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DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.1 Page 8.1-1 of 8.1-4
8.1 INTRODUCTION
8.1.1 DESIGN BASIS The Facility electrical system and the 345 kV switchyard are designed to reliably function and supply power. The electrical system is divided into buses and subsystems to minimize the effects of any electrical fault and maximize the availability of offsite power sources.
The portion of the Facility electrical system which supplies the Facility engineered safeguards will be referred to as the engineered safeguards electrical system. The engineered safeguards electrical system is housed in CP Co Design Class 1 structures in accordance with Subsection 5.9.1.1 and was formerly a Class 1E service as defined in IEEE 308-1978.
Following the implementation of Permanently Defueled Technical Specifications, the Class 1E design requirements of 10 CFR 50.49 are no longer applicable, in accordance with 10 CFR 50.49(a) and 10 CFR 50.82(a)(1). The following sections may refer to components as Class 1E, however, this is considered historical information and is no longer a design requirement.
Because the facility was designed and constructed prior to IEEE 308 requirements, some components/systems that were designated as Class 1E will not have all the necessary attributes to be certified as meeting Class 1E qualifications. Although original facility components/systems were designed and qualified (by analysis) to provide safety related functions, they may not meet all of the design criteria and testing requirements of IEEE 308 and other standards incorporated by reference therein.
The designation of these components/systems as 1E assured that proper safety and quality reviews of function are performed prior to maintenance or replacement. When modifications are performed requiring equipment upgrades, change of function, etc, the new design is evaluated to determine whether upgrading to later standards including IEEE 308 would be practical and warranted. Systems and components originally designed and installed in conformance with 1E requirements will be maintained at least to those standards unless future changes in system/component function make classification as 1E no longer necessary.
Evaluation of safety-related electrical equipment (whether or not part of the Facility electrical system) for seismic service qualifications is discussed in Subsection 8.1.4.
Safety-related electrical equipment not part of the Facility electrical system is covered by Chapter 7.
The system is designed to the two channel concept, defined as two independent electrical control and power systems supplying redundant
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.1 Page 8.1-2 of 8.1-4 engineered safeguards load groups. The engineered safeguards electrical system is intended to meet all requirements identified in IEEE 279-1971 and IEEE 308-1978. Other standards such as IEEE 323-1974, IEEE 344-1975, IEEE 384-1977 and IEEE 383-1974 are intended to be met within the limits of practicability and consistent with original design features. With the implementation of National Fire Protection Association (NFPA) 805, new cables must meet IEEE 383, or equivalent, flame test requirements.
During the Systematic Evaluation Program, NRC and CPCo staff reviewed as built electrical design against licensing criteria current at the time. The purpose of the review was to determine if the designs in older plants provided a measure of safety comparable to that provided by design in newer plants; or as a minimum, were acceptable based on facility specific challenge and response capability. The adequacy of as built characteristics designed to promote safety related availability such as channel separation, isolation and independence was evaluated. In many cases, these reviews concluded that although the existing as built design did not feature the specific configuration required by current criteria, the design was considered acceptable.
Summaries of these reviews are found in NUREG 0820, the NUREG 0820 Supplement, and individually docketed SEP submittals and related NRC Safety Evaluation Reports.
Water spray fire protection is provided for raceways in areas described in the Fire Safety Analyses (Section 9.6.3).
8.
1.2 DESCRIPTION
AND OPERATION The Facility electrical system is shown on Figure 8-1, Facility Single Line Diagrams. The 345 kV switchyard is shown on Figure 8-2, Substation Single Line Diagram.
Seven transmission circuits connect the site switchyard to the power system grid with two circuits on each of three sets of towers and the remaining circuit on a fourth set of towers. The fourth set of towers also includes the one circuit which connects the switchyard to a nearby natural gas fired generating station. The site switchyard is connected to the Facility electrical system using two circuits; one underground and one overhead. The underground and other overhead circuit supply offsite power to the Facility electrical system.
The power source for the Facility 4,160-volt auxiliaries is 345 - 4.16 kV Start-Up Transformers 1-1 and 1-3.
2,400-volt facility loads are supplied from either the offsite power source 345 -
2.4 kV Safeguard Transformer 1-1 or the offsite power source 345 - 2.4 kV Start-Up Transformer 1-2.
The Facility auxiliary electrical system includes four 4,160 volt buses, four 2,400 volt buses, and several 480 volt load centers and 480 volt motor control
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.1 Page 8.1-3 of 8.1-4 centers. Certain 480 volt load center buses receive power from load center transformers energized from the 2,400 volt buses. Other 480 volt load center buses receive power from load center transformers energized from 4,160 volt Buses 1A, 1F and 1G. The 480 volt motor control centers are connected to the 480 volt load center buses.
Four preferred ac systems are energized from the station battery systems through inverters to power instrument and control loads. Two station batteries and four chargers supply the Facility 125 volt dc systems.
The nonvital instrumentation and controls are supplied from a 120 volt ac instrument bus. The instrument bus is normally supplied from one of two 480-120 volt transformers, each transformer being connected to a separate 480 volt motor control center. The transfer to the alternate source is automatic.
The engineered safeguards system includes two 2,400 volt buses (1C and 1D), four 480 volt load centers (11, 12, 19 and 20), eight motor control centers (1, 2, 21, 22, 23, 24, 25 and 26), two dc distribution centers, four battery chargers, two batteries, four preferred ac buses, four inverters and two diesel generators. The engineered safeguards electrical system is designed on a two-independent-channel basis. Each channel is capable of furnishing power to equipment load groups. The system is provided with test facilities and has alarms to alert the operator when certain components trip or malfunction or are not available or operable.
Each channel of the engineered safeguards electrical system has access to the following power sources:
- 1. The offsite power source (Safeguard Transformer 1-1)
- 2. The offsite power source (Start-Up Transformer 1-2)
- 3. The emergency power source (one of two onsite emergency generators)
Each emergency generator may energize only its respective channel buses.
8.1.3 DELETED 8.1.4 SEISMIC QUALIFICATION OF ELECTRICAL EQUIPMENT The seismic design criteria for safety-related electrical equipment, instrumentation and raceways are provided in Section 5.7. Historic information regarding Seismic Category I (Regulatory Guide 1.29) and Class 1E electrical equipment and raceways are listed in Table 5.2-4.
Electrical equipment anchorage and raceway supports for the components listed in that table have been redesigned in the period 1979 to 1981 as Seismic Category I as defined in Regulatory Guide 1.29. Seismic adequacy
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.1 Page 8.1-4 of 8.1-4 of safety-related electrical components is determined by resolution of NRC Generic Letter 87-02 Verification of Seismic Adequacy of Mechanical and Electrical Equipment in Operating Reactors, Unresolved Safety Issue A-46.
8.1.5 DELETED
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.2 Page 8.2-1 of 8.2-3 8.2 NETWORK INTERCONNECTION 8.2.1 DESIGN BASIS The 345 kV switchyard is designed to be the interconnection point between the facility, the nearby natural gas Covert Generating Plant and the power grid system. High-speed clearing of faults and selective reclosing assure maximum availability of power and system grid stability.
8.
2.2 DESCRIPTION
AND OPERATION Description - Switchyard - The switchyard system is shown on Figures 8-2 and 8-9.
The switchyard operates at 345 kV and is arranged to give maximum availability of the power system grid. The equipment is selected to have the capability of isolating system and substation faults with a minimum effect on stability of the power system grid.
The switchyard is designed in a breaker-and-one-half arrangement with two main buses and connections for the Facility safeguard transformer, the Facility start-up transformers, the incoming line from the Covert Generating Plant and seven outgoing lines.
The switchyard 345 kV power circuit breakers, the circuit for the safeguard transformer, and the circuit from the switchyard to the start-up transformers are provided with disconnect switches to permit isolating any power circuit breaker or any circuit from the switchyard buses. See Table 8-1 for ratings and construction of the switchyard components.
High-speed relaying is provided for the circuit from the switchyard to the generator main power transformer and for the two switchyard main buses
("F" bus and "R" bus). The "R" bus relaying includes the circuit from the switchyard to the start-up transformers. The "F" bus relaying includes the circuit to the safeguard transformer. The seven outgoing lines and the incoming line from the Covert Generating Plant are each provided with high-speed relays. In addition, all 345 kV power circuit breakers are provided with relays to trip all adjacent breakers for a failed breaker condition.
Description - Switchyard Control System - The 240 volt and 120 volt, 60 hertz and 125 volt dc switchyard power supplies are shown on Substation Single Line Diagram, Figure 8-9. 2,400 volt Buses 1C and 1E supply the switchyard control power through two 2,400-240/120 volt, 60 hertz switchyard power transformers. Each of the transformers supplies half the 240/120 volt, 60 hertz power requirements for the switchyard; however, either transformer can be connected to carry the total load via a bus tie breaker. The ac load is divided among four power panels; the loss of one power panel will not affect operation of the other three and hence will not jeopardize the total 240/120 volt, 60 hertz auxiliary power in the switchyard. The 345 kV power
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.2 Page 8.2-2 of 8.2-3 circuit breakers have enough air stored in their receivers to permit five breaker operations.
The 125 volt dc auxiliary power is supplied from a 60-cell battery which is located in the switchyard and can supply the switchyard dc power requirements for eight hours without recharging.
Two battery chargers are supplied to keep the battery fully charged and, under normal conditions, to supply the 125 volt dc power requirement. The battery circuit breaker can be used to isolate the battery from the dc power panels in event of a battery fault. The power panels can then be energized by either or both battery chargers. Each battery charger is fed from a separate 240 volt, 60 hertz power panel. The dc load is divided between two power panels; the loss of one power panel will not disrupt all the 125 volt dc auxiliary power in the switchyard.
Operation - The switchyard normally operates energized with all breakers closed. The transmission line breakers are normally controlled remotely by the transmission system owner, and can be controlled locally from the switchyard relay house. A supervisory panel in the Facility main control room monitors circuit breaker status.
Testing - The power circuit breakers may be removed from service and tested. Individual components and partial circuit tests may be carried out while the circuit breakers are carrying load.
The relays are supplied with test switches that will permit the removal of one relay or one set of relays from service for maintenance at any time. Because of the redundancy in the relay circuits, the power circuit will still be relay protected.
8.2.3 DESIGN ANALYSIS The ratings of the 345 kV switchyard have been selected to ensure that the maximum expected fault duty is less than the rating of the equipment.
Reliability is assured by the arrangement of the switchyard which utilizes the breaker-and-one-half scheme. With this scheme, any breaker may be removed from service without affecting the operation of the switchyard.
The switchyard is arranged so that parallel outgoing overhead line circuits are connected to different bays and staggered with respect to buses. If a bay or bus has to be removed from service, only a partial loss of capacity occurs.
The seven transmission lines connecting the grid network to the switchyard and the incoming line from the Covert Generating Plant are routed on four double-line tower poles. Each of the four double-line poles is routed on separate rights of way. See Figure 2-2 for layout of the transmission lines in the vicinity of the Facility.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.2 Page 8.2-3 of 8.2-3 All circuits or portions of the buses and overhead lines have primary and backup relaying. The outgoing lines have three sets of high-speed relays.
The circuit breakers have dual trip coils on separate dc control circuits, and breaker failure relays to trip the adjacent breakers. The two redundant control circuits will operate even with one set of relays out of service.
The control circuit supply is provided by two full-size transformers, each capable of carrying the total load.
The two circuits connecting the switchyard to the onsite Class 1E power system consists of two immediate access circuits. One immediate access circuit consists of a 345 kV to 2,400 volt safeguard transformer, 2,400 volt underground cable and 2,400 volt bus, and cable. The other immediate access circuit consists of an overhead 345 kV transmission line, 345 kV to 2,400 volt start-up transformer and 2,400 volt bus and cable. Each of the immediate access circuits is connected directly to one of the main switchyard buses.
The 2,400 volt cables associated with each immediate access circuit are routed in physically separated locations to the (formerly) Class 1E onsite power system.
8.2.4 TRANSMISSION SYSTEM OWNERSHIP Palisades does not own the transmission system to which it is connected.
Contractual agreements have been executed to assure that transmission system operation, maintenance, and modification activities are appropriately controlled, and that adequacy, availability and reliability of offsite power will continue to satisfy Palisades design and licensing basis.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.3 Page 8.3-1 of 8.3-11 8.3 STATION DISTRIBUTION The safety and seismic classification of the station distribution was revised following the implementation of Permanently Defueled Technical Specifications. Refer to Table 5.2-4 for decommissioned quality and seismic classification.
8.3.1 4,160 VOLT SYSTEM 8.3.1.1 Design Basis The 4,160 volt system is designed to reliably function and supply power to the 4,160 volt station auxiliaries. The system will supply and distribute the 4,160 volt power from the start-up transformers.
8.3.1.2 Description and Operation Description - The Facility's 4,160 volt system is shown on Figures 8-1 and 8-3.
The 4,160 volt system consists of Start-Up (Standby) Transformers 1-1 and 1-3, four 4,160 volt Buses 1A, 1B, 1F, 1G and the incoming and motor feeder circuits.
The 4,160 volt buses consist of metal-clad switchgear with drawout circuit breakers. Wiring in the switchgear and system interconnecting cables pass the vertical flame resistance test in accordance with ASTM D470-59T. With the implementation of National Fire Protection Association (NFPA) 805, new cables must meet IEEE 383, or equivalent, flame test requirements. See Table 8-2 for ratings and construction of the 4,160 volt system components.
The 4,160 volt switchgear is provided with relay protection, grounding and the mechanical safeguards necessary to assure adequate personnel protection and to prevent or limit equipment damage during system fault conditions.
Operation - Power is furnished from the power system grid via the switchyard and Start-Up Transformers 1-1 and 1-3.
Operation of 4,160 volt equipment is effected and monitored in the control room. Breaker status is indicated by red and green indicating lights.
Electrical parameters, such as bus voltage, supply voltage, incoming amperes and motor amperes, are displayed in the control room. Important functions, such as incoming breaker trip, motor breaker trip, bus undervoltage, and failure of bus transfer, are annunciated in the control room.
Provisions are included for testing relays. A faulty relay may be bypassed to permit operation of equipment.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.3 Page 8.3-2 of 8.3-11 8.3.1.3 Design Analysis The ratings of the 4,160 volt system have been selected to ensure that the maximum expected fault duty is less than the rating of the switchgear.
8.3.2 2,400 VOLT SYSTEM 8.3.2.1 Design Basis The 2,400 volt system is designed to reliably function and supply power to the 2,400 volt auxiliary loads from either the offsite source through Safeguard Transformer 1-1, from offsite source through Start-Up Transformer 1-2, or from the emergency diesel generators. Two of the four 2,400 volt buses are an integral part of the Facility engineered safeguards electrical system and were historically identified as Class 1E components; in the defueled condition, Class 1E is no longer applicable (reference Section 5.2.2.7).
8.3.2.2 Description and Operation Description - The Facility's 2,400 volt system is shown on Figures 8-1, 8-3 and 8-4.
The 2,400 volt system consists of Safeguard Transformer 1-1, Start-Up Transformer 1-2, four ungrounded, delta connected 2,400 volt buses (1C, 1D, 1E and safeguard) and the feeder circuits to motors and 480 volt load centers.
2,400 volt Buses 1C, 1D and 1E have access to the following power sources:
- 1. Two immediate access circuits connected to independent offsite power sources.
The first immediate access circuit consists of a 345 kV to 2,400 volt transformer (Safeguards Transformer 1-1) located in the switchyard. The high side of this transformer is connected to the "F" switchyard bus through a motor-operated disconnect switch. The low side of the transformer is connected to the Safeguard Bus located within a Non-Class 1E switchgear house located within the Facility protected area. Connections between the transformer and switchgear house are provided via direct buried cable along the route between the switchyard and protected area. This cable is buried beneath the towers carrying the other immediate circuits to provide for physical separation. The Safeguard Bus is provided to allow for selection of this immediate access circuit.
The second immediate access circuit consists of a 345 kV transmission line between the switchyard and facility site and a 345 kV to 2,400 volt transformer (Start-Up Transformer 1-2) located within the Facility protected area. The high side of this transformer is connected to the "R" switchyard bus
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.3 Page 8.3-3 of 8.3-11 through a motor-operated disconnect switch. The low side of the transformer is connected directly to the 2,400 volt bus incoming breakers.
The low side of 2,400 volt Station Power Transformer 1-2 is connected to the Safeguard Bus via an enclosed bus duct. The Safeguard Bus provides for connections to the first immediate access circuit as the source of power to the 2,400 volt buses.
The Safeguard Bus also provides for connection to the first immediate access circuit and allows for selection of the first immediate access circuit or the delayed access circuit as the source of power to the 2,400 volt buses.
See Table 8-3 for ratings and construction of the 2,400 volt system components.
The 2,400 volt buses consist of metal-clad switchgear with drawout circuit breakers. Wiring in the switchgear and system interconnecting cables pass the vertical flame resistance test in accordance with ASTM D470-59T. With the implementation of NFPA 805, new cables must meet IEEE 383, or equivalent, flame test requirements.
The 2,400 volt switchgear is provided with relay protection, grounding alarm and the mechanical safeguards necessary to assure adequate personnel protection and to prevent or limit equipment failure during system fault conditions. Single grounds will not impede operation of the system.
Two of the 2,400 volt buses, 1C and 1D, supply power to engineered safeguards loads in addition to normal Facility loads and are part of the engineered safeguards electrical system. These engineered safeguards system 2,400 volt buses are designed to withstand Consumers Design Class 1 seismic acceleration forces per Section 5.7 without malfunction.
Following permanent defueling, 1C and 1D are maintained as Seismic Category 1.
The engineered safeguards electrical system is divided into two channels so that multiple pieces of equipment with a common function are fed from opposite channels.
A separate emergency diesel generator supplies each of the emergency 2,400 volt buses (1C and 1D) and each bus supplies redundant equipment or loads consistent with the two-channel power concept.
The emergency buses are physically separated by being located in separate rooms within the Consumers Design Class 1 portions of the auxiliary building.
Separation is maintained between the circuits of the two buses.
Electrical feeder cables from the emergency generators to the 1C and 1D buses and equipment motors are installed within the Consumers Design Class 1 portion of the auxiliary building or in underground ducts.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.3 Page 8.3-4 of 8.3-11 Operation - Power to 2,400 volt Buses 1C, 1D and 1E is normally provided via the immediate access circuit (Safeguard Transformer 1-1) powered from the switchyard "F" bus. Upon loss of this circuit, a fast transfer is provided to the immediate access circuit (Start-Up Transformer 1-2) powered by the switchyard "R" bus. Upon loss of both immediate access offsite power sources the 2,400 volt Buses 1C and 1D are energized from the diesel generators.
Operation of 2,400 volt equipment is normally effected and monitored in the control room. Breaker status is indicated by red and green indicating lights.
2,400 volt breakers on Buses 1C and 1D are also capable of being controlled from the switchgear. Breaker 152-311, feeder to the Service Building Expansion, is not controlled or monitored in the Control Room.
Breakers 152-103, 107, 108 and 110 have special remote/local isolation switches to allow control in the event of fire in certain areas of the Facility.
These switches are provided to ensure operability of safe and stable conditions equipment per 10 CFR 50.48 and NFPA 805. Post-fire safe and stable capability is further enhanced by a remote/local switch provided for Breaker 152-106 which facilitates control of startup power (where available) to Bus 1C.
Important control circuits, such as bus transfer and load shedding, have white indicating lights to show circuit availability. Undervoltage relays initiate an alarm upon loss of potential. Electrical parameters, such as bus voltage, supply voltage, bus amperes and motor amperes, are displayed in the control room. Important functions, such as incoming breaker trip, motor breaker trip, bus undervoltage, bus ground, loss of incoming breaker 125 volt dc control voltage, and failure of bus transfer, are annunciated in the control room.
Provisions are included for testing relays. A faulty relay may be bypassed to permit operation of equipment.
8.3.2.3 Design Analysis The ratings of the 2,400 volt system have been selected to ensure that the maximum expected fault duty is less than the rating of the switchgear.
8.3.3 480 VOLT SYSTEM 8.3.3.1 Design Basis The facility 480 volt system is designed to reliably function and supply power.
Four load centers and eight motor control centers are an integral part of the Facility engineered safeguards electrical system and were identified as Class 1E components. The system is designed to the two-channel concept wherein independent electrical controls and power systems supply redundant 480 volt engineered safeguards load groups.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.3 Page 8.3-5 of 8.3-11 8.3.3.2 Description and Operation Description - The Facility 480 volt system is shown on Figures 8-5 and 8-6, Single Line Meter and Relay Diagrams, 480 Volt Load Centers and Motor Control Centers.
The facility 480 volt system is divided into load center buses and motor control centers. Power for each (except one) load center bus is supplied from a separate 2,400-480 volt station service transformer. The transformers fed from the 2,400 volt system are arranged so that each transformer of a double-ended load center unit is fed from a different 2,400 volt bus. Load center Bus 17 is fed from 4,160 volt Bus 1A through a 4,160-480 volt station service transformer.
The cooling tower 480 volt system shown on Figure 8-5 is divided into load center buses. Power for each load center bus is supplied from a separate 4,160-480 volt station service transformer.
Power for the motor control centers is supplied from the load center buses.
Station Power Transformers 11, 12, 19 and 20, corresponding Load Centers and Motor Control Centers 1, 2, 21, 22, 23, 24, 25 and 26 are an integral part of the engineered safeguards electrical system. This equipment is arranged into two channels so that multiple pieces of equipment with a common function are fed from opposite channels.
The 480 volt buses consist of metal-enclosed drip proof switchgear with drawout circuit breakers. The motor control centers are NEMA 1 enclosures with drip hoods installed on the majority of the equipment. Drip hoods/shields were not installed on Motor Control Centers 1 and 2 because of space limitation. As an alternative, the metal seams at the top of these motor control centers were sealed with RTV sealant to make them waterproof from the fire sprinklers. Wiring in the switchgear and motor control centers and system interconnecting cables pass the vertical flame resistance test in accordance with ASTM D470-59T or IPCEA S-61-402, Section 6.5. With the implementation of NFPA 805, new cables must meet IEEE 383, or equivalent, flame test requirements. See Table 8-4 for ratings and construction of the 480 volt system components.
The 480 volt switchgear and the motor control centers supplying engineered safeguards loads are designed to withstand Consumers Design Class 1 seismic acceleration forces per Section 5.7 without malfunction. Following permanent defueling, only certain 480 volt switchgear and MCCs are maintained as Seismic Category 1.
The 480 volt load centers and motor control centers are solidly grounded Y connected and are provided with the mechanical safeguards necessary to
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.3 Page 8.3-6 of 8.3-11 assure personnel protection and to prevent or limit equipment damage during system fault or overload conditions.
The 480 volt load center breakers are equipped with thermal magnetic or solid state trip devices. Motor control centers are equipped with thermal magnetic breakers for nonmotor loads, and magnetic breakers and starters with thermal protection for the motor circuits.
Starters in the 480 volt motor control centers may be controlled from the control room, from local panels, or both. Status of these starters may be indicated by lights in the control room, at the local panels, or both. Other starters may be controlled at the motor control centers or at local panels.
Motor overload condition for selected loads is annunciated in the control room.
The 480 volt engineered safeguards electrical system is installed in Consumers Design Class 1 portions of the auxiliary building.
8.3.3.3 Design Analysis The ratings of the 480 volt system have been selected to ensure that the maximum expected fault duty is less than the rating of the switchgear.
The 480 volt buses which are part of the engineered safeguards system are installed in Consumers Design Class 1 portions of the auxiliary building.
8.3.4 SECTION DELETED 8.3.5 DC AND PREFERRED AC SYSTEMS 8.3.5.1 Design Basis The dc and preferred ac systems are designed to furnish continuous power to the Facility instrumentation and control systems. The power supply is continuous even during disturbances in the auxiliary electrical system.
8.3.5.2 Description and Operation Description - General - The 125 volt dc and 120 volt preferred ac systems are shown on Single Line Meter and Relay Diagram, Figure 8-7. Equipment was designed to withstand Consumers Design Class 1 seismic acceleration forces as described in Section 5.7 without malfunction. Equipment is provided with fuse protection, grounding and the mechanical safeguards necessary to assure adequate personnel protection and to prevent or limit equipment failure during system fault conditions. See Table 8-5 for ratings and construction of the dc and preferred ac system components.
The systems are located in Consumers Design Class 1 portions of the auxiliary building.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.3 Page 8.3-7 of 8.3-11 DC System - The 125 volt dc system is divided into two independent and isolated systems.
Each system consists of a battery, switchgear, distribution panel, two chargers and instrumentation as shown on Figure 8-7. The switchgear bus consists of two sections, each of which can be fed by a battery charger.
Power to switchgear and the distribution panels is supplied by the station batteries and/or the battery chargers. Protection of the dc cabling in the case of a fire emergency is provided by separate dc distribution panels located in areas allowing emergency shutdown. The following design features assure the availability of 125 volt dc power for the operation of Diesel Generators 1-1 and 1-2, 2,400 volt Buses 1C and 1D, nonsafeguards Buses 13 and 14 and the Auxiliary Shutdown Control Panel C150 in the event a fire damages 125 volt dc distribution equipment in the cable spreading room (see Figure 8-8).
- 1. Fuses between each battery and its bus are located in their respective battery rooms.
- 2. In each battery room, a nonautomatic circuit breaker with a shunt trip is provided in the circuit between the battery fuse and its bus. The shunt trip device of these circuit breakers is a trip coil that is energized by battery voltage via the 125 volt dc distribution panel. The nonautomatic circuit breakers were specified for use in 125 volt dc systems and for a steady-state load of 400 amperes. They are qualified per IEEE 323-1974 and IEEE 344-1975. They do not contain fault detectors and are not intended to interrupt fault currents although they have that capability. They are manually operated open or close with the capability of being opened remotely via the shunt trip device.
If the shunt trip push button is closed inadvertently, the battery will be separated from the principal 125 volt dc bus. An undervoltage relay has been installed on the battery and will detect the separation of the battery from its charging source. Operation of the relay is annunciated in the control room (see later "System Monitoring" description).
- 3. Distribution panels are provided in Switchgear Room 1-C and Diesel Generator 1-2 room connected to their respective batteries with a fuse located in the applicable battery room. Each distribution panel contains a push button for energizing the shunt trip of the above-mentioned circuit breaker.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.3 Page 8.3-8 of 8.3-11
- 4. From each of the distribution panels, circuits for operating and control power are provided for the corresponding diesel generator and 2,400 volt bus with routing avoiding the cable spreading room and the diesel generator and switchgear rooms of the other channel. In addition, the distribution panel serving 2,400 volt Switchgear Bus 1-C supplies the Auxiliary Hot Shutdown Control Panel C-150 and nonsafeguards 480 volt Buses 13 and 14.
The chargers are of the solid-state type. They have provision for two charge rates, one for floating and one for equalizing the battery. The chargers are provided with filters and surge protection to enable either charger to supply the dc loads including the operation of 2,400 volt circuit breakers with the battery disconnected. The two chargers on each 125 volt dc bus are fed from separate 480 volt motor control centers. The motor control centers are supplied with power from 480 volt load centers and arranged so that the power for each is fed from a different 2,400 volt emergency bus. The chargers are provided with filters and surge protection. The battery charger cabinets were specified to operate at a design ambient temperature of 104°F.
Both dc systems are ungrounded and are equipped with ground detectors for continuous monitoring. Monitoring is also provided on other important system parameters, such as bus voltage and current. Abnormal conditions are annunciated in the control room.
Preferred AC System - The 120 volt preferred ac system has four separate buses. Each bus is supplied by an inverter which is connected to a dc bus section. Each dc bus section also has one battery charger connected.
Both sections of each dc bus are interconnected by a nonautomatic breaker.
This ties together two inverters, one charger and one battery to the same bus, the second battery charger being left in standby. The battery on each bus is kept fully charged, floating at approximately 131 volts. The connected battery charger supplies the dc loads including the two inverters which, in turn, feed one preferred ac bus each.
The dc bus monitoring devices consist of:
- 1. Battery voltage (voltmeter); one per battery,
- 2. Battery current (ammeter - charge/discharge); one per battery,
- 3. Battery charger output current (ammeter); one per charger,
- 4. Battery charger output voltage (voltmeter); one per charger,
- 5. DC bus voltage (voltmeter); one per bus,
- 6. DC bus ground current detector (milliammeter); one per bus, and
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.3 Page 8.3-9 of 8.3-11
- 7. DC bus average ground current (recorder); one per bus.
The above indications are centrally located. Items 3 and 4 are located on the charger's front cabinet door. The remaining items are located on metering panels which are installed within approximately ten feet of the charger.
Three control room annunciations are provided to alert the operator of dc power system unavailability. The first annunciation is for dc bus undervoltage or trouble. "125 Volt DC Bus Undervoltage/Trouble" alarm annunciates upon the following inputs:
- 1. 125 volt dc bus tie breaker open (either bus),
- 2. PA system inverter undervoltage (Bus D10 only),
- 3. Battery undervoltage (either battery), and
- 4. 125 volt dc bus undervoltage (either bus).
Alarm Input 1 results from a tie breaker position switch installed on both Bus D10 and D20 tie breakers. Should either (or both) tie breakers be opened, the position switch "a" contacts will energize an auxiliary relay to effect both a control room and a local annunciation.
Alarm Input 2 results from an undervoltage relay installed to monitor the input of the public address system inverter. Should this relay sense an undervoltage condition, both a control room and a local alarm will occur.
Alarm Input 3 results from an undervoltage relay installed between the battery and the battery's downstream fused disconnect. Two relays are installed, one for each battery (see Figure 8-7). The undervoltage relays inform the control room operator whenever the batteries are disconnected from the chargers (eg, the charger feeder breakers or the battery disconnects are open). The undervoltage alarm set point was chosen below the battery's normal "float" voltage on the charger and above the battery's voltage when disconnected from its charger. By providing a control room and local alarm at this set point, the operator is alerted to a system unavailability condition in a timely manner.
Alarm Input 4 is the bus undervoltage function indicating low voltage with regard to the dc loads.
Inputs to the control room alarm also provide a local alarm. A local annunciation relay is provided for each system. Each relay indicates locally which alarm input caused the control room annunciation.
The second annunciation is for battery charger trouble. This control room alarm will occur if a local alarm for low DC voltage, high DC voltage, charger failure or over temperature actuates on any one of the four chargers.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.3 Page 8.3-10 of 8.3-11 The third control room annunciation is for dc bus ground. Should the bus to ground current (milliamperes) on either bus exceed a predetermined set point, a control room alarm will be energized.
The following alarms and indicators are associated with the 120 volt ac preferred power panels:
- 1. Preferred AC bus trouble - common control room alarm (one per bus) from various inputs which each have a local alarm:
-DC Input Overvoltage
-DC Input Undervoltage
-Inverter Failure
-Over Temperature
-Line to Ground
8.3.5.3 Deleted 8.3.6 INSTRUMENT AC SYSTEM 8.3.6.1 Design Basis The 120 volt instrument ac system is designed to furnish reliable power to the Plant instruments other than those supplied from the dc and the preferred ac systems.
8.3.6.2 Description and Operation Description - The instrument ac system is supplied by two three-phase transformers from Motor Control Centers 1 and 2 as shown on Figure 8-7.
Panel breakers are equipped with thermal magnetic trip elements. The neutral of the instrument ac system is grounded. This system can only furnish power to one of the preferred ac buses at a time through a bypass regulator.
Power is supplied to the instrument ac bus from Motor Control Center 1.
Should the power fail from that source, the panel supply will automatically be transferred to Motor Control Center 2. When power to Motor Control Center 1 is restored, the panel supply will automatically transfer back. Transfer in either direction may be made manually.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.3 Page 8.3-11 of 8.3-11 8.3.6.3 Design Analysis Each of the two instrument ac transformers is sized to supply the panel load and one preferred ac panel bus via the bypass regulator.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.4 Page 8.4-1 of 8.4-6 8.4 EMERGENCY POWER SOURCES The emergency power sources are designed to furnish onsite power to maintain safe storage of spent fuel upon loss of normal and standby power.
The emergency power sources are part of the engineered safeguards electrical system and were identified as Class 1E systems; following the implementation of Permanently Defueled Technical Specifications, Class 1E is no longer applicable (reference Section 5.2.2.7).
8.4.1 EMERGENCY GENERATORS 8.4.1.1 Deleted 8.4.1.2 Description and Operation Description - There are two emergency diesel engine-driven generators of equal size. The generators have static-type excitation and are provided with field flashing for quick voltage buildup. Each generator is connected via a generator breaker to a separate 2,400 volt bus.
Support systems associated with each diesel generator include a fuel oil system, air starting system, lube oil system, jacket water system, crankcase exhauster, two starting circuits and a load sequencer (see Figure 8-11). Each system is located in a separate room from its redundant counterpart, except for the load sequencers which are located separate from one another in the main control room.
The diesel engines are designed for air start and a separate compressor and receiver are provided for each engine. There are two receivers and two air-start motors per engine. A separate fuel oil day tank is also provided for each engine. The diesel engines, fuel oil systems and air start systems are equipped with instrumentation to monitor important parameters and annunciate abnormal conditions. Water and oil heaters are provided to maintain the engines in "start" readiness.
The emergency generators are equipped with the mechanical and electrical safeguards necessary to assure personnel protection and to prevent or limit equipment damage during operation or fault and overload conditions. The generators and their 2,400 volt breakers have overcurrent and differential protection. Wiring passes the vertical flame resistance test in accordance with IPCEA S-28-357, Paragraph 3.4. With the implementation of National Fire Protection Association (NFPA) 805, new cables must meet IEEE 383, or equivalent, flame test requirements.
The emergency diesel generators and their auxiliaries were designed to withstand CP Co Design Class 1 seismic acceleration forces per Section 5.7 without malfunction. Refer to Table 5.2-4 for seismic classification in the defueled condition. The emergency diesel generators and their auxiliaries, except for the fuel oil transfer system, are installed in a CP Co Design Class 1 portion of the auxiliary building and the units are separated by a wall.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.4 Page 8.4-2 of 8.4-6 Operations During or After Fire - The 1-1 emergency diesel generator has three remote/local isolation switches (one for the output breaker and two for the diesel generator) to allow control in the event of fire in some facility fire areas. The 1-2 emergency diesel generator does not have remote/local isolation switches, but operability after a fire in some areas could be restored by operation of slide links in the control circuitry. Operation of these slide links is not required by the NFPA 805 Nuclear Safety Capability Assessment.
However, the Appendix R, Safe Shutdown Analysis does credit operation of the 1-2 emergency diesel generator for fires in other areas that would not require operation of the slide links. Operation of the switches or slide links is governed by Abnormal Operating Procedures (AOPs).
8.4.1.3 Design Analysis Each emergency generator and diesel engine is provided with several alarms, interlocks and trips. Each engine may be started and placed in service locally or from the control room. The generators may be synchronized from the control room so that they can be paralleled with the system for loading tests.
Each diesel is located in a separate room as is shown on Figure 1-3. Each room has separate access doors.
Local alarms at each diesel are:
Prelube Oil Pump Failure Low Lube Oil Pressure High Lube Oil Temperature Low Lube Oil Temperature High Lube Oil Filter Differential Pressure High/Low Jacket Water Temperature Low Jacket Water Level Low Raw Water Pressure Overspeed Low Air Pressure Overcrank Low Lube Oil Level Engine Trouble High/Low Fuel Level Low Jacket Water Pressure Bus 1C (1D) Overcurrent Lockout Crankcase Exhauster Failure Any local alarm also results in annunciation of a Diesel Generator Trouble alarm in the control room.
Other diesel generator control room alarms include:
Diesel Generator Fail to Start Diesel Generator Start Signal Blocked
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.4 Page 8.4-3 of 8.4-6 The Diesel Generator Start Signal Blocked alarm is actuated by the following inputs:
Loss of DC control power Overspeed trip Low lube oil pressure trip Low jacket water pressure Overcurrent or differential current In addition, a trip of the diesel generator breakers by anything other than a manual trip is annunciated separately in the control room as is low level in the main fuel oil storage tank, day tank hi-lo level, generator overload, and Bus 1C or 1D overcurrent lockout. The diesel generator breakers will be opened should there be an overload, or generator differential relay operation, or should the diesel shut down. Additionally, a short duration trip signal is provided to the diesel generator breakers whenever a signal is initiated to automatically fast transfer the normal source of power to the start-up transformer. This trip signal ensures that the diesel generator will not be placed in parallel with the offsite source while not in phase.
The diesel will be automatically tripped on generator differential or overcurrent relay action, engine overspeed, low lube oil pressure, or low jacket water pressure, and can be manually tripped at any time from the local station or from the control room.
The engines are nominally rated at 3,500 brake horsepower (bhp), with a predicted overload capacity of 3,840 bhp for two hours.
The generator is rated at 2,500 kW at 0.8 power factor with a two-hour overload rating of 2,750 kW.
Each diesel generator's fuel oil system transfer system consists of an underground fuel oil storage tank, a single supply line and two transfer pumps. Each diesel has its own day tank and belly tank.
Either of two fuel oil transfer pumps are used for transferring fuel oil from the storage tank to the day tanks should additional fuel oil be required. In addition, a connection is available outside the diesel rooms to pump oil directly into the day tanks from an oil tanker truck.
Each emergency generator's fuel oil day tank has its own makeup control system which is redundant to and independent from that of the other. The emergency generator tank makeup control systems interface with the fuel oil transfer pump control systems. Each day tank makeup control system has its own separate control station and is powered from its respective channel.
Each day tank makeup control system can independently demand makeup from a fuel oil transfer pump.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.4 Page 8.4-4 of 8.4-6 The fuel oil transfer pump motors and their control circuits are non-Class 1E.
These circuits are supplied from redundant channels but are not separate and independent. Neither transfer pump's control logic gives the emergency generator day tank makeup systems preference over or isolates those nonessential makeup systems which are also served.
Transfer pump P-18A can be controlled either manually, or automatically via level controls. It is powered from non-Class 1E MCC-8, which is capable of being manually loaded onto EDG 1-2. Those portions of the P-18A control circuit which carry the demand signals from the two independent emergency generator day tank makeup control systems are not electrically isolated or separated from each other; nor are they isolated or separated from circuits for non-essential makeup systems. Transfer pump P-18B can only be controlled manually. It is powered from Class 1E MCC-1, which is automatically loaded onto EDG 1-1. Those portions of the P-18B control circuit which carry the demand signals from the two independent emergency generator day tank makeup control systems are not electrically isolated or separated from each other; nor are they isolated or separated from circuits for non-essential makeup systems.
Each diesel engine has its own self-contained jacket cooling and heating system. A jacket water pump is engine driven with a temperature controlled three-way valve which diverts part of the water through a jacket water heat exchanger which is cooled by the facility service water system. As is shown on Figure 9-1, each heat exchanger is fed from a separate service water header. The jacket water pump on each diesel is connected to a surge line running to a 30 gallon expansion and makeup tank located approximately 10 feet above the crankshaft centerline. Makeup water is from the primary system makeup water system. When the engines are not running, the jacket water is heated by two thermostatically controlled heating elements mounted in the engine jackets.
8.4.2 STATION BATTERIES 8.4.2.1 Deleted
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.4 Page 8.4-5 of 8.4-6 8.4.2.2 Description and Operation Description - The batteries are of the lead calcium type. Special reinforced seismically qualified battery racks with high impact cell spacers are provided to meet the seismic criteria of CP Co Design Class 1 and to prevent damage from shifting of the battery cells.
Each battery is housed in its own ventilated room in the CP Co Design Class 1 portion of the auxiliary building. A sail switch is mounted in the ventilation duct to warn the operator in the control room of a loss of battery room ventilation which could lead to accumulation of hydrogen.
8.4.2.3 Deleted 8.4.2.4 Dedicated Battery Supply to Address Fire Scenarios A nonsafety-related, dedicated 125 VDC battery supply is installed to power alternate 125 VDC controls in the event that a fire renders the normal control capabilities unavailable (see Figure 8-12). Operator actions within the control room are required to disconnect the normal power supply and align the alternate dedicated battery supply.
8.4.3 SECTION DELETED 8.4.4 SECTION DELETED 8.4.5 SUPPLEMENTAL 2400 VOLT POWER SUPPLY 8.4.5.1 Design Basis A supplemental diesel generator is provided for use during beyond design basis events. Supplemental Diesel Generator 1-3 provides a standby power source for equipment powered from facility 2400 volt buses. The supplemental diesel generator is sized to provide an alternate source of power for operation of the battery chargers and the control room heating, ventilation and air conditioning system. Other loads within the diesel generator rating may also be powered. This power supply is non-safety related and is physically separated from the historically Class 1E safety related power supplies. However, during events that are beyond the design basis, emergency procedures are provided to connect Diesel Generator 1-3 to Class 1E loads.
8.4.5.2 Description and Operation Supplemental Diesel Generator 1-3 is a portable Caterpillar 3516B engine with an SR 4 Generator. Output is rated at 1825 kW at 0.8 power factor, 480 VAC 60 Hz. The generator has a standby rating of 2000 kW at 0.8 power factor for 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> per year. A 480/2400 step-up transformer is provided on
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.4 Page 8.4-6 of 8.4-6 the output diesel generator to obtain the 2400 volts required for the safety related buses.
The diesel generator is manually started and connected to the 2400 volts buses locally at the diesel and at nearby switchgear. Connection to the 2400 volts buses can only be made to a dead bus. No provisions are provided for automatically starting the diesel or synchronizing the diesel generator onto an energized ac bus.
Auxiliary power to the diesel generator is provided to power battery chargers, controls and jacket water heaters. This power, provided from a non-safety related source, is required to maintain the diesel generator in a ready-to-start condition (batteries charged and engine coolant warm). The diesel generator is provided with a local fuel oil tank. The capacity of the tank is sufficient to supply the diesel generator at rated load for a minimum of six hours.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.5 Page 8.5-1 of 8.5-7 8.5 RACEWAY AND CABLING SYSTEM 8.5.1 DESIGN BASIS 8.5.1.1 Fire Protection Features The design features of the raceway and cabling system for fire protection of historically safety-related cabling are described in this section. For additional fire protection-related features, refer to Section 9.6.
8.5.1.2 Deleted 8.5.2 DESIGN DESCRIPTION As noted in Subsections 8.1.1 and 8.1.2, the engineered safeguards electrical power and control system buses are divided into two channels and the loads into two groups. Each channel consists of the following buses and power sources: one 2,400 volt bus, two 480 volt load centers, four 480 volt motor control centers, one dc distribution center, one battery, two battery chargers, two preferred ac buses, two inverters and one diesel generator.
The raceways and containment penetrations for these systems are also divided into two groups according to the separation criteria given in Subsection 8.5.3.2. Physical separation is maintained between the two raceway systems and between the two penetration areas. The interconnecting cables for any one channel are run in their respective raceway system.
The circuitry of functions which might be designated as nonsafety related are contained in the same safety-related cables serving the safety-related equipment. (Examples: remote indicating lights for valves, breakers, etc.)
This circuitry has then been treated as "associated" circuitry within IEEE 384 definition and requirements.
Cables installed in ventilated trays, conduit or underground ducts are thermally sized in accordance with NEC or IPCEA/ICEA ampacity values (depending on cable physical size) of concentric stranded insulated cable for the conductor operating temperature of the insulation. Insulation type may be of thermosetting, rubber or plastic. Ampacities are adjusted based on actual field conditions when possible. These adjustments may include, but not be limited to, conductor operating temperature, ambient temperature, cable overall diameter, tray depth of fill, conduit percent fill, and fire-stops.
Analyses performed for densely filled cable trays, conduits and underground ducts determined that the cables were within their temperature ratings.
These analyses are described in References 12 through 14. The ampacity methodology has been reviewed by the NRC and found to be acceptable (Reference 15).
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.5 Page 8.5-2 of 8.5-7 High-voltage cables are run in separate raceways from low-voltage power and control cables. Low-level signal cables are kept in separate raceways.
Cables installed in stacked trays are arranged to have the highest voltage located in highest level tray and low-level signal cable in the lowest tray.
No documentation of the original design basis for the sizing of cables for short circuit has been found. Station power short-circuit levels and discussions with the original AE, however, indicate that the three-phase ac cable short-circuit protection design considered the fault current due to a fault at the load and used high speed fault clearing to prevent cable damage. This design sizes the protective device for a fault at the load to prevent the conductor temperature from exceeding 250°C for thermosetting insulated cable, 200°C for rubber insulated cable, and 150°C for plastic insulated cable. If a fault occurs on the cable, the entire cable upstream of the fault would be inspected and, depending on the fault location and resulting short-circuit current, the appropriate sections would be replaced. This is the present design criteria being used. The 125 volt dc protection design considers the fault current available at the source side of the feeder protective device.
8.5.3 DESIGN EVALUATION The following subsections describe how the raceway and cabling system meets NRC BTP CMEB 9.5-1, Regulatory Guide 1.75 and National Fire Protection Association (NFPA) 805.
8.5.3.1 Compliance With Regulatory Guide 1.75 The safety-related cabling system does not fully meet the requirements of Regulatory Guide 1.75 since the Plant was designed and constructed before the Guide was established. As a result, fixed automatic water fire suppression systems have been provided in areas of dense safety-related cables. Manual hose stations and portable extinguishers are provided as backup.
Although IEEE 383 was not in existence at the time the Palisades electrical cabling was purchased and installed, the cable was specified to meet the vertical flame tests in accordance with IPCEA S-19-81 and ASTM D470-59T.
While such tests, as well as the IEEE 383 tests, provide a measure of comparability of fire retardance between various types of cables, they cannot be considered as indicative of their behavior when found in the configurations in the Facility. Cable insulation has thus been considered as combustible material for fire protection design considerations (See Section 8.7).
Starting in 1979, new cable installations utilize to the extent practical, cable construction that does not give off corrosive gases while burning. With the implementation of NFPA 805, new cables must meet IEEE 383, or equivalent, flame test requirements.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.5 Page 8.5-3 of 8.5-7 8.5.3.2 Raceway and Cabling Separation Criteria Circuits designated as belonging to a safety-related power distribution, Reactor Protective System, engineered safeguards or other safety-related system channel are run in separate raceway systems. The raceway system includes conduit, trays, wall and floor penetrations, containment penetration, panel wire troughs, etc. In general, the circuit isolation and separation requirements are met by the use of physically separate raceways which can afford fire and missile protection. The raceway systems are so arranged that a single failure cannot affect both channels of a power or control circuit. In designing the raceway system for "channeled" circuits and in the routing of these circuits, consideration has been given to the type of hazards that could be present in regard to potential fire, as well as size and type of missiles that may be generated by the equipment in the area. Physical separation (distance) has been considered as the most reliable method of providing the circuit separation and isolation. When raceways are run near one another, a fire barrier and/or a missile shield is provided between the raceway systems.
According to FSAR Amendment 15 of August 26, 1968, original Plant construction did not require rigorous separation of vital and nonvital cables.
Amendment 15 states, "Nonvital cables, except for those required to operate during a DBA, are the same as the cables used in the engineered safeguards circuits. They are sized, rated, protected and, except for separation, use identical type raceways sharing, where convenient, the same trays as engineered safeguards cables." IEEE 384 would require that these "nonvital" cables be classified as "associated circuits" and designed and installed accordingly. Separation as required by IEEE 384 was not an original design requirement and the Plant is not in total conformance with this standard.
Compliance With NFPA 805 Support systems' power and control cabling for the diesel generators, including the power source for the engine crankcase exhausters are not routed through the control room or cable spreading room. Furthermore, the terminations of control room and cable spreading room routed circuitry for Emergency Generator 1-2 and 2,400 volt Bus 1C and 1D switchgear positions are identified readily so that the sliding links of the terminal blocks can be opened to isolate the damaged circuitry. Isolating transfer switches are provided for Emergency Generator 1-1 and selected breakers on Bus 1C. No slide link operations are credited for achieving or maintaining safe and stable conditions per NFPA 805.
Other specific routing criteria have been established to ensure safe and stable conditions per NFPA 805.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.5 Page 8.5-4 of 8.5-7 8.5.3.3 Raceway and Cabling Fire Barriers Fire barriers have been provided to prevent the spread of fire between fire areas.
Cable and cable tray penetration of fire barriers (vertical and horizontal) in safety-related areas of the Facility have been sealed to give protection at least equivalent to that of the fire barrier. The design of fire barriers for horizontal and vertical cable trays meets the requirements of ASTM E119, "Fire Test of Building Construction and Materials," including the hose stream test. Where fire barrier penetration seals require fire resistance characteristics, these seals in safety-related areas have been sealed to a rating equivalent to that required of the barrier. Piping penetrations of fire barriers are sealed in a similar fashion. The adequacy of seals has been demonstrated by testing [Factory Mutual Research Test Reports for Wall Penetrations (4/26/78) and Floor Penetrations (5/10/78)] and/or analysis.
The few cable tray sections in the containment building which communicate between the left and right cable tray systems are fitted with fire stops. These stops are intended to prevent a fire originating in one tray system from traveling along an interconnecting tray and affecting the other tray system.
8.5.3.4 Cable Spreading Room Protection Design This area contains 480 volt dry-type transformers, 480 volt switchgear, cables for power, instrumentation and control for safety-related and nonsafety-related systems, and other equipment related to safety-related ac and dc power supplies. The significant combustible in this area consists of a large quantity of cable in open cable trays stacked three or four levels deep.
In order to meet the intent of Regulatory Guide 1.75 and NRC BTP CMEB 9.5-1, the following design features are provided for protection against a fire in the cable spreading room:
- 1. Fire detection provided by flow alarms in the sprinkler system.
- 2. Fire extinguishment provided by an automatic sprinkler system backed up by water hose stations and portable extinguishers.
- 3. Switchgear protected against flooding by mounting on curbs.
- 4. Physical separation and barriers used to separate redundant cables.
- 5. Smoke detectors to detect incipient fires.
- 6. Ladder to enhance manual fire-fighting capability.
- 7. Fire retardant coatings to close gaps in barriers.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.5 Page 8.5-5 of 8.5-7
- 8. Seal for cable penetrations on both sides.
- 9. Manual suppression capability to suppress fires in lower trays that may be shielded from sprinkler system water.
- 10. The wall to the turbine building is at least a 3-hour wall and to the adjacent switchgear room is at least a 2-hour wall. The floors and ceilings have a 3-hour fire resistance.
- 11. The ventilation ducts leading to the turbine building and into the battery rooms have fusible link fire dampers installed.
- 12. To ensure fire-fighting ability, there are two remote and separate entrances into the cable spreading room, one from the adjacent switchgear room; the cable trays are installed above the floor-mounted switchgear cabinets starting about seven feet high and extending to the ceiling except for the vertical cable runs at the south side of the room; there are four-foot aisles between floor-mounted equipment for ladders or fire-fighting equipment.
8.5.3.5 Cable Penetration Rooms Protection Design There are two cable penetration areas into containment totally separated from each other by distance and fire barriers, one area being at the north side and the other at the southwest side of the containment. When cables penetrate fire barriers, fire rated cable penetration seals are provided.
The significant combustible in each of these areas is a moderate amount of electrical cable insulation stacked in open cable trays.
Fire detection is provided by smoke detection and water flow alarms which are actuated by flow to the sprinkler system. Fire extinguishment is provided by an automatic sprinkler system in each area backed up by portable extinguishers and hose stations located in adjacent areas.
8.5.3.6 Raceway Runs Protection Design Cable trays, raceways, conduit, trenches or culverts are used only for cables; no miscellaneous storage is present. No piping for flammable or combustible liquids or gases is installed in these areas.
The tunnel from the north penetration area to the Switchgear Room 1D and the cable spreading room can be vented with the HVAC system or manually vented with the door to the switchgear room from the outside. Also the tunnel can be vented with the door from the outside leading into the north penetration room.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.5 Page 8.5-6 of 8.5-7 Cables entering the control room pass through penetration seals and terminate in the control room cabinets. There are no floor trenches or culverts in the control room.
8.5.3.7 Safety-Related Cabling Routing Via Nonsafety-Related Areas Routing of electrical cables via nonsafety-related areas does not allow a fire to cause loss of redundant equipment because of the following features:
- 1. Circuit routing for service water pumps is in conduit through the turbine room, or in underground duct.
- 2. Circuit routing to the southwest penetration area is via a combination of underground conduit and trays in the turbine building.
- 3. The turbine lube oil storage area is adequately separated in an interior structure inside the turbine building. The room has fire suppression and is adequately enclosed by fire walls. The room has a recessed floor to contain the single largest lube oil storage tank inventory without leakage.
8.5.3.8 Containment Building Routing Protection The containment building can be isolated to contain any fire source and the containment boundary will prevent any outside fire from entering the containment.
The small amount of oil associated with each primary coolant pump motor does not justify a suppression system. It is not expected that a postulated lube oil fire would cause loss of cables located in the vicinity of a primary coolant pump since an oil collection system is provided to collect and contain leakage or spills.
Cable trays, cables and penetration areas are separated into two divisions with fire stops in trays communicating between the two divisions (see Subsection 8.5.3.3).
As a result of this potential for fire, fire detection devices are provided in the reactor containment instrument room and cable penetration area; primary coolant pump bearing temperature and motor winding temperature readout are also available to give indication of a fire in the primary coolant pump area; portable carbon dioxide and water extinguishers are provided. Also, due to the difficulty of reaching some locations with a hand extinguisher, water hose stations are provided in containment with adequate hose to suppress fires in cables in cable trays.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.5 Page 8.5-7 of 8.5-7 8.5.3.9 Other Areas Routing Protection For routing protection in switchgear rooms, emergency generator rooms and battery rooms, see Section 8.7. For routing protection in control station areas, see Sections 7.4 and 7.7.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.7 Page 8.7-1 of 8.7-5 8.7 PHYSICAL SEPARATION AND SUPPORT SYSTEMS The information contained in this section refers to the design of the two historic trains of safety-related power distribution. Following the implementation of Permanently Defueled Technical Specifications, this is considered historic.
The physical separation of the two safety-related power distribution channels and their support systems is the subject of this section. Protection against fire is included also in this subsection. Protections against physical phenomena (flooding, tornado, missiles, etc) are described in Chapter 5.
8.7.1 DELETED 8.7.2 PHYSICAL SEPARATION 8.7.2.1 General The physical separation of redundant equipment and cabling associated with the two safety-related power distribution channels meets 10 CFR 50, Appendix A, General Design Criterion 3. Review of electrical equipment fire-related design based upon the acceptance criteria of Appendix A to NRC BTP CMEB 9.5-1 has been performed and a summary included in this subsection. See Section 8.5 for generic raceway and cabling design, Section 7.7 for control stations fire-related design, and Section 9.6 for fire protection equipment. These criteria were established to prevent a single fire in any area from disabling both redundant channels. In addition, 10 CFR 50.48, effective date February 17, 1981, required a reevaluation of all areas of the Facility to the separation criteria specified in Paragraph G of Section III of Appendix R to 10 CFR 50. Compliance with Appendix R has been replaced by compliance with National Fire Protection Association (NFPA) 805.
The Palisades Facility has been designed with physical separation to prevent the spread of a fire in safety-related equipment areas. This separation is maintained by compartment isolation of Facility safety systems and by employing redundant equipment, controls and power supplies.
8.7.2.2 Transformers All high-voltage power transformers located within the Facility safety-related areas are dry type.
The main transformer, station power transformers and start-up transformers are located south of the containment vessel and east of the turbine building.
While the transformers are within 50 feet of the containment building, there are no openings in the exterior walls of containment within 50 feet of the transformers and the fire resistance of these walls is in excess of 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. All the transformers are provided with an automatic water deluge system.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.7 Page 8.7-2 of 8.7-5 8.7.2.3 Protection Against Water Damage In order to protect electrical equipment against damage from fire suppression systems, floor drains for water removal are provided in sprinkler areas containing electrical equipment. Many areas have alternate drainage via equipment sumps, door accessways or stairwells-to-sump areas.
Transformers and 480 volt vital load centers are mounted on pedestals.
Switchgear are floor mounted and floor drains are provided since these areas have sprinklers. In addition, valves are available to isolate sections of the firewater piping inside buildings to preclude the buildup of water and thus prevent equipment from being incapacitated due to flooding or inadvertent operation of the fire suppression equipment.
All safety-related diesel day tanks have high curbs around the tanks or the tanks are enclosed in separate fuel oil rooms with door elevated well above floor level.
Cable trays are of the open-top ladder type made of galvanized steel with galvanized steel, painted channel or unistrut-type supports.
The safety-related cabinets housing electrical equipment in the vicinity of automatic sprinklers have been designed as drip proof, and all have had the top cable entry points in the cabinets sealed to prevent water ingress. The rooms in which this equipment is mounted are provided with floor drains to prevent flooding during sprinkler operation. Refer to Section 5.4 for a discussion on flooding.
The switchgear enclosures are louvered to limit water sprays from entering the enclosures.
8.7.2.4 Smoke Control The power supply and controls for the ventilation systems used for smoke control are run outside the fire area served by the system with the exception of the cable spreading room and the two safety-related switchgear rooms.
The normal exhaust fan for the cable spreading room and the two switchgear rooms is mounted in the cable spreading room. The emergency exhaust fan that serves the three above-mentioned rooms is mounted in Switchgear Room 1-D. All these rooms can also be readily vented with portable blowers.
All intakes are remote from locations where smoke could be exhausted.
The cable spreading room and the two switchgear rooms have both normal and emergency exhaust systems which exceed NFPA requirements. The emergency generator rooms have ample natural ventilation. Diesel day tank rooms are enclosed so that there would not be enough air to support combustion. All other locations have exhaust ventilation which exceeds the NFPA criteria.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.7 Page 8.7-3 of 8.7-5 8.7.2.5 Switchgear Rooms Protection There are two redundant 2.4 kV switchgear rooms and an auxiliary electrical equipment room. Each switchgear room contains the switchgear to one of the redundant channels of safeguards equipment and the associated cables.
A tunnel which contains cabling of one safety channel leads from Switchgear Room 1-D to the associated penetration area.
The combustibles in the switchgear rooms consist of a moderate amount of cable in open cable trays. Switchgear Room 1-C also contains piping of propane, hydrogen and acetylene. However, this piping only passes through Switchgear Room 1-C and does not service any equipment in this area.
Additionally, damage to the piping is unlikely since the piping is routed near the ceiling and there is no rotating machinery in the area to present a missile hazard.
An unmitigated fire in one of the switchgear rooms could cause damage to and loss of equipment related to one channel of redundant systems but would not affect the redundant systems due to the barriers separating the rooms.
Both switchgear rooms are used as cable right of ways. Both rooms have closed head sprinkler systems to protect the cables.
The switchgear room for Bus 1C has a 3-hour fire barrier to the diesel generator room and to the turbine building.
The switchgear room for Bus 1D has a 3-hour barrier to the cable spreading room. Floors and ceilings have a 3-hour fire barrier.
Fire detection is provided by smoke detectors and flow alarms actuated by water flow in the sprinkler system. Fire extinguishment capability is provided by an automatic sprinkler system in the switchgear rooms and the cable tunnel, backed up by water hose stations and portable extinguishers.
Additional protection features are provided as follows:
- Smoke detectors for detection of incipient fires (both rooms);
- Cable penetration seals with flame retardant materials (both rooms);
- Redundant safeguards cabling is routed in each switchgear room according to the channel of power source. Local 125 volt dc distribution panels are provided such that the dc control power would not be affected in the case of switchgear room fire (see Subsection 8.3.5.2); and
- Dampers in ventilation duct penetrations of fire barriers.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.7 Page 8.7-4 of 8.7-5 8.7.2.6 Emergency Generators Rooms Protection The redundant diesel generators are each housed in separate rooms, separated from each other by 3-hour fire-rated walls and doors, with a curb at each of the doors to prevent oil from seeping under the door. Where less than 3-hour fire rated separation has been provided between the diesel generators, engineering evaluations have been prepared to technically justify the fire resistance of the subject fire barriers.
The significant combustibles in each room are lube oil, diesel fuel and a small amount of electrical cable insulation. The day tank for each diesel is separated from the diesel generator room by a 3-hour rated fire barrier with diking provided to contain the complete inventory of the day tank.
An unmitigated fire in one of the rooms could cause loss of one diesel generator.
Fire detection is provided by flow alarms activated by water flow in the automatic sprinkler system. Fire extinguishment is provided by a fusible link-type automatic sprinkler system in each room backed up by water hose stations and portable extinguishers.
Floor drains are provided in both emergency generators rooms. Manual venting of smoke is provided by exhaust dampers mounted in the ceiling to the outside and by a door to the outside from the vestibule.
The day tanks are mounted in separate cubicles and are vented to the outside. The day tank cubicles are not provided with sprinkler systems.
Portable fire extinguishers and hose stations serving the diesel generator rooms are available in case of a fire in the day tank cubicles. The day tank rooms do not have sufficient air to support combustion.
The transfer of diesel oil from the underground storage tank to the diesel generator day tanks can be stopped by manually tripping the power supply to the transfer pumps, isolating the supply either in the Diesel Generator 1-2 room or at the transfer pump discharge in the intake structure.
The diesel fuel oil storage tank is located outside and underground away from the auxiliary building and safety-related equipment.
8.7.2.7 Battery Rooms Protection There are two separate battery rooms. They have a 2-hour fire barrier from the cable spreading room and from each other.
The significant combustibles in the battery room are the plastic battery cases and a small amount of electrical cable insulation. Hydrogen buildup from battery charging is precluded by a continuously operating ventilation system.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.7 Page 8.7-5 of 8.7-5 An unsuppressed fire in one of the battery rooms could cause the loss of one, but not both, of the batteries due to the low fire hazard and the fire barriers between the rooms. Hydrogen buildup on loss of ventilation flow is prevented by checking the batteries once a day and by maintaining the hydrogen concentration well below 2% volume through the ventilation exhaust system.
A sail switch in the ventilation duct warns the control room of a loss of battery room ventilation.
Each room is maintained under negative air pressure with air intake from the cable spreading room through fusible link fire dampers. The battery rooms' ventilation exhausts to the outside.
Smoke detection is provided for these rooms. Fire extinguishment is provided by water hose stations located in adjacent areas and by portable extinguishers.
Considering the limited quantity of combustibles, manual fire protection is adequate to extinguish fires in these rooms.
8.7.3 SUPPORT SYSTEMS 8.7.3.1 Ventilation Ventilation for each diesel generator room is supplied by two fans.
Ventilation for the remaining electrical distribution system rooms - the cable spreading room, the two 2,400 volt bus (switchgear) 1C and 1D rooms and the two battery rooms - is supplied from a single duct system. The duct system has one supply fan, one exhaust fan and one recirculation fan. The one recirculation fan is redundant to the supply and exhaust fans.
The cable spreading room can withstand a loss of ventilation for up to six hours before exceeding the upper design temperature limit. High temperature in the room is annunciated in the control room. One of the redundant fans can be connected to emergency power sources.
The 1C and 1D switchgear rooms are not affected by a loss of ventilation since no appreciable heat sources are contained in these rooms. The battery room redundant fans are powered from separate channels of safety-related sources.
Tests have demonstrated that the equipment serviced in these rooms would not be adversely affected by lack of ventilation during loss of offsite power and/or a safe shutdown earthquake as defined in Section 5.7.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.8 Page 8.8-1 of 8.8-1 8.8 MOTOR OPERATED VALVES The Palisades Motor Operated Valve (MOV) Program satisfies the requirements of NRC Generic Letter 89-10 "Safety-Related Motor Operated Valve Testing and Surveillance" and its supplements. Generic Letter 89-10 was issued in June 1989 and superseded IEB 85-03 "Motor Operated Valve Common Mode Failures During Plant Transients Due to Improper Switch Settings." The purpose of Palisades MOV Program is to ensure safety-related MOVs are designed and maintained such that they will perform their design basis function for the life of the facility. Facility procedures identify those MOVs at Palisades subject to the requirements of GL 89-10 and describe the Palisades GL 89-10 Program as it applies to those valves.
Initial compliance to GL 89-10 consisted of a design basis review for each MOV in the Palisades GL 89-10 program to determine the worst case operating condition for each MOV. An evaluation was then performed to determine the ability to each motor operator to operate the valve under the worst case operating condition including operation at degraded voltage during worst case temperatures. Motor operator control switch settings were then calculated to ensure proper operation at the worst case operating condition.
MOV Diagnostic Testing under static system conditions was performed on each MOV to set control switches to the specified control switch setting.
MOV diagnostic testing was also performed, where possible, under dynamic system conditions which duplicated, as much as possible, actual worst case operating conditions. Field data obtained from those MOVs tested under dynamic conditions were used to validate control switch settings in the initial design calculations. For MOVs where testing under dynamic system conditions was not possible, this validation was performed using other sources of test data (ie. best available industry test data, etc.).
The Palisades plan for long term compliance with GL 89-10 consists of periodic testing, both static and dynamic, of GL 89-10 MOVs to verify control switch settings, and monitoring MOV performance through use of a tracking and trending program.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.9 Page 8.9-1 of 8.9-1 8.9 LIGHTING SYSTEMS In addition to the normal ac lighting, there are separate dc and ac emergency lighting systems provided in certain areas of the Facility.
Feeders to lighting panels from power source are carried in the cable tray system. Branch circuits from the lighting panels are carried in conduits. The emergency dc light circuits from the panel to the lights are in conduits dedicated to these circuits only. The lighting panels serving safety equipment areas are at various locations in the auxiliary and turbine buildings.
The feed to the emergency dc Panels D41 and D42 is from the D20 main dc distribution panel in the cable spreading area. The feeds to the emergency dc panels are in separate diverging trays, except at the location of emerging from the Source Panel D20 and are separated from the trays carrying the ac lighting panel feeders. The latter feeders are generally in trays separate from each other.
Fixed battery pack lights are provided for access/egress. This lighting is in addition to facility normal and emergency ac and dc lighting. The lighting is also available to support fire fighting activities when applicable. Where fixed battery pack lighting is not available, hand held lighting is relied upon to support operator manual actions.
The fixed battery pack lighting has been designed to provide 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> operation.
Emergency lighting inside containment is provided for personnel safety and to assist in safe handling of fuel. Their operability testing is specified in the Operating Requirements Manual.
DSAR CHAPTER 8 - ELECTRICAL SYSTEMS Revision 36 SECTION 8.10 Page 8.10-1 of 8.10-1 8.10 QUALITY CONTROL For a discussion of the Quality Assurance Program, see Chapter 15.