEM Big Rock Point utilizes a 138 kV transmission line from the Consumers Power System as the primary source of off-site power. This line also served as the feeder line to the Consumers Power System for all electrical power produced by the Big Rock Point generator. A second offsite power source, a 46 kV transmission line wa6 added in 1968 (Reference 1) to improve the availability of of f site power. The two sources are not normally simultaneously synchronized to the onsite AC system, but rather the 46 kV line is automatically transferred to the AC system upon loss of voltage from the 138 kV line. The 46 kV line is not used as a feeder line to the system for Big Rock Point generation.
Although the two transmission lines share a common "right-of way" for approximately 1/2 mile, they originate from two different points on the Consumers Power System. The 138 kV line originates from the Emmet substation and the 46 kV line f rom the Charlevoix substation.
8.1.2 ONSITE AC POWER SYSTEM The main 2400 volt station power bus can be fed from three power sourcest (1) The main generator through the #1 Station Power Transformer (2) The 138 kV line through the #1 Main Transformer and $1 Station Power Transformer (3) The 46 kV lins through the #7 Station Power Transformer 3
The voltage from any of the three sources is controlled by the station power regulator prior to feeding the 2400 VAC station power bus. The 2400 VAC bus feeds four large motors used for power cycle operation along with two 480 volt systems. The general philosophy of design of this system is to supply duplicated services from different buses, wherever possible, so that f ailure of one bus would still perfeit operation of the alternate unit. This is done primarily for continuity of plant operation and not in support of safety systems.
The emergency AC power system provides power for those services necessary to prevent serious damage or hazards to equipment and personnel in the event of loss of normal AC power. Emergency power is obtained from a diesel generator which is automatically started on loss of normal AC power.
A second diesel generator is available as a backup, but requires a manual start and breaker closure. Both units feed a single 480 volt emergency bus to supply safety loads. Other loads can be added to the emergency power by performing switching operations.
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As part of modifications completed in 1985 in compliance with 10 CFR $0 Appendix R requirements, alternate feeder circuits were installed to-safe shutdown equipment. These circuits can supply AC power directly to these loads independent of the 480 volt emergency bus.
The reactor instrumentation and protection circuits are fed from three 120 volt AC buses. Two buses are supplied from a different 480 volt system through its own motor generator set.
Each motor generator is equipped with a flywheel to sustain operation durir.g normal-power system disturbances..The third 120 VAC bus is normally supplied from the DC System through an inverter.
8.1.3 ONSITE DC POWER SYSTEMS Two 125 volt DC battery systems furnish power for normal switchgear control, turbine control, annunciators, and various emergency equipment.
Each system includes a 60 cell battery bank and associated battery charger. The original station battery system provides the power for the majority of plant loads. The second system was installed-in 1985 to provide a feeder circuit to safe shutdown equipment independent of the original station battery in compliance with 10 CFR 50 Appendix R requirements.
l Three 24 volt DC battery systems furnish the power for starting the three diesel engines onsite.
l (1) Emergency Diesel Generator 1.
l (2) Diesel Fire Pump (3) Standby Diesel Generator Four deu: tor Depressurization System uninterruptible power supplies (UPS) eh consisting of a 125 VDC battery, battery changer, and 120 VAC is o e at supply power to each channel of the RDS. UPS Battery A
.alse e polies control power for the emergency diesel generator output breaker control scheme.
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8.2 OFFSITE POWER SYSTEM-8.2.1 FUNCTIONAL DESIGN DESCRIPTION The function of the offwite power system is to provide a reliable source of AC power to support equipment operation while the generator unit is not in service. The offsite system also prnvides the capability e
to transmit the power produced at Big Rock Point to the Consumers Power grid and to the station loads during plant operation.
l Two sources of offsite power from the Consumers Power grid are supplied to the Big Rock Point substation. One is the original 138 kV feed from the Emmet substation and the second is a 46 kV feed installed in 1968 from the Charlevoix substation. Consumers Power Drawing 0740030101 shows an outline of these systems.
8.2.1.1 138 kV Line The tie to the 138 kV transmission line is controlled by a 138 kV oil circuit breaker (199). This breaker is located between the high-voltage side'of the main transformer and the transmission line exit. The-transmission line is connected to the 138 kV system at Emmet substation through an oil circuit breaker.
Isolating disconnects exist to remove the circuit breakers from service for maintenance. The 199
(N OCB has a pneumatic operating mechanism and sufficient air storage to
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provide at least five (5) operations of the OCB. Breaker control power is provided by the 125 VDC station battery and can be operated from the control room.
The No. 1 main transformer located between the 199 OCB and the 116 OCB/ Station Power Transformer No. 1 is rated at 48/64/8 HVA. High side voltage rating is 138 kV and low side 13.8 kV.
The No. I station power transformer steps down the 13.8 kV bus voltage to 2.4 kV.
This transformer is tapped off from the 13.8 kV bus between the generator oil circuit breaker (116) and the main transformer No. 1 and is rated at 6250 kVA.
The 1126 OCB controls the low side output of the No. I station power transformer to the station power regulator. The spring-operated oil circuit breaker is rated at 250 MVA and operated from the control room.
8.2.1.2 46 kV Line The 46 kV transmission tie to the Big Rock substation was installed in 1968, as reported in Reference 1, to improve the availability of an AC power source to the plant under all expected conditions.
Operating history since plant start-up through 1968, had shown that for the following reasons, AC availability had not met design
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expectations:
4 8.2-1 HIO689-0253A-BX01
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q l-(a) The turbine generator, designed to accommodate a 100% load rejection and maintain station power, was not reliable above ~40%
power.
(b) The automatic recloser on the 199 OCB was removed from Lervice following an investigation which disclosed that the turbine-generator could not handle the resultant phase shift during recloser operation, causing separation of the plant from the system during transmission line upsets. This left the single 200 kW, 480 volt diesel generator as the sole source of standby station power.
The tie to the 46 kV transmission line is through Station Power Transformer No. 7.
This 5000 kVA transformer drops down the 46 kV high side potential to the 2400 VAC required at the station power bus. Control of this source through the 7726 spring-operated oil circuit breaker rated at 250 MVA and operated from the control room.
The 46 kV line also feeds Station Power Transformer No. 77 from the low side of Station Power Transformer No. 7.
The No. 77 bank drops the voltage from 2.4 kV to 480 volts to feed the service building and annex office areas.
l 8.2.1.3 Cenerator Feed O
During plant operation with the generator online station power is fed d
through the 116 generator output breaker. The 116 is a pneumatic operated breaker with air storage capable of at least five (5) operations. The 13.8 kV breaker is rated at 1500 MVA. Breaker control power is provided by the 125 VDC station battery and can be operated from the control room. The output of the 116 breaker is connected to the No. 1 Station Power Transformer to supply station loads and the No. 1 Main Transformer for power transmission to the Consumers Power System.
8.2.1.4 Station Power Voltage Regulation The power fcom either Station Power. Transformer No. I through the 1126 OCB or No. 7 through the 7726 OCB is supplied to the 2400 VAC voltage regulator. The unit is rated at 1200 amps with a regulation range of 15%. Voltage regulation is accomplished by a load tap changer which operates over a tapped regulating auto-transformer, selecting the proper voltage tap and polarity relation to obtain the desired range of regulation. Two switches are located in the control room for regulatur control, one for " automatic" or " manual" mode and the other for " raise" or lower".
The Station Power Voltage Regulator is provided with disconnects to isolate and bypass the unit during I
plant operation.
l 8.2.2 0FFSITE POWER FREQUENCY DECAY SEP Topic VII-6, Frequency Decay (Reference 2) evaluated Big Rock Point to a frequency decay event and the effects on previous accident 8.2-2 HIO689-0253A-BX01
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analysis. Concern is that rapid frequency decay has the potential for slowing down the reactor recirculation pumps thereby reducing the coclant flow rates to levels not considered in previous analyses.
In summary, the evaluation shows that the conditions required for pump slowdown are a sustained and rapid decrease in frequency while
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maintaining bus voltage. These conditions are only realized in a highly capacitive system using large amounts of buried transmission cables. On the basis ti.at Consumers Power System does not use large amounts of buried transmission cable, the conditions necessary for an unacceptable frequency decay rate are not present, thus the staff concluded the issue to be not applicable to Big Rock Point.
8.2.3 DISTRIBUTION SYSTEM VOLTAGES AND DECRADED CRID PROTECTION Three initiatives and associated evaluations were conducted to access the adequacy the onsite distribution system in conjunction with the offsite power sources:
SEP Topic VIII-1.A " Potential Equipment Failures Associated With Degraded Grid Voltage" Multiplant Issue B-48, " Adequacy of Station Electrical Distribution System Voltages" Hultiplant Issue B-23 " Degraded Grid Protection for Class 1E Power Systems" The SEP Topic VIII-1.A was a review of evaluations for Multiplant l.
Issues B-23 and B-48 and did not result in additional analysis. The original NRC Safety Evaluation (Reference 3) was updated (Reference 4) to address all three initiatives in a single document.
The intent of the reviews was to:
(a) Determine analytically the capacity of the offsite power power system and the onsite distribution system to start automatically and to operate all required loads within their required voltage rating in the event of 1) an anticipated transient,-or 2) an accident (such as LOCA) without manual shedding of any electric l2 loads.
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(b) Determine if there are any events or conditions which could result in the simultaneous or consequential loss of both required circuits from the offsite network to the onsite electric distribution system thus violating the requirements of General Design Criteria
- CDC 17.
8.2.3.1 Evaluation Consumers Power conducted an evaluation as documented in Reference 5 w/
to examine the adequacy of the station power voltages for all possible
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8.2-3 M10689-0253A-BX01
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operating conditions. Possible steady-state overvoltages and under-I voltages have been examined for the following Plant operating scenariost (a) Base load conditions generator feed (b) LOCA conditions - 138 kV feed (c) LOCA conditions - 46 kV feed j
(d) Cold shutdown conditions - 138 kV feed (e) Cold shutdown conditions - 46 kV feed (f) Unit start-up conditions - 138 kV feed (g) Loss ot offsite power - Emergency diesel generator feed (h) Loss of offsite power - Standby diesel generator feed The voltage assumptions and equipment ratings utilized in the evaluation are summarized as follows:
(a) Turbine Generator Voltage Limits The maximum turbine generator terminal voltage assumed for this study was analytically calculated to be 14.19 kV and is based on the present maximum voltage schedule of 143 kV and a maximum unit dispatch of 63 MW and 53 Hvar (overexcited). The minimum turbine generator terminal voltage assumed for this study was analytically calculated to be 12.59 kV.
It is based on the present minimum voltage schedule of 140 kV and a maximum unit dispatch of 63 MW and 21 Hvar (underoxcited).
Although operation above the analyzed
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output (63 MW) is acceptable, excitation limits should be met.
(b) Diesel Generator Voltage Limits The maximum and minimum voltage ratings of the emergency and-standby emergency diesel generators were assumed for this study to be 15% of each diesel generater nominal voltage rating.
Therefore, the 480 V emergency diesel generator has a maximum voltage rating of 504 volts and a minimum voltage rating of 456 volts. The 460 V standby emergency diesel generator has a maximum voltage rating of 483 volts and a minimum voltage rating of 437 volts.
l (c) System Voltage Limits - General Critical to the maximum and minimum station' power voltages at the Big Rock Plant during LOCA, start-up or cold shutdown conditions are the assumed 138
'<V and 46 kV network voltages. The maximum and minimum 138 kV-and 46 kV transmission network voltages were analytically determined using a single-failure criterion (Reference l
Ceneral Design Criteria - CDC 17 and NUREC 75/087 II-1.b).
(d) System Voltage Limits - Regulator In Service The maximum 138 kV voltage at the Big Rock Point Plant with the Ib unit off line was determined to be 142 kV.
The minimum 138 kV jU voltage with the unit off line was analytically determined to be l
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131 kV and assumes the Livingston 345/138 kV transformer is out of service and that three peaker units are placed on line at Caylord or the Straits peaker and one or more Caylord peakers are on line.
The maximum 46 kV voltage with the unit off line was established by system review and calculations to be 46 kV.
The minimum voltage was analytically determined to be 42 kV.
This assumes the Big Rock to Emmet 138 kV line is out of service.
(e) System Voltage Limits - Regulator Out of Service In order to establish the maximum and minimum 138 kV voltages, a e
single failure criterion was used. Thus any single component feeding the station power supply must be considered when evaluating the maximum and minimum voltages throughout the Plant. The 2400 V voltage regulator can be bypassed and taken out of service by opening and closing available 2000 A Delta-Star disconnect switches. Once the regulator is taken out of service, it is considered a single failure. Thus, maximum and minimum 138 kV system voltages with the regulator out of service are established assuming normal-system operating conditions. The maximum 138 kV voltage with the regulator out of service is the same as with it in service and was established as outlined in Part IC to be 142 O
kV.
The minimum voltage, however, was established to be 134 kV.
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liaximum and minimum voltages for the 46 kV system were not established with the 2400 V regulator out of service since transfer to the 46 kV system would represent a double contingency (2400 V regulator out of service and loss of the 138 kV Emmet-Big Rock feed).
l (f) Station Power Equipment - Assumed Voltage Ratings and Limitations l
The following voltage limits were assumed for the station power equipment at the Big Rock Point Plant:
Hotors - 1 10% of nominal voltage.
The most limiting minimum equipment voltages occur on the 120 V I&C power supplies which have the following voltage ratings as seen at 480 V HCC lAt i
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HIO689-0253A-BX01
O Power Supply Bus 1A Voltage Limit Max Min ES8512A 513 V 432 V ES8512B 513 V 432 V ES3171 512 V 420 V ES2165 525 V 431 V ES2160
$13 V 421 V ES2162 513 V 421 V ES2161 510 V 418 V ES2163 510 V 418 V In addition to these equipment voltage limits, the 2400 V undervoltage relays drop out at 89% of nominal and trip the 2400 V bus af ter a ten second time delay transferring station power. loads to the emergency diesel generator.. This places an additional limitation on the acceptable station power voltage as seen at the 2400 V bus. This system is further discussed in Section 8.2.3.5 of this chapter, 8.2.3.2 Maximum and Minimum Steady-State Station Power Voltages During Various Operational Conditions (Initial Evaluation)
(a) Base Load Conditions - Generator Feed l/}
No overvoltages occur with or without the 2400 V regulator in
(,,f service for present maximum generator voltage conditions of 14.19 kV.
No undervoltages on station power equipment occur during present minimum generator voltage conditions of 12.59 kV l
with the 2400 V regulator in service. However, with the 2400 V
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regulator out of service and the minimum generator voltage of -
L 12.59 kV, the voltage or. MCC 1A drops to 413 V which is below the minimum voltage ratings of the I&C power supplies ' summarized in Part IF of this report.
In addition to these I&C power supplies, the battery chargers fed from MCC 2A will be subjected to a 413 V voltage which is 4.3% below their minimum 90% rating. Motors rsted 460 V will also be subjected to slight undervoltages throughout the Plant (Class 1E motors,.however, are rated 440 V and will not be subjected to undervoltaged conditions).
(b) LOCA Conditions - 138 kV Feed No overvoltages occur with or without the 2400 V regulator in service during LOCA conditions for maximum system voltage conditions-of 142 kV (1.029 pu).
Undervoltages will occur with the 2400 V regulator in service and a minimum 138 kV voltage of 131 kV on c11'460 V rated motors, all I&C power supplies fed from MCC 1A and the battery chargers fed from MCC 2A, In addition to these undervoltages, the minimum required pickup voltages on 480 V AC Contactors (assuming manufacturer recommended ratings) fed from l
MCCs 1A, IF, 10, ID, IE, IP and 2B are below 85% and are considered l (f-m marginal. Undervoltages will also occur with the.2400 V regulator
' - 's out of service and a minimum 138 kV of 134 kV on all 460 V and 8.2-6 MIO689-0253A-BX01
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O 440 V motors, all 160 power supplies fed from MCC 1A and the battery chargers fed from MCC 2A.
In addition, 480 V AC Contactor voltages on all HCCs are below 85% and may not pick up.
1 (c) LOCA Conditions - 46 kV Feed No overvoltages occur with the 2400 V regulator in service during a LOCA for the maximum 46 kV voltage of 46 kV.
A slight undervoltage occurs on I&C Power Supply ES2108 with the regulator in service I
and a minimum 46 kV voltage of 42 kV.
(d) Cold Shutdown Conditions - 138 kV Feed No overvoltages occur with or without the 2400 V regulator in service during cold shutdown-conditions for maximum system-voltage conditions of 142 kV.
No undervoltages on station power equipment occur during cold shutdown with the 2400 V regulator in service and a minimum system voltage of 131 kV.
However, with.
the 2400 V regulator out of service and a minimum system _ voltage of 134 kV, undervoltages will occur on I&C Power Supplies ES8512A, ES8512B, ES2165 and ES2108. The battery chargers fed from Bus 2A will also be undervoltaged 1.4% below their minimum 90% rating.
(e) Cold Shutdown Conditions - 46 kV Feed No overvoltages occur with the 2400 V regulator in service during cold shutdown conditions for a maximum 46 kV bus voltage of 46 l-kV.
No undervoltages occur with the 2400 V regulator in service I
and a minimum 46 kV voltage of 42 kV.
(f) Unit St rt-Up Conditions - 138 kV Feed i
Steady-state maximum and minimum station power. voltages were not examined during unit start-up condition since maximum steady-state voltages occur during cold shutdown conditions (minimum Plant load) and minimum steady-state voltages occur during LOCA conditions (maximum Plant load).
8.2.3.3 Actions Taken To Alleviate Undervoltages i
In order to alleviate the undervoltage conditions identified in 8.2.3.2, the following actions were completedt (1) The main transformer tap was changed from the 145/13.5 kV tap to the 140/13.5 kV tap.-
(2) The No. 11 Station Power Transformer tap was changed from the 2400/480 V tap to the 2340/480 V tap.
(3) The No. 22 Station Power Transformer tap was changed from the
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2400/480 V tap to the 2340/480 V tap.
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Setting the 2400/480 V station power banks on the 2280 V (-5%) tap-results in excessively high voltages on 440 V motors during base load conditions and cold shutdown conditions (light station power loads) with or without the regulator in service.- Setting the main transformer on the 135/13.5 kV tap position results in severe generator Hvar restrictions while operating in the overexcited mode.
It:was found, however, that the combination of changing the main transformer to the 140/13.5 kV tap and the 2400/480 V transformers to the 2340/480 V tap t
would alleviate undervoltaged conditions for all Plant operating conditions with the regulator in service and a degraded 138 kV system voltage of 131 kV.
Table 8-1 summarizes the undervoltage problems identified in 8.2.3.2 and the resulting problems from tap changes to the No. 11 and No. 22 station power transformers and main transformer.
The tap changes, however, did not completely eliminate the UV condition at the input of the battery chargers or at the input of the I&C power supplies. Additional analysis showed that the minimum voltage at the input of the battery chargers (at bus 2A) in this condition (with the tap changes made) was 430 V, leaving an UV condition of only 0.3%
which was considered insignificant.
It should be noted that the battery charger manufacturer states that the chargers will provide rated output given input voltages within 10% of its rating.
The UV condition at the input of the 160 power supplies was also q
determined to be insignificant. The minimum voltage at the input of
< y the power supplies was 423 V after the taps had been changed. To be I
conservative, additional analysis was performed on the power supply with the highest minimum voltage rating. The analysis was performed on power supply ES-8512B which has a minimum rating 432 V.
The additional power supply analysis proved that given an input-of 423 V at ES-8512B, the loop transmitter output would be insignificantly affected and would continue to maintain an output current proportional to its pressure input.
From the above information, it can be seen that there are no significant undervoltages present with the.'400 V voltage-regulator out of service.
Changing the main transformer tap to the 140/13.5 kV position does affect turbine generator operation, which now limits the generator to a 40 Hvar' net output (overexcited) due to the' generator voltage restriction of 14.5 kV.
The 40 Mvar net capability should'be sufficient during peak system conditions and the present maximum voltage schedule of 143 kV.
Generator terminal voltages will be improved in the underexcited mode for the minimum voltage schedule of 140 kV.
Final maximum and minimum generator terminal voltages are expected to be 14.5 and 13.1 kV with the lower tap setting.
Table 8-2 summarizes the expected steady-state station power. voltages with the tap changes above. Bus voltages are expected to approach (n) 489 volts during cold shutdown conditions without the voltage regulator
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in service and a maximum 138 kV line voltage of 142 kV.
Actual 440 V 8.2-8 MIO689-0253A-BX01
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motor terminal voltages, however, will be below their maximum 110%
voltage ratings due to_ motor feeder cable voltage drops not indicated in Table 8-2.
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8.2.3.4 Diesel Cenerator Operation Essential station power power loads are maintained by either the 480 V, 250 kVA emergency diesel generator or the recently installed 460 V, 312 kVA standby emergency diesel generator upon loss of offsite power. Sequencing of essential station power loads onto the emergency diesel generator, following loss of offsite power, and are summarized in Table 8-3.
Maximum equipment voltages occur during the first 1/2 hour (minimum loading conditions). Minimum equipment voltages occur after all loads are sequenced on line including-the 100 hp fire pump (maximum loading conditions).
8.2.3.4.1 Emergency Diesel Generator - Loss of Offsite Power The 480 V, 250 kVA emergency diesel generator is connected directly to 480 V Bus 2B via 300 feet of 350 kemil cable. The current range of acceptable operating generator terminal voltages is 480-490 volts.
Load flow cases were run at both 480 V and 490 V and minir am loading conditions as summarized in Table 8-4.
Overvoltages occur on several 440 V motors with an operating voltage of 490 volts while no over-O voltages occur with the 480 V operating voltage. Therefore, the-V diesel generator voltage during loss of offsite power should be 480 V to avoid overvoltages on 440 V motors during minimum diesel generator loading conditions.
Load flow cases were run at the minimum acceptable 480 V operating voltage and maximum diesel generator loading conditions. Total connected station power loads will approach 314 kVA. Approximately 21.6 kVA, however, is considered intermittent load and is not included in the steady-state continuous loading. These loads include the RDS-UPS supplies, station battery chargers, personnel lock and equipment lock. Thus, the resultant-diesel generator load will be 292 kVA. An additional 38 kVA of load can be removed if the loading of the diesel, which is closely monitored during Plant emergency conditions, approaches the maximum 275 kVA rating. Thus, the 250 kVA diesel generator has adequate kVA capacity to maintain the unit in a safe shutdown condition. Table 8-4 summarizes the minimum station power voltages with a maximum diesel generator loading of 260 kVA and a minimum operating voltage of 480 V.
As can be seen, all operating voltages are adequate. Surveillance tests include a voltage requirement of 485 V (+0, -10V) for loaded conditions.
8.2.3.4.2 Standby Diesel Cenerator - Loss of Offsite Power The 460 V, 312 kVA standby diesel generator is connected to 480.V Bus 2B as indicated in Figure 6.
The current range of acceptable operating h
generator terminal voltages is 456-504 volts. Operating at a generator V
terminal voltage of 504 volts exceeds the generator voltage rating of 8.2-9 HIO689-0253A-BX01
I 483 volts and results in overvoltages on 440 V induction motors during minimum loading conditions. Operating at a generator terminal voltage of 456 volts will result in undervoltages on I&C supplies fed from Bus 1A and battery chargers fed from Bus 2B during maximum loading conditions.
Load flow cases were run at 460 volts and 483 volts during maximum loading conditions and are summarized in Table 8-4 As can be seen in Table 8-4, even operating at 460 volts will result in undervoltages on Buses IA and 2A. Operation at 483 volts, however, results in acceptable station power voltages during maximum and minimum loading conditions. Therefore, the standby diesel generator is operated at a terminal voltage of 483 V during maximum and minimum loading conditions to provide adequate voltage profiles to essential station auxiliary equipment. Surveillance test includes a voltage requirement of 480'V (+10, -8V) for loaded conditions.
8.2.3.4.3 Starting the Largest Safety-Related Motor - Minimum Voltage The largest safety-related motor which may be required to start during minimum voltage conditions is a 440 V, 100 Hp fire pump which is fed from 480 V HCC 2B.
Typical Class 1E motors are normally capable of starting and accelerating their loads provided at least 70% of rated terminal voltage (308 volts) is available during start-up.
While voltage below 70% may not necessarily result in the motor being unable to start and accelerate its load, the 70% voltage requirement i
O can be used to indicate potential design deficiencies in Plant Electrical Systems during motor start-ups. Motor starting evaluations were performed for each operating condition assuming minimum voltage conditiuns with results shown in Table 8-5.
The starting voltage when operating from the 138 kV or 46 kV feeds are significantly above the required starting voltage. When operating from the diesel generator, motor terminal voltage can drop to 65.8%. Though below j
the assumed 70% minimum starting voltage rating of the motor, the 65.8% motor terminal voltage was determined to be sufficient to l
breakaway and accelerate the fire pump.
It was calculated that a voltage of 65% of maximum developed a starting torque of 42% full load torque (FLT), while the pump manufacturer (Worthington) indicated the Fire Pump motor required only 20% FLT. With this in mind, it is expected that the fire pump motor will start and begin rotating the pump when automatically started on the preloaded generator given 65%
voltage at the motor's input.
It is also expected that the motor will accelerate to running ~ speed as the motor voltage should return to normal within a few seconds. The starting voltage when operating from the standby diesel generator drops to 70% which is above the full load torque requirements discussed for the other diesel generator.
Emergency and standard operating procedures also require that the l.
Fire Pump is started prior to the operator manually applying load to l
the Emergency Diesel Generator following a Loss of Offsite Power.
This provides assurance that, prior to starting the Fire Pump, the maximum load on the Emergency Diesel Generator will only be that of j
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HT0689-0253A-BX01
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L the Emergency Diesel Generator'c initial step load which is auto-matica11y assumed as soon as its output breaker closes in on the emergency bus.
8.2.3.5 Degraded Crid Protection Facility Change 468 was completed in 1981 which installed a second level of undervoltage protection for the onsite power system at Big Rock Point. This undervoltage scheme consists of three undervoltage relays arranged in a three-out-of-three coincident logic scheme on i
the 2400 volt bus. These relays monitor the 2400 volt bus that feeds the safety-related bus 2B and have a setpoint of <89.25%.
These relays have a time delay of 5,0.6 second. The three out of three coincident signal is fed through a single time delay relay set at 10-(1.05) seconds. Upon actuation this logic will trip the 1136 feeder breaker to the 2400 volt bus separating the plant distribution from the offsite power system. This, in turn,_will trip the loss-of-voltage relays (27-1, 27-2) on bus 2B and initiate the diesel generator start and bus 2B loading.
The 89.25% setpoint reflected down to the 480 volt bus 2B corresponds to a voltage of 403.9 volts. This value can only occur when the generator is off-line and the plant is utilizing off-site power assuming the voltage drops through the transformers. This setpoint-reflected from 2B bus to the 100 HP electric fire pump is 397.3 V I
using a voltage drop of 1.5%.
As this is the worst case conditions and the motor is capable for 396 volts -(4401 10%), the setpoint of 89.25% is acceptable. The time delay total of 11.1 seconds is long enough to override any short, inconsequential grid disturbances and still prevent thermal damage to the safety-related motors.
8.2.3.6 Conclusions In the reports contained in Reference 4, evaluations performed by the NRC and EC&G reached the following conclusions concerning the Adequacy of Station Electric Distribution System Voltages.
The onsite distribution system in conjunction with the offsite power source are capable of providing acceptable voltages to the Class 1E equipment under worst case station loads and expected grid limits. Voltages within the operating limits of the Class 1E equipment are supplied for all projected combinations of plant load and normal offsite grid conditions.
CPCo had determined that there is no potential for either a simultaneous or a consequential loss of both offsite power sources. However, there are portions of the Big Rock Point distribution system where a single component failure can disable both sources. This condition exists because Big Rock Point was licensed prior to the promulgation of 10 CPR 50, Appendix A, O
"Ceneral Design Criteria for Nuclear Power Plants," specifically g
CDC 17.
8.2-11 MIO689-0253A-BX01
G O
O TABLE 8-1 Summary of Undervoltages and Effect of Tap Changes 4
i Description of Undervoltaged Equipment Plant Operating Condition Previous Tap Settings Present Tap Settings Base Load - Cenerator Feed, Min V, I&C Supplies, Battery Chargers, None
[
Regulator Out of Service 460 V Motors LOCA - 138 kV Feed, Min V, Regulator I&C Supplies, Battery Chargers, None in Service 460 V Motors, AC Contactors LOCA - 138 kV Feed, Min V, Regulator I&C Supplies, Battery Chargers, I&C Supplies ES8512A, ES8512B,
- Dut of Service 460 V and 440 V Motors, AC and ES2165, Battery Chargers Contactors LOCA - 46 kV Feed, Min V, Regulator None None in Service Cold Shutdown - 138 kV Feed, Min V, I6C Supplies ES8512A, ES8512B, None Regulator Out of Service and ES2165, Battery
't Chargers
- Resolution discussed in Section 8.2.3.3 l
8.2-12 MIO689-0253A-BX01
O O
O TABLE 8-2 Summary of Station Power Voltages 138 kV 46 kV Generator 2400 V 480 V 480 V 480 V 440 V Plant Operating Condition Bus Bus Terminals Swgr MCC 2A MCC 1A MCC 2B Fire P' Base Load - Generator Feed, Max V 143 kV 14.5 kV 2424 V 472 V 473 V 473 V OFF Base Load - Generator Feed, Min V 140 kV 13.1 kV 2424 V 472 V 473 V 473 V OFF LOCA - 138 kV Feed, Max V 142 kV 13.6 kV 2405 V 467 V 460 V 459 V 454 V LOCA - 138 kV Feed, Min V 131 kV 12.5 kV 2311 V* 445 V 439 V 438 V 432 V LOCA - 46 kV Feed, Max V 46 kV 2407 V 469 V 462 V 462 V 456 V LOCA - 46 kV Feed, Min V 42 kV 2340 V 455 V 447 Y 446 V 440 V Cold Shutdown - 138 kV Feed, Max V 142 kV 13.7 kV 2407 V 473 V 476 V 476 V OFF Cold Shutdown - 138 kV' Feed, Min V 131 kV 12.6 kV 2393 V 471 V 473 V-473 V OFF Cold Shutdown - 46 kV Feed, Max V 46 kV 2407 V. 473 V 476 V 476 V OFF Cold Shutdown - 46 kV Feed, Min V 42 kV 2364 V 465 V 467 V 467 V OFF Cold Shutdown - 138 kV Feed, Max V 142 kV 13.7 kV 2467 V 487 V 489 V 489 V OFF Reg O/S**
Regular on last tap
- Only case with regulator out of service t
8.2-13 MIO689-0253A-BX01
C\\
d TABLE 8-3 Summary of Station Power Loads - Loss of Offsite Power A.'
Immediate Loads Load I&C Transformer 2B 11-15 amp Cland Seal Exhauster No 2 2 amp Substation Service 6 amp RDS - UPS A 2 amp RDS - UPS B 2 amp Emergency Bearing Seal Oil Pump 11 amp Panel 2P Supply
- 12 hp + 18 kW RDS - UPS C
-2.5 amp RDS - UPS D 2.5 amp No 3 Air Compressor 22 amp Canal'Sampic Pump 1 amp Well. Ilouse Supply 18 amp B.
Additional Load Within 30 Minutes of Loss of Power Load Control Rod Drive Pump 40 hp C.
Additional Loads 1 Hour After Loss of Power Load Station Battery Cl.arger 7 amp Demineralized Water Pump 5 hp Heating Boiler Auxiliaries **
5 hp Screenhouse Heater **
24 kW D.
Additional Load 8 Hours After Loss of Power Load Emergency Lighting (from station battery) 30 amp E.
Other Loads Load Personnel Air Lock 5 amp Equipment Air Lock 6 amp Clean and dirty sumps, lighting Transformers 4 and 5, and poison tank heaters
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[b
- Cold weather only 8.2-14 HIO689-0253A-BX01
O O
O TABLE 8-4 l
Diesel Generator - Summary Max and Min Voltages Emergency Diesel Generator Standby Emergency Diesel Generator Bus or Load Max V - 490 Max V - 480*
Min V - 480*
Max V-- 483*
Min V - 483*
Min V - 460 l
MCC 1A 486 V 476 V 467 V 475 V 453 V 429 V Sub Service Control Rod No 1 MCC IC 485 V 475 V 464 V
-475 V 451 V 427 V
.i Canal Sample 485 V**
475 V 464 V 474 V 453 V 427 V MCC 1F 486 V 476 V 466 V 475 V 453 V 429 V MCC IE 486 V 476 V 466 V 475 V 452 V 428 V MCC 2A 487 V 477 V 459 V 477 V 445 V 421 V Emer Bearing P 486 V**
476 V 457 Y 475 V 444 V 420 V Air Comp No 3 486 V**
476 V 457 V 475 V 444 V 420 V Control Rod No 2 455 V 441 V A17 V MCC 2P MCC 2B 487 V 478 V-467 V 477 V.
454 V 430 Y Personnel Lock Fire PP 462 V 448 V 423 V I&C XFMR 2B 487 V 477 V 467 V 476 V 453 V 429 V Cland Seal Ex No 2 487 V**
477 V 467 V 476 V 453 V 429 V Diesel Terminals 490 V 480 V 480 V 483 V 483 V 460 V
- Off Recommended max or min voltage for corresponding diesel
- Above 110% rating.of 440 V motor 8.2-15 MIO689-0253A-BX01
TABLE 8-5 i
Summary of Voltages - Fire Pump Start-Ups Plant Operating Condition 2400 V Bus MCC 2B Fire Pump Terminals LOCA 138 kV Feed, Minimum V 2292 Volts t.06 Volts 420 Volts i
LOCA 46 kV Feed, Minimum V 2311 Volts 407 Volts 417 Volts Emergency Diesel Generator Feed 313 Volts 316 Volts
- Generator at 480 V.
Standby Diesel Generator Feed 327 Volts 336 Volts Generator at 483 V l
1 A
- Below the assumed 70% rating of the motor Resolution discussed in Section 8.2.3.4.3 i
I i
-I
'8.2-16 j
MIO689-0253A-BIO 1
8.3 ONSITE AC POWER SYSTEM 8.3.1 FUNCTIONAL DESIGN DESCRIPTION A regulated 2400 VAC supply from the station power regulator is fed to the 2400 VAC main plant bus. In addition to supplying the large plant motors, the 2400 VAC bus supplies two step-down transformers to supply the two 480 VAC-load groups (Load Center Bus 1 and Bus 2).
These two load centers feed all the 480 VAC buses in the plant except for the loads fed from station power transformer $77. Where needed the 480 VAC buses feed step-down transformers to supply panels used for lighting and low voltage loads.
Under loss of offsite power conditions, two emergency 480 VAC diesel i
generators are available at the plant site. The emergency diesel generator located at the plant screenhouse automatically starts and supplies voltage to bus 2B on loss of normal voltage. This diesel can also supply voltage to the 10 CPR 50 Appendix R safe' shutdown loads directly through switching circuits should bus 2B be unavailable.
The standby diesel generator located near the plant well house can be used to supply bus 2B.
This unit is considered a back-up and must be manually started and connected to the bus.-
Consumers Power Drawings 0740C30101, 0740C30102 Sh #1 and Sh #2 i
provide an outline of the Onsite AC Power System.
8.3.2 2400 VAC BUS 8.3.2.1 Description The 2400 VAC Bus /Switchgear is fed from the station power regulator and located in the air compressor / electrical equipment room. The switchgear housing is comprised of seven units containing a 2400 VAC Air Circuit Breaker (ACB). These ACBs can be closed or tripped from the Control Room or locally. The loads associated with the seven ACB aret i
Breaker Load 152-101
- 1 Reactor Recire Pump Motor (400 HP) l 152-102 (1199)
Station Power Transformer fil (750 KVA) 152-103
- 1 Reactor Feed Pump Motor (1500 HP) 152-104 (1136)
Incoming Feed for the Station Power Regulator 152-105 f2 Reactor Feed Pump Motor (1500 HP) 152-106 (2299)
Station Power Transformer #22 (750 KVA) 152-107
- 2 Reactor Recirc Pump Motor (400 HP) 8.3-1 M11289-0466A-Bx01
1 l
b.3.2.2 2400 VAC Switchgear Protective Relaying Relays, monitoring the 2400 volt Station Power Bus, protect various plant equipment from operating during undervoltage conditions. ~These relays also provide the necessary station power time sequencing for undervoltage load shedding and returning of associated equipment to service.
Three undervoltage relays (K-127-10XY, K-127-10YZ, K-127-ZX) in combination with time-delay relay (K-127-9) provide undervoltage protection for the 2400 VAC Bus and equipment on the 480 volt buses caused from a postulated degraded grid. This modification (Facility Change 468) is discussed in Section 8.2.3.5.
Relays K-127-1 and K-127-2 load shed the Reactor Recirculating Pumps 1 and 2, respectively, for loss of voltage conditions via tripping of
-each pumps associated ACB (ie, ACB 152-101 and 152-107, respectively).
Both of the ACBs require manual closure after a trip. Relays K-127-3 and K-127-4 load shed the Reactor Feedwater Pumps 1 and 2, respectively, for loss of voltage conditions after a time delay of 2 seconds.- Both of these ACBs require manual closure after a' trip.
Relays K-127-5 and K-127-6 load shed the Condensate Pumps 1 and 2, respectively, for loss of voltage conditions following a time delay 7-g of 2 seconds.
Both of these ACBs will automatically reclose af ter a
( j time delay of 6 seconds upon return of voltage, unless manually-tripped. Relays K-127-7 and K-127-8 load shed the Condenser Circulating Water Pumps 1 and 2, respectively, for loss of voltage conditions following a time delay of 4.5 seconds. Both ACBs will autom?tically reclose after a time delay of 2 seconds upon return of voltage, unless manually tripped.
l These relays and associated time-delay circuits were installed in 1968 as part of the 46 kV line addition. Load shedding of the-large motors is essential to prevent an overcurrent/undervoltage condition during transfer from the 138 kV to 46 kV source.
l l
The 2400 VAC switchgear bus is equipped with ground indication and alarms. The scheme provides local indication and an alarm in the control room. Actuation of the relay requires a manual reset to clear both the trip target and alarm.
8.3.3 480 VAC BUSES 8.3.3.1 Description The 480 VAC Buses at Big Rock Point are supplied by Station Power -
Transformers 11 and 22.
Transformer 11 supplies Load Center Bus 1 and Transformer 22 supplies Load Center Bus 2.
Each load center contains four 480 VAC circuit breakers each with internal overcurrent G
./
g device, with the motor control center feeder breakers having delayed
-(_/
overcurrent tripping and the motor feeder breakers having overload 8.3-2 H11289-0466A-BX01
l
[/).
\\ _-
alarms and instantaneous overcurrent tripping. These breakers can be closed or tripped from the control room or tripped ' locally at the switchgear unit. The loads associated with Load Centers 1 and 2 ares.
Load Center Bus 1 Breaker Load 52-11 Condenser Circulating Water Pump #1 (200 HP) 52-12 Condensate Pump #1 (200 HP) 52-1A MCC Bus lA 52-lF Bus IF Load Center Bus 2 Breaker Load
~
52-21 Condenser Circulating Water Pump (2 (200 HP) 52-22 Condensate Pump #2 (200 HP)
/~~N i )
52-2A MCC Bus 2A s
52-2F Bus 2F All the remaining MCCs are fed from buses lA, IF, 2A or 2F, with 1A and IP associated with Load Center Bus 1 and 2A and 2F aroociated with Load Center Bus 2.
Circuit breakers utilized within the MCCs are appropriately sized to satisfy the load current of the equipment they supply.
The remaining plant buses and 480 V panels are fed from the above four MCCs as follows:
a Bus Description Supply MCC Bus 1C Screenhouse Bus lA MCC Bus 2C Screenhouse Bus 2F MCC Bus ID Ventilation System (Turbine Bldg)
Bus IF MCC Bus 2D Ventilation System (Rx Bldg)
Bus 2F MCC Bus 1E Radwaste Bus IF Panel IP Shop Power Bus.1F.
Panel 31L Well House Bus 1C Panel 2E Utility Loads Bus 2F Panel 2P Reactor Building Bus 2A L) 8.3-3 Mil 289-0466A-BX01
The 480 VAC HCC-2B is considered the Emergency Bus at Big Rock Point 1
and is located in the Air Compressor / Electrical Equipment Room.
MCC-28 is normally fed from bus 2A but it can be fed from HCC Bus 1A, the Emergency Diesel Generator, or the Standby Diesel Generator.
Table 8-6 identifies the Bus 2B equipment and power distribution.
8.3.3.2 480 VAC Bus Protective Relaying Motor Control Center buses 1A and 2B are equipped with ground indication and alarms.
Ground indication and alarm for Bus 2A is provided through its normal connection to bus 28.
The schemes provide local indication and an alarm in the control room. Actuation of the ground relays require a manual reset to clear both the trip target and alarm.
l Loss of voltage relays are connected to selected large load circuits.
l These relays provide the necessary station power time sequencing for loss of voltage load shedding and returning of the associated equipment to service.
These relays and associated circuits were installed in 1968 as part of the 46 kV line addition to permit successful auto-transfer from the 138 kV to 46 kV source. The 480 VAC loads having this feature are as follows:
Breaker Load Description h
52-1A34 Air Compressor il 52-1A35 Air Compressor #2 52-2A35 Air Compressor #3 52-1A57 Control Rod Drive Pump fl i
52-2A58 Control Rod Drive Pump #2 52-1C15 Service Water Pump fl-52-2C15 Service Water Pump #2 52-1A41 Reactor Cooling Water Pump fl 52-2A41 Reactor Cooling Water Pump #2 52-1D15 Plant Exhaust Fan #1 52-lD26 Plant Exhaust Fan #2 52-2A25 Auxiliary Oil Pump
{
52-2A22 AC Bearing & Seal Oil Pump
- 52-2F2D Ventilation Bus 2D
- 52-1FIE Radwaste Bus IE 52-1C22 Screen Wash Pump Each of the above loads shed on loss of voltage via time delay tripping. Restarting will occur automatically upon return of voltage and after a time delay provided the associated control switches are not in the "OFF" position. Loads identified with an asterisk (*)
automatically trip on loss of voltage but do not reclose which-requires a manual reset at the motor control center.
Voltage and frequency indication of Bus 2B is also provided in the e
control room to monitor bus parameters during diesel generator operation.
8.3-4 HI1289-0466A-BX01
i SEP Topic III-10.A " Thermal-Overload Protection For Motors of Hotor-Operated Valves" was evaluated for Big Rock Point to provide assurance that the application of thermal-overload protection devices does not result in needless hindrance of the performance of valve safety functions.
In a letter (Reference 21), CPCo justified the present design for most HOVs on the basis that they are not required to function during an accident. For the remaining six (6) valves list ed below, modifications were completed via Facility Change FC-573 which permits bypassing of the thermal overloads during normal operation. Thermal overload circuits are administrative 1y controlled to only be in service during surveillance and testing.
HO-7052, HO-7062:
Emergency Condenser Inlet Valves HO-7070, HO-7071:
Back-Up Core Spray Valves HO-7066, HO-7080*: Firewater to Core Spray Heat Exchanger HO-7068:
Back-Up Containment Spray Valve This valve was added via Facility Change PC-578.
p Accordingly, the staff concluded that Big Rock Point satisfies the Q
current licensing criteria for safety-related valve functions (Reference 12).
8.3.4 EHERCENCY DIESEL CENERATOR 8.3.4.1 Description The Emergency Diesel Generator (EDC) provides three phase 480 volt ac emergency power to the 480 volt ac emergency bus, MCC-2B, to support I
essential loads in the event of a loss of off-site power.
Equipment in addition to those on the 2B bus can be powered from the emergency
)
diesel generator via selective manual breaker manipulations provided that the emergency diesel generator output' rating is not exceeded.
The emergency diesel generator output can be manually disconnected l
from the 480 volt emergency bus HCC-2B and connected to the alternate l-shutdown system should the 2B bus become inoperable due-to fire.
This transfer is accomplished via a manual transfer switch located in the emergency diesel generator room.
Provisions for full load testing of the emergency diesel generator are provided.
The diesel engine is rated at 319 horse power at 1800 rpm.
The generator has a full load rating of 200 kW (ie, 250 kVA at an 80 h) percent _ power factor) at the rated generator speed of 1800 rpm. A
's static exciter is an integral part of the generator, providing 18.5 8.3-5 HI1289-0466A-BX01
i 1
l I
amps at 125 volt de for generator excitation. The generators output i
is 480 volt ac, three phase at a frequency of 60 hertz. Generator output voltage can be adjusted via a hand rheostat located on the cast side of the exciter cabinet. The DC starting system for the diesel generator is discussed in Section 8.4.4.
Diesel Engine cooling is achieved via a closed loop cooling system and heat exchanger.. The cooling system is further discussed in Section 9.5.7.
The Diesel Fuel Oil Storage is discussed in Section 9.5.4.
The fuel oil to operate the diesel is pumped via a diesel driver pump from the storage tank. A day tank is utilized to ensure a positive source of fuel during the initial starting of the unit.
The lube oil system is self-contained using a shaft mounted pump.
Facility Change PC-544 installed in 1983 added improved ventilation to the Emergency Diesel Cenerator room to reduce room heat load during long term operation. This system is discussed in Section 9.4.5.
8.3.4.2 Operation The emergency diesel can be started manually or automatically upon loss of bus 2B voltage. Two undervoltage relays monitor voltage on bus 2B.
On loss of potential, a start permissive is received by-diesel unit. Once the diesel is started and at rated. speed, an output voltage relay initiates shedding of 2B bus by opening tie-breakers to buses IA and 2A.
Following isolation the emergency diesel ;enerator output breaker automatically closes energizing bus 28.
No load shedding and sequencing is~ utilized on the bus and all loads are simultaneously re-energized. Additional loads, other than those on bus 2B, can be added via manual breaker operations up to the rated output of 200 kW.
The starting circuit for the emergency diesel generator is shown on Consumers Power Drawings 074]C30105 and 0740030869 Sh #2.
Operation of the diesel generator in conjunction with the alternate shutdown system is discussed in Section 9.6.
SEP Topic VIII-2 evaluated. diesel generator loading against the criteria in Regulatory Guide 1.9. 'The maximum loading of the diesel-generator will occur 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> after the loss of offsite power during a LOCA. At that time, the diesel generator loading is expected to be 215.8 KVA. The maximum automatically connected load of 166.1 KVA will occur after the diesel generator has started and attained operating voltage and frequency. The diesel generator full load rating is 200 kW at 0.8 PF or 250 KVA. The maximum predicted load is 86% of the full load rating and is, therefore, in compliance with
[
}
current licensing criteria. Ilowever, the frequency decrease encountered kd' when starting the electric fire pump is less than the 95% of nominal 8.3-6 HIl289-0466A-BX01
frequency required by Paragraph C.4 of NRC Regulatory cuide 1.9 and is, therefore, not in compliance with current licensing criteria.
In responding to frequency concern (Reference 20) CPCo concluded that the output frequency (91% of nominal) during the loading transient is acceptable on the following basis.
First, it is the opinion of CPCo-that the performance of any of the loads comprising the EDC initial step load group is not degraded below their minimum requirements (which is consistent with IEEE 387-1977).
Second, current licensing criteria allows frequency excursions beyond 95% of nominal frequency in circumstances not unlike those at Big Rock Point.
Regarding the quality of the EDC output frequency during load assumption, the output frequency remains within the Regulatory Guide recommended tolerance of 95% of nominal throughout the entire transient with the exception of only 0.65 seconds. During this 0.65-second period, the frequency drops _to a minimum value of 91% and then recovers and rises above the lower 95% recommended limit.
It is the opinion of CPCo that this frequency excursion will have an insignificant ef fect on the individual loads that comprise the EDG initial step load group.
i During starting conditions, the electric fire pump alone comprises i
between 80% and 90% of the total starting kVA load imposed on the EDC. For these reasons, CPCo feels justified in stating that the Big Rock Point EDC carries only one large connected load.
Paragraph 3
5.1.2(5) of the IEEE Standard states that a diesel generator unit shall be capable of " maintaining voltage and frequency at the generator terminals within limits that will not degrade the performance of any of the loads comprising the diesel load below their minimum requirements, including the duration of transients caused by load application or removal." It is the opinion of CPCo that the Big Rock Point EDC provides an output in accordance with this criteria.
The NRC Safety Evaluation to SEP Topic VIII-2 (Reference 17) supported the conclusions discussed above as acceptable in meeting the NRC cri t eria.
8.3.4.3 Instrumentation and Relaying Temperature switches monitor the dier.el cooling system. Upon actuation of both switches exceeding a setpoint of 200 i 10*F, the engine is tripped and alarm in the control room (Facility Change FC-401).
Engine lube oil pressure is monitored by two pressure switches.
Actuation of both switches upon decreasing pressure below the setpoint of 20 psig cause an engine trip and control room alarm (Facility Change FC-403).
-i The engine is equipped with an overspeed trip switch set to actuate when the engine speed exceeds 115% of rated (2070 1 36 rpm). Actuation causes engine trip and control room alarm.
8.3-7 mil 289-0466A-Bx01
?
Three overcurrent relays monitor each phase of the generator output.
Actuation of two out of three will cause an engine trip and alarm in the control room (Facility Change PC-401).
Facility Change FC-434 added an alarm scheme to notify plant operators of conditions that prevent the diesel from starting to an automatic start signal. Loss of 125 VDC control voltage or placement of-the selector switch in the "0FF" position actuate the alarm.
Further description of the Emergency Diesel Generator Alarm and Control Circuitry is provided in Section 9.5.6.
8.3.4.4 Diesel Engine Start Time The start time requirement for the Diesel Generator is 31.2 seconds-and is measured from open indication of the tie-breaker until closure of the emergency diesel generator output breaker. This time is based on assumptions made in the derivation of ECCS limits (ie, MAPLHCR and Maximum Bundle of Section 5.2.1 of the Big Rock Point Technical Specifications) for Exxon fuel types.
In performing the ECCS analysis, the Design Basis Accident (DBA) and
.375 ft breaks yield peak cladding temperatures closest to the 2200'F l
4 limit established by 10 CPR 50, Appendix K.
All other break sizes yic1d lower peak cladding temperatures and would therefore not be as restrictive as to equipment actuation times. The 15 second core spray valve opening time is most important for the.375 ft break where valve actuation is delayed by the attaining of the low reactor i
pressure condition at 46.5 seconds (low reactor water level occurs within seconds of low drum level for breaks this large). The fire i
pump start time assumption (45 seconds), on the other hand, is most critical for the largest break (DBA) where rated spray is not assumed until low drum level actuation signal is generated (1.2 seconds) plus j
the time required for the pump to start and come up to speed (for a-i total of 46.2 seconds to rated spray).
The emergency diesel generator start time criteria is dictated by DBA requirements. Assuming that rated spray is required'at 46.2 seconds as dictated by the diesel fire pumps start time assumption, and assuming that ac core spray valves are effectively full open 15 seconds after the 2B bus is energized, the diesel generator start time is simply the dif ference between these two values (46.2 seconds
- 15 seconds = 31.2 seconds).
8.3.4.5 Testing Requirements The testing and surveillance requirements for the diesel generator and associated electrical circuits are contained in Section 11.3.5.3 of the Big Rock Point Technical Specifications.
8.3-8 i
HI1289-0466A-BX01 l
1
i i
i l
~ (V NRC Ceneric Letter 84-15 " Proposed Staff Actions to Improve and Maintain Diesel Generator Reliability" was reviewed and changes L
implemented to attain the goals of the staff actions.
l CPCo concurred with the NRC objective for reducing " cold fast starts" I
and returned the surveillance testing back to that described in the Technical Specifications.
Previous commitments to Regulatory Guide 1.108 which terulted in starts approximately every three (3) days were withdrawn.
Although no formal EDC reliability program erists, the Big Rock Point Plant maintains a proceduralized system for ensuring the reliability and availability of its EDC. The system. consists not only of surveillance test procedures to monitor EDC operation but also consists of procedural based activities to inspect and test sub-components at each refueling outage.
During outage inspections,.
components are examined for wear, tested and repaired or replaced-when defective or marginal.
8.3.5 STANDBY DIESEL CENERATOR 8.3.5.1 Description and Operation The standby diesel generator is powered by a diesel rated at 415 HP i
at 1800 rpm to provide 480 VAC back-up emergency power to bus HCC-28.
l t
A standby diesel generator is required to be available for operation within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after a loss of coolant accident. This requirement is based upon the.NRC evaluations (Reference 18) which are needed to assure the availability of AC power:
" Modify the emergency procedures to assure a second emergency diesel will be obtained and operational within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after a LOCA."
Following the modifications performed via Facility Change FC-511C, the standby diesel generator was located at the plant well~ house with permanent wiring and transformers to tie the unit to bus HCC-2B.- The transformers are necessary to raise the tie voltage to 2400 VAC in order to reduce the voltage drop incurred due to the distance between the standby diesel and bus 28.
A manually operated circuit breaker provides the connection to 2B bus. This breaker is padlocked in the open position to ensure isolation from 2B bus until needed.
Cooling for the unit is achieved via a closed loop cooling system
)
utilizing a forced air radiator. DC starting system is discussed in L
Section 8.4.4.1 and fuel ~ storage in Section 9.5.4.1.
The unit is manually started at the well house prior to tie-in at 2B bus. Use of the standby diesel in Alternate Safe' Shutdown is discussed in Section 9.5.4.3.
Od 8.3-9 MI1289-0466A-BX01
p pl j
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8.3.5.2 Instrumentation and Relayina l
Indication of cooling system temperature, lube oil pressure, fuel oil l
pressure, charging current, and generator output are provided at.the j
diesel generator unit. Actuation of high temperature, low oil l
pressure switches or a mechanical or electrical overspeed trip will result in an automatic engine shutdown.
i l
t i
10 l
l r%J 8.3-10 MI1289-0466A-BX01
TABLE 8-6 48A VAC MOTOR CONTROL CENTER 2B i
Position / Breaker Load Description 2B11 480V' System Ground Detector Relay 480V System Ground Indication Lights 2B12 480V System =Undervoltage Relay 52-2B13 Distribution Panel 4Y.
2B14 (Main Lug) 28 Feed From HCC-1A (52-1A2B)
(Main Lug) 2B Feed From MCC-2A (52-2A2B)-
52-2B21 ac Cland Scal Cond Exhauster 2 52-2B22 Personnel Lock 52-2B23 Instr and Control Pwr Transf 2B (Pnl 1Y, 2Y, 3Y) 52-2B24 Emerg Lighting Transf LT3 52-2B25 Equipment Lock 52-2B26 Fire Pump 52-2B27 Emergency Diesel Cencrator 2B31 Space 2B32 Space
]
2B33 Space q
O-2B34 Space j
2B35 Space 2B36 Space i
2B41 Space 52-2B42 MO-7071 Reactor Emerg Cig Spray Viv l
52-2B43 MO-7070 Reactor Emerg C1g Spray Viv-52-2B44 Spare 52-2B45 MO-7068 Reactor Bldg Emerg Spray Backup Valve 1
52-2B46 Distribution Panel 5Y (Pn1 SY)'
l 52-2B47 LE-RE08 and LE-RE09 Heat Tracing l
2B48 Space 2B49 Space 52-2B51
-Standby Diesel Generator 52-2B52 Spare 52-2B53 Spare 2B54 Space 2B61 Space 52-2B62 MO-7080 Fire Wtr to Redundant Core Spray-52-2B63 Spare 2B64 Space o
1 8.3-11 HI1289-0466A-BX01
l l
t
{
V 8.4 ONSITE DC p0WER SYSTEMS 8.4.1 STATION BATTERY SYSTEM i
8.4.1.1 Punetton/ Description The station power batteriec (BAT-1) consist of 60 single cell (lead i
acid) batteries, eac't rsquired to have a cell voltage of 32.0 volts and a specific gravity of 11..l.
The batteries utilized are an Exide type EA-13, having a3 eight hisur discharge rating of 66.6 amperes and a nominal amp-hour reting of $30.
The stat.lon battery capacity is based on the ability of the battery, i
without the support of the associated charger, to operate equipment required to mitigate the consequences of a loss of coolant accident (LOCA).
The station battery chargers are Exide Model USF 130-3-50 full wave, solid state rectifier units. The two chargers are connected in parallel with one of the two chargers in operation at all times.
4 Each cf the chargers can provide up to 50 amps of continuous current, a floating voltage from 118 to 139 volts and an equalizing voltage from 128 to 144 volts.
O An automatic current limit control protects the charger against overcurrent conditions by limiting the maximum charger output current to approximately 110 percent of the rated charge current (50 amp x 110 percent = $5 amp), thus preventing tripping of the chargers input or output breakers. In the event that the station de load is greater than the charger output, the extra current is obtained from the station batteries.
480 volt ac for both chargers operation is obtained from the 480 volt motor control center HCC-2A, position 52-2A32.
Both chargers 480 volt ac input and 125 volt de outputs are provided with circuit breakers.
125 Volt dc % stor Control Center (HCC) - The 125 volt de MCC is a CE motor contrc,1 center of the same type and construction as that of the 480 volt MCCs.
125 volt de HCC positions, provided for valve motor circuits, contain breakers with thermal and magnetic trip elements and reversing type contactors. These ACBs can be manually tripped and reset at the MCC but actual equipment control is carried out from the control room.
A single line diagram of the Station Battery System is shown on Drawing 0740C30102 Sh. 1.
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8.4-1 H10789-0279A-BX01 1
/
8.4.1.2 Station Battery Load Profile The Station Battery capacity is sized assuming a large break Loss of Coolant Accident coincident with a Loss of Offsite Power. The battery sising also includes momentary loads associated with closing of breakers needed to restore station power. Battery sizing is calculated in accordance with IEEE Std 485-1978. The Station Battery Load Profile is shown on Flaure 8.1 and the following summarises these loads per Reference 7.
Constant 2 Hour Loads Breaker Number Description Current 72-1D28 HO-7072 Indication
.03$ A 72-ID32 MO-7064 Indication
.132 A 72-22 D.C. Oil Pump Indication
.03$ A 72-31 MO-7061 Indication
.068 A 72-32 H0-7051 Indication
.068 A 72-43 MO-7067 Indication
.035 A 72-1D11 Fire System / Access Alarms
.48 A 72-1013,24 Poison System Valves
.1 A
72-1D14, 31, 33, Pan Alarm Annunciators 5.08 A ID34, 37, 38 (assume 1/2 or 254 alarms on)
C 72-lD15 V)
Amplidyne Indication
.035 A 72-ID16 Turbine Controls
.175 A 72-IDl?
Deluge Isolation Valve
.07 A 72-1D18 Turbine Trip & Test
.3 A
72-ID20 Steam Bypass Auxiliaries
.15 A 72-1D21 138kV Line Transmitter / Trip
.435 A 72-ID22 RPS Bus 3 Invertor 2.55 A 72-1D26 Rx Building Vent valves 2.508 A 72-lD29 Rx Building Vent Valves Indication.665 A 72-1D35 Main Transformer Alarms
.096 A 72-lD36 Hydrogen Panel Alarm
.384 A 72-1D40 Breaker Control Scheme
.42 A 72-ID42 Field Rheostat & Exciter
.07 A 72-1D43 2400V Breaker control
.956 A 72-1D44 Stack Lighting 10 A
72-SS-A 7726 OCB Indication
.07 A 72-SS-B 1126 OCB Indication
.162 A 72-SS-D 116 OCB Indication
.132 A 72-SS-E 199 OCB Indication
.298 A Total (Two Hour Continuous Loads) 25.51 Amps O
8.4-2 HIO789-0279A-BX01
/%
Profile For The 1st Minute Using the guidance of 4.2.3 of IEEE Std 485, loads are tabulated to show maximum current. To insure worst case conditions, LOCA and Loss of Power occur at t = 0 seconds.
Description Em_e Duration Amps D.C. Oil Pump Starting Current t=0
$ sec 240 A Rod Position M/C Set Starting Current t=0 5 sec 35 A MO-7067 Closes t=0 35 see 15 A MO-7064 opens t=0 55 sec 4.3 A MO-7051, 61 Open t=0-25 sec 5_. 8 A 300.1A Since breaker loads are very short duration (<1 sec) the maximum current draw was determined at any one time period and that value added to the above one minute total.
Breaker actuations occurring af ter five seconds need not be considered due to the 55 sec. 275 amp assumed load from the motor starting currents.
Breaker loads before that point aret Description Time Duration Amps Q(j 199 OCB Opens t=0 3 cycles 11.1A i
Recirc Pump Trip t=0 3 cycles 12.0A 116 OCB Opens t=1 3 cycles 9.4A Feed Pumps Trip t=2 3 cycles 12 A cond Pumps Trip t=2 3.5 cycles 3.8A 1F-1E & 2F-2D OCBs Trip t=2 5 cycles 5.0A 1126 OCB opens t=3 3 cycles 10 A 7726 Closes After 1126 Opens t=3+
30 cycles 24 A Circ Water Pumps Trip t=4.5 3.5 cycles 3.8A 1136 OCB Opens t=10 3 cycles 6 A This concludes that the closing of the 7726 OCB establishes the maximum load due r.o breaker operations in this time period of 24 amps.
t In addition, relays are actuated during this sequence and are added to this time period total.
72-1D11 - Fire System Alarms
.192 A 72-1D20 - Load Rejection Operation 7.30 A 7.492 A I
8.4-3 M10789-0279A-BX01
(U Total Load For the 1st Minute:
Continuous Loads 25.51 A Motor Operations 300.1 A Breaker Operations 24.0 A Relay Actuations 7.5 A 357.11 A Load From 1 Minute To 2 Hours Continuous Loads 25.51 A D.C. Oil Pump 80.0 A Rod Position M/C Set -
11.5 A 117.01 A Load During Last Minute to Restore Of f site Power i
Assuming the 138 kV line is restored at t=2 hours the following actions will occurt Descrir. tion Time Duration Amps t
Operator trips the 7726 OCB 3 cycles 10 A operator closes the 199 OCB 3 cycles 6A
/]
Operator closes the 1126 OCB 30 cycles 24 A
' V Cond Pump close 6 see after 1126 closes
+6 sec 5 cycles 54 A Cire Pump close 10 see after 1126 closes
+10 sec 5 cycles 54 A Operator closes 1136 0C8 3 cycles 95 A Assume one feed pump started 3 cycles 58 A Since those loads are eithe. manual manipulations or automatic reclosures all of short duration, the 95 amp load of the 1136 OCB is used for the one minute duration. This encompasses the demand of the remaining loads.
Total Load For The Final Minutes Continuous Load 25.51 A Rod Pos H/C Set 11.5 A 1136 oCB 95.0 A 132.01 A Reference 8, Amendment 94 to the Technical Specifications approved
^
the design load profile time interval of two hours which meets the l
criterion of SEP Topic VIII-3.A.
NRC review of load profile, sir.ing calculations, and assumed two hour scenario concluded consistency with current staff guidance and requirements.
O V
8.4-4 H10789-0279A-BX01
l 8.4.1.3 Station Battery Testina Requirements i
SEP Topic VIII-3.At Station Battery Capacity Test Requirements (Reference 9) evaluated the BRP Technical Specification testing requirements against the industry standards (IEEE Std. 450-1975).
This review concluded that the surveillance / test requirements for the station battery satisfy current licensing requirements. Surveillance requirements are contained in the BRP Technical Specifications.
I 8.4.1.4 DC Power System Bus Monitorina I
SEP Topic VIII-3.B (Reference 10) evaluated BRP to assure the design adequacy of the DC Power System Battery and Bus Voltage Monitoring and annunciation schemes such that the operator can (1) prevent loss of an emergency DC Bust or (2) take timely corrective action in the event of loss of an emergency DC bus. Control Room monitoring of the 125 VDC Station Battery System consists of a "125 VDC System Trouble" alarm which activates on the following Battery / Battery Charger overcurrent Positive or Negative bus ground i
Loss of charger input supply voltage 125 V DC Bus undervoltage
, O Additionally, an indicator light in the control room monitors battery
{ Q voltage is greater than 125 VDC.
Local indication consists of charger output current and bus voltage, current, and ground.
1 In responding to the deficiencies identified in the SEP Topic VIII-3.B review, Consumers Power (Reference 11) procedural changes were implementri to provide assurance that the system is ready to perform its intended function. The staf f was concerned since the plant staff does not have an adequate means to verify at frequent intervals that the 125 VDC station battery output terminals and cell-to-cell connections are free of corrosion. According to the staff, corrosion could conceivably result in significant resistance and cause voltage drops and current reduction to occur in the system when the battery is called upon to carry plant load (normal plant load is carried by the in-service charger with only a trickle charge supplied to the battery).
Procedural changes were implemented to control the charger transfer such that information regarding the condition of battery connections can be observed and recorded.
The changes accomplish the desired results in the following mannert 1.
Battery voltage, charger current and 125 VDC system current is recorded prior to removing the charger from service.
Atg 8.4-5 H10789 0279A-BX01
o 2.
The in-service charger is removed and the same parameters are recorded. Acceptance criteria specifies that the 125 VDC load current should remain essentially the same (at this time, the battery is carrying station load).
3.
The alternate charger is placed in service and the same parameters are again recorded. Acceptance criteria specifies that the charging current must be equal to or greater than the load current thereby verifying that the charger-to-battery connections are good and the battery charge is being replenished.
NRC review of these changes are documented in Reference 12 as being i
acceptable with logging of weekly pilot cell readings to assure operability of the DC System.
8.4.2 ALTERNATE SHUTDOWN (ASD) BATTERY SYSTEM 8.4.2.1 Func t ion /Desc ri pt ion The ASD Battery System was installed in 1985 to provide a feeder circuit to safe shutdown equipment independent of the Station Battery as part of modifications (Facility Change 462J) to comply with 10 CFR 50 Appendix R requirements.
(
The ASD battery consists of 60 single cell (lead calcium) batteries, cach required to have a cell voltage of 2 2.1 volts and a specific gravity of 11.215 10.010 at 77 degrees Fahrenheit. The battery type utilizing Allied C&D type KC-7 or KCR-7 cells having an eight hour discharge rate of 250 amp hours.
The ASD battery system is located in the Alternate Shutdown Bui ding.
The output of the ASD Battery is connected to the 125 VDC distribution panel 2D.
Drawing 0740C30102 Sh 2 provides a one-line description of the system.
The ASD battery charger, is an Allied C&D auto-regulator model designed to float charge a battery while supplying a continuous load.
This charger is designed to provide up to 25 amps of continuous current, a float voltage of 132-135 volts de and an equalizing voltage of 140-143 volts de.
The charger is equipped with input and output protection via an ac circuit breaker and a de circuit breaker respectively, each appropriately sized for the associated loads. The charger is further protected on its output via a current limiting device, high voltage shutdown and a current walk-in device.
8.4.2.2 Alternate Shutdown Battery Load Profile The ASD battery capacity is sized to, without support from its associated charger, operate associated continuous loads for nine days followed by three days of fire protection loads, all with battery i
t cell temperature of only 25 degrees Fahrenheit. Battery sizing was L
calculated in accordance with IEEE Std 485-1978. The Alternate 8.4-6 HIO789-0279A-BX01
Shutdown Battery Load Profile is shown on Figure 8.2 and the following summariaes these loads per Ref erence 13.
The design of the bank assumes a period of nine days (216 hours0.0025 days <br />0.06 hours <br />3.571429e-4 weeks <br />8.2188e-5 months <br />) with a load of.25 amps without a battery charger at the beginning of the load prufile. This provides assurance that a redundant charger is not necessary in that nine days is enough time to repair or replace the charger if a failure should occur.
This 216 hour0.0025 days <br />0.06 hours <br />3.571429e-4 weeks <br />8.2188e-5 months <br />,.25 amp normal loads (converter and miscellaneous indicating lights) is represented as an equivalent four hour,14 amp load step at the beginning of the profile.
Profile For 4 Hour to 4 Hour + 1 Minute Description Duration Amps Normal ASD Load 1 min
.25 A HO-7050 MSlv 1 min 37.4 A HO-7053 ECS Valve 1 min 7.9 A HO-7063 ECS Valve 1 min 7.9 A Emergency Lights 1 min 0.6 A
$4.05 Acps Profile For 4 Ilour 1 Minute to 4 Hour, 2 Minutes Description Duration Amps Normal ASD Load 1 min
.25 A HO-7053 ECS Valve 1 min 7.9 A HO-7063 ECS Valve 1 min 7.9 A Emergency Lights 1 min 0.6 A 16.65 Amps Profile From 4 Hour, 2 Minutes to 4 Hour. 14 Minutes Description Duration Amps Normal ASD Loads 12 min
.25 A Emergency Lights 12 min
.6 A
.85 Amps *
- This value is conservatively shown as 2 amps on the test profile.
Profile From 4 Hour. 14 Minutes to 4 Hours. 15 Minutes Description Duration Amps Normal ASD Loads 1 min
.25 A HO-7053 ECS Valve 1 min 7.9 A HO-7063 ECS Valve 1 min 7.9 A
)
Emergency Lights 1 min
.6 A
V 16.65 Amps 8.4-7 HIO789-0279A-BX01
I
(
Profile From 4 Hours. 15 Minutes to 8 Hours i
I This portion of the profile represents an equivalent loading for the remaining 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of the design interval. The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> duration is based on 10 CFR 50 Appendix R III.L.l.(d) " achieve cold shutdown conditions within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />." Until cold shutdown is achieved, the ASD battery supports maintaining hot shutdown. Besides the normal ASD Load and Emergency Lights, the additional load is the operation i
of SV-4947 to provide fire water make-up to the Emergency Condenser.
Since continuous make-up is not required, the total load is adjusted to reflect operation 10 minutes out of every 30 minutes.
t Description Duration Amps Normal ASD Loads 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />
.25 A Emergency Lights 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />
.6 A
SV-4947
.5 A
Total Equivalent load is then calculated as follows:
1 Total amps (min SV-4947 operates /hr) +
Ieq
=
total amps - SV-4947 (min SV-4947 does not operate /hr) 1.35 amps (
) + 0.85 amps ( ' " ")
Ieq
=
Ieq 1.016 amps
=
For testing purposes, this 1.02 amp load for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is represented as an equivalent loading of 20 amps over the 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />, 45 minute time period on the profile.
8.4.2.3 Al t ernate Shutdown Bat t ery Test ing Requirement s Testing requirements for the ASD Battery System were developed to comply with the evaluation contained in SEP Topic VIII-3. A and IEEE Std. 450-1975. The testing and surveillance requirements are described in the Big Rock Point Technical Specifications.
1 8.4.2.4 Alternate Shutdown Battery System Monitorina Charger operation is monitored via local metering and status indicators.
Remote alarming of the charger is also provided in the control room (Alternate Shutdown Building Trouble Alarm).
An ammeter and a voltmeter, located on the front of the charger, is provided for monitoring the chargers de output. Loss of ac input extinguishes the chargers ac failure lamp, actuates an amber indicating lamp (Loss of AC Voltage) on the alternate shutdown control panel
- n
(
C-31 and alarms in the control room (Alternate Shutdown Building Trouble Alarm). Indication of high voltage, low voltage and/or no l
8.4-8 M10789-0279A-BX01
O charge current conditions are provided on the charger via the illumination of an associated red indicating lamp. These conditions are also alarmed on the alternate shutdown control panel C-31, via the illumination of associated amber indicating lamps identified as
" Battery Charger High Voltage", " Battery Charger Low Voltage" and "No Charge From Br.ttery Charger", and in the control room (Alternate Shutdown Building Trouble Alarm).
Positive and negative ground conditions are also alarmed on the alternate shutdown control panel C-31, via the illumination of associated amber indicating lamps identified as "Cround On Positive Leg" and "Cround On Negative Leg", and in the control room (Alternate Shutdown Building Trouble Alarm).
Additional alarms which annunciate on the C-31 panel and the control room are the alternate shutdown building " Low Temperature" and " Loss of Ventilation Flow."
8.4.3 RDS UNINTERRUPTIBLE POWER SUPPLIES 8.4.3.1 Func t ion /Descri pt ion Four (4) Uninterruptible Power Supplies (UPS) were installed in 1976 via Facility Change FC-315, as part of the Reactor Depressurization System Modificction.
Each UPS is made up of a 50 amp battery charger, a bar.k of batteries to provide 125V de and an inverter to convert the 125V de to 120V ac.
The units supply power to the sensor cabinets, actuation cabinet, and RDS valves associated with each channel (A-D).
UPS A supplies power to SCA, ACl and Channel I valves.
UPS B supplies power, to SCB, ACI and Channel 2 valves. UPS C supplies power to SCC, AC3 and Channel 3 valves. UPS D supplies power to SCD, AC4 and Channel 4 valves. The UPS A 125V de output is also used in the emergency diesel generator circuitry and for 480V indication in the Control Room.
A single-line drawing of the power supplies is chown on Drawina 0740031001.
The UPS are single-failure proof, in that a loss of cae unit will not cause an inadvertent blowdown and the remaining three units can complete the required safety function. The UPS are Seismic qualified in accordance with IEEE 344-1971 with details provided in Specification No. 34490-1600-402 of Facility Change FC-315.
8.4.3.2 UPS Battery Load Profiles The UPS Battery Load Profiles represent the loads experienced by each I
UPS battery bank during a LOCA with RDS actuation coincident with a loss of offsite power. The service cycle is one hour, consistent with the UPS specification. The load profile for UPS Batteries B, C and D is shown on Figure 8.3.
The load profile for UPS Battery A 8.4-9 MIO789-0279A-BX01
V which also supplies the Diesel Cencrator actuation scheme is shown on Figure 8.4 The load profiles were developed as discussed in Reference 14.
Modif' cations performed in 1986 (Specification Change SC-86-021) which installed larger solenoid tops and the depressurization valves increased the current demand by 0.5 amps in the 2 through 60 minute t
period.
l The load demand for the diesel generator circuit on UPS-A was determined by test in 1976 (Maintenance Order MO #76-EPS-183-05).
The results showed a load of 8.3 amps during the starting sequence (<1 minute) followink a loss of offsite power and a normal load for indicating lights of 0.1 amps.
8.4.3.2.1 UPS A Load Profile Descri ption Time Duration Amps Emergency Diesel Start t=0 1 min 8.3 A RDS Actuation t=0 1 min 6.6 A (includes fire pump relay in rush =.07A)
TOTAL t=0 1 min 14.9 Amps RDS Actuation t=1 1 min 6.5 A
\\
Emergency Bus Indication t=1 1 min 0.1 A TOTAL t=1 1 min 6.6 Amps RDS Actuation After Trip t=2 58 min 8.1 A (includes output relay in rush = 0.1 Amps)
Emergency Bus Indication t=2 58 min
.l.A TOTAL t=2 58 min 8.2 Amps 8.4.3.2.2 UPS B. C and D Load Profile Description Time Duration Amps RDS Actuation t=0 2 min 7.0 A (includes fire pump relay in rush =.07 A)
RDS Actuation After Trip t=2 58 min 8.1 A (includes output relay in rush = 0.1 A) 8.4.3.3 UPS Battery System Testing Requirements The UPS Batteries were included within SEP Topic VIII-3. Al Station O
Battery Capacity Test Requirements (Reference 9) which evaluated the BRP Technical Specification requirements against the industry standard-8.4-10 MIO789-0279A-BX01
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(IEEE Std 450-1975). This review concluded that the surveillance / test requirements including the one hour service period satisfy current licensing requirements. Surveillance requirements are contained in i
the BRP Technical Specifications.
8.4.3.4 UPS System Bus Monitorina SEP Topic VIII-3.B (Reference 10) evaluated BRP to assure the design adequacy of the bus voltage monitoring. Control Room monitoring of the UPS consists of a "UPS Abnormal" alarmi local indication consists of battery output current, charger output current and voltage, inverter input current, and inverter output current, voltage, and frequency. Although the control room monitoring does not meet current guidelines, the NRC staff concluded (Reference 12) that additional monitoring of the UPS battery system is not necessary because of the small loads, short load duration, and multiple redundancy provided in the RDS design. The small loads and short load duration make it less likely that a DC system failure that can be masked by battery charger performance will occur.
8.4.4 DIESEL STARTING SYSTEMS 8.4.4.1 Function /Descri pt ion I
Three diesel starting systems using 24V de battery banks are utilized l
at Big Rock Point for the following units:
The Emergency Diesel Generator The Standby Diesel Generator The Diesel Fire Pump The emergency diesel control circuit is powered by a battery charger with additional current capacityt via two, six cell, 12 volt (lead acid) series connected batteries providing a combined battery voltage of 24 volts and a current capacity rating of 225 amp hour.
l The emergency diesel generator battery charger is capable of providing up to six amps of current, a float voltage from 26.5 to 28.8 volts de on s two hour repeating cycle and an equalizing voltage from 25 to 28.8 volts de on a thirty minute equalizing cycle, maintaining the batteries at full charge.
Both the floating and the equalizing voltage can be adjusted if required. The charger operates on 120V ac powered from panel 10L.
l The standby diesel control circuit is also powered via two, six cell, 12 volt (lead acid) series connected batteries providing a combined battery voltage of 24 volts and a current capacity rating of 225 amp l
hturs. The standby diesel generator batteries are located next to l
the engine.
8.4-11 HIO789-0279A-BX01
C
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The standby diesel is equipped with a 24 volt alternator, capable of j
providing 35 amp for diesel operation and battery charging. Should the standby diesel generator batteries require a freshening charge, a portable charger is used.
l The diesel fire pump electrical system (24V de) has three separate circuitst the charging circuit, the starting circuit and the low amperage circuit. Some of the electrical system components are used i
in more than one circuit. The batteries, circuit breaker, ammeter, cables and wires from the battery are all common in each of the circuits. The charging circuit is in operation when the engine is running. An alternator provides the means for the charging circuit.
The system utilizes two separate 24V de storage batteries equipped with a battery charger powered by panel lY. The charger is an on-off device, wherein each of the two batteries is placed on charge periodically. A timing switch alternates the charger connections to each battery and initiate charging in the automatic mode, operation in the manual mode stops all. automatic functions and places the selected battery on continuous charge.
8.4.4.2 Battery Loading and Test Requirements SEP Topic VIII-3.A Station Battery Capacity Test Requirements (Reference
- 9) evaluated the need to perform discharge tests on the batteries for the diesel units. The staff concluded that discharge tests are not required based upon the following:
1.
Battery ratings are based on discharge rates (and discharge efficiencies) that are considerably different from those experienced during engir.a cranking.
l 2.
The monthly starting tests (essentially service tests) are of a sufficient test of cranking battery capability because batteries that have too high an internal resistance for cranking service can still provide ample power for lesser current demands such as those encountered in the traditional discharge testing of standby batteries that are seldom used.
3.
The five year test discharge requirement is not appropriate or needed for the starting batteries because their function is to start the engines and their ability to perform that function is tested every month.
Surveillance and test requirements for the batteries associated with the diesel units are contained in the BRp Technical Specifications.
Although not addressed in Technical Specifications, the Standby Diesel Generator is also started once a week and battery conditions is monitored periodically.
8.4-12 M10789-0279A-BX01
t i
L/
8.4.4.3 Diesel Startina System Honitoring Control room monitoring of the Diesel Generator and Diesel Fire Pump starting systems consists of an " Emergency Generator Engine Trouble" alarm and a " Diesel Fire Pump Trouble" alarm, respectively. SEP Topic VIII-3.B as discussed in the BRP Integrated Plant Safety Assessment (Reference 12) concluded that since the batteries for the diesel generators and diesel fire pump are load tested during the monthly diesel starts; therefore, additional instrumentation is not recommended.
I O
l l
l l
l l
i L/
- ~
MIO789-0279A-BX01
l FICURE 8.1 STATION BATTERY SERVICE TEST LOAD PROFILE Amps i
5et-i det-1 4
t
}GS-l 299-f too-6-
-- ( )
10
'5 28 25 25
')5 c5 be 1' e l' 5 12e 125
)
Hinutes prain Current Duration 1
3 358 Amps 1 minute 2
=
118 Amps 119 minutes ON 3
- 13) Amps 1 minute a
8.4-14 HIO789-0279A-BX01
l
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FICURE 8.2 ALTERNATE SHUTDOWN BATTERY LOAD PROFILE Asps j
I att-96-86-1 74-60-50-O 36-6
]<
1 3&4 20-I gg_
4 t=
0 l!
l 4
0 0
V l l l
M l
l prain Current Duration Drain Current Duration 1
14 Amps 4.4 Hours 4
s 2 Anpa 12 minutes
- 54 Amps 1 minute
- 16.6 Anpa
'l minute
=16.6 Amps 1 minute a 20 Anpa 3 Hrs 45 minutes i
8.4-15 M10789-0279A-BX01
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D' FICURE 8.3 UPS - B. C. D LOAD PROFILE il
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kJ FIGURE 8.4 UPS - A LOAD PROFILE T
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M10789-0279A-BX01
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ELECTRICAL PENETRATION ASSEMBLIES Electrical penetration assemblies are utilized at Big Rock Point to l
. provide electrical power and control circuit feeds into and out of containment, while maintaining containment integrity. The penetration assemblies are designed to 41.7 psia and 23$'F as well as Electrical Equipment Qualification Requirements as discussed in Section 3.11.
SEP Topic VIII-4 Electrical Penetrations of Reactor Containment evaluated the BRP penetrations to determine the capability of penetrations to maintain containment integrity during short circuit current conditions and the worst expected transient fault current resulting from single random failures of circuit overload protection devices.
Consumers Power submitted a Probabilistic Risk Assessment (Reference
- 22) to estimate the affect on radionuclide release due to containment penetration failure and to determine to what extent additional modifications or testing of these penetrations may be necessary to decrease the risk presented by these failures. The resultant radio-t nuclide release through a penetration was shown to be negligible when
+
realistic assumptions are taken into account, even if these assumptions are still on the conservative side.
- O The low risk, coupled with the high estimated cost of modifications conclude that no further action should be taken on this topic.
The staff concurred with the CPCo evaluation in the Integrated Plant Safety Assessment (Reference 12) and determined that no dominant sequence involved electrical penetration failure as-a release mechanism.
Failure of penetrations is less signifiaant because the potential leakage paths are smaller than those for piping penetrations and containment ventilation isolation valve failures. Therefore, the staff concludes that this issue's importance to risk is low.
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M11289-0466A-BX01 i
Chapter 8 References 1.
Letter to AEC dated 6/24/68 - Semi-Annual Report 2.
Letter from NRC dated 9/21/81 - SEP Topic VII-6 3.
Letter from NRC dated 11/30/81 - Adequacy of Station Electrical Distribution System Voltages 4.
Letter from NRC dated 7/8/82 - Adequacy of Station Electrical Distribution System Voltages and Degraded Grid Protection for Class IE Power Systems and SEP Topic VIII-1.A 5.
Letter to NRC dated 5/18/82 - BRP - Station Electrical Distribution System Voltages 6.
Letter to CPCo dated 3/8/82 - Technical Specification Amendment 51 7.
Big Rock Point Engineering Analysest EA-E-BRP-86-05 and EA-SC-87-023-1, (Internal Analyses discussed in Reference 8 and the latter was submitted by CPCo letter dated October 26, 1989 - Station Battery Service Test) 8.
Letter from NRC dated 2/15/89; Technical Specificati0n Amendment 94 9.
Letter from NRC dated 2/27/81; SEP Topic VIII-3.A O
!.y 10.
Letter from NRC dated 2/22/82; SEP Topic VIII-3.B 11.
Letter to NRC dated 3/10/831 Response to SEP Topic VIII-3.B 12.
NURt:C-0828, May 1984; BRP Integrated Plant Safety Assessment 13.
Big Rock Point Engineering Analysisi EA-FC-462J-02, (Internal Analysis).
14.
BRP 0.S.A. No. A-BR-76-35-01 dated 2/2/77, (Internal Analysis).
15.
Letter to NRC dated 2/25/80 - ECCS Equipment. Timing Requirements 16.
Letter from NRC dated 4/7/77 17.
Letter from NRC dated 9/2/82 - SEP Topic VIII-2 18.
NRC Hemorandum and Order to CPCo dated 5/26/76 19.
NRC letter to CPCo dated 10/17/77 - Amendment 15 20 Letter to NRC dated 8/3/82 - Response to SEP Topic VIII-2 21.
Letter to NRC dated 2/14/83 - Response to SEP Topic VII-10.A h) 22.
Letter to NRC dated 4/25/83 - Response to SEP Topic VIII-4 MIO689-0253A-BX01