ML19329D990
| ML19329D990 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 10/31/1967 |
| From: | SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | |
| References | |
| NUDOCS 8004090509 | |
| Download: ML19329D990 (33) | |
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TABLE OF CONTENTS 8.
ELECTRICAL SYSTEMS Section Page 8.1 DESIGN BASIS 8.1-1 8.2 ELECTRICAL SYSTEM DESIGN 8.2-1 8.2.1 ELECTRICAL SYSTEM DESIGN NETWORK INTERCONNECTIONS 8.2-1 8.2.1.1 Network Interconnections 8.2-1 8.2.1.2 System Diagrams 8.2-1 8.2.1.3 Reliability Considerations 8.2-1 8.2.2 STATION DISTRIBUTION SYSTEM 8.2-2 8.2.2.1 Systems Desien 8.2-2 8.2.2.2 Power Generation and Transmission 8.2-3 8.2.2.3 Unit Auxiliary and Start-Up Transformers 8.2-3 8.2.2.4 6900-Volt System 8.2-3 8.2.2.5 4160-Volt System 8.2-3 8.2.2.6 480-Volt System 8.2-4 8.2.2.7 Control Rod Drive Power 8.2-5 8.2.2.8 125-Volt D-C Sys tem (Figure 8.2-3) 8.2-5 8.2.2.8.1 Single Failure Analysis of the 125-Volt D-C System 8.2-7 8.2.2.9 120-Volt A-C Essential Power System (Vital Buses -
8.2-7
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8.1-1
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8.2 ELECTRICAL SYSTEM DESIGN 4
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8.2.1 ELECTRICAL SYSTEM DESIGN NE1VORK INTERCONNECIIONS 8.2.1.1 Network Interconnections The unit will generate electrical energy at 22 kv which will be transmitted I
to the unit main transformer where it will be stepped up to 230 kv trans-mission voltage. Five overhead transmission lines will transmit energy 2
from the generating station switchyard to switchyards in the area transmis-sion network. The transmission system and the Rancho Seco switchyard include provisions for a second generating unit.
8.2.1.2 System Diagrams Figure 8.2-1 is a single line diagram of the bus irrangement for the Rancho Seco switchyard. Figure 8.2-2 gives the projected 1973 transmission system of Sacramento Municipal Utility District.
8.2.1.3 Reliability Considerations Re' liability considerations to minimize the probability of power failure due to faults in the electrical system are as follows:
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Flexibility and capability will be designed into 230 kv network interconnections by installing five transmission circuits from the generating station switchyard to switch-yards in the area transmission network. The area transmis-sion system is capable of transmitting all area generation to load centers under adverse conditions with any one line out of service.
b.
Three circuits will be installed on two double circuit towers; space for one additional circuit will be available.
Two circuits will be installed on a double circuit tower following a different route.
2 c.
The data for each line connected to the Rancho Seco switch-yard is described as follows:
Minimum Longtime Expected Annual To Length Capability Outage Rate Tesla 60.0 mi 400 NW l.2 Hedge 22.5 mi 275 MW 0.42 Hurley 27.5 mi 275 NW 0.52 Bellota #1 28.5 mi 605 FN 0.40 Bellota #2 28.5 mi 605 FN 0.40
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Amendment 2 8.2-1
Electrical System Design Approximately 2.9 line outages per year are anticipated for
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all lines terminated at the switchyard, more than 90 percent of which are of transient nature. Outages for a period 2
longer than one second are expected to be approximately 0.25 per year. These estimates are made on the basis of routine maintenance being performed at the time of normal plant shut-down for maintenance and refueling.
d.
The bus arrangement in Figure 8.2-1 will provide two 230 kv main buses. Primary and backup relaying will be provided for each circuit along with circuit breaker failure backup pro-tection. The switchyard provisions will permit the following:
(1) Any circuit can be switched under normal or fault condi-tions without affecting any other circuit.
(2) Any single circuit breaker can be isolated for mainten-ance without interrupting the power or protection to any other circuit.
(3) Faults on a main bos will be isolated without interrupt-ing service to any circuit.
(4)
Backup relaying will insure against primary relaying failure to trip.
2f (Deleted) 8.2.2 STATION DISTRIBUTION SYSTEM 8.2.2.1 Systems Design The plant distribution system will consist of the various electrical systems designed to provide reliable electric power during all modes of operation and shutdown conditions; and mechanical safeguards necessary to assure adequate personnel protection, including protective relaying, grounding and prevention or limitation of equipment damage during system fault conditions.
The systems will be designed with suf ficient Mwer sources, redundant buses, and the required switching to provide these functions.
Engineered safeguards auxiliaries will be arranged so that loss of a single bus for any reason will still leave sufficient auxiliaries to safely perform the required function.
On complete loss of power, the emergency diesel generators will start 1
automatically. One-line diagrams of the system are shown on Figures 8.2-1 and 8.2-3.
A multiple bus system ensures the reliability of the station auxiliary power distribution system. The buses have access to:
The Rancho Seco generator when running via unit 1l
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auxiliary transformers, j
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21 b.
The 230 Kv system via start-up transformer No. 1.
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8.2-2 Amendment 2
Electrical System Design c.
The 230 kv system via start-up transformer No. 2.
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2-d.
The emergency diesel generators.
The station distribution system is capable of starting the largest drive with the remainder of the motor load in service.
Protective relaying is arranged for selective tripping of circuit breakers, thus limiting the I
loss of power to the af fected area.
8.2.2.2 Power Generation and Transmission Electrical energy generated at 22 kv is fed through an isola ted phase bus to the main transformer.
Overhead conductors carry this power to the switchyard for transmission over outgoing lines. The 230 kv system is 2-also the source of power for the two startup transformers.
8.2.2.3 Unit Auxiliary and Start-Up Transformers During normal operation the source of electrical power for all normal 4160-volt plant auxiliaries load will be provided by the 4160-volt unit auxiliary transformer which is connected to the generator isolated phase 3
bus. All nuclear services auxiliaries load will normally be provided by 4160-volt start-up transformer No. 2 which is connected to the 230 kv switchyard.
During normal operation all of the 6900-volt auxiliaries load l1 will be provided by the 6900-volt unit auxiliary transformer which is l
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connected to the generator isolated phase bus.
The unit auxiliary trans-l3 i (.)
formers as well as the start-up transformers will be sized to carry full 1
plant auxiliaries load.
During start-up and shutdown, and af ter a unit trip, all of the plant auxiliary power is provided by the two start-up transformers.
One secondary winding of start-up transformer No. I will have a 4160-volt tap in each phase. These taps will provide a second 2
source of off-site power to the 4160-volt nuclear service buses.
8.2.2.4 6900-Volt System The 6900-volt auxiliary system will be designed for the reactor coolant pump motors.
The system will be arranged into two bus sections. During y
normal operation, both buses will be fed from the unit auxiliary trans-former. During start-up and shutdown, the two buses will be fed from l3 6900-volt start-up transformer No. 1.
Normal " live-bus" transfers between the start-up transformer source and the unit auxiliary transformer source 2
during startup and shutdown are manually initiated with momentary source paralleling during transfer.
On loss of the unit auxiliary transformer or unit trip, there will be an automatic transfer to start-up transformer 3
No. 1.
8.2.2.5 4160-Volt System Six 4160-volt buses will be provided, two for the normal 4160 volt reactor /
turbine auxiliaries, two for the engineered safeguards 4160-volt auxiliaries, l2 7
and two for the circulating water pumps and one condensate pump.
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On loss of the unit auxiliary transformer or unit trip, there will be an automatic transfer of the unit auxiliaries to start-up transformer No. 2.
.34 Amendment 3 8.2 3 3
Electrical System Design On normal or emergency shutdown of the unit, a second or standby source of off-site power will be available for the nuclear services 4160-volt auxili-3 aries.
It will bc supplied by start-up transformer No. 1 and will be applied by automatic transfer when normal supply is lost. A bus tie cir-cuit is provided between the nuclear service buses.
2 Upon loss of normal and standby power sources, the two 4160 volt nuclear service buses will be energized from the emergency diesel generators.
Bus load shedding, bus transfer to the diesel generators, and pickup of engineered safeguards loads will be automatic as required.
2 No single failure shall result in the loss of more than one nuclear service
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switchgear bus.
The nuclear service buses at the 4160-volt level are redundant.
No single failure shall prevent the connection of a power source to a suf-ficient number of buses to safely shut down the reactor.
No single failure shall result in a total elapsed time, starting at initia-7 tion by protection systems and ending at full speed of the high pressure injection and decay heat pumps, of more than 25 seconds.
All safeguards buses can be tested as follows:
a.
Components connected to any nuclear service bus can be tested 2I individually at any time.
b.
Disconnecting normal supply breaker to the nuclear services bus 1B will initiate automatic transfer to the standby supply source subject to voltage being available from start-3 up transformer No. 1.
c.
Disconnecting bus supply breakers for either bus 1B or 1C will initiate starting sequence of the appropriate diesel generator and trip the tie breakers between the buses.
8.2.2.6 480-Volt System The 480-volt system is divided into four buses, two for the normal 480-volt reactor / turbine auxiliaries and two for the engineered safeguards 480-volt auxiliaries.
Power for each bus is supplied from a separate sta-tion service transformer which will be fed from the 4160-volt system and arranged so that each transformer is fed from a different 4160-volt bus.
Various 480-volt motor control centers will be located throughout the plant to supply power to normal or safeguards equipment within the respec-tive areas.
t The system is arranged so that multiple pieces of equipment with a common function will be fed from different buses; thus, the loss of any one 480-volt bus will not deprive the facility of all equipment associated with that particular function. Bus tie circuits are provided between nuclear 3
service buses with two circuit breakers in series to prevent the loss of two buses when there is trouble with one of the tie circuit breakers.
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@ B!suur 335 8.2-4 Amendment 3 J
Electrical System Design
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8.2.2.7 Control Rod Drive Power
. u-Two 480-volt, 3-phase sources are provided for the control rod drive power.
Each source is fed from one 480-volt normal switchgear bus and has the capacity to supply the total rod drive requirements.
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8.2.2.G 125-Volt D-C System (Figure 8.2-3)
The 125 volt d-c system will be designed to provide a source of reliable continuous power for d-c pump motors, control, and instrumentation.
The 125 volt d-c system will consist of six isolated bus sections.
Four l1 (4) for the reactor plant, and two (2) for the turbine plant.
Each bus I
section will be supplied by a 60-cell battery and one battery charger.
One standby charger will be provided for the two turbine plant buses and l1 one for each pair of reactor plant buses.
The battery charger units for each 125-volt d-c bus will be energized from the 480-volt nuclear service 2
buses which, in turn, have diesel power available.
Two chargers can be operated in parallel for fast recovery or emergency conditions.
Each charger will provide continuous d-c load and floating charge, with occasional equalizing charge as required.
Charger failure will be annunciated in the control room, as initiated by voltage failure relays in the d-c output and 480-volt a-c supply. Each bus section will include a d-c motor control k-[Cl
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center and distribution panel.
The anticipated -loads on each battery bus are as follows:
a.
Battery 1E - Turbine Plant: One-Half Hour Emergency Load 1
(1) Turbine emergency oil pump.
(2)
Boiler feed pump turbine emergency oil pumps.
(3)
Emergency seal oil pump.
(4) Reactor coolant pump emergency bearing oil pumps.
b.
Battery IF - Turbine Plant: Two-Hour Emergency Load c
1 (1) Turbine plant switchgear control.
(2) Miscellaneous turbine control.
(3) Generator and auxiliaries control.
(4)
(5)
Inverter - computer.
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00 336 8.2-5 Amendment 2
Electrical System Design c.
Batteries 1A, IB, 1C and ID - Reactor Plant:
Two-Hour 1
Emergency Load 2
(1)
Inverter - reactor control and protection and engineered safeguards.
(2) Nuclear service switchgear control.
1 (3) Emergency lighting.
(4) Miscellaneous reactor control.
2l (5) Nuclear service d-c buses (lA and ID only).
6 (6) Control Rod clutch power d-c buses (lB and 1C only).
1 The reactor plant batteries IA, 1B, 1C and ID will be designed with suf fi-cient capacity to carry their respective loads for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. The normal and standby battery chargers connected to these batteries will be fed from 21 diesel-powered nuclear service buses.
The turbine plant batteries IE and IF will be designed with suf ficient capacity to carry their respective loads as shown above.
Battery capacities 1
will be determined on basis of discharge to 1.75 volts / cell. The normal battery chargers connected to these batteries will be fed from turbine plant motor control centers. The standby battery charger connected to these 21 batteries will be fed from either diesel-powered nuclear service motor con-
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trol center.
All norroal and standby battery chargers will be designed to fully recharge their respective battery in 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The reactor plant battery chargers
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1 will be designed to carry the connected load under all operating conditions except for complete loss of all on site and off site a-c power. The turbine plant battery chargers will not be designed to carry the connected motor loads.
Tests to be performed on the batteries will be as follows:
a.
Individual cell specific gravity and voltage will be checked once a month, using at least 2 pilot cells per battery.
b.
Water level will be visually checked at the same time.
c.
Once a year all inter-cell and inter-tier connectors will be checked for corrosion and tightness.
I d.
Voltmeters and ammeters will be provided as well as battery ground indication.
Upon installation and periodically thereafter a discharge e.
rate for 1/2 hour will be ic: posed upon the battery.
A check of battery voltage before and af ter the test will prove whether the battery discharge characteristics remain on the s
predicted curve.
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Electrical System Design x
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8.2.2.8.1 Single Failure Analysis of the 125-Volt D-C System
- w, As shown in Table 8. 2-1, the 125-volt ds: system will be arranged such that a single fault within the system will not preclude the reactor protective system, engineered safeguards protective system and the engineered safe-guards from performing their safety functions.
8.2.2.9 120-Volt A4: Essential Power System (Vital Buses - Figure 8.2-3)
The 120-volt a-c essential power system will be designed to provide a reli-able source for essential power, instrumentation, and control loads under all operating conditions.
The system will consist of four 120-volt as bus sections, each supplied from a static inverter.
Each static inverter will be supplied from a separate 125-volt d< system bus.
System low voltage or
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frequency will be annunciated in the control room.
Each of the four bus sections will include a distribution panel.
- 8. 2. 2. 9.1 Single Failure analysis of the 120-Volt Vital Power Buses The system is arranged such that any type of single failure or fault will not preclude the reactor protective system, engineered safeguards protec-tive system and engineered safeguards from performing their safety func-tions. This is evident in Figure 8.2-3 since there are four independent l
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buses available to the unit, and a single failure within the system can
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involve only one bus.
8.2.2.10 120-Volt AsC Unregulated Power System (Figure 8. 2-3)
A low voltage 120-volt a-c power system will be provided to supply instru-mentation, control, and power loads requiring unregulated 120-volt a-c power.
It will consist of distribution panels and 480-120-volt transformers fed from motor control centers.
8.2.2.11 Lighting Lighting is provided to permit the safe performance of operating and main-tenance duties. Adequate emergency lighting is provided in essential opera-ting areas to permit the safe performance of emergency operating duties.
The switchyard and plant perimeter lighting is supplied at 277/480 volts.
Plant normsl lighting is supplied at 120 volts and 277/480 volts; and emer-2 gency lighting is supplied at 120 vo'*s, all ied from the main lighting distribution switchboard. A portion of the a-c lighting switchboard is automatically ' transferred to the 125-volt d-c battery system, providing emergency backup lighting to vital areas.
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bb Amendment 2 8.2-7
6 TABLE 8.2-1 SINGLE FAILURE ANALYSIS FOR Tile 125-VOLT D-C SYSTEM Component Malfunction Comments and Consequences J
1.
125-Volt IM: Power Loss of power from one The 125-volt d-c bus would continue to Supply - Battery receive power from its respective battery Charger without interruption.
A standby charger can be manually placed in service.
2 125-Volt D-C Loss of power from one The 125-volt d-c bus will be supplied from Batteries the battery charger.
3.
125-Volt D-C Bus 1A, Loss of power from one The four 125-volt d-c control panelboards are g
e Bus 1B, Bus 1C or Bus arranged such that loss of one bus will not 10 preclude safe shutdown or operation of engi-2 neered safeguard systems.
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125-Volt D-C Bus IA, Grounding single bus or The 125-volt d-c system is an ungrounded electrical y
Bus IB, Bus 1C or Bus conductor system.
Ground detector equipment will be provided n
ID to tr.onitor and alarm a ground anywhere on the 125-l1 volt d-c system.
A single ground will not cause any g
malfunction or prevent operation of any safety system.
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5.
125-Volt D-C Bus 1A, Gradual decay of voltage Each 125-volt bus will be monitored to detect the g
Bus IB, Bus 1C or Bus on one bus voltage decay on the bus and initiate an alarm at g
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a setting above a voltage where the battery can a
j u deliver its power for safe and orderly shutdown of g
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Electrical System Design
( 7~~~'s 8.2.3 EMERGENCY POWER SYSTEM
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8.2.3.1
System Design
When the nuclear unit is installed at Rancho Seco, there will be four sources of power available to the unit. Each source will have various
!2 degrees of redundancy and reliability as outlined below:
a.
As described in 8.2.2.3, all of the normal power supply to l3 plant auxiliary loads will be provided through the 4160-volt l1 unit auxiliary transformer connected to the generator bus, I
and all nuclear service auxiliary load will be provided by l3 4160-volt start-up transformer No. 2, which is connected to the 230 kv system.
During normal operation all of the 6900-2 volt auxiliary load will be provided by the 6900-volt unit auxiliaries transformer. However, the unit auxiliaries transformers as well as the start-up transformers will be 3
sized to carry full plant auxiliary loads.
Upon separation of the unit from the 230 kv system with no inplant emergency, neither the reactor nor the turbine will be tripped. Load will be abruptly reduced to that required l2 by the plant auxiliary demand, and the unit will continue in I
service. At.tomatic provisions for abrupt loss of load are covered in section 7.2.3.4 The unit auxiliary transformers 2
A will thus supply power except when:
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(1) The nuclear generating unit is not running.
(2)
There is an equipment failure which prevents continued operation of the turbine-generator.
b.
If power is not available from the unit auxiliary transformers, y
it will be obtained from the start-up transformers. Start-up transformer No. 2 will be connected to 4160 volt nuclear l2 service buses 1B and IC.
The 4160-volt tap on 6900-volt winding of start-up transformer No. I will be connected t 3
4160-volt nuclear service Bus 1B by automatic transfer on loss of start-up transformer No. 2.
c.
Power to the start-up transformers will be provided by a separate 230 kv connection from each bus which in turn will 2
be supplied from any one of five 230 kv transmission circuits
'l connected to the two buses.
The start-up transformers will supply power except when:
(1) There is a 230 kv system blackout.
(2) Multiple equipment failure.
l2 (3) Connections to the 230-kv switchyard fail.
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340 Amendment 3 8.2-9
Electrical System Design d.
Upon loss of all sources of power described in (a) through 2I (c) above, power will be supplied from tw'o automatic, fast start-up emergency diesel engine generators.
2,l These generators will be sized so that' either one can carry
,l the total required engineered safeguards load for DBA on the main unit, including plant blackout shutdown requirements.
A preliminary estimate of the rating of each emergency genera-2I tor is 2,850 kw.
1i 21 Each emergency generator will feed one nuclear service 4160-volt bus.
Each unit will be located in a separate room 2lI in the reactor auxiliary building; separated by Class I fire-proof walls.
There will be no interconnecting piping, wiring, or ventilation ducts through these walls.
Each diesel will be air started by its own independent system which will include tanks, piping and valving. Air will be supplied by che plant air system, check valves at each tank 1
Will prevent back flow in the event the main air supply is lost. The air tanks will be sized to be capa'.sle of two sequential starts without recharging.
Each diesel will have its own independent lubricating system and will be provided with a fuel tank with sufficient capacity for approximately two hours full load operation. The level in j
each tank will be maintained automatically.
Two independent i
emergency fuel tanks, each with a 7 day fuel supply, and each with dual transfer pumps, will be located remotely from 3
each other on opposite sides of the plant.
They will supply fuel automatically to the individual diesel generator fuel tanks.
2l The diesel generators will be air cooled using two indepen-1l dent cooling systems.
2l Control signals for the two diesel generators will be in 1l separate cables, routed through separate trays and conduits.
2l This separation will also be maintained at the switchgear and at the control boards.
1 Each diesel generator will be protected by a permanently installed fire protection header system. A rate of tempera-ture rise detector, which will actuate a fire alarm signal locally and in the control room, will be provided for each 2l of these two systems.
Each diesel generator will be started upon the oc urrence of any of the following incidents:
1 (1)
Initiation of safety injection operation.
2l (2) Loss of external power from 's,tartup tra'nsformers.
341 8.2-10 Amendment 3
Electrical System Design
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Loss of voltage on the 4160-volt nuclear service buses l2 -
wAth which the emergency generators are associated.
The sequence of operation following the diesel generator starting signal will be as follows:
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Step 1.
Automatic tripping of all breakers on the bus, including bus tie breakers.
Step 2.
After the units come up to speed and voltage, the emergency generator breakers will auto-matically close.
Step 3.
Manual starting of equipment as required for safe plant operation.
If there is a requirement for engineered safeguard systems l2 operation coincident with the loss of voltage on the 4160-volt bus, step 2 will be automatically followed by the sequential starting of safeguards equipment.
The sequential-loading of the diesel-engine generator with engineered safeguard auxiliaries will be accomplished by the l2 use of a high speed excitation system and by using machine voltage and excitation recovery as initiating events for n
('v) starting of the next auxiliary in the chain.
Loads will be
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added in blocks within the diesel engine generator's capabil-ity of accepting them.
Timers will be used to (1) prevent a race with the next auxiliary in the chain, and (2) initiate tripping of a component which fails to start within a reason-able time, thereby preventing the sequence from stopping.
When starting the diesel-engine generators from a dead start, the safety injection systems will be in operation within 25 seconds.
e.
All of the power sources that supply power to the 4160-volt bus sections which serve the engineered safeguards' auxilia-ries and reactor protective systems will pe arranged so that a failure of any single bus section will not prevent the respective systems from fulfilling their protective functions.
f.
Postulating Loss of Off-Site Power Combined With a Design Basis Accident Single Failure Analysis for the Engineered Safety System 1
Component Malfunction Comments & Consequences (1) Nuclear Short circuit (With the loss of 2
Service external power each
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4160 Volt Bus 4160 v bus will be i1 1B or 1C isolated from the l2 others.) The l1 00, 342 Amendment 3 8.2-11
Electrical System Design G,')
1 Component Malfunction Comments & Consequences 2
rresponding 480 volt nuclear service switchgear and motor control cen-ter will be lost, how-1 ever, there are redun-dant valves and auxil-iaries connected to 3l the remaining switch-gear sections and motor 1
cc;ntrol center for safe shutdown.
(2) Nuclear Service Short Circuit (a) The f aulted bus will 2
480-Volt Bus be isolated by pro-1]
1B or 1C tective circuit breaker 3l action so that no 480-volt auxiliaries will 1
be lost.
2I (b) One 480-volt nuclear ser-vice switchgear section and motor control center will be lost.
Suffi-cient redundant auxil-1 aries will be fed from
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the remaining switch-1 gear and motor control center. The d-c feeds to two battery chargers will be lost, but the respective battery will carry the load.
2l (3) Motor Control Short Circuit The faulted motor con-Center Bus trol center will be isolated by protective circuit breaker action.
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The a-c feeds to two battery chargers will be lost, but the respective battery I
will carry the load.
No protective function will be lost and suf-ficient redundant valves and auxiliaries will be operative for safe shutdown.
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8.2.12 Amendment 3
Electrical System Design
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Component Malfunction Comments & Consequences w/
(4) Any Bus or Open circuit The consequences could, l2 Feeder at the most, result in the loss of one 4160-volt bus and the cor-responding 480-volt bus and motor control center.
Sufficient y
redundant valves and auxiliaries would remain in service for safe shutdown.
(5) Nuclear Service Short circuit There are two circuit j
2 480-Volt Bus across and to breakers between 480-volt Tie Circuit ground nuclear service buses Breaker 1B and IC.
Any such f'ailure would be iso-lated from the unfaulted y
switchgear by the second circuit breaker.
The remainder of the analysis would be identical to 2.
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(6) Diesel Gen-Failure The consequences would i
erator A or B be identical to those of 1 above.
Sufficient redundant valves and auxiliariec would remain in service for 1
sa fe shutdown, fed from the remaining diesel generator.
2 (7) Any Engineered Failure Separate undervoltage Safety Feature detection, relaying Device.
and logic are provided for each diesel gener-ator and the corres-ponding 4160-volt and 480-volt switchgear I
buses. The maximum result of a failure 1
of any component would be that of loss of one diesel generator sys-tem.
Sufficient aux-iliaries would remain
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in service to safely shutdown the plant.
Amendment 2 8.2-13
l Electrical System Design Component Malfunction Comments & Consecuences 1
2l (8) Any Load Malfunction (a) There are two circuit Shedding or breakers between buses 1
Connecting and failure of one to Circuit open or undesired closing Breaker of one will have no ef fect.
3l Failure-to-trip the incoming circuit breaker will result in lockout of the corresponding diesel generator.
(b) Malfunction of a load I
shedding circuit breaker would result in the inclusion of that load in the first block of equipment started by the corresponding diesel generator.
Each diesel generator will be capable of starting any two safe-2 guards motors simultane-ously.
The other diesel generator system would i
not be affected.
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(c) Failure-to-close of one 1
diesel generator breaker would result in the loss of a redundant sytem, as described in 1 above.
2 (9)
Battery 1A, Loss of one If the loss of a IB, 1C or ID battery occurred dur-ing the first 10
. seconds after initia-tion of diesel engine starting, the d-c feed
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to one inverter, one channel of reactor 1
Protection and some instrumentation cir-cuits would be lost during this period but would be recovered when the a-c buses reenergize on closing
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545 8.2-14 Amendment 3
Electrical System Design (7'N Component Malfunction Comments & Consequences t
the generator breaker.
Since the reactor pro-tection system operates on a two out of four y
basis, the loss of one channel would not cause an inadvertent trip.
The d-c feed to one 4160-volt nuclear ser-2 vice bus would be lost thereby preventing closure of the diesel 1
generator breaker.
The consequence would be as described in 7C l2 above.
If the loss of a battery occurred after the diesel gen-erator breaker was closed, the battery charger would catzv the above mentioned loads.
346 Ot.
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Amendment 2 8.2-15
Electrical System Design 8.2.3.2 Diesel Generators 2l The capacity of each of the two diesel generators will be adequate to supply 100 percent of the 4160 and 480-volt engineered safeguards and emergency power requirements fcr safe plant shutdown independent of unit and 230 kv sources of power.
The units will be sized for the maximum steady state load under DBA and/or blackout conditions including the capacity to supply motor starting inrush requirements.
The following loads will be automatically applied in the sequence shown in the event of a loss-of-coolant accident coincident with a loss of power:
2' Loading Sequence
- Description Load Block 1 1 - Make-up pump 700 hp 3
Energize at:
1 - Decay heat removal pump 400 hp 0 + 15 sec.
Isolation valves, emergency air compressor, air compressor, air conditioner, etc.
150 hp 2 - Battery chargers @ 30 kva 60 kva Block 2 2 - Reactor building emergency air cooler @
Energize at:
100 hp 200 hp 0 + 25 sec.
1 - Reactor building spray pump 250 hp 2
Block 3 1 - Nuclear Service raw water pump 450 Energize at:
1 - Nuclear Service cooling water pump 200 hp
)
0 + 40 sec. 2410 hp Block 4**
1 - Auxiliary feed pump started manually if 1000 hp required Total 3410 hp
- Diesel started at' time 0 + 1 sec.
- This motor not required oq.a DBA condition.
The above represents 2800 kw for the most heavily loaded bus and will not exceed the diesel-generator nameplate rating. When both diesel-generators are running the interlocking will be provided such that the tie breakers 2
connecting the engineered safeguard buses cannot be closed to parallel the generators.
In addition, provision will be made to prevent. paralleling the diesel with the exchange system when the two are out of phase.
8.2.3.3 Station Batterv The capacity of each 60-cell station battery is adequate to supply the 125 volt d-c power and control requirements for safe plant shutdown inde-pendent of outside sources of power and to provide control power to re-energize the plant auxiliary systems upon restoration of the start-up source.
O,1 s
a 347
- m 8.2-16 Amendment 3 J
/
1 Electrical System Design I)^'T 8.2.3.4 Post Accident Operation 1
~
Electrical components within the containment (reactor building) required for proper functioning of the engineered safeguard systems are as follows:
l2 a.
Electric motor isolation valves.
I b.
Reactor building emergency cooling fan motors.
c.
Instrument cables, d.
Power and control cables.
e.
Penetrations f.
Reactor building sump level instruments.
g.
Pressure Switches.
8.2.3.4.1 Component Operation The valves must operate long enough to isolate the reactor building.
The emergency cooling fans must operate to cool the reactor building environ-ment following the accident.
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The reactor building sump level instruments must operate following the
((,,
accident.
Cables associated with each of the above equipment need to operate as long as the equipment is required.
All of this equipment will be designed to perform its required function during the reactor building i
design basis accident.
It is expected that the final analysis of operating requirements for engineered safeguards equipment will indicate that the reactor building emergency cooling fans, the reactor building sump level instruments and associated cabling will be the only equipment required to operate for an appreciable time in post accident ambient conditions.
8.2.3.4.2 Testing' The instruments will be of a type which have demonstrated capability to perform under the environments specified.
[2 The fan motors to be furnished with the reactor building emergency cooling fans will be designed so that windings and bearing surfaces are protected against the accident ambient. Motor housings will withstand 60 psi and 1
will be provided with an air-to-water heat exchanger to be supplied from the same source as its accompanying ventilating cooling coil. The heat exchanger will be selected to maintain a low humidity internal ambient with t'~N
,(kl 1
I
' Amendment 2 8.2-17
\\
Electrical System Design safe winding temperatures.
By proper selection of insulation type and allow-able temperature rise, plus a rating in excess of load, the motor operating
/
temperature would be at or near the accident temperature.
Bearings will be of a seal type which will withstand the pressure pulse and will be cooled along with the motor internal air.
Purchase specifications will require that tests have been performed on duplicate components of equipment and cable representative of those items required for post accident operation.
Certified test data will be requested prior to purchase.
The tests performed will simulate the actual environmental conditions during the 40 years of plant life plus the added exposure of an accident.
The length of accident exposure will depend on the length of time that the component is required to function after the accident. All components must survive the cumulative effects of all tests while performing at rated 2
current and potential.
Gamma radiation tests will be performed on all components consistent with total exposure determined on the basis of 40 year plant life and accident time.
Pressure-temperature transient test will be performed on all components in a test chamber having an initial condition of 120 F ambient temperature and atmospheric pressure.
Steam will be admitted into the chamber at a rate simulating the temperature and pressure transient of an accident with a pressure rise to 150 percent of containment design pressure.
T)
All components listed above will be subjected to the tests described herein.
The tests to be performed will be specified and included as a requirement of the equipment and material supply contracts. Certified test reports of equivalent equipment or material subjected to similar tests will be accept-able, subject to approval.
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349 8.2-18 Amendment 2
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1 PLACER COUNTY SMUD HYDRO HYDRO JAYBIRD FOLSOM ~ HYDRO 2 WHITE ROCK 69 d goS [ gAN CAMINO g GENERATING SOURCES CONNECTED TO 230 KV SYSTEM )LD BUS GE NERATION MW (NAMEPLATE) 'L ELVERTA FOLSOM HYDRO 170 ELVERTA & HEDGE SMUD HYORO 630 (6 PLANTS) RIO OSO AND PITT RIVER AND 2007 (18 PLANTS) TABLE MOUNTAIN FEATHER RIVER HYDRO GOLD HILL PLACER COUNTY HYDRO 192 (4 PLANTS) COTTONWOOD KESWICK, SHASTA, 833 (5 PLANTS) KESWICK AND TRINITY HYDRO BELLOTA MOKELUMNE RIVER HYDRO 298 (6 PLANTS) TESLA PITTSBURG & CONTRA 2554 (2 PLANTS) / COSTA STEAM 230 KV & 500 KV SYSTEMS ARE INTERCONNECTED AT TABLE MOUNTAIN & TESLA, EFFECTIVELY CONNECTING ALL MAJOR WESTERN GENERATING SOURCES INTO THE NETWORK RANCHO SECO (NUCLEAR PLANT) r TO BELLOTA FIGURE 8.2-2 TRANSMISSION SYSTEM $SMun 353 SACRAMENTO MUNICIPt* UTluTY DISTRICT I Amendment 2 [.
,F" w =.d n => z 125 V DC EU >M BATTERY I A hk v o d TO 480 V E -k v NUCLEAR ~ I SERVICE "4 % 9 v MCC IS mm NSSS CONTROLS v NUCLEAR a -a t V SERVICE TO 480 V NUCLEAR >8 POWER [< SERVICE C> m MCC I 6 $n CONTROL ROD g ~ CLUTCH POWER = Z v tw - 8 NSSS CONTROLS v" TO 480 V 2 NUCLEAR ha 5m f " SERVICE H r v 3 MCC #5 U g m w a , S "< 125 V DC j g s BATTERY IB v gan }(( TO 480 V TURB-NORM E ) r U =G' v MCC # 2 W Em L m 5-ga Z y8 125 V DC g ,m< _o TO 480 V Z BATTERY lE v m $G 7 -- TURB-NORM <p O< MCC # 1 U 125 V DC y Z MOTORS U TO 480 V 8H - O v NUCLEAR P 3 ERVICF a
=_ MCC #' 5 o" c o-m 0 TO 480 V w O a 5 NUCLEAR Z + SERVICE 6 0-- 0 MCC # 6 v U TURB PLANT 4 7 Y $5 CONTROLS TO 480 V U - TURB-NORM o_ m q T MCC # 2 m E Oo 125 V DC >gd l l s b< BATTERY IF m< EH 9 Ro -O ] TO 480 V n Ey ) NSSS-NORM 8% MCC # 3 mU ,5" 125 V DC l g BATTERY IC I v - o n TO 480 V Z NUCLEAR i"i EM S,,_.__ v v 1 1 SERVICE g MCC # 6 U m NSSS -4> s ) CONTROLS o.__ J ~ v 'K U CONTROL ROD g g, kj $h j CLUTCH POWER TO 480 V W F mg NUCLEAR [a Me m SERVICE mem -zQ zos c> MCC# 5 m dmh
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e 7"'N 8.3 DESIGN EVALUATION The redundancy of transformers and buses in the plant and the division of load between buses yields a system that will have a high degree of relia-bility and integrity. The physical separation of nuclear service and 12 normal buses, system components and vital circuits will limit or localize the consequences of electrical faults or mechanical accidents occurring at any point in the system. There are four independent nuclear service buses (two 4160-volt and two 480-I2 volt), each with its associated engineered safeguards' equipment that can be connected to the emergency diesel generators. The buses are connected such that if a fault occurs on one bus, that bus will be isolated by open-ing its supply or bus tie breakers, thus leaving the other buses and their required equipment available for use. ~ In case the normal auxiliary power sources are lost, the diesel generators are designed to start automatically and carry essential loads for an indefinite period. The diesel generators each feed a nuclear service bus l2 directly. All of the loads connec':ed to the 125-volt d-c system, except the motor loads can be supplied by the battery chargers. The chargers will be supplied from multiple sources of plant auxiliary power including the diesel generators. Each battery system is located in separate ventilated rooms having concrete ( block walls. (C
- 8. 3.1 EVALUATION OF THE PHYSICAL LAYOUT The electrical distribution system equipment will be located in such a way th at the vulnerabilicy of vital circuits to physical damage as a result of accidents will be minimized.
The proposed locations are as follows: a. The unit auxiliary and start-up transformers will be located out of doors, physically separated from each other. Lightning arrestors will be used where applicable for lightning protec-tion. Transformers will be well spaced to minimize their exposure to fire and mechanical damage, b. The unit normal reactor / turbine auxiliary 6900-volt switchgear, 4160-volt switchgear, and 480-volt switchgear will be located in four separate rooms to minimize exposure to mechanical, fire, l2 and water damage. This equipment will be properly coordinated electrically to permit safe operation of the equipment under normal and short circuit conditions. The two sets of engineered safeguards equipment switchgear will c. be located in separate rooms in order to minimize exposure to mechanical, fire, and water damage. This equipment will be n coordinated electrically to permit safe operation under normal i and short-circuit conditions. 356 Amendment 2 8.3-1
Design Evaluation d. 480-volt motor control centers and load centers will be located in the areas of electrical load concentration. Those associated with the turbine-generator auxiliary system in general will be located below the turbine-generator operating floor level. Those associated with the nuclear steam supply system will be located in the auxiliary building. Motor control centers will be located in areas which minimize their exposure to mechanical, fire, and water damage. e. The plant batteries and associated chargers and inverters will be in separate rooms in order to minimize vulnerability to damage from any source. f. Nonsegregated, metal-enclosed 4160- and 480-volt buses will be used for all inter-bus connections where large blocks of cur-rent are to be carried. This metal-enclosed bus will be routed in such a manner that its exposure to mechanical, fire, and water damage will be minimized. 8.3.2 ACCIDENTAL PHASE REVERSAL Before plant operation, phase reversals due to inadvertent misconnection will be found by tests such as jogging motors. During plant operation it is not credible that an accidental phase reversal will occur since this involves the disconnecting and connecting of two leads of a three phase system. I The engineered safeguards systems, makeup and purification (high pressure 1 injection), decay heat removal system and reactor building spray system were analyzed for the consequences of an accidental phase reversal at an emergency bus under accident conditions. For this analysis it was assumed that the consequences as a result of a phase reversal would be the reverse rotation of a pump or the opposite movement of a motor operated valve from its intended direction. The analysis presented in Table 8.3-1 is based on the assumption that a major loss-of-coolant accident had occurred and that a phase reversal at an emergency bus exists. It is not credible that the diesel can be started backwards since the starting air is injected into the cylinders when the pistons are beyond top dead center. 357
- llll, 1
J 8.3-2 Amendment 2
Design Evaluation '7"'N ( !. .s .w.< TABLE 8.3-1 PHASE REVERSAL FAILURE ANALYSIS 3 Component Failure Comments & Consequences
- a. High Pressure Injection System 2
High Pressure Reverse rotation Standby pump is available Injection Pump of pump for operation
- b. Decay Heat Removal System 1_
Decay Heat Pump Reverse rotation The remaining pump will l2 of pump deliver required fl ow Electric Motor Valve remains Two lines and valves are Operated Valve closed provided Permitting Suction from Reactor Build-ing Sump
- c. Reactor Building Spray System
,,m, (() Reactor Building Reverse rotation Flow and cooling capacity Spray Pump of pump reduced to 50 percent of 1 design. In combination with emergency coolers, 150 percent of total design requirements is still provided. Electric Motor Valve remains Second header delivers Operated Valve closed 50 percent flow. See in Spray Header Comments for C-1 above. Motor driven emergency safeguard pumps all have redundancy. If one pump runs in reverse, it will pump at reduced head against its closed check valve, and the resultant ammeter reading will be lower than the normal pumping load. l2 ~~ Phase reversal after initial check out is in itself a remote possibility but should it ever occur, the consequences are in no case serious as 1 indicated from the above analysis. . r~ ( Uu_a58 8.3-3 Amendment 3
8.4 TESTS AND INSPECTIONS Periodic ' operating tests and routine maintenance will be performed on the s diesel generators, the emergency lighting system and the charger and inverter units. This will include fast starting of the diesel generators and synchronizing with the station auxiliary system to operate at full load for approximately 30 minutes. 4 A program of regular inspections and functional checks of equipment and protective devices common to normal central station practice will ensure the operability of auxiliary distribution system components. The 230 kv circuit breakers will be inspected, maintained, and tested as follows: .~ a. Transmission line circuit breakers will be tested on a routine basis. This can be accomplished without removing the transmis-sion line from service. b. Generator circuit breakers can be tested with the generator in service. Transmission line protective relaying will'be tested on a routine basis. Generator protective relaying will be tested when the generator is off-line. The 6900, 4160, and 480-volt circuit breakers may be removed to [_ _ the " test" position and tested by closing and opening the circuit breakers with the unit of f-line. Circuit breakers and contactors for redundant d circuits may be tested in service without interferring with the operation w of the station. Contactors for motor operated isolatirs valves will be tested with the unit off-line. The un3 rounded d-c system will have detectors to indicate when there is a ground existing on any portion of the system. A ground on one portion of the d-c system will not cause any equipment to malfunction. D-c control circuits will be designed in such a manner that the de-energized condition will lead to the desired equipment alignment to meet accident conditions. Grounds will be located by a logical isolation of individual circuits con-nected to the faulted system, while taking the necessary precautions to maintain the integrity of the vital bus supplies, a 4' %ME , o) t Or 389 8.4-1 l}}