Text

3 to Updated Final Safety Analysis Report, Section 8, Electrical Power (Redacted)
	ML21104A365
Person / Time
Site:	Davis Besse
Issue date:	09/25/2020
From:	Blake Purnell; Plant Licensing Branch III
To:	Brown T; Office of Nuclear Reactor Regulation
	Purnell B
References
	L-20-234
	Download: ML21104A365 (119)
	v • d • e

Davis-Besse Unit 1 Updated Final Safety Analysis Report SECTION 8 TABLE OF CONTENTS Section Title Page 8.0 ELECTRICAL POWER 8.1-1

8.1 INTRODUCTION

8.1-1 8.1.1 Utility Grid 8.1-1 8.1.2 Onsite Systems 8.1-1 8.1.2.1 Main Generation System 8.1-1 8.1.3 Essential Functions 8.1-3 8.1.4 Essential Loads 8.1-4 8.1.5 Design Bases 8.1-4 8.2 OFFSITE POWER SYSTEM 8.2-1 8.2.1 Description 8.2-1 8.2.1.1 Reliability Consideration 8.2-1 8.2.1.2 Stability Analysis 8.2-3 8.2.1.3 Switchyard DC System 8.2-4 8.2.1.4 Switchyard Systems 8.2-4 8.3 ONSITE POWER SYSTEMS 8.3-1 8.3.1 AC Power System 8.3-1 8.3.1.1 Description 8.3-1 8.3.1.1.1 Unit Auxiliary and Startup Transformers 8.3-2 8.3.1.1.2 13800 Volt Auxiliary System 8.3-2 8.3.1.1.3 4160 Volt Auxiliary System 8.3-3 8.3.1.1.4 Diesel Generators 8.3-5 8.3.1.1.4.1 Emergency Diesel Generators 8.3-5 8.3.1.1.4.2 Alternate AC Source - Station Blackout Diesel Generator 8.3-15 8.3.1.1.5 480V AC Auxiliary System 8.3-16 8.3.1.1.6 120V AC Auxiliary System 8.3-19 8.3.1.1.7 Channels 8.3-20 8.3.1.1.8 Physical Arrangement of the AC Electrical System Components 8.3-20 8.3.1.1.9 Tests and Inspections 8.3-23 8.3.1.1.10 Administratively Controlled Devices 8.3-24 8.3.1.1.11 Cross Ties Between MCC E11B and F11A 8.3-24 8.3.1.1.12 Motors 8.3-24 8.3.1.2 Analysis 8.3-24 8.3.1.2.1 Switching 8.3-25 8.3.1.2.2 Independent Circuits 8.3-25 8.3.1.2.3 Onsite Standby Emergency Diesel Generator Units 8.3-25 8.3.1.2.4 Power Distribution System 8.3-25 8.3.1.2.5 DELETED 8-i UFSAR Rev 30 10/2014

Davis-Besse Unit 1 Updated Final Safety Analysis Report TABLE OF CONTENTS (CONTINUED)

Section Title Page 8.3.1.2.6 Parallel Operation 8.3-25 8.3.1.2.7 Testing 8.3-25 8.3.1.2.8 AC Electrical System 8.3-25 8.3.1.2.9 Controls 8.3-26 8.3.1.2.10 Electric Power 8.3-26 8.3.1.2.11 Protection Systems 8.3-26 8.3.1.2.12 Instrumentation 8.3-26 8.3.1.2.13 Periodic Testing 8.3-26 8.3.1.2.14 Cables and Raceway Functions 8.3-26 8.3.1.2.15 Cable 8.3-31 8.3.1.2.16 Safety Feature Actuation System (SFAS) and Reactor Protection System 8.3-31 8.3.1.2.17 Markers 8.3-32 8.3.1.2.18 Essential Cables 8.3-32 8.3.1.2.19 Power Cables 8.3-33 8.3.1.2.20 Routing of Class 1E Circuits 8.3-33 8.3.1.2.21 Electrical Conductors 8.3-35 8.3.1.2.22 Base Ampacity Ratings of Cables 8.3-35 8.3.1.2.23 AC Power Circuits 8.3-36 8.3.1.2.24 Cables for Reactor Protection Systems 8.3-36 8.3.1.2.25 Redundant Class 1E Instruments 8.3-36 8.3.1.2.26 Cable Spreading Room 8.3-39 8.3.1.2.27 Circuit Schedules and Connection Diagrams 8.3-39 8.3.1.2.28 Q-List Items 8.3-39 8.3.1.2.29 Penetrations 8.3-40 8.3.1.2.30 Cable for Class 1E Service 8.3-42 8.3.2 DC Power System 8.3-42 8.3.2.1 Description 8.3-42 8.3.2.1.1 DC Motor Control Centers 8.3-42 8.3.2.1.2 Station Batteries 8.3-43 8.3.2.1.3 Battery Chargers 8.3-44 8.3.2.1.4 Essential 125V DC Panels 8.3-44 8.3.2.1.5 Rectifiers 8.3-46 8.3.2.1.6 Monitoring and Surveillance 8.3-47 8.3.2.1.7 Physical Arrangement of DC Electrical System Components 8.3-48 8.3.2.1.8 DELETED 8.3.2.1.9 Tests and Inspection 8.3-49 8.3.2.1.10 Administratively Controlled Devices 8.3-49 8.3.2.2 Analysis 8.3-49 8.3.2.2.1 DC System 8.3-49 8.3.2.2.2 Reliability 8.3-49 8.3.2.2.3 250V DC System 8.3-49 8-ii UFSAR Rev 30 10/2014

Davis-Besse Unit 1 Updated Final Safety Analysis Report TABLE OF CONTENTS (CONTINUED)

Section Title Page 8.3.2.2.4 125V DC Control Panel Boards 8.3-49 8.3.2.2.5 Station DC System 8.3-50 8.3.2.2.6 Battery Chargers 8.3-50 8.3.2.2.7 Design Criteria for Cables and Raceways 8.3-50 8.3.2.2.8 Redundancy in DC Control Power 8.3-50 8.3.2.2.9 DELETED 8.3.2.2.10 Quality Assurance Procedure 8.3-50 8.3.2.2.11 Drawings 8.3-50 8-iii UFSAR Rev 30 10/2014

Davis-Besse Unit 1 Updated Final Safety Analysis Report LIST OF TABLES Table Title Page 8.3-1 Emergency Diesel Generator Load Tables 8.3-51 8.3-2 Administratively Controlled Circuits (AC) 8.3-55 8.3-3 Administratively Controlled Circuits (DC) 8.3-56 8.3-4 Environmental Requirements for Class 1E Cable 8.3-57 8.3-5 DELETED 8-iv UFSAR Rev 30 10/2014

Davis-Besse Unit 1 Updated Final Safety Analysis Report LIST OF FIGURES Figure Title 8.2-1 DELETED 8.2-2 345kV Switchyard One-line Diagram 8.3-1 AC Electrical System One-Line Diagram, Sheet 1 8.3-2 AC Electrical System One-Line Diagram, Sheet 2 8.3-3 DELETED 8.3-4 4.16 Feeder Breakers Bus C1 Tripping and Lockout and Sychro Check Relays 8.3-5 4.16kV Feeder Breaker Bus Tie XFMR BD Brkr ABDC1 Control 8.3-6 4.16kV Feeder Breaker Bus Tie XFMR Brkr ABDC1 Control 8.3-7 4.16kV Feeder Breaker Buses C1, C2 Tie Brkr AC 110 Control 8.3-8 4.16kV Feeder Breaker Buses C1, C2 Tie Brkr AC 110 Control 8.3-9 4.16kV Feeder Breaker - Bus C1 (D1) Tripping and Lockout Relays &

Synchro-Check Relays 8.3-10 4.16kV Feeder Breaker - Bus C1 (D1) Voltage and Aux Relays 8.3-11 4.16kV Feeder Breaker - Essential Unit Substations E1 & F1 Control, Sheet 1 8.3-12 4.16kV Feeder Breaker - Essential Unit Substations E1 & F1 Control, Sheet 2 8.3-13 Auxiliary Building Sections 8.3-14 E Buses 480V Unit Substations One-Line Diagram, Sheet 1 8.3-15 F Buses 480V Unit Substations One-Line Diagram, Sheet 2 8.3-16 Water Treatment and Turbine Bldg 480V Unit Substations One-line Diagram, Sheet 3 8-v UFSAR Rev 30 10/2014

Davis-Besse Unit 1 Updated Final Safety Analysis Report LIST OF FIGURES (CONTINUED)

Figure Title 8.3-17 480V Unit Substation Lighting Distribution One-Line Diagram, Sheet 4 8.3-18 PZR and Annulus Heaters 480V Unit Substation One-Line Diagram, Sheet 5 8.3-19 Essential Unit Substations E1 and F1 Incoming Feeder Circuit Breakers, Sheet 1 8.3-20 Essential Unit Substations E1 and F1 Incoming Feeder Circuit Breakers, Sheet 2 8.3-21 Essential Unit Substations Incoming Feeder Circuit Breakers, Sheet 3 8.3-22 Essential Unit Substations MCC Feeder Circuit Breakers, Sheet 4 8.3-23 480V AC MCC (Essential) One-Line Diagram, Sheet 1 8.3-24 480V AC MCC (Essential) One-Line Diagram, Sheet 2 8.3-25 250/125V DC and Instrumentation AC One-Line Diagram 8.3-26 DELETED 8.3-27 DELETED 8.3-28 DELETED 8.3-29 DELETED 8.3-30 DELETED 8.3-31 Raceways and Grounding, Containment Details 8.3-32 Raceways, Containment EIev. 4 (603) 8.3-33 Electrical Penetration Arrangement, Shield Bldg 8.3-34 Electrical Penetration Details 8.3-35 Raceway Cable Spreading Room Fire Barriers 8.3-36 Raceway Cable Spreading Room Fire Barriers 8-vi UFSAR Rev 30 10/2014

Davis-Besse Unit 1 Updated Final Safety Analysis Report LIST OF FIGURES (CONTINUED)

Figure Title 8.3-37 Raceway Cable Spreading Room Fire Barriers 8.3-38 Criteria for Interposing Trays Fire Hazard 8.3-39 Raceway Separation Criteria Fire Hazard (Excludes External Source) 8.3-40 Raceway Separation Criteria Fire Hazard (Excludes External Source) 8.3-41 Raceway Separation Criteria Fire Hazard (Excludes External Source) 8.3-42 Raceway Separation Criteria Fire Hazard (Excludes External Source) 8.3-43 Fire Barrier Details 8.3-44 Fire Barrier Details 8.3-45 Fire Barrier Details 8.3-46 125/250V DC MCC No.1 (Essential) One-Line Diagram, 8.3-47 125/250V DC MCC No.2 (Essential) Single-Line Diagram, 8.3-48 480V AC MCC (Essential) One-Line Diagram 8-vii UFSAR Rev 30 10/2014

Davis-Besse Unit 1 Updated Final Safety Analysis Report SECTION 8 8.0 ELECTRICAL POWER

8.1 INTRODUCTION

The electric power systems for Davis-Besse Nuclear Power Station are designed to be electrically self-sufficient and to provide adequate, redundant, and reliable power sources for all electrical equipment for start-up, normal operation, safe shutdown and handling all emergency situations.

8.1.1 Utility Grid The primary Toledo Edison transmission voltage is 345 kV (nominal). Davis-Besse is connected to nearby 345 kV substations at Bay Shore (NW of Davis-Besse), Lemoyne (SW of Davis-Besse), Ohio Edison - Beaver substation (SE of Davis-Besse) and Hayes substation (SE of Davis-Besse). Office building support equipment at Davis-Besse receives some power from local distribution systems, but there are no transmission connections other than the four 345 kV connections described above.

Toledo Edison uses other transmission voltages than 345 kV. The most important voltage used, other than 345 kV, is 138 kV (nominal). There are several interconnections to other utilities at 345 kV and 138 kV. Utilities connected to the Toledo Edison grid include Detroit Edison, American Electric Power, and Ohio Edison. Each of the 345 kV substations connected to Davis-Besse is associated with at least one inter-utility connection.

8.1.2 Onsite Systems The onsite electrical systems consist of the 13.8kV, the 4.16kV, and the 480V AC distribution systems, the 120V AC instrumentation and control system, the 250/125V DC systems two 4.16kV emergency diesel-generator units and one non-Class 1E 4.16 kV diesel generator which serves as the alternate AC source for station blackout. The normal source is the unit auxiliary transformer. The reserve power supply and startup sources are the two startup transformers.

The standby power supply is provided by the two emergency diesel-generators. All voltages are nominal.

8.1.2.1 Main Generation System The main generator is rated at 1069 MVA at 0.9 power factor, 25kV, 60 Hz. The protection for the main turbine generator consists of generator protection and turbine protection.

The generator protection system can be divided into the following categories:

1. abnormal conditions originating in the grid system

2. abnormal conditions originating in the main generation system.

Abnormal conditions originating in the grid system are identified on the generator as:

1. out of step 8.1-1 UFSAR Rev 31 10/2016

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2. under frequency

3. negative phase sequence

4. over current (voltage restraint)

Abnormal conditions originating in the main generation system are identified as:

1. generator low field and loss of field

2. unit auxiliary transformer 11

a. sudden pressure

b. primary phase over current

c. secondary ground

d. differential

3. main transformer 1

a. sudden pressure

b. differential

4. generator differential

5. dual volts/hertz (overexcitation)

6. generator reverse power

7. generator field ground (alarm only)

8. generator stator ground When the unit is in normal operation, with auxiliary power supplied through the unit auxiliary transformer, the occurrence of any one of the above conditions originating in either the grid system or the main generator system will result in isolation of the turbine-generator unit from the 345kV grid system by opening breakers 34560 and 34561. The 13.8kV buses A and B are immediately fast transferred from the unit auxiliary transformer 11 to the startup transformer(s) 01 and/or 02. The specific startup transformer(s) is determined by preselection using the reserve source selector switches.

These switches can align either startup transformer to each 13.8kV bus. The immediate fast transfer of the electrical auxiliary system to the startup transformer(s) is performed for trips initiated by both categories of generator protection because all trips initiated by category 1 do not indicate the existence of a grid condition which is incapable of supplying the auxiliary system. While station auxiliaries could operate during some of the category 1 transient, the generator-turbine must be isolated to minimize the possibility of damage. Using the fast transfer scheme to take advantage of a potentially stable grid may reduce the number of challenges to the emergency diesel generators. Should the power system grid be incapable of supporting the 8.1-2 UFSAR Rev 31 10/2016

Davis-Besse Unit 1 Updated Final Safety Analysis Report station auxiliaries, existing relays will detect that condition and initiate appropriate changes in the stations electrical line up.

The turbine protection system detects abnormal conditions relating to the turbine. The more significant malfunctions or faults which cause turbine trips are listed in section 10.2.3.

Any of these abnormal conditions or trips results in a turbine trip which closes the main steam stop valves and the combined intercept valves. With the closure of these valves and any of the breakers 34560, 34561, HX11A, or HX11B closed, the generator anti-motoring circuit becomes functional in combination with a reverse power relay. The output of the anti-motoring circuit in series with the output of the reverse power relay operates a relay which trips breaker(s) 34560, 34561, HX11A, and HX11B.

Under normal operation with breakers 34560 and/or 34561 closed and breakers HX11A and HX11B closed, a turbine trip results in a delayed transfer of the 13.8kV buses A and B from the unit auxiliary source to the preselected startup transformer(s). The actual transfer is a fast transfer, but the transfer initiation is delayed by the generator protective relaying.

In addition to protecting the main turbine generator and the turbine, a turbine trip, if it occurs above a certain reactor power setpoint, will initiate the Anticipatory Reactor Trip System (ARTS) which trips the reactor. This system is also actuated by the trip of both main feedwater pump turbines or an SFRCS trip.

8.1.3 Essential Functions The station essential functions are:

1. Emergency Core Cooling

2. Containment Cooling

3. Containment Isolation

4. Emergency Ventilation

5. Safe Shutdown

6. Containment Vessel Combustible Gas Control 8.1-3 UFSAR Rev 31 10/2016

Davis-Besse Unit 1 Updated Final Safety Analysis Report 8.1.4 Essential Loads The station essential loads, related essential functions, and type of electric power supply to each load are:

Related Essential Function (refer to Load Section 8.1.3) Power Supply High pressure injection pumps (1) 4.16kV AC Decay heat removal pumps (1) 4.16kV AC Component cooling pumps (1)(2)(5) 4.16kV AC Service water pumps (1)(2)(5) 4.16kV AC Containment spray pumps (2) 480V AC Containment air cooler fans (2) 480V AC Containment vessel hydrogen dilution (6) 480V AC blowers Hydrogen recombiner (6) 480V AC Containment vessel isolation valves (3) 480V AC Emergency ventilation fans (4) 480V AC Control room emergency ventilation fans (4) 480V AC Emergency diesel generator auxiliaries (1)(2)(3)(4)(5)(6) 480V AC Engineered safety feature valves (1)(2)(3)(5) 480V AC and 125V DC Auxiliary feed pump controls (5) 125V DC Safety features actuation system (1)(2)(3)(4) 120V AC Reactor protection system (5) 120V AC Main steam atmospheric vent valves (5) 125V DC 8.1.5 Design Bases The electrical systems are designed to ensure that no single component failure will prevent operation of engineered safety systems. Redundant power sources are provided to ensure continuous operation of equipment under all modes of operation. Testing of systems is possible with the station in operation. Electrical and physical separation of cables and equipment associated with redundant elements is provided.

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Davis-Besse Unit 1 Updated Final Safety Analysis Report The design documents that are implemented in the design of the electrical systems are listed below:

Document No. Title Approval Date

1. AEC Safety Independence Between Redundant Standby (Onsite) 3-10-71 Guide 6 Power Sources and Between Their Distribution Systems Safety Selection of Diesel Generator Set Capacity for Standby 3-10-71 Guide 9 Power Supplies Safety Periodic Testing of Protection System Actuation 2-17-72 Guide 22 Functions Quality Assurance Requirements for the Installation, 8-11-72 Safety Inspection, and Testing of Instrumentation and Electric Guide 30 Equipment Safety Use of IEEE Standard 308-1971 Criteria for Class 1E 8-11-72 Guide 32 Electric System for Nuclear Power Generating Stations 10CFR50, General Design Criteria for Nuclear Appendix Power 2-10-71 Appendix A Plants (as applicable)

2. IEEE 308 Criteria for Class 1E Electric Systems for Nuclear Power 9-16-71 Generating Stations 317 Electrical Penetration Assemblies In Containment 2-4-71 Structures For Nuclear Fueled Power Generating Stations 323 General Guide for Qualifying Class 1E Electric 2-4-71 Equipment for Nuclear Power Generating Stations 334 Type Tests of Continuous-Duty Class 1E Motors 9-16-71 Installed Inside the Containment of Nuclear Power Generating Stations 336 Installation, Inspection, and Testing Requirements for 9-16-71 Instrumentation and Electric Equipment During the Construction of Nuclear Power Generating Stations 344 Seismic Qualification of Class 1E Electric Equipment for 9-16-71 Nuclear Generating Stations 387 Criteria for Diesel-Generator Units Applied as Standby 12-2-71 Power Supplies for Nuclear Power Generating Stations 8.1-5 UFSAR Rev 31 10/2016

Davis-Besse Unit 1 Updated Final Safety Analysis Report

3. In addition to the above, the relevant ANSI, IPCEA and NEC recommendations are used as guides in the design.

4. An ongoing program for environmental qualification is being implemented by DBNPS to qualify Class 1E equipment to the requirements of 10CFR50.49.

5. The design basis for the Emergency Diesel Generator excitation system also includes the following standards or regulatory documents used to qualify the replacement system. The first two guidelines below apply only to the RA70 Microprocessor-based Reference Unit.

EPRI TR- Guideline on Licensing Digital Upgrades: Endorsed by NRC 102348, TR-102348, Revision 1, NEI 01-01: A Regulatory Issue Revision 1 Revision of EPRI TR-102348 to Reflect Summary 2002-22 Changes to the 10CFR50.59 Rule.

EPRI TR- Guideline on Evaluation and Acceptance of Accepted by NRC SER 106439 Commercial Grade Digital Equipment for March 1997 Nuclear Safety Applications, October 1996.

EPRI TR- Guidelines for Electromagnetic Interference Issued November 2000 102323, Testing of Power Plant Equipment Revision 2 During the design phase of Davis-Besse Unit 1, complete adherence to the (February 1974)

Regulatory Guide 1.75 Physical Independence of Electric Systems was not possible since plant design pre-dated the issuance of 1.75 as well as IEEE 384-1974. However, the independence principles followed in the design are considered adequate to preclude a common failure mode for any design basis event and do, in fact, represent partial conformance. IEEE 279 and IEEE 308, both 1971, were used as guides during the design phase of the plant with the exception, noted in Chapter 7. Separation between redundant Class 1E equipment and circuits is mainly by separate safety class structures (rooms). However, distance and barriers are utilized as acceptable alternates. Further, there is compatibility of mechanical and electrical system design which provides that failure of related mechanical equipment of one redundant system cannot disable Class 1E circuits and equipment essential to the operation of the other redundant system. The routing of non-Class 1E cables is discussed in Subsection 8.3.1.2.18.

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Davis-Besse Unit 1 Updated Final Safety Analysis Report 8.2 OFFSITE POWER SYSTEM 8.2.1 Description Station output generated at 25kV, is fed through an isolated phase bus to the 980 MVA main transformer where it is stepped up to 345kV transmission voltage and delivered to the station switchyard. The 345kV switchyard includes one line to Bayshore Substation, one line to Lemoyne Substation, one line to Beaver Substation (Ohio Edison), and one line to Hayes Substation.

Three overhead 345kV lines are provided from the switchyard to the onsite station distribution system, one line to each of the two startup transformers and a third line to the main transformer (see Figure 8.2-2).

One or both of the two 345kV overhead lines to the startup transformers will be available to supply all essential loads within a few seconds of a loss-of-coolant accident. The third overhead line to the main and auxiliary transformers can be made available to supply all essential loads following a loss of all onsite alternating current power supplies by removing the generator main leads disconnecting links and changing the auxiliary transformer tap.

The third overhead line to the main and auxiliary transformers may be utilized in place of a startup transformer to supply all essential loads within a few seconds of a loss-of-coolant-accident provided the unit auxiliary transformer is aligned to the 13.8kV bus(es) and the generator main leads disconnecting links are removed.

8.2.1.1 Reliability Considerations The possibility of power failure due to faults in the network interconnections and the associated switching is minimized by the following arrangements:

a. Any one of the four 345kV transmission lines may be interrupted, and the others will be capable of carrying the load.

b. There are no offsite transmission line crossovers which would jeopardize availability of offsite power.

c. There are no transmission line crossovers onsite which would jeopardize the availability of offsite power. The 345 kV transmission tie lines between the switchyard and startup transformers No. 01 and 02 originate at separate positions in the switchyard and are routed on separate structures, adequately separated to minimize the possibility of their simultaneous failure.

d. There are no known offsite structures such as microwave towers or sources of fire, explosion or missiles, which, if postulated to fail in the worst possible manner, could result in damage which precludes meeting the requirements of General Design Criterion 17.

There are no onsite structures such as microwave towers which, if failed, would result in the loss of both sources of offsite power. The microwave tower is located in the southwest corner of the site, remote from the switchyard and transmission lines.

8.2-1 UFSAR Rev 31 10/2016

Davis-Besse Unit 1 Updated Final Safety Analysis Report The only source of fire, explosion, or missiles in the switchyard that if postulated to fail in the worst possible manner could result in not meeting the requirements of Criterion 17 are the two switchyard a-c station service transformers and the 345 kV power circuit breakers.

The two a-c station service transformers are separated by a masonry firewall and are located remote from any essential switchyard equipment.

The 345 kV power circuit breakers are adequately separated (minimum 100 feet) to minimize the possibility of missile damage to equipment in separate positions in the event of a breaker blowup.

e. Two of the 345kV transmission lines are constructed on the same right of-way for a part of their length (about 2 1/2 miles), but the lines are supported on independent structures set far enough apart to avoid the possibility of structural collapse of one causing an outage of both lines.

f. The 345kV system is protected from lightning and switching surges by lightning protection equipment and by overhead grounded shield wires.

g. The 345kV system stability will be maintained on the loss of the generator.

h. The bus switching arrangement in the 345kV switchyard includes two full capacity main buses. Primary and backup relaying (redundant systems) are provided for each circuit along with circuit breaker failure backup protection. These provisions permit the following:

1. Any transmission line can be cleared under normal or fault conditions without affecting any other transmission line.

2. Any single circuit breaker can be isolated for maintenance without interrupting the power or protection to any circuit.

3. Short circuits on a section of bus will be isolated without interrupting service to any circuit, other than that connected to the faulted bus section.

4. Short circuit failure of power circuit breaker No. 34562 will result in the loss of the startup transformer No. 02 and the Bay Shore line until the point of the fault is isolated by disconnect switches.

5. Short circuit failure of power circuit breaker No. 34561 will result in the loss of the main unit and the Bay Shore line, until the point of fault is isolated by disconnect switches.

6. Short circuit failure of power circuit breaker No. 34564 will result in the loss of the Ohio Edison tieline and the Lemoyne line, until the point of fault is isolated by disconnect switches.

7. Short circuit failure of power circuit breaker No. 34560 will result in tripping the generator main breakers, the loss of the unit from the system and of startup transformer No. 01, until the point of fault is isolated by disconnect switches.

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Davis-Besse Unit 1 Updated Final Safety Analysis Report

8. Short circuit failure of power circuit breaker No. 34563 will result in the loss of the startup transformer No. 01 and the Lemoyne line until the point of fault is isolated by disconnect switches.

9. Short circuit failure of power circuit breaker No. 81-B-67 will result in the loss of startup transformer No. 02 and the Hayes line until the point of fault is isolated by disconnect switches.

10. Short circuit failure of power circuit breaker No. 81-B-66 will result in the loss of startup transformer No. 01 and the Hayes line until the point of fault is isolated by disconnect switches.

11. Short circuit failure of power circuit breaker No. 81-B-65 will result in the loss of startup transformer No. 02 and the Ohio Edison (Beaver) line until the point of fault is isolated by disconnect switches.

Providing all switchyard circuits, breakers, and transformers are in service, there are no known aspects of the Davis-Besse design that do not meet the requirement of General Design Criterion (GDC) 17. A single switchyard circuit or breaker(s) can be removed from service and the remaining circuits, breakers, and transformers will still meet the requirements of GDC 17.

8.2.1.2 Stability Analysis Completed system studies have shown that the system meets Criterion 17. The results show that losing station output will not adversely affect the capability of providing offsite power to the essential buses.

These analyses are reviewed and revised as needed following significant long-term changes in the transmission or loading characteristics of the FirstEnergy grid, or when a system operating event otherwise demonstrates a need for analysis update. These analyses are generally performed by offsite personnel responsible for system planning or transmission system design.

The results of the most recent analyses are summarized below:

A steady state analysis simulated anticipated summer loads with normal system conditions, single element outages, and multiple element outages. There were no thermal or voltage criteria issues identified at the Davis-Besse Nuclear Power Station.

A voltage stability analysis modeled anticipated load, system reinforcements, and topology for summer operating conditions. The analysis evaluated a single generator and one line out of service and evaluated two lines and one generator out of service. For all of the applied FirstEnergy Planning outage contingencies to the voltage stability analysis, there were no voltage stability issues identified with the Davis-Besse Nuclear Power Station.

Transient stability studies performed by PJM (Pennsylvania-New Jersey-Maryland Interconnection) evaluated a number of contingencies and determined that all faults were stable and that the Davis-Besse Power Station had acceptable damping. The evaluated contingencies include:

1. Loss of the main generating unit.

2. Three phase fault on each transmission line.

3. Stuck breaker conditions for clearing single phase fault on each transmission line.

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Davis-Besse Unit 1 Updated Final Safety Analysis Report

4. Back-up relay breaker clearing for three phase fault at remote terminal of each transmission line.

8.2.1.3 Switchyard DC System The design of the 125V DC system for the switchyard consists of two independent systems. A fused safety switch permits these two systems to be connected during periods of battery/battery charger maintenance and testing. This fused safety switch will normally be locked open to maintain system independence. Each consists of one 125V DC, 290 amp-hour battery (nominal), one battery charger, and one 125V DC 400 ampere distribution panel. Cable separation is maintained between the two systems.

There are two batteries for the control and protective relay functions of the 345kV switchyard and transmission lines. The two batteries are located on opposite walls in the switchyard relay house basement. Each battery is supplied by a separate battery charger, each charger is supplied from a separate and independent AC station service distribution panel. In the event of the loss of one battery, the other battery has sufficient capacity to supply all the DC circuits required to detect and clear a single fault including faults requiring initiation of breaker failure protection.

The DC circuits associated with each battery are routed in physically separate raceway systems. DC circuits for transmission line protective relays, J and K Bus differential relays, and 345kV breaker trip coils are completely redundant. The AC supplies to each battery charger are also physically separated.

8.2.1.4 Switchyard Systems During normal operation, a single failure caused by a malfunction of either of the two switchyard DC systems will not affect the fault detection and fault clearing capabilities of the other system.

The ability of the switchyard to supply offsite power to the station will not be affected by the loss of the two 125V DC systems because a loss of DC power will not cause equipment to change state.

8.2-4 UFSAR Rev 31 10/2016

Davis-Besse Unit 1 Updated Final Safety Analysis Report 8.3 ONSITE POWER SYSTEMS 8.3.1 AC Power System 8.3.1.1 Description The station distribution system consists of various auxiliary electrical systems designed to provide reliable electrical power during all modes of station operation and shutdown conditions (see Figures 8.3-1 and 8.3-2). The systems are designed with sufficient power sources, redundant buses and required switching, to ensure reliability. Engineered safety feature circuits are arranged so that a loss of a single bus section, for any reason, results in only single losses of auxiliaries leaving redundant auxiliaries to perform the same function.

The station distribution system is capable of starting and accelerating the largest required drive with the remainder of the connected motor loads in service. The system will have a fast transfer to the reserve power source following a turbine generator or reactor trip, without the loss of auxiliary load.

Protective relaying is arranged for selective tripping of circuit breakers or fused disconnect switches, thus limiting the loss of power to the affected area.

Separate analyses were performed assuming the power sources from the offsite network to the safety reIated buses as derived from (1) unit auxiliary transformer and (2) the startup transformer(s). For each case it was assumed that the need for electric power was initiated by an anticipated transient such as a unit trip or an accident, whichever presented the largest load demand. Manual load shedding was not assumed. The computer model developed to perform the analyses incorporated preliminary load data collected at the plant with the unit operating at 100 percent of the electrical output power. In addition, the computer model used actual test data for the installed equipment. The plants existing electrical auxiliary system configuration (e.g., breaker status, transformer taps, etc.) was included in the computer model.

Additional calculations were performed to analyze the transients caused by starting either a reactor coolant pump or condensate pump under full load conditions plus with all Class 1E loads already running. This was performed for different onsite distribution conditions and the bus voltages were determined for each case. The analyses show that the transient voltage dips caused by starting a reactor coolant pump or condensate pump do not fall below the voltage values needed by the Class 1E equipment to traverse the transient. Class 1E equipment is not required to actuate during the transient since all Class 1E loads are running in these cases.

Calculations were also done to determine the voltages on safety-related buses from a SFAS start which confirm that the equipment would be operating within their capabilities to perform their functions.

In conclusion the analyses have demonstrated that adequate voltage will exist on the safety-related buses so that the safety systems can perform their functions. The analyses have included contingency cases which further support the capabilities of the plants electrical auxiliary system. The analyses have included comparison of the safety-related equipment capabilities to continuous operating conditions, transient conditions and actuation conditions.

The steady-state analysis shows that the voltage on the Class 1E 4160V bus does not drop below the degraded voltage relay setting during the worst operating conditions of full auxiliary load and full Class 1E load.

8.3-1 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report 8.3.1.1.1 Unit Auxiliary and Startup Transformers During normal operation of the station, the 52/69 MVA unit auxiliary power transformer, connected to the generator isolated phase bus, provides the normal source of electrical power for station auxiliaries.

Two startup transformers, each 39/52/65 MVA, are supplied from different 345kV switchyard bus sections. Each startup transformer provides power for startup, shutdown, and post-shutdown requirements. The two transformers will also serve as a complete reserve power source for the station auxiliaries in the event of failure of the unit auxiliary transformer supply.

The impact of open phase conditions on the capability of the startup transformers to perform their functions was evaluated. The conditions analyzed consisted of single (one of three) and double (two of three) open phase conductors on the high voltage (345 kV) side of the startup transformers. The analysis considered open phase conditions with and without a ground. Open phase detection and isolation systems for the startup transformers were installed to ensure that plant structures, systems, and components important to safety can perform their intended functions under postulated open phase conditions. Upon detection of an open phase condition, the system will isolate the affected startup transformer and provide operator indication of the open phase condition.

After initial installation, the OPPS will be operated with the automatic isolation function of the OPPS disabled for initial monitoring period, which is expected to last up to one operating fuel cycle. The monitoring period will used to confirm that the system performance and associated setpoints provide the correct level of protection.

During Operational Mode 3, 4, 5, 6, or defueled, the circuit connecting the 345 kV switchyard to the 13.8 kV buses through the main transformer and the auxiliary transformer may be utilized in place of a startup transformer, provided the generator main leads disconnecting links are removed and the auxiliary transformer tap is changed. Additional restrictions apply to bus configuration when the backfeed alignment is in use. Refer to the Technical Specification bases for more information.

Normally each startup transformer is the reserve power source of only one 13.8kV bus.

However, if either transformer is out of service, the remaining startup transformer is available (by manual pre-selection) to automatically supply both 13.8kV buses should the normal source (auxiliary transformer) fail. Note that in MODES 1, 2, 3 and 4, a single startup transformer and a single bus tie transformer, supplying the loads normally served by two startup transformers and two bus tie transformers, can not be guaranteed to provide adequate voltage to all equipment required for safe shutdown following a LOCA.

The secondaries of all three transformers are of low-resistance grounded, wye-connected construction.

8.3.1.1.2 13800 Volt Auxiliary System During normal operation each 13.8kV bus is fed from one of the 13.8kV secondary windings of the unit auxiliary transformer. During startup and shutdown, each bus is fed from the 13.8kV secondary winding of either startup transformer No. 01 or No. 02, or, during operational Mode 3, 4, 5, 6, or defueled, backfed through the main power transformer and unit auxiliary transformer with the generator links removed and the auxiliary transformer tap is changed.

8.3-2 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report The unit 13.8kV auxiliary distribution system consists of two 2000 A buses: A and B (see Figure 8.3-1). Each bus supplies the following loads:

two 9000 HP Reactor Coolant Pumps two 4500 HP Circulating Water Pumps one 12/16 MVA Bus Tie Transformer six 1000/1150kVA Nonessential Unit Substation Transformers The transfer of a 13.8kV bus between the three sources of electrical power can be either manual or automatic. Manual transfer is initiated by the operator from either the control room or the switchgear room, and automatic transfer is initiated by the action of generator or transformer protective relays. Reserve source selector switches are provided to preselect the alignment of startup transformers for buses A and B. This pre-selection of the alignment is for the fast bus transfers. When power is being supplied to a 13.8kV bus by a startup transformer, the reserve source selector switch for that bus can preselect the alternate startup transformer source. This permits a fast bus transfer to the alternate startup transformer source should the original source fail.

The control circuits of the feeders will not allow multiple power sources to be connected to either bus A or bus B except for a momentary paralleling of sources by manual transfer on station startup or shutdown.

Manual bus transfer between the sources is a live bus transfer scheme allowing the incoming source feeder circuit breaker to first close onto the energized bus, and then its interlocks cause the outgoing source feeder circuit breaker to trip when the operator releases the control switch of the incoming breaker. This transfer scheme results in no power interruption to the bus. The live transfer is supervised by a synchro-check relay permitting the completion of the transfer only if the two sources are in phase. Manual transfer is provided between any of the three power sources as preselected by the operator.

Automatic fast bus transfer of a 13.8kV bus from the unit auxiliary 11 transformer to an available startup transformer during normal power operation with the electrical auxiliary systems being supplied power from the unit auxiliary 11 transformer is initiated by generator protective relays, transformer protective relays, or by opening 345kV breakers 34560 and 34561. Transfer is made to the startup transformer that has been preselected as the reserve power source for the given 13.8kV bus by means of a selector switch in the control room or switchgear room.

Automatic transfer occurs only from the normal to the reserve sources or between the two reserve power sources; the transfer from either of the startup transformers to the unit auxiliary transformer can only be done manually.

The fast bus transfer scheme for opening of the 345kV breakers 34560 and 34561 to transfer from the unit auxiliary transformer 11 to the startup transformers 01 and/or 02 is further enhanced by fast acting synchrocheck relays. Opening of the 345kV breakers 34560 and 34561 during normal power operation with the electrical auxiliary systems being supplied power from the unit auxiliary transformer 11 will result in these relays monitoring the phase angle difference between the secondary voltage of the unit auxiliary transformer 11 and the startup transformer(s) secondary voltage during the fast bus transfer. Should the angle exceed 35 degrees the transfer will be blocked to prevent out of phase re-energization and the associated over-voltage stresses on the plants electrical auxiliary system provided neither the generator protective relays nor the transformer protective relays have actuated.

8.3-3 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report A startup transformer is available as a reserve source to a bus if:

a. Its secondary voltage is normal.

b. Its protective lockout relay is not tripped.

c. The bus feeder breaker closing DC voltage is available.

8.3.1.1.3 4160 Volt Auxiliary System Power supply to the 4160 volt system is from two 12/16 MVA bus tie transformers which step down the voltage from 13800 volts to 4160 volts. Each bus tie transformer normally supplies one essential and one nonessential 4160 volt bus and is available as a reserve source for the other two 4160 volt buses. The capacities of the transformers and circuit breakers are sufficient to permit full station operation with one bus tie transformer out of service, providing both startup transformers are available. (Analysis has shown that the impedances of the bus tie and startup transformers are such that acceptable voltage levels can not be guaranteed for all accident scenarios with the entire station load being simultaneously supplied through a single bus tie transformer and a single startup transformer.) Each essential 4160 volt bus is provided with a fast bus transfer scheme that will transfer the bus from its normal source to an alternate source of power.

The 4160V auxiliary distribution system consists of five 4160V, 2000 amp buses (see Figure 8.3-1).

When the unit is off line with nominal loading on the buses, the startup transformer taps may be changed to maintain voltage within an acceptable range. When the unit is brought back on line, the two startup transformers taps are reset for unit power operation.

When the unit is offline with nominal loading on the buses, the unit auxiliary transformer can be made available to supply loads by removing the generator main leads disconnecting links and changing the unit auxiliary transformer taps to maintain voltage within an acceptable range.

Two essential buses C1 and D1 provide power to engineered safety feature equipment for safe station shutdown. Each of the essential 4160V buses supplies the following loads:

Motor HP Quantity (Nameplate) 1 Service Water Pump 600 1 High Pressure Injection Pump 600 1 Decay Heat Pump 400 1 Component Cooling Pump 400 1 Essential 4160-480V Unit Substation Transformer 1000kVA Also, each bus supplies power to one 450 HP makeup pump motor.

In addition, a third 600 HP service water pump and a third 400 HP component cooling pump are provided. Each of these two pumps is connected to two 4.16kV Kirk Key interlocked, manually controlled transfer switching breakers. The Kirk Key interlock permits only one breaker to be closed at a time. Each breaker of a motor pair is connected to a separate essential 4.16kV bus.

8.3-4 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report Further interlocks are provided to prevent more than one component cooling pump breaker and one service water pump breaker from automatically closing and connecting to either emergency diesel generator at the same time. It should be noted that while swapping the running and spare Component Cooling pumps, both pumps are temporarily running on the same bus, and would remain on the bus if the emergency diesel generator was started. Administrative controls will alert operators to this unconventional EDG loading and to minimize the time during which two CCW pumps are connected onto one bus. Also, the sequences of aligning the pumps 4KV breakers are administratively controlled to ensure a pump is available for auto-loading onto each essential bus.

The two 4.16kV nonessential buses C2 and D2 supply power to non-safety-related station auxiliaries indicated on Figures 8.3-1 and 8.3-2. In the event of a station blackout, bus D2 can be aligned to either essential 4.16 kV bus for the purpose of using the Station Blackout Diesel Generator (SBODG) to supply loads required for coping with a loss of all AC power.

In normal operation, the secondary winding of each bus tie transformer is connected through a 2000 amp circuit breaker to its associated nonessential 4.16kV bus. This bus then feeds the corresponding essential 4.16kV bus through a 1200 amp circuit breaker. Each essential bus can also be energized directly from the other bus tie transformer.

Transfer schemes are provided to switch each 4.16kV bus from its normal bus tie transformer to its reserve. The transfer between the two sources is done either manually, initiated by the operator at the control room, or automatically initiated by a protective relay action. Manual transfer is a live bus scheme while automatic transfer is a fast one.

The 4.16kV system is low resistance grounded. The grounding point is the neutral of each source transformer.

The attached schematic diagrams (see Figures 8.3-5 through 8.3-12) are provided to permit an evaluation of compliance with the safety criteria.

Each 4.16kV safety-related bus is provided with two levels of voltage protection. Four relays at each level function as a coincidental logic to preclude spurious trips of the offsite power source.

The time delays associated with the relays are chosen so as to minimize the effect of short duration disturbances from reducing the availability of the offsite power source, to assure that the allowable time duration of a degraded voltage condition does not result in failure of safety systems or components, and to assure the starting times of equipment assumed in the accident analysis are not exceeded. The Degraded Voltage Relays automatically initiate disconnection of the offsite power source whenever the voltage setpoint and time delay have been exceeded.

The Loss of Voltage Relays automatically initiates disconnection of the offsite power source, load shed the bus, and starts the diesel generator whenever the voltage setpoint and time delay have been exceeded. See Technical Specification and Technical Requirements Manual for voltage and time delay values.

Starting one reactor coolant pump or circulating water pump can result in a voltage reduction on the 4.16 KV buses because the voltage drop on the 13.8 KV buses which supply power to the pump motors is fed through to the 4.16 KV buses. In order to block the low voltage trip when these pumps are started, a push button bypass allows the degraded voltage relays to be bypassed for up to one minute during pump starts.

8.3-5 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report 8.3.1.1.4 Diesel Generators General

Description:

8.3.1.1.4.1 Emergency Diesel Generators Two redundant emergency diesel generator units, one connected to essential 4.16kV bus C1 and the other connected to essential 4.16kV bus D1, are provided as onsite standby power sources to supply their respective essential buses upon loss of the normal and the reserve power sources. Bus load shedding and isolation, bus transfer to the emergency diesel generator, and pickup of critical loads is automatic.

Each emergency diesel generator has the following ratings and characteristics:

Continuous rating 2600 kW

2000 hr. rating 2838 kW 200 hr. rating 2946 kW

30 minute rating 3035 kW

Short term rating 2860 kW Generator rating 3250 kVA Assumed power factor 0.8

Short-term rating is the electric power output capability that the emergency diesel generator can maintain in the service environment for two hours in any 24-hour period.

Any combination of normally connected (and operating) loads and loads that are automatically connected (and operating) following a loss of offsite power and/or LOCA will not exceed the smaller of the 2000 hour0.0231 days 0.556 hours 0.00331 weeks 7.61e-4 months rating or 90 percent of the 30-minute rating (i.e., 3035* 0.9 = 2731.5 kW) of the emergency diesel generator, after taking into account actual expected loading (vs.

rated load). Refer to Table 8.3-1 for the applicable load tabulations. (Reference Safety Guide 9, Regulatory Position C.2)

The emergency diesel generator is capable of attaining rated frequency and voltage approximately 10 seconds after the engine start signal is received.

Each of the two emergency diesel generators has the capability to:

a. Supply continuously the sum of the load on the essential 4160V bus needed to be powered at any one time.

b. Start and accelerate to rated speed in the required sequence its dedicated engineered safety features loads. At no time during the loading sequence, will the frequency and voltage decrease to less than 95 percent of nominal and 75 percent of nominal, respectively, except that during the first step in the required loading sequence, there may be a voltage dip below 75 percent of normal lasting for a few cycles due to the essential unit substation transformer excitation inrush.

During recovery from transients caused by step load increases or resulting from disconnection of largest load, the speed of the diesel engine will not exceed 75 percent of the difference between nominal speed (900 rpm) and the overspeed trip setpoint.

Each diesel will receive a starting signal when any one of the following occurs:

8.3-6 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report

a. Loss of essential bus voltage

b. A safety feature actuation signal (SFAS level 2)

c. Manual start (local or remote)

d. Test signals to simulate any of the above Any of the above conditions will initiate a start signal to the emergency diesel engine. However, except for manual synchronizing during routine testing, the essential bus will be isolated only upon loss of voltage or a bus fault, and the emergency diesel breaker will be closed only on loss of voltage without a bus fault.

Relays connected to potential transformers at the emergency diesel generator terminals will detect generator rated voltage and provide a permissive interlock for the closing of the respective generator circuit breaker. Interlocks are provided to prevent automatic closing of an emergency diesel generator breaker to an energized or faulted bus.

Emergency Operation:

Loss of essential bus voltage will be detected by the Loss of Voltage Relays. In addition, the Degraded Voltage Relays will permit continuous operation at reduced voltage conditions for a period of time not exceeding the time delay specified in Technical Specifications and the Technical Requirements Manual, after which the incoming 4.16kV essential bus source breakers will be tripped.

If loss of power is confirmed, by loss of voltage at either essential 4.16kV bus, the following will occur:

1. All bus load breakers, except the breakers supplying power to the 480V essential unit substation supply breakers and component cooling pump breakers, will be tripped.

2. Both source breakers will be tripped and the bus will be isolated.

3. The associated emergency diesel generator set will be started, if not already running.

4. When the emergency diesel generator reaches rated voltage, the corresponding emergency diesel generator breaker will close energizing the 4.16kV and 480V essential buses.

5a. In case the safety features actuation system has been tripped, the engineered safety features loads will be automatically energized according to the predetermined loading sequence given in Table 8.3-1.

5b. In case the safety features actuation system has not been tripped, the emergency diesel will be loaded manually; except that in any case, the component cooling water pumps, service water pumps, previously running makeup pump and the essential 480 volt buses will be started/energized. The loading sequence is provided in the Notes of Table 8.3-1. Also see Section 9.2.7.3 for details.

8.3-7 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report In the event of loss of power, there will be an interruption of approximately 10 seconds in power supply to the previously running component cooling pumps. The standby component cooling pump will start 10 seconds after the EDG output breaker closes.

However, there will be no effect on the diesel generator performance since each diesel is capable of operating without cooling water for three minutes at startup and for one minute at rated full load.

The diesel generators will remain on-line during this interval since the engine high temperature (high jacket water) trip of each diesel is defeated during emergency operation.

Testing:

The emergency diesel generator units have been tested according to IEEE 387. Periodic testing requirements of the emergency diesel generators are given in the Technical Specifications. Each emergency diesel generator is equipped for test purposes only with means for periodically testing, synchronizing, and loading without interrupting service. Only one emergency diesel generator is loaded at any one time. During testing, interlocks will prevent paralleling an emergency diesel generator with the auxiliary or startup transformer until the generator has been manually synchronized by the operator and the synchronism-check relay contacts are closed. Also for testing purposes, an idle start/stop feature in the diesel generator control circuit allows the diesels to be started to an idle setting via the local idle start circuit and allows for a normal stop 10-minute idle cooldown.

A normal or emergency start signal overrides this feature, with exception of the start pushbutton on C3621 (C3622). The idle start/stop feature is intended to prolong the life and reliability of the diesel generators.

Mechanical/Electrical Protection:

Each emergency diesel generator is equipped with mechanical and electrical interlocks to ensure personnel protection and to prevent or limit equipment damage. During a non-emergency diesel generator operation (for example, on-line testing) some of the following mechanical and electrical protective devices are capable of initiating a diesel generator trip.

However, during an emergency operation, namely on a loss of essential bus voltage or an SFAS level 2, controls limit the diesel generator trip to generator differential relay action (87/DG), and engine overspeed (OTS). This measure is taken to minimize the possibility of the above devices needlessly preventing the diesel from operating when required, as during a DBA.

However, alarms are still provided for high crankcase pressure, low lube oil pressure, high engine temperature, and electrical protective relays. The 51V-2 relay is also not bypassed which will trip the EDG output breaker due to fault on the essential bus. This relay enhances the availability of the diesel generator.

8.3-8 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report Except as modified by a loss of essential bus voltage signal or SFAS level 2, the installed protective type devices that are incorporated in the design to protect the diesel generators from exceeding operating limits are as follows:

A. Electrical Protective Relays:

Description Function Reverse power relay (32/DG): Trip breaker

- provides anti-motoring protection for the diesel to preclude the danger of explosion and fire from unburned fuel.

Generator ground relay (51G/DG): Trip breaker

- provides protection for ground faults in the generator, the 4.16kV essential bus, and the cabling between the generator and the bus. It also provides ground-fault back-up protection for feeder faults.

Generator differential relays (87/DG): Trips engine/breaker

- provide protection for faults in the zone between the generator neutral and its associated 4.16kV essential bus.

Voltage controlled, over current relays (51V-1/DG,51V-2/DG): Trip breaker

- provide generator fault backup protection as well as system fault backup protection.

Loss of field relay (40/DG): Trip breaker

- provides generator protection due to loss of field.

Negative phase sequence relay (461DG): Trip breaker

- provides generator rotor overheating protection due to unbalanced faults.

Over and under-voltage (27-59/DG): Alarm only

- alarms if generator voltage exceeds limits.

Voltage balance (60/DG): Prevent false trip by

- senses an imbalance between the bus potential transformers emergency diesel generator and the emergency diesel generator potential transformers voltage controlled, over-due to a blown fuse. current relays Synchronism-check relay (25/DG): Manual breaker permissive

- provides generator protection from being manually loaded onto a 4160V bus out of phase.

8.3-9 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report B. Mechanical Protective Devices:

(Nominal Setpoints - for variances on these setpoints, see the Instrument Index Drawing M-720I)

Description Function High Jacket Water Temperature Switch (HJWTS) set at 205°F Trips engine/breaker High Crankcase Pressure Switch (CPS) - set at 1 of water Alarm only Low Lube Oil Pressure Switch (LOPS) - set at 20 psi Trips engine/breaker Engine Overspeed Trip (OTS) - set at 1035 rpm 115% speed Trips engine/breaker Manual Emergency Shutdown: Trips engine/breaker

- A manual emergency shutdown pushbutton which does not get by-passed during emergency operation is located locally at the engine control panel. This device is provided for personnel and equipment protection.

Essential Subsystems:

The following are descriptions of the essential subsystems for the diesels:

a. Starting air system - each of the two emergency diesel generators has a complete starting air supply system including starting air compressor, two air reservoirs (each of which has the capacity to provide 5 starts without recharging), and two sets of two starting motors in parallel, one set from each reservoir. The compressor has sufficient capacity to recharge two air reservoirs from minimum to maximum starting air pressure in not more than 30 minutes. Each air compressor will charge one of the two air reservoirs in the starting systems for each of the two emergency diesel engines. A third compressor, which can be manually aligned to act as either of the normally aligned compressors, is available when either of the other two compressors has been isolated. (Figure 9.5-8A - Diesel Generator Air Start System, and Figure 9.5 Diesel Generator Day Tank Location)

b. Lubricating oil system - each diesel engine has its own independent lube oil system which is an integral part of the engine. The lube oil system consists of the following (Figure 9.5 Emergency Diesel Generator Auxiliary Systems):

1. Lube oil filtering and cooling system - this system draws oil from the engine sump through a cleanable basket strainer by means of an engine-driven scavenge pump. The oil is directed to a full flow filter, and then to an oil cooler. Thermostatically controlled engine jacket water cools and maintains the lube oil temperature automatically at the proper operating condition. The cooled oil returns to an engine-mounted strainer.

2. Main lubrication and piston cooling systems - these systems draw oil from the oil cooler through the duplex strainer by the gear-driven pressure pump. The main lubrication oil system supplies oil pressure to all necessary moving parts of the engine. The piston cooling pump discharges oil in continuous sprays on the underside of the piston crown. All oil from these systems drains into the engine oil sump. A dipstick oil level gauge is provided, and the oil is added at the strainer.

8.3-10 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report

3. Turbocharger cooling system - an independent, essentially powered, AC motor-driven turbo oil pump draws oil from the sump and delivers it to the turbocharger bearings through a replaceable cartridge filter. This pump is always kept running to provide pre-lubrication of the turbocharger bearings for starting and post-lubrication at stopping. The oil drains from the turbocharger housing into the oil sump. An alarm is actuated if sufficient oil pressure is not provided to the turbocharger bearings. An electric, DC motor-driven pump acts as a back-up to the AC turbo oil pump. The DC motor-driven pump is normally in standby (not running) but will automatically start when the discharge pressure from the AC motor-driven turbo pump drops off.

4. An essentially powered AC motor-driven circulating oil pump draws oil from the engine sump and circulates it through the main lube oil filter, the lube oil cooler, and the main lube oil gallery. This pump is always kept running to provide pre-lubrication of the engine with warm, filtered oil.

c. Jacket water cooling system - each emergency diesel engine water jacket cooling system includes a heat exchanger, expansion tank, lube oil cooler, automatic cooling water temperature regulating valve, and engine-driven water pumps.

Jacket cooling water is circulated in a closed loop through the engine lube oil cooler, the engine cooling water passages, and the shell side of the raw water heat exchanger. The raw water flowing through the tube side is a part of the component cooling water system.

An electric immersion heater powered from an essential source is provided in the diesel engine jacket water system, and is controlled by a temperature switch. The immersion heater keeps both the jacket water and lube oil systems warm during standby conditions to enhance reliability and fast starting of the emergency diesel generator set. The heated water is circulated by thermo-siphoning through the lube oil cooler where the circulating oil gets heated up, and is maintained above 85°F. A low jacket water temperature alarm monitors the operation of the immersion heater. (Figure 9.5 Emergency Diesel Generator Auxiliary Systems)

d. Fuel oil system - the diesel oil system includes seven days storage of fuel oil for each emergency diesel generator. This system consists of the emergency diesel generator day tank, bulk storage (week) tank, pumps, and associated piping and valves to the respective diesel generator. The oil storage tank and the fuel oil transfer system are designated as Class 1E structures within the meaning of IEEE 308. A complete description of the diesel fuel oil system is given in Subsection 9.5.4.

The fuel oil filtering system is composed of a number of devices to guarantee fuel oil purity. Before entering the suction of the engine driven fuel pump, the oil passes through a strainer which protects the pump. The oil discharged from the pump then passes through a duplex cartridge filter. The fuel supplied by the DC motor-driven, redundant fuel pump is filtered in the same manner as that supplied by the engine driven pump, except that a duplex basket strainer is used on the suction of the pump. (Figure 9.5 Emergency Diesel Generator Auxiliary Systems, and Figure 9.5 Diesel Generator Day Tank Location) 8.3-11 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report The factors which are used to determine that the emergency diesel generator day tank capacity is sufficient for approximately 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months at 110 percent full load operation are as follows:

The emergency diesel generator day tank normally stores approximately 5000 usable gallons of fuel oil, (4728 gals at the tank low level switch setpoint for starting the Transfer Pump to 5155 gallons at the tank high level switch setpoint for shutting off the Transfer Pump). At 100 percent rated load, 5000 gallons of usable fuel oil is sufficient to continue operation for approximately 25 hours2.893519e-4 days 0.00694 hours 4.133598e-5 weeks 9.5125e-6 months . If loading is 110 percent this quantity of fuel oil is sufficient to continue operation for approximately 23 hours2.662037e-4 days 0.00639 hours 3.80291e-5 weeks 8.7515e-6 months , assuming a reasonable increase in the fuel oil consumption rate (lbs. of fuel oil per bhp per hour) above the rate at 100 percent load. However, a low-low level alarm is established with approximately 4530 gallons usable fuel still remaining in the tank. This quantity of fuel oil can maintain full load diesel operation for approximately 23 hours2.662037e-4 days 0.00639 hours 3.80291e-5 weeks 8.7515e-6 months or approximately 21 hours2.430556e-4 days 0.00583 hours 3.472222e-5 weeks 7.9905e-6 months at 110 percent loads, assuming the same reasonable increase in the fuel oil consumption rate used earlier.

e. Air intake and exhaust systems - the air intake structure and filtering system for each diesel consists of an intake filter assembly, an intake silencer, and interconnecting piping to the diesel engine-mounted air inlet flexible connector.

The filtered air then enters the impeller-end of a turbocharger where its pressure is increased for combustion and exhaust gas removal. The exhaust system consists of an engine-mounted manifold, turbine-end of the turbocharger, and inter-connecting piping to an exhaust silencer. (Figure 9.5-8A - Diesel Generator Air Start System)

The physical arrangement of the air intake and exhaust for the emergency diesel generators is shown in Figure 8.3 Auxiliary Building Sections, and Figure 9.5 Diesel Generator Day Tank Location. The air intake filter and intake and exhaust silencers are located outside at the roof top of the auxiliary building above the diesel rooms. Suitable enclosures are provided to protect the filter and silencers from missiles, tornadoes, snow, rain, etc. Since the air intake is located outside of the diesel building, there is no possibility of fire extinguishing agents being drawn into the air intakes. The physical separation of the intake and exhaust preclude significant recirculation of exhaust gas into the air intake.

f. Excitation and voltage regulating system - a solid state excitation and voltage regulating system of the series boost static regulator type, is provided for each emergency diesel generator unit. The exciter is of the static type having fast response characteristics and reliability for allowing the startup of a heavy load parallel with a running load. The voltage regulator is a static type with silicon type rectifiers and provides the necessary excitation control to maintain the adjusted generator voltage with the generator operating at loads ranging from zero up to and including its overload capacity at rated power factor and frequency. The generator reactances, excitation system, and regulator response time are such that adequate voltage is provided to meet automatic loading requirements in accordance with AEC Safety Guide 9. The electric power supply for field flashing will be taken from the respective station battery. Sufficient electrical instrumentation is furnished to survey the variables required for successful operation of the excitation and voltage regulation system.

8.3-12 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report Electrical instrument power supplies will be 120V AC and 125V DC from redundant essential instrument power distribution panels.

Sufficient mechanical and electrical instrumentation is provided for each emergency diesel to survey the variables required for successful operation.

The systems monitored included the starting system, lubrication system, fuel system, cooling system, combustion air system and exhaust system.

Separation/Hazards Figure 3.6-3 indicated the physical arrangement of the diesel generators, fuel oil day tanks, and starting air system. Physical separation is provided to each diesel generator and its associated auxiliary systems. The floor drains in the two EDG rooms are interconnected, and therefore not physically separated and independent. An evaluation of this common drain design verified that no credible single event would disable both EDG units (see also Flooding in this subsection).

The redundant emergency diesel generating units are located in separate, adjacent rooms in the Seismic Class I auxiliary building (also see Subsection 8.3.1.1.8). A fire wall and door are provided between the two rooms. The local control and auxiliaries for each emergency diesel generating unit are located in the same room as the diesel with which they are associated.

Missiles Internal missiles generated by one unit will not affect the redundant unit since the walls act as missile barriers. A high crankcase pressure switch is provided which will alarm. These units are located in the auxiliary building which is protected from external missiles generated by a tornado. There are no other external missiles which can affect these units.

Fires Each diesel generator room is protected by a pre-action sprinkler system. Water is admitted to the system through an automatically actuated valve located outside the diesel generator rooms, which is automatically activated by photoelectric smoke detectors. Pressure switches are provided. Photoelectric smoke detectors are provided for alarm. In addition, a hose station and portable fire extinguishers are provided for each room. The diesel oil day tank rooms are protected with a wet pipe, automatic sprinkler system. Flow switches are also provided. Fire walls and doors separate each diesel generator and its associated auxiliary systems.

Flooding Four-inch drains are provided in each room to accommodate fire suppression water, fuel oil spills or leak in a diesel engine heat exchanger component cooling water line. The floor drains in these two rooms are tied together and the drainage rate is limited due to the oil interceptor that these drains connect to. Fire suppression activities that introduce water at a rate in excess of the capacity of this common drain system require that the one of the outside doors to one of the rooms be opened or suppression activities minimized to prevent flooding in both rooms.

See Table 9.2-6 for a single failure analysis of the component cooling water line.

Mechanical Failures The intake, exhaust, fuel oil, cooling water, and lube oil systems are independent systems for each diesel generator unit.

8.3-13 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report The starting air systems are interconnected. Each compressor charges one air receiver for each unit. One compressor can be lost with the redundant compressor capable of charging one air receiver for each unit. Likewise, the loss of one air receiver and its associated piping and valves will not prevent starting from the redundant air receiver. In addition, a third swing compressor can be aligned to act automatically as either of the other two compressors.

Interconnecting piping between redundant starting systems is typically isolated by double valving. However, with other alignments, such as the third compressor in service, interconnecting piping between redundant starting systems is isolated minimally by a single manual valve, as can be seen in Figure 9.5-8A. Also, there are two air lines on each EDG that tap off downstream of the air start solenoid valves, pass through a check valve, and then combine into a common header for the hydraulic governor air booster servomotor. The check valves prevent air back-leakage into the other air side.

Auxiliary Support Systems The following are Seismic Class I auxiliary systems which supply the emergency diesel generator rooms of the auxiliary building:

- Fuel Oil System: this system is fully described in Subsection 9.5.4 and 8.3.1.1.4.1.

(Figure 9.5 Diesel Generator Day Tank Location, and Figure 9.5 Emergency Diesel Generator Auxiliary Systems)

A Seismic Category 1, missile protected, fuel oil storage and transfer system that meets IEEE 308 requirements is provided.

- Component Cooling Water System: this system is fully described in Subsection 9.2.2.

(Figure 9.2 Component Cooling Water System)

Subsection 8.3.1.1.4.1 describes, in detail, the diesel generator jacket water cooling system.

- Ventilation System: this system is described in Subsection 9.4.2.1.2.

Subsections 9.4.2.1.2.3 and 9.4.2.1.3.3 describe, in detail, the emergency diesel generator room ventilation system.

During the winter, heating for the emergency diesel generator rooms is supplied by means of an electric heating system which maintains a 60°F minimum temperature with an outdoor design temperature of -10°F.

In addition, the ventilation fans in each room automatically start whenever the diesel in that room is operating. Outside air is mixed with the recirculation air, as required, to maintain design conditions in the room. The fan motors are energized from the essential 480V motor control centers to guarantee their availability.

- Station batteries: as noted in Subsection 8.3.2.1.4, some battery power has been assigned to each emergency diesel generator. This assignment is for control and field flashing, not for cranking service.

8.3-14 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report 8.3.1.1.4.2 Alternate AC Source - Station Blackout Diesel Generator The purpose of the non-class 1E 4.16kV, 2865KW Station Blackout Diesel Generator (SBODG) is to provide AC power to all systems required for coping with a Station Blackout as defined in 10CFR50.2. This alternate AC power source meets the criteria specified in Appendix B to NUMARC 87-00, Guidelines and Technical Bases for NUMARC Initiative Addressing Station Blackout at Light Water Reactors and in Regulatory Guide 1.155, Station Blackout.

The SBODG and support systems (auxiliaries), except the engine radiator, are located in a separate structure south of the Station within the protected area. To protect the SBODG from likely weather events which could initiate a loss of off-site power, this structure shall conform to Ohio Basic Building Code. Additionally, all cabling between this structure and the Station is routed through buried duct bank. The SBODG engine radiator is designed for outdoor installation.

Two 1200 amp circuit breakers in series connect the SBODG to the Stations nonessential 4.16 kV Bus D2. The circuit breaker which is at Bus D2 is normally closed and supplies power to SBODG auxiliaries during standby conditions. Closing the normally open 1200 amp circuit breaker which is located in the SBODG building connects the generator to Bus D2. During emergency conditions, power to the SBODG auxiliaries is supplied by the generator itself.

The SBODG is capable of supplying either of the Stations essential 4.16kV buses through nonessential Bus D2 and is available within ten minutes of the onset of Station Blackout. During an emergency, the SBODG can be manually started and loaded onto Bus D2 from the Control Room auto starting and loading is not provided. Operation of circuit breakers to make an SBODG line up to either essential bus can also be accomplished from the Control Room. The SBODG is capable of unattended operation at rated full-load for at least four hours. The SBODG has the following ratings and characteristics:

Continuous Rating 2865kW, 3580kVA 2000 Hour Peaking 3135kW, 3918kVA Power Factor 0.8 Reactances xd = 2.35 xd = 0.42 xd = 0.27 A 125V battery system is included among the SBODG auxiliaries. These batteries have sufficient capacity to maintain DC control power and diesel-generator starting and loading ability. SBODG Breaker AD213, which is normally closed, receives control power from the Stations Train 2 D.C. Distribution System.

A compressed air system is used for SBODG engine starting. The primary system components are two ASME Code VIII air receivers and two electric motor driven air compressors.

The fuel oil supply for the SBODG engine is separate from the fuel oil supply used by the Stations Emergency Diesel Generators. The SBODG fuel oil supply tank has enough capacity to provide an eight-hour supply with the generator at rated load. Four hours of fuel must be stored in this tank to meet the Sites Station Blackout duration.

The SBODG building is protected by fire protection systems.

The diesel engine cooling system is a closed loop system. Cooling is provided using a force draft radiator with engine-driven cooling water pumps.

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Davis-Besse Unit 1 Updated Final Safety Analysis Report SBODG testing follows the recommendations presented in Appendix B of NUMARC 87-00. To facilitate testing, a sync-check relay prevents paralleling the SBODG with the auxiliary transformer or either start-up transformer until the generator has been manually synchronized.

8.3.1.1.5 480V AC Auxiliary System The station 480V AC distribution system consists of:

Two 1000kVA 4160-480V AC essential unit substations (E1 and F1) for the supply of power to the 480V AC safety loads.

Six 1000kVA, 13800-480V AC nonessential unit substations (E2, E3, F2, F3, EF4, and EF6) for the supply of power to the 480V AC normal auxiliaries.

One 1000kVA, 4160-480V AC nonessential unit substation (F7) for the supply of 480V AC to Station Auxiliaries.

One 225kVA, 4160-480V AC distribution center for supplying 480V AC power to the station blackout diesel generator auxiliaries.

Two 750kVA, 4160-480V AC lighting substations (E5 and F5) for station lighting.

One 112.5kVA, 4160-480V AC outdoor distribution center for outdoor lighting.

Two 500kVA, 4160-480V AC switchyard distribution centers for supplying 480V AC power to the switchyard.

See Figures 8.3-14 through 8.3-18.

The two 4160-480V AC essential unit substations are double ended (two transformers) with transformer secondaries wye connected and the neutral high resistance grounded. The six 13800-480V AC nonessential unit substations are double-ended (two transformers) with transformer secondaries wye connected and the neutral solidly grounded, except for transformers AE3 and BF3, which are high resistance grounded. The capacity of each transformer is sufficient to permit station operation with one transformer out of service. The two 4160-480V AC essential and four of the 13800-480V AC nonessential unit substations have a single bus; each of the remaining two 13800-480V AC nonessential unit substations has a two bus arrangement with a tie breaker between the buses.

Each 4160-480V AC essential unit substation is supplied from its corresponding 4160V AC essential bus through redundant normally closed 1200 ampere circuit breakers; one feeder is connected to the primary side of each transformer. The transformer secondary side is connected to the 480V, 1600 amp bus through a 1600 amp circuit breaker. During normal operation both of the essential 4160-480V AC unit substation transformers are energized with one transformer carrying the load and the second transformer carrying no load. Transfer from one transformer to the other is by manual control only; automatic transfer is not provided. It is possible to accomplish either a live (bus energized) or a dead (bus de-energized) transfer at the operators discretion (see Figures 8.3-19 through 8.3-22).

Each 13800-480V AC nonessential unit substation is supplied from alternate 13800V AC Buses A and B. Apart from the arrangement of the incoming primary feeders, four of these substations are designed to operate in the same manner as the essential substations. Each of the 8.3-16 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report remaining two substations has a manual transfer scheme between the two main circuit breakers and the bus tie circuit breaker such that only two breakers can be maintained in the closed position at the same time. The bus tie breaker is normally open.

The 4160-480V AC nonessential unit substation F7 is supplied from 4160V Bus D2 through a normally closed 1200 ampere circuit breaker. The transformer secondary side is connected to the 480V AC 1600 amp bus through a 1600 amp circuit breaker.

The nonessential 225kVA 4160-480V AC distribution center consists of a 480V AC motor control center BF81 which supplies power to the station black out diesel generator (SBODG) auxiliaries. The center is fed from transformer DF8, a 4160-480V transformer through breaker BF8105. Transformer DF8 is powered through a fuse from 4160V Bus D3 by either the SBODG via breaker AD301 or from Bus D2 via AD213. The normal feed for D3 (and DF8) is from Bus D2 breaker AD213.

Each of the two lighting substations has a single bus arrangement and one transformer. The primary side of the transformer is connected to one 4.16kV AC nonessential bus. The secondary side is connected to the 1600 amp bus through a 1600 amp circuit breaker. The two lighting substation 480V AC buses are connected through a normally open tie breaker. Either transformer can supply the entire station lighting load.

An outdoor distribution center supplies 480V AC power for outdoor lighting and other miscellaneous loads. The distribution center transformer is connected to one of two alternate 4.16kV sources through a manual throw-over switch.

Two switchyard distribution centers are provided to supply the switchyard AC requirement of 480V AC and below. Each distribution center transformer is connected on the primary side to one 4.16kV AC nonessential bus.

The 480V AC system also contains approximately 70 motor control centers about two-thirds of which supply nonessential station loads, and the remainder serve engineered safety features and other safety loads. The motor control centers are supplied from the unit substations.

The equipment is arranged and switching accomplished such that the loss of any 480V bus or any single failure would deprive the station of only part of the safety-related equipment associated with that particular function. The remaining operational equipment will be adequate in these circumstances to allow the station to continue to operate and supply all safety functions (see Figures 8.3-23 and 8.3-24).

The circuit breakers shown on Figure 8.3-2 identified as being without automatic tripping device and described as follows.

The breakers are molded case type which have continuous current ratings equal to the frame size, but are not equipped with automatically operating over current circuit tripping elements.

The breakers are designed to function as manually operated, high capacity disconnect switches only. Normal circuit protective functions are assigned to other system breakers, i.e., those breakers with over current tripping elements.

The use of this type of breaker can be justified in the design of a Class 1E power system since, as stated previously, circuit protective functions are properly assigned to breakers equipped with automatic over current tripping elements or current limiting fused disconnect switches.

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Davis-Besse Unit 1 Updated Final Safety Analysis Report The following is a description of the design of the Class 1E electric power systems downstream of the 480V switchgear buses E1 and F1 (Figure 8.3-2), to demonstrate conformance with IEEE Standard 308-1971 and Regulatory Guide 1.6.

As noted on the revised Figure 8.3-2, all possible cross connections, except three, between buses E1 and F1 and a fourth between F1 and non-essential Bus F7, have been eliminated. These remaining four listed below, are designed with both electrical and manual mechanical interlocking to guarantee independence between buses E1 and F1 and between F1 and F7; this conforms to Regulatory Guide 1.6, position 4 (d). In addition, transfer between E1 and F1 and between F1 and F7 is non-automatic, and thus conforms to Regulatory Guide 1.6, positions 4 (a) through 4 (c).

a. Motor control center F13 is non-safety related. It has its associated incoming, non-automatic circuit breakers, BF1310 and BF1304, mechanically interlocked by a Kirk key system which precludes having both breakers in the closed position at any one time. The associated upstream motor control center normal feeder breaker, BF705, at bus F7 is automatically tripped by an electrical interlocking contact from breaker BF1304 if breaker BF1304 is open. Similarly, the upstream motor control center alternate feeder breaker, BF113, at bus F1 is automatically tripped by an electrical interlocking contact from breaker BF1310 if breaker BF1310 is open. Thus there is no direct interlocking between buses F7 and F1. In addition, an alarm in the control room is established if a non-normal breaker alignment (based on Figure 8.3-2) is set up.

b. Motor control center EF15 has a split bus arrangement, one bus for high speed and the second for low speed operation of containment cooler fan 1-3. Kirk key type mechanical interlocking is provided between breakers BEF152 and BEF154 and between breakers BEF151 and BEF153. This prevents both paired breakers from being in the closed position at any one time. Breakers BEF151 and BEF152 are electrically interlocked with their associated upstream substation breaker BE105. In addition, breakers BEF153 and BEF154 are electrically interlocked with their associated upstream substation breaker BF105. The electrical interlocking is actuated to trip the substation breaker if either of its associated downstream breakers is open. An alarm in the control room is established if a non-normal breaker alignment (based on Figure 8.3-2) is set up.

c. Motor control center EF12C can be fed from either bus E1 or bus F1 via motor control centers E12A or F12A, respectively. Kirk key type mechanical interlocking is provided between fused disconnect switches BEF121 and BEF122 in order to preclude having both fused disconnect switches closed at the same time.

Electrical interlocking is provided between fused disconnect switch BEF121 and its associated upstream, latch-in type contactor at BE1280 of motor control center E12, section E12C and between fused disconnect switch BEF122 and its associated upstream, latch-in type contactor at BF1280 of motor control center F12, section 12C. In both cases, electrical interlocking prevents contactor closing if the associated downstream fused disconnect switch is open. The electrical interlocking also trips the contactor if the downstream fused disconnect switch is opened after the contactor has been closed.

d. Motor control center EF12D can be fed from either bus E1 or bus F1 via motor control centers E12A or F12A. Kirk key type mechanical interlocking is provided 8.3-18 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report between breakers BEF128 and BEF129 in order to preclude having both breakers closed at the same time. Electrical interlocking is provided between breaker BEF128 and its associated upstream contactor at BE1207 on MCCE12A and between breaker BEF129 and its associated contactor at BF1224 on MCCF12A.

In both cases, electrical interlocking prevents contactor closing if the associated downstream breaker is open.

8.3.1.1.6 120V AC Auxiliary System The station 120V AC system (see Figure 8.3-25) consists of:

Four essential instrument distribution panels each supplied from a 125V DC/120V AC inverter.

The four essential instrument distribution panels are comprised of six physical panels, Y1, Y1A, Y2, Y2A, Y3, and Y4. The two physical panels for Channel 1, Y1, and Y1A, are administratively controlled as a single panel, identified as bus Y1. The two physical panels for Channel 2, Y2, and Y2A, are administratively controlled as a single panel, identified a bus Y2. Buses Y3 and Y4 are each comprised of a single distribution panel.

Two regulated instrument distribution panels each supplied from one 480/120V AC static voltage regulator.

Two uninterruptible instrument distribution panels each supplied from a 250V DC/120V AC inverter.

All inverters are fed from the DC power supplies as described in Subsection 8.3.2.

Each of the four 120 volt single phase, 60 Hertz essential instrument distribution panels supplies power to one of the four channels in the reactor protection system and the safety features actuation system. The essential instrument AC system is arranged so that any type of single failure or fault will not prevent the reactor protection system or safety features actuation system from performing their safety functions. There are four independent panels available, and a single failure within the system can involve only one panel. A combination of simultaneous failures or faults on any two of the channels will trip the reactor and trigger the safety actuation system.

The inverter and rectifier for channels 1, 2, 3, and 4 are equipped with a static automatic bypass switch for fault clearing capability and for maintaining power to the 120V AC essential distribution panels upon inverter failure. The alternate source for channels 1 and 3, and 2 and 4 inverters are essential 480V AC busses E1 and F1 respectively through a 480/120V AC constant voltage transformer (CVT). Although the essential CVT is available as a maintenance backup source, a non essential regulated instrumentation distribution panel is also available as an alternate source to the 120V AC distribution panel via manual transfer.

Each uninterruptible instrument distribution panel is fed from one 50kVA single phase, 60 Hertz 250V DC/120V AC inverter and supplies important non-safety related loads, as shown in Figure 8.3-25.

Each of the two regulated instrument panels is fed from one of two static voltage regulators, from a separate AC source, and supplies non-safety-related instrument and miscellaneous controls.

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Davis-Besse Unit 1 Updated Final Safety Analysis Report 8.3.1.1.7 Channels Davis-Besse Nuclear Power Station Unit No. 1 has four essential Channels 1, 2, 3, and 4.

8.3.1.1.8 Physical Arrangement of the AC Electrical System Components The physical locations of electrical distribution system equipment are such as to minimize vulnerability of essential circuits to physical damage as a result of accidents. Redundant Class 1E distribution switchgear (both medium and low voltage), some motor control centers, and distribution panels are located in separate, rooms in the Seismic Class I auxiliary building.

In two cases, where redundant Class 1E motor control centers are located within the same room, horizontal separation distances are 6 and 17 feet. The MCCs separated by 6 feet have a block wall fire barrier located approximately midway between them. The locations are as follows: (See Figures 8.3-31 through 8.3-34.)

a. The auxiliary, startup, and bus tie transformers are located out of-doors, physically separated from each other. Lightning arresters are provided for the startup transformers. All outdoor transformers are protected by automatic water spray systems to extinguish oil fires quickly and prevent the spread of fire. Fire walls are installed between transformers to minimize the exposure to fire and mechanical damage.

b. The medium voltage switchgear buses are located indoors in physically isolated rooms as follows:

13.8kV bus A and 4.16kV buses C1 (Channel 1) and C2 are located in room 325; 13.8kV bus B and 4.16kV buses D1 (Channel 2) and D2 are located in room 323; 4.16kV manual transfer breakers (Channel 3) are located in room 324.

c. Low voltage switchgear room 428 contains the following:

480V AC unit substations F1 (Channel 2) and F2; 480V AC motor control center F12A (Channel 2);

480V AC motor control center F14 (Channel 2);

480V AC motor control center F15 (Channel 2);

480V AC motor control center F16A (Channel 2);

120V AC panel Y2 and 125V DC/120V AC inverter YV2 (Channel 2);

120V AC panel YBU and 250V DC/120V AC inverter YVB; 480-120V AC Constant Voltage Transformer XY2 120V AC regulated panel YBR and 480V/120V AC static voltage regulators XYB; 8.3-20 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report 480V AC lighting substation F5 (non-essential). The other 480V AC lighting substation E5 is located in the turbine building

d. Low voltage switchgear room 429 contains the following:

480V AC unit substations E1 (Channel 1) and E2; 480V AC motor control center E12A (Channel 1);

480V AC motor control center E14 (Channel 1);

480V AC motor control center E15 (Channel 1);

120V AC panel Y1 and 125V DC/120V AC inverter YV1 (Channel 1);

120V AC panel YAU and 250V DC/120V AC inverter YVA; 120V AC regulated panel YAR and 480V AC static voltage regulator XYA.

480-120V AC Constant Voltage Transformer XY1

e. Low voltage supply room 428B contains 120V AC panel Y4 and 125V DC/120V AC inverter YV4, both Channel 4.

480-120V AC Constant Voltage Transformer XY4

f. Low voltage supply room 429A contains the following:

120V AC panel Y3 and 125V DC/120V AC inverter YV3, both Channel 3; 480-120V AC Constant Voltage Transformer XY3 480V AC motor control center EF15 (Channel 3).

g. The remaining 480V AC motor control centers are located indoors in areas of electrical load concentration. Physical separation is maintained between essential motor control centers fed from redundant channels.

h. The redundant Class 1E emergency diesel generating units which serve as the standby power supplies are located in separate, adjacent rooms (318 and 319) in the Seismic Class I auxiliary building. A fire wall and door are provided between the two rooms. Starting air for each diesel is provided by independent air reservoirs, two (2) per diesel, one (1) for each set of starting motors.

The local control and auxiliaries for each emergency diesel generating unit are located in the same room as the diesel with which they are associated.

i. Four separate rooms, two on the east and two on the west side of the containment, are provided for electrical penetrations. The two rooms on each side are on different floors (see Figure 8.3-33).

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Davis-Besse Unit 1 Updated Final Safety Analysis Report Class 1E containment electrical penetrations carry only Class 1E circuits except as noted below. Redundant Class 1E containment electrical penetrations are widely dispersed around the circumference of the containment. Wherever possible, redundant circuits are run through separate penetration rooms. The center-to-center spacing between penetrations at the outside of the containment is 32 inches horizontally and 60 inches vertically. Separate penetrations are provided for power, control and instrumentation cables. For essential redundant systems in a given penetration room, penetrations are kept as far apart as possible, and in no case will they be less than 9 feet apart. Cables in the annulus space are installed as shown on Figure 8.3-34.

The minimum physical separation for redundant electrical penetrations inside the containment are listed below:

1E Channels Distance 1 to 2 22 1 to 3 24 1 to 4 23 2 to 3 10 2 to 4 21 3 to 4 24 As discussed in Subsection 8.3.1.2.29, all containment electrical penetrations, regardless of circuit function assignments, are designed and tested to meet IEEE Std. 317-1971. Conax penetration assemblies were designed and tested to meet IEEE 317-1976 as modified by NRC Regulatory Guide 1.63, Revision 2. Cables which are part of Class 1E circuits are assigned to penetrations which are exclusively dedicated to Class 1E service, whereas cables which are part of non-Class 1E circuit functions are assigned to penetrations dedicated for that service.

Exceptions are as follows:

1. The non-Class 1E cables that feed the motor space heaters associated with two containment cooler fans. These heater circuits are de-energized when the fans are running.

2. The cables for the Reactor Vessel Vent Line Temperature thermocouples, which are non-Class 1E circuits that utilize a penetration dedicated exclusively to Class 1E instrumentation circuits. This situation has been analyzed and found to have no adverse affect on Class 1E circuits in the same penetration.

3. The non-Class 1E cables associated with Containment Recirculation Fan 2 motor. These cables were originally Class 1E and were later downgraded to non-Class 1E. However, they physically remain with Class 1E circuits, and are considered associated Class 1E circuits. They have been evaluated and found not to present the potential to degrade the integrity of their Class 1E power supplies.

Redundant Class 1E containment electrical penetrations are widely dispersed around the circumference of the containment.

The electrical penetration assemblies are described in Subsection 3.8.2.1.10.

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Davis-Besse Unit 1 Updated Final Safety Analysis Report

j. The applications, installation and routing of control, instrumentation and power cables are such as to minimize their vulnerability to damage from any source and to maintain the integrity of their respective redundant channels and/or branches.

k. All Class 1E cables are run in solid bottom trays when not in embedded conduit, exposed conduit, or wireway except for cables in the annulus space and manholes, In general, all Class 1E powercables are run in conduit except for those instances mentioned in Subsection 8.3.1.2.19.

l. The locations of redundant Class 1E actuated equipment such as pump drive motors and valve operating motors have been reviewed to ensure the minimum required functional capability despite any single design basis event or result therefrom.

8.3.1.1.9 Tests and Inspections The AC electrical systems are designed to permit testing and inspecting the operability and functional performance of the components of the system as well as the operability of the system as a whole. Essential and safety-related systems are provided with complete redundancy to permit testing of one system while the redundant system is performing the same function. This ensures no interruption of station operation.

The 345kV circuit breakers will be inspected, maintained and tested on a routine basis. This can be accomplished without removing the generator, transformers and transmission lines from service.

Transmission line protective relaying will be tested on a routine basis. This can be accomplished without removing the transmission lines from service. Generator and unit auxiliary transformer relaying will be tested when the generator is off line. Startup transformer relaying will be tested while the transformer is off the line.

The 13800, 4160 and 480 volt circuit breakers and associated equipment may be tested while individual equipment is shut down. The circuit breakers may be placed in the test position and tested functionally. The breaker opening and closing may also be exercised. Circuit breakers and contactors for redundant or duplicated circuits may be tested in service without interfering with the operation of the unit.

Manual and automatic transfer schemes among the various power sources will be tested on a routine basis to prove the operability of the system.

The capability of the essential buses to provide power to engineered safety features components will be demonstrated as part of the surveillance requirements of the station Technical Specifications. Additionally, continuous normal operation of selected service water and component cooling pumps on the 4160V essential buses, of selected containment air cooler fans on 480V essential buses, and operation of the RPS, SFAS, and radiation monitoring systems on the 120V AC essential instrumentation buses will verify essential power availability.

Emergency diesel generator availability will be verified according to Technical Specifications.

Local indication of 480V fused disconnect switch status is provided at the fused disconnect switch MCC bucket. A status light provides visual confirmation of a satisfactory circuit status for all 3 phases, which indicates fuse condition and disconnect switch closure.

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Davis-Besse Unit 1 Updated Final Safety Analysis Report 8.3.1.1.10 Administratively Controlled Devices Administratively controlled circuit opening devices are listed in Table 8.3-2 by device number, type and location.

8.3.1.1.11 Cross Ties Between MCC E11B and F11A The primary and backup boron dilution flow paths each have a Train 1 and Train 2 essentially powered isolation valve in series. These four valves are:

Line Valve Channel MCC Valve Location MCC Location Primary Flowpath Auxiliary pressurizer El. 585 spray HV2735 1 E11B Inside cont. Room No. 304 Auxiliary pressurizer El. 603 spray HV2736 2 F11A Outside cont Room No. 427 Backup Flowpath Decay heat El. 603 suction HVDH11 2 F11A Inside cont. Room No. 427 Decay heat El. 585 suction HVDH12 1 E11B Inside cont. Room No. 304 Should one of the two redundant emergency diesel generators fail, should the 4 kV bus C1 or D1 fail, or should 480V bus E1 or F1 fail; it would be necessary to provide power to at least one of the affected two valves from the unaffected power supply. This would be accomplished by administratively utilizing the tie path between MCC F11A and MCC E11B as provided in Davis-Besse Emergency Operating Procedures (refer to Figures 8.3-23 and 8.3-24).

Interconnecting cables are designated as Channel 12 and are run in conduit dedicated exclusively for these cables.

8.3.1.1.12 Motors All safety related Limitorque actuators shall be purchased to a specification which insures the motor will be able to perform its intended safety function with 70 percent of motor rated nameplate voltage, or, on an individual basis where the 70 percent of motor rated nameplate voltage does not apply, be purchased to a percentage of rated nameplate voltage which assures satisfactory operation under all required conditions.

While most initial purchase specifications required valve operation at 70 percent terminal voltage; in some cases subsequent evaluations have determined that required torque is greater than originally determined. In those cases operation of the valve has been established using available voltage at the Limitorque actuators terminals, as determined by calculation.

8.3.1.2 Analysis The station AC electrical system as described under Sections 8.2 and 8.3 ensures the following:

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Davis-Besse Unit 1 Updated Final Safety Analysis Report 8.3.1.2.1 Switching Three physically independent transmission lines are provided from the transmission network to the station switchyard minimizing power failure due to faults in the network interconnection and the associated switching (see Subsection 8.2.1.1).

8.3.1.2.2 Independent Circuits Three independent circuits are provided to supply power to the onsite electrical distribution system, and with any two circuits in service the requirements of NRC General Design Criterion 17 are fulfilled.

8.3.1.2.3 Onsite Standby Emergency Diesel Generator Units Two onsite standby emergency diesel generator units are provided. Independence and physical separation between the two units and between each unit and the other power sources is maintained so that no credible single event will disable more than one unit. The floor drains in the two EDG rooms are interconnected, and therefore not physically separated and independent. An evaluation of this common drain design verified that no credible single event would disable both EDG units (see also Flooding in Subsection 8.3.1.1.4.1).

8.3.1.2.4 Power Distribution System The two engineered safety features power distribution systems are connected to different 4.16kV essential buses, and they are redundant in that completion of the starting and loading of one emergency diesel is adequate to satisfy the minimum engineered safety feature requirements.

8.3.1.2.5 DELETED 8.3.1.2.6 Parallel Operation Parallel operation of the emergency diesel generators is not permitted.

8.3.1.2.7 Testing During modes 1, 2, 3, or 4 an emergency diesel generator (EDG) can be tied to the grid (loaded) only if the other EDG is operable. If one EDG is inoperable during modes 1, 2, 3, or 4, the remaining operable EDG can be started for testing, but shall not be tied to the grid (loaded).

In modes 5 or 6 with one EDG inoperable, the remaining operable EDG can be started and may be tied to the grid (loaded) for testing purposes. lf the remaining operable EDG is loaded in modes 5 or 6, the Technical Specification requirements for the required EDG being inoperable shall be followed.

8.3.1.2.8 AC Electrical System The station essential AC electrical system consists of two electrically isolated and physically separated load groups. Each has access to normal (unit auxiliary transformer), reserve (startup transformer), and onsite standby (emergency diesel generators) power sources.

8.3-25 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report 8.3.1.2.9 Controls Automatic and manual controls are provided to permit the following:

a. selection of the most suitable power source for the distribution system;

b. disconnecting the appropriate loads when normal and reserve sources are not available;

c. starting and loading the standby power supply.

8.3.1.2.10 Electric Power Systems and equipment that provide electric power for the safe shutdown of the reactor are classified as Class 1E (essential) and are designed to perform their functions when subjected to any design basis event. The variation of voltage and frequency during switching of such equipment will not degrade the performance of any load to the extent of damaging the reactor coolant system or fuel rods.

8.3.1.2.11 Protection Systems Protection systems are provided and designed to initiate automatically the operation of the appropriate equipment. Necessary protective devices are provided to isolate failed equipment and to identify the equipment that has failed. For the protection system related to the engineered safety features and essential functions, complete redundancy, independency, and inservice testability is maintained.

8.3.1.2.12 Instrumentation Essential instrumentation, control, and power requirements are supplied by reliable, independent, and redundant sources designed to ensure that no single failure will result in loss of power to safety-related equipment.

8.3.1.2.13 Periodic Testing All essential electrical systems are designed to permit periodic testing of the operation of individual system components with the station in operation.

8.3.1.2.14 Cables and Raceway Functions Cable functions are divided into three categories: Power (P), Control (C), and Low Level Instrumentation (L). In addition cables are classified according to their service as essential and non-essential. Cable tray and wireway are classified according to their service as carrying essential and nonessential cables and according to their function. Conduit are only classified according to their service. Four essential channels are provided.

8.3-26 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report Essential Channels Cables are identified with the color and by the first digit of the cable number corresponding to the channel, and the second character corresponding to the function as follows:

Channel Function Designation Color Designation 1 Green Power (P) 2 Orange Control (C) 3 Light Blue Instrumentation (L) 4 Maroon Cable tray and wireway are identified with the label background color corresponding to the channel, and the color of the label alphanumeric identifier corresponding to the function. The first digit of the identifier indicates the channel and the second character indicates the function.

Channel Function Designation Color Designation Color 1 Green Power (P) Black 2 Orange Control (C) White 3 Light Blue Instrumentation (L) Yellow 4 Maroon Conduit containing essential cables are banded with the color associated with the essential channel. Scheduled conduit (excludes lighting and communication circuits) in Containment and the Auxiliary buildings have an alphanumeric identifier which is stamped on a metal tag and attached to the conduit. Function is not included in the labeling of any scheduled conduit.

Interconnections Between Essential Channels The 2 out of 4 logic design of the NI/RPS & SFAS necessitates running interconnecting cables between control room cabinets having different essential channel designations. The identifiers are 12, 13, 14, 23, 24, and 34.

Each cable is marked with the color corresponding to the channel which is designated by the first character of the cable number. For example. cable number 12SFSP01 means that the cable runs between Channel No. 1 and Channel No. 2 cabinets and is colored green which corresponds to Channel No. 1.

The interconnecting cables between the SFAS cabinets of different channels and between the RPS cabinets of different channels are routed through raceways that are independent of any other raceway. Interconnecting cables having different identifiers do not share a common raceway once outside the cabinets. Wireways containing the interconnecting cables have the same identifier as the cables, i.e., the first two characters of the raceway number are the same as the first two characters of the cable number.

External to the SFAS/RPS cabinets physical separation is required between interconnecting cables that are prefixed with 12, 13, 14, 23, 24 or 34. Physical separation is achieved by 8.3-27 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report installing the differently prefixed cables in independent raceway system. Cables having the same prefix (identifier) share the same raceway. The interconnecting cables may contact non-essential cables of any channel (A, B, or C) provided bridging does not occur. (Bridging occurs when a single non-essential cable or conductor is simultaneously bundled, routed, or formed with cables or conductors of two different essential channels.)

Raceways connected to the RPS, with the exception of those used for NI loops, do not contain voltages in excess of the isolation device circuit ratings. The NI loop cables have a working voltage of 1200V for the intermediate and power range channels and 2400V for the source range channels. These cables, however, are run entirely in their own separate conduits from the detectors to the RPS cabinets.

RPS and SFAS In-Cabinet Isolation As discussed in Subsection 7.3.2.3, physical separation between redundant channels of the SFAS is accomplished by locating each redundant channel in a separate cabinet assembly.

Internal to the SFAS cabinets, physical separation is maintained between interconnecting cables and input sensor cables. Physical separation is required between interconnecting cables and non-essential cables where bridging could occur. All cables pass through fire stops at cable entrances/exits. Isolation is provided between trip signals in interconnecting cables and essential cables. The isolation device circuits are designed to withstand the effects of short circuits, open circuits, grounds, electrical transients and the application of AC or DC potential as listed below:

1. Analog signal isolation device circuits are capable of withstanding a maximum of 600V DC or AC peak across their output without affecting the input.

2. Digital signal isolation device circuits have a minimum dielectric strength rating of 450V AC (RMS) between the input and output signals.

The isolation device circuit includes the isolation device, internal wiring and field wiring connection terminal strips. No single failure of an isolation device circuit will compromise the operating ability of the redundant system.

Analog signal isolation devices, with individual power supplies, are provided between the sensing channel and the logic channel. Digital signal isolation devices are provided between the logic channel trip bistables and the output modules of the actuation channel.

Electrical noise transient testing was performed on the SFAS equipment during system functional testing at the vendor facility. Noise transients were generated in close proximity to all interconnecting wiring including essential and nonessential wiring. All equipment was operational with inputs and outputs simulated. It was verified that the equipment operation was not affected by the transients. The noise test report has been submitted as part of the docket under separate cover.

As a further precaution against electrical noise, particularly radio interference, no portable radio transmitters (with attached transmitting antenna) or any other radio transmitting antennae will be allowed in the control/cabinet room or cable spreading room.

8.3-28 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report A test program was implemented by TED to demonstrate the adequacy of noise rejection isolation devices and internal cable routing of the RPS and SFAS for credible electrical faults introduced from non-Class 1E systems and equipment.

An evaluation of the Station and Instrument Ground Systems at the Davis-Besse Nuclear Power Station was performed by the Lawrence Livermore National Laboratory, California.

The reactor protection system was subjected to electromagnetic, electrostatic, and noise level tests. Also, system isolation tests were performed on selected devices of the RPS. A complete test description (test parameters, schematics, equipment list, procedures, and specifications) for each test was submitted by Toledo Edison Co. Each test consisted of four basic parts: type of test, acceptance criteria, pretest values, and post-test values. After the system or device was subjected to a selected type of test, the test values were analyzed to determine if the system or device failed to meet the acceptance criteria.

The scope of the testing for the SFAS was to demonstrate that the isolation capability of the digital and analog isolation devices are not degraded to unacceptable levels following the inadvertent application of postulated electrical faults in excess of normal operating currents.

Also, that due to the intermix of non-Class 1E and Class 1E signal wiring, postulated electrical faults appearing on the non-Class 1E circuitry will not produce unacceptable effects in the Class 1E circuitry by means of mutual inductance and/or capacitive coupling.

The isolation device testing consisted of testing one of each type of device used in the SFAS Class 1E to non-Class 1E circuitry, while system testing consisted of utilizing one complete channel of the SFAS.

Based on the above, the isolation noise testing performed on the RPS and SFAS was found to be acceptable.

The reactor protection system has adequately demonstrated its capability to perform the Class 1E protective functions when subjected to electrostatic, electromagnetic, isolation and noise level tests. The above tests, performed to NRC approved test methods and MIL-N-19900B as required, concluded that:

(1) no significant degradation to the Class 1E circuitry occurred as a result of the fault tests; (2) no spurious trips or resets of the relays occurred as a result of the fault tests; and (3) no spurious trips, resets, or reactions of the SFA system occurred as a result of the fault tests.

NRC reviewed the tests and documents submitted and issued a Safety Evaluation Report accepting the tests and results, concluding that an analysis and testing of the ground grid systems has been conducted per NRC criteria and the ground ties found in the ground grid systems which do not meet design criteria have been isolated and corrected.

As discussed in Subsection 7.2.2.1, physical separation between redundant channels of the RPS is accomplished by locating each redundant channel in a separate cabinet assembly. The cabinet assembly provides physical protection of the cabinet internal equipment from external hazards such as missiles and fire. All openings between the cable spreading room and RPS 8.3-29 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report cabinets through which RPS cables pass, are sealed to prevent the passage of fire, smoke, and fumes.

Internal to the RPS cabinets, the independence of redundant channels is maintained by isolation device circuits. The isolation device circuits have been tested and analyzed to protect against short circuits, open circuits, grounds, and the application of AC or DC potential as listed below:

1. Analog signal isolation device circuits are capable of withstanding a minimum of 400V DC or AC peak across their output without affecting the input.

2. Digital signal isolation device circuits have a minimum dielectric strength rating of 480V AC RMS between the input and output signals.

The isolation device circuits include the isolation device, internal wiring, and field wiring connection terminal strips. The isolation device is an isolation amplifier for analog signals and a relay for digital signals. The isolation device circuit internal wiring and field connection terminal strips have the same characteristics (flame retardancy, maximum operating temperature, dielectric strength) as the wiring and terminal strips used internally within the cabinets for Class 1E service.

The isolation device circuits have been tested and analyzed by type tests and type analysis to establish the isolation device characteristics. The RPS isolation device circuits for Toledo Edison Davis-Besse 1 Nuclear Power Generation Station are production units of the circuits tested and analyzed by type. The isolation test report was submitted as part of the docket under separate cover.

The RPS exhibits a high degree of immunity to the effects of electromagnetic and electrostatic-induced noise on non-Class 1E signal output leads and Class 1E input leads. The immunity to noise has been established by operating experience, tests, and noise-rejection circuits. The Noise Test Report was submitted as part of the docket under separate cover.

ASP In-Cabinet Isolation Physical separation between redundant channels of the Auxiliary Shutdown Panel (ASP) is accomplished by locating each redundant equipment system and its terminations in separate and independent, fully enclosed subsections of the panel. Refer to Subsection 7.4.2.5 for additional design features for the ASP.

Internal to the ASP, the separation of 1E and non-1E analog circuits is maintained by an isolation device circuit. The circuit configuration for the analog isolation in the ASP differs from the configuration used in the NI/RPS only in that the operational amplifier in the ASP is used in the non-inverted mode while the amplifiers in the NI/RPS are used in the inverted mode. The voltage isolation capabilities of the ASP configuration is very similar to that of the Nl/RPS.

Analysis performed on the ASP circuits has shown the same isolation capabilities as the NI/RPS.

Clarification to Essential Channels of the SFAS The logic of the safety actuation Channel No. 1 requires that both the terminating relays of sensing and logic Channels No. 1 and No. 3 be de-energized to initiate the actuation of Channel 8.3-30 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report No. 1. Similarly it is required that sensing and logic Channels No. 2 and No. 4 be de-energized to initiate actuation Channel No. 2. See Subsection 7.3.1.1.2.

Approximately fifty percent of the field cable terminations of actuation Channel No.1 are made in the Channel No. 1 SFAS cabinets while the remaining field cables of actuation channel No. 1 are terminated in the Channel No. 3 SFAS cabinets. Similarly for actuation Channel No. 2, the terminating field cables are in Channel No. 2 and Channel No. 4 SFAS cabinets.

The field cables are coded by the color of the actuation channel that it serves.

Nonessential Channels Nonessential, i.e., non-Class 1E, functions are divided into channelized categories for improving station reliability. Classifications are alphabetized as contrasted to the numerical essential channels and are designated as Channels A, B, and C.

Nonessential cables may have any mix of black, white, or yellow jackets when routed in raceways designed to carry nonessential cables. Nonessential cables that are routed in raceways designated to carry Class 1E cables are color coded, as a minimum:

1. At the exit/entrance of the shared raceway and at numbered junction boxes when the nonessential cable terminates at non-Class 1E equipment.

2. At the exit/entrance of the shared raceway, at numbered junction boxes, and at each end when the nonessential cable terminates at Class 1E equipment.

When non-essential cables are routed in raceways designated to carry essential cables (see Subsection 8.3.1.2.18), color coding is as follows:

Designation Color Channel A Dark blue Channel B Tan Channel C Silver Fleck 8.3.1.2.15 Cable Each cable is identified at each end with a cable number: the first digit indicates the channel, and the second digit indicates the function. In addition, the jacket of each essential cable is marked with the color corresponding to its channel every 5 feet (maximum) when in tray/wireway and at end points and intermediate pull points when installed in conduits.

As a minimum, cable routed in conduits is color coded at the termination points and intermediate pull points. In addition, each essential cable is identified at each end with its associated alphanumeric designation as described above.

8.3.1.2.16 Safety Feature Actuation System (SFAS) and Reactor Protection System The Safety Features Actuation System and Reactor Protection System logic cabinets are painted in the corresponding channel colors.

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Davis-Besse Unit 1 Updated Final Safety Analysis Report 8.3.1.2.17 Markers Each tray carrying essential cables is identified with colored plastic markers at intervals averaging every fifteen (15) feet, in compliance with Paragraph 5.1.2 of Regulatory Guide 1.75 giving the tray number. The first digit of each tray number indicates the channel, and the second digit indicates the function. Where a mixture of functions occurs in a common tray or wireway (see Subsection 8.3.1.2.18, below, for cases where mixtures exist), the second digit of the tray or wireway number indicates the function of the majority of the cables in the raceways.

Markers have background colors corresponding to the channel and the digit color corresponding to the function. The markers are color-coded on the basis of the majority of the cables in the raceway. Trays carrying control and instrumentation cables are amply sized to contain the required number of cables.

Each essential conduit is color coded according to channel at all entry and exit points through which the conduits are run, as well as all attach points to equipment or trays.

Control trays are those trays that contain conductors that carry continuously 10A or less at 150 volts or less.

Instrumentation trays are those trays that contain conductors that carry 50 ma or less.

8.3.1.2.18 Essential Cables Essential cables only run in raceways specifically designated for the corresponding channel.

Nonessential cables may run in raceways designed to carry essential cables; however, no nonessential cable will run in the raceways of more than one essential channel. Cables for a given function are only run in raceways designated for that function, except (1) that small motor-operated valve leads and solenoid valve leads may be classified as control cables and routed accordingly and (2) where physical limitations prevent the installation of independent raceways for a given function (a mixture of functions occurs in the following raceways: 1CJQ10, 1CJR10, 1CJS10, 3LP63D, 4LP56D, 1PGS01, and 1PGS03).

Exception (1) is allowed since the operating voltage of the control and power section of a particular valve circuit (solenoid or small motor operated valve) are the same (120 volts) and are actually derived from the same power supply. Consequently, classifying and routing the entire circuit as control is of no concern.

Exception (2) concerning raceways 1CJQ10, 1CJR10, and 1CJS10 is allowed since both 480-volt power and 120 volt control are derived from the same motor control center (MCCE11C), the lengths of raceways are very short (approximately 2 feet) and all cable contained therein has an insulation rating of 600 volts. Furthermore, these raceways are physical extensions of the MCC to the MCC crown box.

Exception (2) concerning raceways 3LP63D and 4LP56D is allowed since the control cables carry low voltages (6 volts AC and 24 volts DC) and will not generate noise within the instrumentation cable which is shielded and twisted. In addition, these voltages are well below the ratings of the analog isolation devices in the SFAS as discussed in Subsection 8.3.1.2.14.

The nonessential control cable that is run in raceways 1PGS01 and 1PGS03 is allowed since the nonessential cable does not come in contact with cables of more than one essential channel.

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Davis-Besse Unit 1 Updated Final Safety Analysis Report Furthermore, there is no safety channel violation associated with any of these exceptions.

8.3.1.2.19 Power Cables All essential power cables are run in exposed steel or embedded nonmetallic conduit, except in the annulus space, in manholes, where physical limitations exclude the installation of conduit, and where channel separation is required in manholes. When physical limitations exist and/or channel separation in manholes is required, the power cables are run in tray or wireway. Power cable is contained in the following trays/wireways: 1CJQ10, 1CJR10, 1CJS10, 1PBM01, 1PJA01, 1PAM01, 1PAM02, 2PAM02, 3PAM01, 1PGS01, 1PGS02, and 1PGS03.

Justification is as follows:

1CJQ10, 1CJR10, 1CJS10: The space available was insufficient to terminate all conduits destined for the various vertical stacks of MCCE11C. Short sections of tray, in lieu of cabinet extensions, were used to gather and deploy the cable to the appropriate stacks (see Subsection 8.3.1.2.18).

1PBM01, 1PJA01: Physical limitations that imposed restrictions on conduit bending radius and space limitations at the containment penetration terminal boxes prevented the installation of conduits at penetration terminal boxes P1P2MI and P1P2MX. Short sections of wireway were used to gather the cable and nest the cable to the penetrations.

There is no separation conflict in this instance.

1PAM01, 1PAM02, 2PAM02, 3PAM01 (located in manhole 3001): Wireways were used to achieve channel separation, by use of a metal barrier, inside manhole 3001. Wireway was used in lieu of conduit because the need for channel separation was not apparent until after the cables were pulled.

1PGS01, 1PGS02, 1PGS03: The location of embedded conduit stub-outs with respect to the penetration terminal box, in conjunction with structural steel interferences, prevented the installation of conduit.

The embedded nonmetallic conduits are in concrete duct banks which are Seismic Class I structures. Class 1E cables of different essential channels are run in separate nonmetallic conduits encased within the duct bank and separation between these conduits is a minimum of 1-1/2 inches.

8.3.1.2.20 Routing of Class 1E Circuits The routing of Class 1E circuits has been reviewed for exposure to potential hazards such as high-pressure piping, missiles, flammable material, and flooding (see Chapter 3). All raceways are flame retardant.

Trays carrying essential control and instrumentation cables are amply sized to preclude overfill.

Control cable trays are filled to 60 percent of tray cross-sectional area or less except at tray cross fittings where the limit is 54 percent in the entering and exiting legs of the cross. The cable cross sectional area above the tray side rails is included with the cable cross-sectional area within the side rails in determining tray fill percentage. Instrumentation and control cable tray loading is permitted to the height of the side rails. At crosses, tees, and where large conduit spills into trays, the height of the fill may exceed the side rails height due to cable crossover. Where the intent of vertical cable tray separation criteria would be negated by cable 8.3-33 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report exceeding the tray rail heights, the inclusion of a thermal insulating material provides the required separation. In addition, all trays are ladder type with solid bottoms. Trays passing through fire walls, floors and ceilings are provided with fire stops.

The minimum cross-sectional area of the cable tray cross fittings used is 90% of the combined cross-sectional area of the two (2) intersecting trays, and therefore, in order to maintain the 60%

fill limitation within the cross fitting, limits the fill to 54% (90% of 60%) in the entering and exiting legs of the cross. In no instance is there any essential system tray cross fitting with entering or exiting legs having a cable fill in excess of 54%. The identified 54% fill limitation will be maintained for tray cross fittings legs on essential system trays.

By not exceeding the 54% fill limit on each leg, recognizing that cables cannot terminate within a Tee, the exceeding of the 60% fill of the Tee is prevented.

Separation between trays carrying redundant Class 1E circuits is usually accomplished by locating these trays in separate rooms. However, as defined in Section 5.1.4 of Regulatory Guide 1.75, in some general plant areas, defined as areas from which potential hazards such as missiles, external fire, and pipewhip have been excluded, open top trays carrying redundant Class 1E circuits are normally separated by a minimum of 4 feet vertically (bottom to bottom) and 18 inches horizontally. These minimum distances are considered adequate, since (1) the tray system is solid bottom rather than open ventilated, and (2) cable jackets have a self-extinguishing and non-propagating flame resistance characteristic as supported by certified test results.

The cable spreading room and main control room do not contain high-energy equipment such as switchgear, power transformers (except a 30 KVA dry type lighting transformer in the cable spreading room), rotating equipment, or potential sources of missiles or pipe whip and will not be used for storing flammable material. Separation criteria for open top cable trays in the cable spreading room are the same as for the general plant areas discussed above (4 feet vertically and 18 inches horizontally).

In both the general plant area and cable spreading room, where there are conditions of either convergence of trays carrying redundant Class 1E cables or crossings of trays carrying redundant Class 1E cables, where vertical or horizontal distance cannot be maintained, solid covers, flame retardant barriers, and/or thermal insulating materials are used. The locations of these installations in the cable spreading room are shown on Figures 8.3-35, 8.3-36, and 8.3-37.

The minimum vertical separation distance of 4 feet between trays carrying redundant Class 1E cables does not exclude trays carrying non-Class 1E cables from being interposed between the trays carrying Class 1E cables. This arrangement can be justified since (1) the trays carrying non-Class 1E cables are also solid-bottom type and (2) the flame retardance of the non-Class 1E installed cable is the same as that of the Class 1E cable discussed previously with minor exceptions. The criteria are shown on Figure 8.3-38. Where such distances are not met, fire barriers are installed.

The separation criteria between trays, wireways, and conduits are as shown on Figures 8.3-39 through 8.3-42. Enclosed tray, wireway, and conduit are equated insofar as these criteria. The fire barrier details associated with Figures 8.3-39 through 8.3-42 are shown on Figures 8.3-43, 8.3-44, and 8.3-45.

8.3-34 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report The above minimum separation distances do not necessarily apply to embedded conduits carrying redundant Class 1E cables. However, they do apply at points where these embedded conduits leave the embedding material and the previously enclosed cables do not continue in exposed conduit.

Thermal blankets (Kaowool or equivalent) will be provided in all open top trays with certain exceptions (e.g., trays inside containment and other selected areas). These exceptions will be documented on controlled documents.

Design and control of the cable systems layout is in accordance with approved Design Control Procedures. Trays, wireways, and conduits carrying essential cables are clearly marked on all layout drawings, and each is reviewed and approved prior to being utilized in the field. Review has included consideration of failure of a non-seismically qualified equipment affecting both redundant channels of essential components and failure of a high energy line in the vicinity of Class 1E equipment to ensure the design criteria are not violated.

During installation, electricians are responsible for installation of the equipment and cable systems in accordance with the issued drawings using approved procedures. After installation, the system is inspected in accordance with another approved procedure and the results recorded. Any deviations from issued drawings are documented and reviewed to ensure design intent is not violated. This information is then included on final, as-built drawings.

Pulling and inspection of cable within the installed raceways is performed using similarly approved procedures and results of final inspection documented.

8.3.1.2.21 Electrical Conductors Class 1E electrical conductors except heat trace cables have insulating materials which resist heat, moisture, radiation, and ozone. Jackets are also applied over the insulations. These jackets make the cables self-extinguishing and prevent flames from spreading. Heat trace cables are not considered here, since they are used as heating elements for piping and instrumentation rather than as system interconnections. Ground wires may be bare or covered with an insulation or jacket material. Minor amounts of PVC Cables are routed in non-essential trays in the unit.

Prototypes or actual production samples of each type construction have been tested to demonstrate that all cables will withstand the environmental conditions specified (see Table 8.3-4).

Interconnections between cabinets of the SFAS are achieved by using the same single conductors as that used within the SFAS cabinets. This wiring is supplied as a part of the SFAS equipment. It is single conductor with one layer of an insulation/jacketing of polytetrafluoroethylene material which is compatible with the environmental service conditions.

The wireways in which these SFAS interconnections are run are sealed with silicone foam for additional fire retardancy as necessary.

8.3.1.2.22 Base Ampacity Ratings of Cables Base ampacity ratings of cables are established as published in IPCEA P-46-426 and in accordance with the manufacturers standards. To this basic rating a grouping derating factor, also in accordance with IPCEA tables, is applied.

8.3-35 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report Credit is taken for load diversity factors where applicable.

Motor feeder power cables are selected on the basis of 100% load factor and continuously rated for 125% of the motor full load current. If exception is taken to this requirement then the basis shall be documented in an evaluation which demonstrates that the feeder cables are capable of carrying their design load under normal and emergency conditions of operation for their design life expectancy.

Power and control cables for services required to operate for extended periods after a loss of coolant accident are suitable for operation under condition of high ambient temperature, radiation, pressure, and humidity prevailing after an accident.

8.3.1.2.23 AC Power Circuits All AC power circuits have circuit protection provided by either circuit breakers or fused disconnect switches. Fuses are also used on some AC power circuits for fault current backup protection.

Thermal overload protective devices are not used to trip any safety-related motor operated valve. The tripping contacts on the overload protective device are not connected to the coils of the valve motors reversing starter. Many of the heaters in the overload protective devices have been replaced with shorting bars which prevent the overload device from sensing an overload condition. However, motor thermal overload devices are used to trip some safety and non-safety related motors for pumps, fans, dampers and drives.

8.3.1.2.24 Cables for Reactor Protection Systems Essential cables for reactor protection systems and safety features actuation system equipment are installed within Seismic Class I structures. The cable installation is Q (Nuclear Safety Related) and as such is subject to quality assurance procedures to ensure that the design criteria are met through all stages of design, procurement, and installation.

8.3.1.2.25 Redundant Class 1E Instruments Redundant Class 1E instruments are located in separate cabinets or in separate compartments of the same cabinet. When this is not feasible, physical separation of 12 inches is maintained between redundant essential channels or metal barriers and conduits, either rigid or flexible metal, are utilized for maintaining separation. The cabinets are located in plant areas which minimize potential hazards such as missiles, external fires, and pipe whip.

Redundant Class 1E sensors and their connections to the process system have been sufficiently separated to ensure that the functional capability of the protection system has been maintained despite any single design basis event or result therefrom. Sensor to sensor separation is a minimum of three (3) feet.

The main control board is located within a fire wall type control room in the Seismic Class I auxiliary building. The control room is protected from and does not contain high-energy equipment such as switchgear, power transformers, rotating equipment, or potential sources of missiles or pipe whip. The separation distance between redundant Class 1E equipment and circuits internal to the control board is a minimum of 12 inches. Barriers such as flexible or rigid metallic conduit are installed where separation distance is less than 12 inches. Wiring is flame retardant. Class 1E incoming cable and internal board wiring identification uses color coding as 8.3-36 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report discussed in Subsection 8.3.1.2.14. Where common devices accommodate redundant Class 1E circuits the minimum separation is met by use of barriers.

Cable entrance to the main control board is through blockouts in the control room floor.

Typically, each block out is dedicated to only one redundant Class 1E channel.

Instrument Cabinets Blockouts for cable entrances beneath the Reactor Protection System and Safety Features Actuation System cabinets enclose cables for the various sub-logic matrices which are necessary to establish the two-out-of-four logic described in Subsection 7.3.1.1.2.

All sensor input cables to the SFAS cabinets are enclosed in either rigid or flexible metallic conduit.

Further, no single event which fails all cables passing through a particular block out can preclude proper operation of the Reactor Protection System or Safety Features Actuation System as appropriate (see Sections 7.2, 7.3 and Subsection 8.3.1.2.14).

Some sensor-to-process connections of redundant sensors have a common section of line.

This is justified since failure of this connection will cause the sensors to fail in the safe position.

The locations of redundant Class 1E actuated equipment such as pump drive motors and valve operating motors have been reviewed to ensure the minimum required functional capability despite any single design basis event or result therefrom.

The main control boards have the following fire stops and separation barriers:

a. All control room vertical panels shall have the cable runs in the base of the panels enveloped with low density silicone foam up to a height level with the base of the panel.

b. All control room control consoles shall have the cable runs in the base of the consoles enveloped with low density silicone foam up to the top of the cable tray in the base of the consoles.

c. All essential cable conduits in the base of the control room cabinets and consoles shall be sealed with low density silicon foam, if the conduit end is in the base.

d. All essential cable runs in the base of the control room cabinets not in conduit shall have the cable runs coated with low density silicone foam up to the cable identification tag affixed to the cable or eight (8) inches above the base of the panel. This eight (8) inches provides the fire stops and cable separation for cable crossover between essential channels and between control panels.

e. Openings in fire barriers through which cables pass into the main control boards are closed with fire rated seals equal to the rating of the barrier. If the cable is routed to the control boards in conduit, the conduit is sealed internally as required to maintain the fire barrier rating.

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Davis-Besse Unit 1 Updated Final Safety Analysis Report

f. Panel C5716 A horizontal barrier is installed to completely close the top of this vertical panel.

The center barrier extends up to the additional horizontal barrier at the top of the panel.

The center barrier is extended and completed down to the enveloped cable in the base of the panel.

A vertical barrier is installed to complete the sides of this panel, and C5716 is isolated from C5715 and the void between C5716 and C5717.

All joints in barriers and voids around cables penetrating the center barriers are sealed with silicone rubber.

g. Panel C5717 A horizontal barrier is installed to completely close the top of the vertical panel.

Vertical barriers are installed to complete the sides of this panel, and C5717 is isolated from the void between C5717 and C5716.

A readily removable barrier is installed to extend the center barrier to complete isolation between Channels 1 and 2.

h. Panel C5718 A horizontal barrier is installed to completely close the top of the vertical panel.

A vertical barrier is installed to complete panel isolation at the bottom of the vertical panel between C5717 and C5716.

i. In Panels C5715, C5716, C5717, and C5718, smoke detectors are installed to maintain fire detection now that these panels are completely isolated.

j. Barriers required by the above are made from 1/2 - inch - thick Marinite. Barriers to isolate C5717 and C5716 from the void between these panels may be installed within the void if more convenient than within the panels.

Within enclosures (control boards, instrument cabinets, distribution panels, motor control centers, etc.), non-Class 1E wiring may be routed, bundled, or formed with Class 1E wiring.

The following specific criteria are used to guide the installation. Deviations from these criteria, as well as the other separation criteria, may occur. However, these deviations are documented and analyzed as a prerequisite for acceptance. The non-Class 1E with Class 1E criteria are:

a. When located in the same enclosure with essential cables, Channel A cables may be bundled, routed, or formed with Channel 1 cables. Similarly, Channel B cables may be bundled, routed, or formed with Channel 2 cables.

b. In enclosures designated for Channel 3 use, Channel A cables stay be bundled, routed, or formed with Channel 3 cables. Similarly, in enclosures designated for 8.3-38 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report Channel 4 use, Channel B cables may be bundled, routed, or formed with Channel 4 cables. However, in the specific case where Channel A is bundled, routed, or formed with Channel 3 (and conversely Channel B is bundled, routed, or formed with Channel 4), a verification is made that bridging does not exist. (Bridging occurs when a single nonessential cable or conductor is simultaneously routed, bundled, or formed with cables or conductors of two different essential channels.)

c. If an enclosure contains both Channels 1 and 3 cables, Channel A cables will preferably be run with Channel 1 cables. Similarly, if an enclosure contains both Channel 2 and 4 cables, Channel B cables will preferably be run with Channel 2 cables. However, in the specific case where Channel A is bundled, routed, or formed with Channel 3 (and conversely Channel B is bundled, routed, or formed with Channel 4), a verification is made that bridging does not exist.

d. When located in the same enclosures with essential cables, Channel A cables will not be bundled, routed, or formed with Channel 2 or 4 cables. Similarly, when located in the same enclosures with essential cables, Channel B cables will not be bundled, routed, or formed with Channel 1 or 3 cables.

e. Channel C cables will not be bundled, routed, or formed with any essential cables.

f. Any single nonessential cable will not bridge two or more essential channels within enclosures.

8.3.1.2.26 Cable Spreading Room All cables in the cable spreading room associated with essential channels are arranged so that redundant circuits for each of the individual systems are isolated either by physical separation or by fire barriers where physical separation cannot be maintained.

8.3.1.2.27 Circuit Schedules and Connection Diagrams Circuit schedules and connection diagrams have been prepared to give a permanent record of the routing and termination of all cables.

8.3.1.2.28 Q-List Items All electrical equipment classified as Q (Nuclear Safety Related) have been designed in accordance with the latest codes and standards as of the date of licensing of the plant to perform under the environmental conditions required. To ensure the proper design has been accomplished and that the equipment is subsequently fabricated and installed as specified, a detailed Quality Assurance/Quality Control program has been instituted and is described in further detail in Chapter 17.

Each safety-related electrical purchase is covered by a procurement package which ensures that appropriate technical requirements and environmental conditions are applied during design of the equipment, includes any special quality control procedures to be followed by the manufacturer, and includes any required acceptance testing. The design development process is monitored so that all design additions/deletions changes are reviewed and approved prior to incorporation in the station. The manufacturing process is monitored by inspectors representing the Davis-Besse Nuclear Power Station (DBNPS) Nuclear Group with the authority to reject any non-conforming material.

8.3-39 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report The electrical installation contractor is responsible for the proper handling and installation of the electrical equipment after it arrives at jobsite. All work in relation to the receipt, handling, storage, installation, and testing of Safety Related items is performed in accordance with procedures that have been reviewed and approved by the Davis-Besse Nuclear Power Station (DBNPS) Nuclear Group or its agents prior to use. Representatives of Davis-Besse Nuclear Power Station (DBNPS) Nuclear Group monitor all phases of this work ensuring the procedures are properly followed and have the responsibility for giving final approval prior to acceptance of a complete installation.

Adequate records such as inspection and test reports are maintained to demonstrate the traceability of all Safety Related material from the time of manufacture to final installation.

8.3.1.2.29 Penetrations The purpose of the electrical penetration assemblies (EPAs) is to provide continuity of electrical circuits through the containment structure, while maintaining the integrity of the containment pressure boundary. The electrical penetration assemblies consist of Conax and Amphenol modules in a header plate.

The Amphenol electrical penetration assemblies are designed and tested to meet IEEE Standard 317-1971.

The replacement Conax penetration assemblies are designed and tested to meet IEEE 317-1976 as modified by NRC Regulatory Guide 1.63, Revision 2.

Short-circuit tests were performed on two Amphenol prototype penetrations, as required by IEEE Standard 317-1971, to ensure that the penetration assemblies can withstand, without loss of mechanical integrity, the maximum possible fault current vs. time conditions.

The two prototype penetrations tested were a medium-voltage penetration consisting of a unitized header 26 inches OD, 3 inches thick, with 6 modules, and a low-voltage penetration consisting of 3 x 350 kcmil in a single hole plate.

The prototype penetrations withstood the following currents for the indicated times:

Start 1/4 Time Start Symmetric Symmetric Number Asymmetric RMS Amperes RMS Amperes of RMS Amperes 3 Phase 3 Phase Cycles Medium-voltage 70,000 Penetration (C phase) 44,700 33,700 26.5 41,300 Low-voltage Penetration (B phase) 23,400 20,400 30.5 After completion of the short-circuit tests, a leak test was performed on each prototype penetration. The results of that test met the requirements of the above-mentioned standard.

In addition, prior to the performance of the above-mentioned tests, each prototype penetration successfully passed radiation and environmental (LOCA) tests.

8.3-40 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report The electrical system design provides both primary and backup fault protection for power circuits which are energized during plant operation and are routed through electrical penetrations. Should the primary protection fail to act, the backup will act in sufficient time to preclude thermal and mechanical damage to the penetration assembly under fault conditions.

The basic philosophy of this type of protection is to provide selective tripping of circuit breakers in order to maintain maximum continuity of service by removing that section of the system where the fault has occurred. The primary protection is set to trip the breakers instantaneously under high-fault currents. In the event the primary protection or the corresponding breakers fail to act, the backup protection will respond to disconnect the affected circuit. During some high current faults the backup protection may act before or in unison with the primary protection. The tripping time of the backup protection has been set in such a way that it will trip faster with higher fault currents, i.e., it has inverse time characteristics. Diversity of 125V DC control voltage (for 13.8 kV buses A and B between source breakers and load breakers) is utilized to further assure that the backup breaker will trip if the load breaker fails due to a loss of control voltage.

Initial short circuit studies performed for Davis-Besse Unit I determine the worst case maximum symmetrical short circuit current which might flow through the 13.8kV electrical penetrations.

The calculated permissible tripping time for the fault current is based on a correlation of current and time using the relationship I12 t 1 I22 t 2 . Under this fault current the primary and secondary protection will act to preclude the damage of the penetration. This protection is adequate for the medium voltage penetrations.

Similarly, for the low voltage penetrations, the calculated worst case maximum symmetrical short circuit current and the calculated permissible tripping time for this fault current has been determined. Under this fault current, the primary and secondary protection will act to preclude the damage of the penetration.

Subsequently, a calculation was performed for circuits with lower maximum symmetrical short circuit currents.

These analyses establish the adequacy of the primary and backup protection of the electrical penetrations.

Electrical penetration assembly (EPA) terminal boxes, installed inside the containment structure are used to house the terminations of the electrical penetration assembly pigtails to their respective field cables. For circuits which are required to function in an accident environment the termination of the field cable/EPA pigtail combination is performed utilizing an environmentally qualified (Raychem) splice kit.

During a postulated accident condition, these terminal boxes are subject to a pressure rise; imploding could result. To reduce the differential pressure across the terminal box, each box is fitted with a vent hole in the bottom, proportional to the size of the box. Since the cable splicing located internal to these boxes are environmentally qualified, the vent holes do not have an adverse effect on safety.

A nitrogen supply system is connected to the EPAs to monitor the leak integrity of the penetration assemblies. The nitrogen supply system consists of two separate trains, one in the west auxiliary building (electrical penetration Room 1 [Room 402]) and the other in the east auxiliary building (electrical penetration Room 2 [Room 427]). The nitrogen gas cylinders are permanently connected to the electrical penetration assemblies header tubing to provide a 8.3-41 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report continuous pressurization to a value recommended by both Amphenol and Conax and greater than containment pressure. The nitrogen pressure is checked periodically and the cylinders replaced as necessary to maintain the recommended nitrogen pressure.

The dry nitrogen serves the following functions:

a. Maintain the penetration dry during both normal and LOCA conditions.

b. Prevent leakage from the Containment Vessel interior to the environment.

c. Monitor EPA integrity. A high nitrogen consumption would indicate that an EPA might be leaking.

The only redundant circuits which are routed through the same penetration room are the power supplies and the space heater supplies to the containment cooler fans numbers 2 and 3 in room 427.

The separation of 9 feet will preserve the integrity of the redundant circuits.

8.3.1.2.30 Cable for Class 1E Service Each manhole (i.e., 3001 , 3004, 3005, 3006, 3020, 3041, and 3042) that accommodates cable for Class 1E service is provided with a sump and a sump pump. In addition, essential cable is suitable for direct burial service.

The insulation resistance of essential power leads passing through manholes will be tested per station procedures as part of the motor and equipment maintenance program on a periodic basis to assure cable insulation integrity over the design life of the station.

8.3.2 DC Power System 8.3.2.1 Description The station DC equipment consists of two 250/125V DC motor control centers, four batteries, six battery chargers, four essential distribution panels, four 480V AC/125V DC rectifiers, and four nonessential distribution panels.

The system is designed to provide a continuous, reliable, and redundant 250/125V DC power source for control, instrumentation and DC loads required for normal operation and orderly shutdown and control of the station. The system is arranged to form two completely independent load groups as shown in Figure 8.3-25. The DC equipment is classified as Class 1E except nonessential distribution panels.

8.3.2.1.1 DC Motor Control Centers Two redundant 250/125V DC motor control centers are provided. Each motor control center has a positive, a negative, and a neutral bus arranged to form a 250/125V DC system. Each live bus is connected to a corresponding 125 volt battery, a normal battery charger source, and a manual standby battery charger as indicated in Figures 8.3-46 and 8.3-47. The standby charger is connected to the bus through a normally open manual switch. In the event of AC 8.3-42 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report power failure, the motor control center will be supplied from its respective batteries without any interruption of power.

Each of the two motor control centers supplies two 125V DC essential distribution panels, five 250V DC oil pump motors, two 250/125V DC emergency lighting feeders and one 250V DC/120V AC nonessential inverter.

DC motor control center 1 also supplies power to the motor operations of the auxiliary feed pump discharge stop valve to steam generator 1 (MV3870), the auxiliary feed pump turbine 1 main steam isolation valve (MV106) and the DC lube oil pump motor for the high-pressure injection pump 1-1 (MP197-2).

DC motor control center 2 also supplies power to the DC lube oil pump motor for the high pressure injection pump 1-2 (MP198-2).

8.3 .2.1.2 Station Batteries Four 125V DC approximately 1500 ampere-hour, on eight hours discharge basis, lead-sold batteries are provided and arranged to form two independent 250/125V DC systems. Using 1.75 volts per cell as the minimum cell voltage each battery has the following capacity:

Amperes Rating Discharge Time 187 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months 750 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months 1400 1 min Each battery is maintained in a fully charged condition and is normally float charged at approximately 132 volts from its associated battery charger. Battery discharge will occur either when the DC requirements temporarily exceed the charger capacity or during a loss of a battery charger supply. Each battery is connected to one 125V DC bus of one of the two DC motor control centers as shown in Figure 8.3-25.

Design Bases The station batteries are sized to supply the station DC and instrument AC loads for a period of one hour without AC power availability. Manual shedding of some loads is required within 30 minutes of a loss of AC power to maintain adequate voltage at all required DC loads. An age factor of at least 1.25 is applied in the station battery sizing analysis to ensure that the batteries will supply the required loads when battery capacity decreases to 80 percent of the manufacturers rating.

The loads on each battery are as follows: Station battery 1P supplies the loads of essential 125V DC distribution panel D1P, motor operated stop valve for Auxiliary Feed Pump 1-1 discharge to Steam Generator 1-1 (MV3870), and the lube oil pump for the HPI Pump 1-1 (MP197-2). Station battery 1N supplies the loads of essential distribution panel D1N and motor operated isolation valve for Main Steam Line 1 to Auxiliary Feed Pump Turbine 1-1 (MV106).

Also batteries 1P and 1N feed the 250V DC MCC1 loads.

Similarly, station battery 2P supplies the lube oil pump for the HPI pump 1-2 (MP198-2) and essential distribution panel D2P. Station battery 2N supplies essential distribution panel D2N.

Also, station batteries 2P and 2N feed the 250V DC MCC2.

8.3-43 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report The battery loads, operating requirements, and load shedding requirements during the worst case accident with no AC power available for battery chargers are detailed in the DC System Analysis.

The DC load list (contained in the DC System Analysis) establishes the one-hour duty cycle for each battery. The battery with the largest load was used in sizing the capacity and ampere rating of all four batteries. The first minute of the duty cycle includes the momentary loads and non-continuous loads that may occur at random during the one hour duty cycle. It also includes the continuous loads carried by the battery immediately following a design basis event coupled with a loss of ac power to the battery chargers. The first minute loads include the starting current for certain dc motors, the dc load current associated with operation of 13.8kV, 4.16kV, and 480V breakers, and the starting and field flashing of the emergency diesel generators.

The plate requirement which satisfies the above load cycle is a battery with ten positive plates and with performance characteristics equal to or better than a GNB model NCX-21.

8.3.2.1.3 Battery Chargers Six static solid state battery chargers are provided. Each is rated at 480V AC, 3 phase, 60 Hertz input and has a nominal output of 125V DC. Each charger is capable of supplying all steady-state DC loads required under any condition of operation while recharging the battery to a fully charged condition over a period of 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months from the maximum discharge condition established in the DC System Analysis.

Technical Specification surveillance testing assures that each charger is capable of delivering the necessary current and voltage for an extended period of time to demonstrate this design capability. The six chargers are arranged into two groups. Each group consists of three chargers, two of which are supplied from one essential 480V AC motor control center and constitute the normal DC supply to both live buses of the corresponding DC motor control center. The third charger is provided as a standby source and is supplied from a separate 480V AC bus on the same essential channel. The third charger can be manually switched to supply either live bus on the given DC motor control center. Each charger has a circuit breaker in its AC power incoming feeder and a fused disconnect switch in DC power output circuit for isolating the charger.

8.3.2.1.4 Essential 125V DC Panels Four redundant 125V DC panels are provided, as a part of essential power systems, to supply 125V DC power to safety-related loads. The four panels are designated D1P, D2P, D1N, and D2N, and supply DC loads as follows:

a. Essential DC panel D1P (Channel 1) supplies:

1. Essential safety features actuation system solenoid valves (Channel 1)

2. 480 Volt essential unit substation Bus E1

3. 4.16kV essential switchgear Bus C1

4. 120V AC essential inverter YV1 through a coupling diode 8.3-44 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report

5. Emergency diesel generator 1-1

6. Nonessential DC panel DAP

7. Radiation sampling system solenoid valves

8. Relay cabinets for: 120/240 VAC System: Reactor Coolant Pump: and SFRCS

9. Auxiliary Feedwater Pump Turbine 1-1 control circuits

10. Component Cooling Water Pump and Emergency Ventilation System flow indicators

11. Control Rod Drive shunt trip breaker B

12. 4160 Volt essential transfer switchgear CD

b. Essential DC panel D2P (Channel 2) supplies:

1. Essential safety features actuation system solenoid valves (Channel 2)

2. 480 Volt essential unit substation Bus F1

3. 4160 Volt essential switchgear Bus D1

4. 120V AC essential inverter YV2 through a coupling diode

5. Emergency diesel generator 1-2

6. Nonessential DC panel DBP

7. Radiation sampling system solenoid valves CH-2

8. Relay cabinets for: 120/240 VAC; Reactor Coolant System; Reactor Coolant Pump; SFRCS

9. Auxiliary Feedwater Pump Turbine 1-2 control circuits

10. Component Cooling Water and Emergency Ventilation System flow indicators

11. Control Rod Drive shunt trip breaker A

12. Motor Driven Feedwater Pump control valve position controller

13. 4160 Volt essential transfer switchgear CD 8.3-45 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report

c. Essential DC panel D1N (Channel 3) supplies:

1. 480 Volt essential unit substation Bus E1 (alternate source)

2. 4.16kV essential switchgear C1 (alternate source)

3. 120V AC essential inverter YV3 through a coupling diode

4. Emergency diesel generator 1-1 (alternate source)

5. Nonessential panel DAN

6. Reactor Coolant Pump relay cabinet

7. Motor Driven Feedwater Pump control valve position controller

8. Control Rod Drive shunt trip breaker D

d. Essential DC panel D2N (Channel 4) supplies:

1. 480 Volt essential unit substation Bus F1 (alternate source)

2. 4.16kV essential switchgear D1 (alternate source)

3. 120V AC essential inverter YV4 through a coupling diode

4. Emergency diesel generator 1-2 (alternate source)

5. Nonessential DC panel DBN

6. Reactor Coolant System and Reactor Coolant Pump relay cabinets

7. RC2A PROV solenoid

8. Control Rod Drive shunt trip breaker C Each essential panel is fed normally from one DC motor control center with a manually switched reserve supply from the second DC motor control center as shown in Figure 8.3-25.

Four 125V DC nonessential panels are provided. Each supplies DC loads as indicated on Figure 8.3-25.

8.3.2.1.5 Rectifiers Four rectifiers are provided to supply normal DC power to the four essential inverters. Each rectifier output is connected in parallel with the DC panel reserve supply to the inverter and is rated at 480V AC, 3-phase, 60 Hertz input, 125V DC nominal output. The output voltage is maintained at least 3 volts higher than the station battery voltage, which reverse-biases a coupling diode to prevent current flow from the reserve supply, and to prevent back-feeding the DC system. The failure of the rectifier Ac source and/or of the rectifier itself will forward bias the coupling diode, and cause the battery and/or battery charger to become the DC source to the essential inverter with no power interruption.

8.3-46 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report Channel 1 and 3 rectifiers are fed from a Channel 1 essential 480V AC motor control center, while Channel 2 and 4 rectifiers are fed from a Channel 2 essential 480V AC motor control center.

8.3.2.1.6 Monitoring and Surveillance Instrumentation, relays and indicators are provided locally and at the main control board to monitor the status of the DC system equipment.

The locally mounted instruments are:

a. On each motor control center:

1. DELETED

2. Two 125V DC ammeters 800-0-800 ampere each to read battery current flow.

3. Two DC voltmeters relays each connected to a separate bus and set to alarm in the control room at an under-voltage or an overvoltage.

4. One ground detector to alarm in case any of the three buses is grounded.

5. Two directional current relays with time delay to alarm battery discharge.

b. On each battery charger:

1. One under-voltage relay on the input side set to alarm when battery charger input voltage drops below the design capability of the battery chargers.

2. One under-voltage alarm relay on the output side.

3. One DC ammeter.

4. One DC voltmeter.

5. One Over Temperature alarm relay.

6. One Fan Failure alarm relay.

7. One Charger Failure alarm relay.

c. On each 125V DC essential panel:

1. One under voltage alarm relay.

2. One indicating light, indicating low voltage DC.

The main control board mounted instruments are:

a. Four DC ammeters 800-0-800 amperes indicating each battery output current.

8.3-47 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report

b. Two DC voltmeters 0-300V each to measure motor control center bus voltage.

c. Four DC voltmeters 0-150V one for each essential 125V DC panel.

d. Eight indicating lights, two for each essential 125V DC panel; one indicates the status of the normal feed switches, and the second indicates the status of the alternate feed switches.

e. Four indicating lights; each indicates the status of the DC motor control center disconnect switches associated with the standby battery chargers.

f. Four indicating lights; each indicates the status of the feed switch from each essential 125V DC panel to the respective essential inverter.

8.3.2.1.7 Physical Arrangement of DC Electrical System Components DC distribution system components are arranged and located in areas to minimize their vulnerability to physical damage as a result of accidents.

Battery chargers as well as the other listed equipment (below) for the Class 1E batteries are located in separate fire wall type rooms adjacent to their associated batteries.

Low voltage Switchgear Room 428 contains the following:

a. DC motor control center 2

b. Battery chargers DBC2P, DBC2N, and DBC2PN

c. Essential distribution panels D2P (Channel 2)

d. Distribution panels DBP and DBN Low voltage Supply Room 428B contains essential distribution panel D2N (Channel 4)

Low voltage Switchgear Room 429 contains the following:

a. DC motor control center 1

b. Battery chargers DBC1P, DBC1N, and DBC1PN

c. Essential distribution panel D1P (Channel 1)

d. Distribution panels DAN an DAP Low Voltage Supply Room 429A contains essential distribution panel D1N (Channel 3).

Low Voltage Battery Room 429B contains 125 volt batteries 1P and 1N, and Room 428A contains batteries 2P and 2N. In each room the two 125 volt batteries are mounted on two racks separated by an aisle approximately 5 feet wide.

The Class 1E batteries are located in separate battery rooms in the Seismic Class I auxiliary building. Each battery room has fire walls and is served by an independent Class 1E ventilation 8.3-48 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report system. Air flow alarm is provided in the Control Room to assure that hydrogen buildup is prevented in the battery rooms.

8.3.2.1.8 (TEXT DELETED HERE AND PLACED IN 8.2.1.3) 8.3.2.1.9 Tests and Inspection The ungrounded DC system has detectors to indicate when there is a ground existing on any portion of the system. A ground on one portion of the DC system will not cause any equipment to malfunction. Grounds will be located by logical isolation of individual circuits connected to the faulted system while taking the necessary precautions to maintain the integrity of the essential bus supplies.

The station batteries are under continuous automatic charging and will be inspected and checked on a routine basis while the unit is in service according to the surveillance requirements of Technical Specifications.

8.3.2.1.10 Administratively Controlled Devices Administratively controlled circuit opening devices are listed in Table 8.3-3 by device number, type and location.

8.3.2.2 Analysis Analysis of the station DC system described in Subsection 8.3.2.1 is given in the following subsections.

8.3.2.2.1 DC System The DC system provides continuous DC power source to essential instrument, safety features systems, and necessary control systems regardless of auxiliary electrical system conditions.

The system is designed to permit periodic testing of individual components as well as the system as a whole during station operation.

8.3.2.2.2 Reliability The reliability of the system is increased by providing redundancy of equipment and circuits.

8.3.2.2.3 250V DC System The 250V DC system consists of two independent load groups. A failure in one group will not affect the other.

8.3.2.2.4 125V DC Control Panel Boards Four separate 125V DC control panel boards are provided. Each panel is supplied by redundant feeders from both 250/125V DC buses through manual throw-over switches to prevent any DC panel from being supplied from more than one battery at a time. These DC panels provide DC instrument and control power as necessary for proper functioning of the unit.

8.3-49 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report 8.3.2.2.5 Station DC System The station DC system is arranged so that a single fault within the system will not prevent the reactor protective system, engineered safety feature control system, and the engineered safety features from performing their safety functions. The batteries are mounted on Seismic Class I racks, installed in separate rooms within a Seismic Class I structure, and separated by fire walls to minimize the possibility of simultaneous damage to both batteries.

8.3.2.2.6 Battery Chargers The battery chargers are designed to prevent the AC source from becoming a load on the battery due to a power feedback as a result of the loss of AC power to the chargers. This preserves the battery.

8.3.2.2.7 Design Criteria for Cables and Raceway The design criteria for cables and raceways routing, loading, sizing. and marking are identical to those described under Subsection 8.3.1.2.

8.3.2.2.8 Redundancy in DC Control Power Redundancy is maintained in the DC control power supply to the 13800, 4160, 480 volt AC systems by providing two DC control feeders for each separate bus or appropriate group of circuit breakers. Each feeder is supplied from a separate 125V DC battery.

8.3.2.2.9 (TEXT DELETED HERE AND PLACED IN 8.2.1.4) 8.3.2.2.10 Quality Assurance Procedure A quality assurance procedure identical to that described under AC system (Subsection 8.3.1.2) ensures that the design criteria through all stages of design, procurement and installation are met.

8.3.2.2.11 Drawings Section 1.6 provides a cross reference between USAR figures and electrical control drawings.

8.3-50 UFSAR Rev 33 9/2020

Davis-Besse Unit 1 Updated Final Safety Analysis Report TABLE 8.3-2 Administratively Controlled Circuits (AC)

DEVICE TYPE OF DEVICE NO. DEVICE TYPE LOCATION OPERATION ITEM 1 CBY305 Circuit Breaker Panel Y3 Kirk Key CBY105 Circuit Breaker Panel Y1 ITEM 2 CBY405 Circuit Breaker Panel Y4 Kirk Key CBY205 Circuit Breaker Panel Y2 ITEM 3 Y101/YAR04 Transfer Switch Panel Y1/YAR SPDT ITEM 4 Y101A/YAR06 Transfer Switch Panel Y1A/YAR SPDT ITEM 5 Y201/YBR04 Transfer Switch Panel Y2/YBR SPDT ITEM 6 Y201A/YBR06 Transfer Switch Panel Y2A/YBR SPDT ITEM 7 Y301/YAR05 Transfer Switch Panel Y3/YAR SPDT ITEM 8 Y401/YBR05 Transfer Switch Panel Y4/YBR SPDT ITEM 9 BE F154 Non Automatic BE F152 Circuit Breaker MCC EF15 Kirk Key BE F153 Circuit Breaker MCC EF15 Kirk Key BE F151 Non Automatic Circuit Breaker ITEM 10 BE F121 BE F122 Circuit Breaker MCC EF12C Kirk Key ITEM 11 BE F128 Non Automatic BE F129 Circuit Breaker MCC EF12D Kirk Key ITEM 12 BF 1310 Non Automatic BF 1304 Circuit Breaker MCC F13 Kirk Key ITEM 13 AC108, AD108 Circuit Breaker 4160 V Swgr. Insert or Withdraw AC113, AD113 C1, D1 Breaker ACD2, ACD3 Non Automatic Transfer Open or Close with Circuit Breaker Swgr. CD Kirk Key Interlock ITEM 14 BE1168/BE2238 Circuit Breaker MCC E11C/E22A Kirk Key ITEM 15 BE1167/BE2237 Circuit Breaker MCC E11C/E22A Kirk Key ITEM 16 BF1114/BF6204 Circuit Breaker MCC F11A/F62 Kirk Key ITEM 17 BF1115/BF6205 Circuit Breaker MCC F11A/F62 Kirk Key ITEM 18 ACD4, ACD5 Non Automatic Transfer Swgr. CD Kirk Key Circuit Breaker 8.3-55 UFSAR Rev 31 10/2016

Davis-Besse Unit 1 Updated Final Safety Analysis Report TABLE 8.3-3 Administratively Controlled Circuits (DC)

TYPE OF DEVICE NO. DEVICE TYPE DEVICE LOCATION OPERATION ITEM 1 D1P02 Disconnect Switch Panel D1P Sliding Bar D1P01 D201 Disconnect Switch DC MCC2 Open 400 A Fuse DC MCC2 Remove ITEM 2 D1N02 Disconnect Switch Panel D1N Sliding Bar D1N01 D232 Disconnect Switch DC MCC2 Open 400 A Fuse DC MCC2 Remove ITEM 3 D2P02 Disconnect Switch Panel D2P Sliding Bar D2P01 D102 Disconnect Switch DC MCC1 Open 400 A Fuse DC MCC1 Remove ITEM 4 D2N02 Disconnect Switch Panel D2N Sliding Bar D2N01 D133 Disconnect Switch DC MCC1 Open 400 A Fuse DC MCC1 Remove ITEM 5 D1N05 Circuit Breaker Panel D1N Kirk Key D1P05 Circuit Breaker Panel D1P ITEM 6 D1N07 Circuit Breaker Panel D1N Kirk Key D1P07 Circuit Breaker Panel D1P ITEM 7 D1N09 Circuit Breaker Panel D1N Kirk Key D1P09 Circuit Breaker Panel D1P ITEM 8 D2N05 Circuit Breaker Panel D2N Kirk Key D2P05 Circuit Breaker Panel D2P ITEM 9 D2N07 Circuit Breaker Panel D2N Kirk Key D2P07 Circuit Breaker Panel D2P ITEM 10 D2N09 Circuit Breaker Panel D2N Kirk Key D2P09 Circuit Breaker Panel D2P ITEM 11 43DC/HA01 Transfer Switch HA01 DPDT 43DC/HAAC Transfer Switch HAAC DPDT ITEM 12 43DC/HB01 Transfer Switch HB01 DPDT 43DC/HB14 Transfer Switch HB14 DPDT ITEM 13 B302 Circuit Breaker DBC1PN Kirk Key B303 Circuit Breaker DBC1PN ITEM 14 B302 Circuit Breaker DBC2PN Kirk Key B303 Circuit Breaker DBC2PN 8.3-56 UFSAR Rev 30 10/2014

Davis-Besse Unit 1 Updated Final Safety Analysis Report TABLE 8.3-4 Environmental Requirements for Class 1E Cable WITHIN SECONDARY SHIELD WALL TEMPERATURE HUMIDITY PRESSURE RADIATION CHEMICAL SUPPLIER**

DBA 287 °F 100% RH 40 psig - 1 Week 108 RAD Total 2800 PPM Borated BIW Water 1-Week***

NORMAL 122 °F 100% RH +/-0.5 psig 3.5 x 107 RAD Total None WITHIN PRIMARY CONTAINMENT DBA 287 °F 100% RH 40 psig - 1 Week 108 RAD Total 2800 PPM Borated KERITE, Water 1-Week*** BIW NORMAL 122 °F 70% RH 0.0 psig 3.5 x 107 RAD Total None WITHIN AUXILIARY BUILDING DBA 122 °F 100% RH 0.0 psig 3.5 x 107 RAD Total* None OKONITE, NORMAL 122 °F 100% RH 0.0 psig 3.5 x 107 RAD Total* None KERITE, BIW, CCC OUTSIDE ENVIRONMENT DBA Same requirement as within Auxiliary Building OKONITE, NORMAL Same requirement as within Auxiliary Building KERITE, BIW

Requirements are not applicable to interconnecting cable between SFAS Cabinets which will withstand 104 RAD. The dose in the Cable Spreading Room and the Control Room will not exceed 5 RAD over 40 years of normal operation plus 5 RAD during the DBA.

- Suppliers are listed for historical information only. Other suppliers may be used as long as requirements are met.

- - For pH Control reference Section 9.3.3.2 8.3-57 UFSAR Rev 30 10/2014

Removed in Accordance with RIS 2015-17 DAVIS-BESSE NUC:LEAR POWER STATICI RACEWAY CABLE SPREADING RtXII FIRE BARRIERS;w!l'&l'_,:.,1 )

<E-356),-Q_ 9,. , 2.

FIGURE 8.3-35 J

ML21104A365

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8.1 INTRODUCTION

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ML21104A365

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8.1 INTRODUCTION

8.1 INTRODUCTION

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