ML13004A062

Units 1 and 2, Updated Final Safety Analysis Report, Revision 14, Chapter 8.0 - Electric Power

ML13004A062
Person / Time
Site:	Byron, Braidwood
Issue date:	12/14/2012
From:	Exelon Generation Co
To:	Office of Nuclear Material Safety and Safeguards, Office of Nuclear Reactor Regulation
References
RS-12-221
Download: ML13004A062 (162)

Text

B/B-UFSAR 8.0-i CHAPTER 8.0 -

ELECTRIC POWER TABLE OF CONTENTS PAGE 8.0 ELECTRIC POWER 8.1-1

8.1 INTRODUCTION

8.1-1 8.1.1 Independence Between Redundant Standby (On- site) Power Sources and Between Their Distribution System 8.1-8

8.1.2 Selection

of Diesel-Generator Set Capacity for Standby Power Supplies 8.1-9 8.1.3 Periodic Testing of Pr otection Syste m Actuation Functions 8.1-10 8.1.4 Seismic Design C lassification 8.1-11 8.1.5 Quality Assurance Requirements for the Installation, Inspec tion and Testing of Instrumentation and Electric Equipment 8.1-11 8.1.6 Use of IEEE Standard 308-1971, "Criteria for Class 1E Electri c Systems for Nuclear Power Generating Stations 8.1-12 8.1.7 Qualification Tests of Continuous-Du ty Motors Installed Inside the Containment of Water- Cooled Nuclear Power Plants 8.1-12 8.1.8 Preoperational Testing of Redundant Onsite Electric Power Syste ms to Verify Proper Load Group Assignments 8.1-13 8.1.9 Bypassed and Inopera ble Status Indication for Nuclear Power Plant Safety Systems 8.1-13 8.1.10 Application of the Single-Fa ilure Criterion to Nuclear Power Plant Protection System 8.1-13 8.1.11 Manual Initiation of Protective Actions 8.1-15 8.1.12 Electrical Penetrations 8.1-15 8.1.13 Qualification Te sts of Electrical Valve Operators Installed Insi de the Containment of Nuclear Power Plants 8.1-21 8.1.14 Physical Independence of Electric Systems 8.1-21 8.1.15 Shared Emergency and Shutdown Electric Systems for Multi-Unit Nucle ar Power Plants 8.1-22 8.1.16 Qualification of Class 1E Equipment for Nuclear Power Plants 8.1-22 8.1.17 Availability of Electric Power Sources 8.1-22 8.1.18 Conformance to IEEE 33 8-1975 (Pe riodic Testing of Nuclear Pow er Generating Station Class 1E Power and Protection System) 8.1-22 8.1.19 Conformance to IEEE 344-1971 (Recommended Practices for Se ismic Qualification of Class 1E Equipment for Nuclear Power Generating Station) 8.1-22

B/B-UFSAR 8.0-ii REVISION 9 - DECEMBER 2002 TABLE OF CONTENTS (Cont'd)

PAGE 8.1.20 Conformance to IEEE 387-1972 (Criteria for Diesel Generator Units Applied as Standby Power Supplies f or Nuclear Power Generating Stations) 8.1-23 8.1.21 Conformance to IEEE 42 0-1973 (IEEE Trial- Use Guide for Class 1E Control Switchboards for Nuclear Power Generating Stations) 8.1-23

8.2 OFFSITE

(PREFERR ED) POWER SYSTEM 8.2-1 8.2.1 Description (Byron) 8.2-1 8.2.1 Description (Braidwood) 8.2-3 8.2.2 Analysis 8.2-5

8.2.3 References

8.2-12

8.3 ONSITE

POWER SYSTEMS 8.3-1 8.3.1 Onsite A-C Power Systems 8.3-1 8.3.1.1 Description 8.3-1 8.3.1.1.1 Unit Non-Class 1E Auxiliary Power Systems 8.3-1 8.3.1.1.2 Unit Class 1E Power Systems 8.3-3 8.3.1.1.2.1 Distribution and Normal Offsite Power Sources 8.3-3 8.3.1.1.2.2 Emergency On site Power S ources (Diesel Generators) 8.3-8 8.3.1.1.2.3 Instrument and C ontrol Power System 8.3-21 8.3.1.2 Analysis 8.3-21 8.3.1.3 Physical Identificat ion of Safety-Related Equipment 8.3-26 8.3.1.3.1 General 8.3-26 8.3.1.3.2 Raceway Identification 8.3-27 8.3.1.3.3 Equipment Identification 8.3-27 8.3.1.3.4 Cable Identification 8.3-27 8.3.1.3.5 Junction Box Identification 8.3-28 8.3.1.4 Physical Independence of Redundant Systems 8.3-28 8.3.1.4.1 Criteria and Design Basis 8.3-28 8.3.1.4.1.1 Cable Tray, Ca ble Penetrations, and Conduit System Design Basis 8.3-29 8.3.1.4.1.2 Cable Definitions and Rating Design Basis 8.3-31 8.3.1.4.2 Physical Separation Criteria 8.3-33 8.3.1.4.2.1 Class 1E Equipment Separation 8.3-33 8.3.1.4.2.2 Raceway Separation Criteria 8.3-33 8.3.1.4.3 Cable Separation Criteria 8.3-37a 8.3.1.4.4 Class 1E Equipme nt in Remote Structures (Byron) 8.3-40 8.3.1.4.4 Class 1E Equipme nt in Remote Structures (Braidwood) 8.3-42 8.3.2 D-C Power System 8.3-43 8.3.2.1 Description 8.3-43

B/B-UFSAR 8.0-iii TABLE OF CONTENTS (Cont'd)

PAGE 8.3.2.1.1 Class 1E 125-Vdc Power Systems 8.3-43 8.3.2.1.2 Class 1E 24-Vdc AFW Pump Diesel Batteries 8.3-47 8.3.2.1.3 Non-Safety-Related 125-Vdc Loads 8.3-48 8.3.2.2 Analysis 8.3-48 8.3.3 Fire Protection for Cable Systems 8.3-48 8.3.4 References 8.3-49

B/B-UFSAR 8.0-iv CHAPTER 8.0 -

ELECTRIC POWER LIST OF TABLES NUMBER TITLE PAGE 8.1-1 List of Applicable Criteria 8.1-24 8.1-2 Motor-Operated V alves Requiring Power Lockout (Byron) 8.1-32 8.1-2 Motor-Operated V alves Requiring Power Lockout (Braidwood) 8.1-33 8.1-3 Penetration Co nductor and Fault Current Data 8.1-34 8.3-1 Byron Unit 1 D-C Control Power Source 8.3-50 8.3-2 Byron Unit 2 D-C Control Power Source 8.3-51 8.3-3 Braidwood Unit 1 D-C Control Power Source 8.3-52 8.3-4 Braidwood Unit 2 D-C Control Power Source 8.3-53 8.3-5 Loading on 4160-Volt ESF Buses (Byron) 8.3-54 8.3-5 Loading on 416 0-Volt ESF Buses (Braidwood) 8.3-59 8.3-6 Relay Protection of 4160-V Equipment 8.3-64 8.3-7 Tabulation of Diesel-Generator Supervisory and Protective Functions 8.3-68 8.3-8 Cable and Equipment Color Coding 8.3-70 8.3-9 Deleted 8.3-72 8.3-10 Engineered Safety Feature Equipment (Byron) 8.3-76 8.3-10 Engineered Safety Feature Equipment (Braidwood) 8.3-77

B/B-UFSAR 8.0-v REVISION 10 - DECEMBER 2004 CHAPTER 8.0 -

ELECTRIC POWER LIST OF FIGURES NUMBER TITLE 8.1-1 Deleted 8.2-1 345-kV Switchyard Bu s Arrangement (Byron) 8.2-2 Transmission System Interconnections (Byron) 8.2-3 Property Plan (Byron) 8.2-4 Diagram of Switchyar d D-C Control System 8.2-5 345-kV Switchyard Bus Arrangement (Braidwood) 8.2-6 Transmission System In terconnections (Braidwood) 8.2-7 Property Plan (Braidwood) 8.3-1 Deleted 8.3-2 Deleted

8.3-3 Deleted 8.3-4 Deleted 8.3-5 Deleted 8.3-6 Deleted

B/B-UFSAR 8.0-vi REVISION 9 - DECEMBER 2002 CHAPTER 8.0 -

ELECTRIC POWER DRAWINGS CITED IN THIS CHAPTER

• The listed drawings are included as "General Re ferences" only; i.e., refer to the drawings to obtain ad ditional detail or to obtain background info rmation. These drawin gs are not part of the UFSAR. They are controlled by the Control led Documents Program.

DRAWING* SUBJECT 6E-0-4001 Byron Station On e-Line Diagram 6E-1-4002E Single Line Diagram, 120Vac ESF Inst rument Inverter Bus 111 and 113, 125Vdc ESF Distribution Center 111, Byron Station Unit 1 6E-1-4002F Single Line Diagram, 120Vac ESF Inst rument Inverter Bus 112 and 114, 125Vac ESF Distribution Center 112, Byron Station Unit 1 6E-1-4008E Key Diagram, 480V Auxiliary Building ESF MCC 131X2 (1AP25E) and 131X2A (1AP25E-A), Byron St ation Unit 1 6E-1-4030DG01 Schematic Diagram, Die sel Generator 1A Feed to 4.16kV ESF Switchgear Bus 141 ACB #1413, Byron Station Unit 1 6E-1-4030DG02 Schematic Diagram, Die sel Generator 1B Feed to 4.16kV ESF Switchgear Bus 142 ACB #1423, Byron Station Unit 1 6E-1-4030SI11 Schematic Diagram, Accumulat ors 1A and 1B Discharge Isolation Valves 1SI-880 8A/-8808B, Byron Station Unit 1 6E-1-4030SI33 480V Feed to ECCS Water Supply Isolation Valves at MCC 131X1A and 131X2A, B yron Station Unit 1 20E-0-4001 Braidwood Station One-Line Diagram 20E-0-4002E Single Line Diagram, 120Vac ESF Inst rument Inverter Bus 111 and 113, 125Vac ESF Distribution Center 111, Braidwood Station Unit 1 20E-0-4002F Single Line Diagram, 120Vac ESF Inst rument Inverter Bus 112 and 114, 125Vdc ESF Distribution Center 112, Braidwood Station Unit 1 20E-0-4008E Key Diagram, 480V Auxiliary Building ESF MCC 131X2 (1AP25E) and 131X2A (1AP25E-A), Braidwood Station Unit 1 B/B-UFSAR 8.0-vii REVISION 9 - DECEMBER 2002 DRAWINGS CITED IN TH IS CHAPTER* (Cont'd)

DRAWING* SUBJECT 20E-1-4030DG01 Schematic Diagram, Die sel Generator 1A Feed to 4.16kV ESF Switchgear Bus 141 ACB # 1413, Braidwood Station Unit 1 20E-1-4030DG02 Schematic Diagram, Die sel Generator 1B Feed to 4.16 kV ESF Swtichgear B us 142 ACB #1423, Braidwood Station Unit 1 20E-1-4030SI11 Schematic Diagram, Acc umulators 1A and 1B Discharge Isolation Valv es 1SI-8808A/-8808B, Braidwood Station Unit 1 20E-1-4030SI33 480V Feed to ECCS Water Supply Isolation Valves at MCC 131X1A and 131X2A, B raidwood Station Unit 1

B/B-UFSAR 8.1-1 CHAPTER 8.0 -

ELECTRIC POWER

8.1 INTRODUCTION

The electric power s ystem connections to the Byron/Braidwood Stations, described in detail in Section 8.2, are designed to provide a diversity of reliable power sources which are physically and e lectrically isolated so that any single failure will affect one source of supply only and will not propagate to alternate sources. The onsi te electric powe r system is described in det ail in Section 8.3.

The station auxiliary electric power sys tem is designed to provide electrical iso lation and physical separation of the redundant power supplies for s tation requireme nts which are important to plant s afety. Means are pr ovided for automatic isolation of system faults.

In the event of total loss of auxiliary power from offsite sources, auxiliary power required for safe shutdown will be supplied from diesel g enerators located on s ite. The diesel generators are p hysically and electric ally independent.

Redundant loads, important to plant safety, are split and diversified between redu ndant ESF switchgear groups. Redundant batteries are provided as sources of control power for the ESF electric power systems.

The safety loads that require electric power to perform their safety function are i dentified by function in Table 8.3-5.

The functions of these s afety loads are descri bed in Chapter 6.0 and Chapter 7.0, w ith the emergency core cooling system being described in Section 6.3.

Conformance of the eng ineered safety fea tures electr ic system to various industry standards and NRC guidance documents is indicated in Table 8.1-1.

The safety design bases used for the Cla ss 1E electric systems are given in Table 1, "Design Basis Events," of IEEE 308-1971, "IEEE Standard C riteria for Class 1E Electric Systems for Nuclear Power Genera ting Stations."

The plant consists of two main generating units designated as Unit 1 and Unit 2.

Each main generator is directly connected to two half-size mai n power transformers through an isolated phase electrical bus duct.

The two half-siz e main power transformers are connected in pa rallel at their high and low voltage terminals and tr ansform the output of ea ch generator from a generator voltage of nominal 25-kV to a nominal 345-kV transmission s ystem voltage.

The output of each unit's main power transform er is connected to a 345-kV switchyard section consisting of circuit breakers, B/B-UFSAR 8.1-2 REVISION 4 - DECEMBER 1992 disconnect switches, buses, and associated equipment arranged in a double ring bus configurati on as shown in F igure 8.2-1 for Byron and Figure 8.2-5 for B raidwood. O verhead 345-kV transmission lines dis tribute power to t he various points of the transmission system.

The 345-kV system provides p ower to each unit's two system auxiliary power transf ormers. Each unit

's set of system auxiliary transformers has sufficient capaci ty to handle the auxiliary power requir ements of the unit whe n operating at full load. Each unit's sys tem auxiliary power su pplies are available to all safety auxili ary equipment of both units and, therefore, serve as the second source of offsite power to t he other unit.

Normal auxiliary power f or each unit is supp lied from the unit auxiliary power transf ormers, which are connec ted to the main generator leads, and from the system a uxiliary power transformers, which are connected to a 345-k V ring bus. Startup auxiliary power is p rovided through the system auxiliary power transformers via the 3 45-kV switchyard ring bus.

BYRON-UFSAR 8.1-3 REVISION 4 - DECEMBER 1992 Offsite (Preferred) Power Sy stems - Summary Description The Commonwealth Edison transmis sion system is interconnected with the MAIN (Mid-America Inter pool Network) re gion utilities.

The 345-kV transmission lines connect the By ron Station to the transmission system, as shown in Figure 8.2-1.

Electric energy generated at the station is stepped up to 345-Kv by the main power tra nsformers and fed into the station's 345-kV transmission te rminal. The 3 45-kV overhead lines exit the s tation via three separate rights-of-way and are connected into Commonw ealth Edison's 345-kV system as shown on Figure 8.2-2.

The preferred power system is co nsidered as having three major sections, each of which must provide two phy sically separate and electrically independent circuit pat hs between the o nsite power system and the trans mission network (the transmission network excludes the station switchyard).

The three sections are:

1. The transmission lines e ntering the station switchyard from the transmission network.

2. The station switchya rd. (A common s witchyard is allowed by GDC 17).

3. The overhead tra nsmission lines, SATs, buses between the switchyard, and the on site power system.

Two physically separate and electrically indepen dent circuits are provided for each unit, one via the unit's assigned system auxiliary transformers a nd the other from the system auxiliary transformers of the other unit.

BRAIDWOOD-UFSAR 8.1-4 REVISION 4 - DECEMBER 1992 Offsite (Preferred) Power Sy stems - Summary Description The Commonwealth Edison transmis sion system is interconnected with the MAIN (Mid-America Inter pool Network) re gion utilities.

The 345-kV transmission lines connect the Braidwood Station to the transmission system, as sh own in Figure 8.2-5.

Electric energy generated at the station is stepped up to 345-kV by the main power tra nsformers and fed into the station's 345-kV transmission te rminal. The 3 45-kV overhead lines exit the s tation via separate ri ghts-of-way and are connected into Commonw ealth Edison's 345-kV system as shown on Figure 8.2-6.

The preferred power system is co nsidered as having three major sections, each of which must provide two phy sically separate and electrically independent circuit pat hs between the o nsite power system and the trans mission network (the transmission network excludes the station switchyard).

The three sections are:

1. The transmission lines e ntering the station switchyard from the transmission network.

2. The station switchya rd. (A common s witchyard is allowed by GDC 17).

3. The overhead tra nsmission lines, SATs, buses between the switchyard, and the on site power system.

Two physically separate and electrically indepen dent circuits are provided for each unit, one via the unit's assigned system auxiliary transformers a nd the other from the system auxiliary transformers of the other unit.

B/B-UFSAR 8.1-5 REVISION 7 - DECEMBER 1998 Onsite Power Systems The main turbine-generator pow er system is d esigned for the generation of electric power: (1) for distribution to the offsite power system, and (2) to provide an independent source of onsite power for the onsite station auxil iary electric power system. Loads important to p lant safety are divi ded into redundant groups (Division 11 [21]

and 12 [22] for Uni t 1 [Unit 2]) and are fed from redundant C lass 1E engineer ed safety feature (ESF) switchgear groups.

In the event of loss of the unit's offsi te auxiliary power, the auxiliary power required for safe shutdown is supplied automatically from red undant Class 1E di esel-generators located on the site. The diesel generators are physically and electrically independent.

Batteries are provided as sources of control power for the ESF electrical power systems. T he engineered safety features electric systems are designed in accordance with IEEE standards insofar as they apply except as otherwise indicated in the text.

There are no provisi ons for startup without offsite power. A number of stations on the Co mmonwealth Edison system have "black start" capability to supply adequate startup power to the remaining stations through various t ransmission system emergency configurations.

Auxiliary A-C Power System The basic function of the au xiliary a-c power system is to provide power for plant auxiliaries during startup, operation, and shutdown and to provide hi ghly reliable redundant power sources for loads which are ne cessary to plant safety. The auxiliary a-c power syst ems for the two-unit p lant are shown in Drawings 6E-0-4001, "Byron Sta tion One Line Diagram," and 20E-0-4001, "Braidwood Stati on One Line Diagram".

Two unit auxiliary tra nsformers (23.7-6.9/4.16-kV) are provided for each unit. These tr ansformers are conne cted directly to the main generator buses by isolated phase bus d uct. They are the normal power sources for t he non-safety-re lated 4160-volt buses. Two system auxiliary transformers (345-6

.9/4.16-kV) are also provided for each unit. Each tr ansformer is normally energized, providing offsite power to an engineered safety features (ESF) 4160-volt bus of the unit. Ea ch transformer also serves as a second source of offsite power for the corresponding ESF bus of the other unit.

Each system auxiliary tr ansformer and unit a uxiliary transformer can serve as a power source for the unit

's non-safety-related 6900-volt buses.

B/B-UFSAR 8.1-6 REVISION 4 - DECEMBER 1992 The unit's four non-sa fety-related 6900-volt switchgear serve the reactor coolant pumps as well as other large auxiliary loads. Each-6900 volt switchgear group has a feed from a unit auxiliary transformer (UAT) and a system aux iliary transformer (SAT). Automatic transfer is pr ovided in the ev ent of the loss of either power source.

Each unit has four 4160-volt switchgear. Two buses (141 and 142 for Unit 1; 241 and 242 for Unit 2) supply power to ESF loads as well as certain essenti al (but not sa fety-related) loads (such as light ing and the turbine bear ing oil pump). The other two buses supp ly power to large, non-safety-related, auxiliary loads as w ell as small, non-safety-related loads.

All non-safety-related loads that require access to the diesel-generators are fed from these buses.

A cross-tie breaker between the 41 60-volt ESF bus and the 4160-volt non-safety-related bus may be manually c losed (by operator action) in the e vent of the loss of both the UAT and SAT power sources to feed these loads.

Each 4160-volt E SF bus has (1) a normal feed f rom the system auxiliary transformer, (2) a second (res erve) feed from the other unit's SAT, and (3) an e mergency feed from its respective diesel generator. Upon a loss of the ESF bus's norm al offsite power supply (the SA T), the respective d iesel generator will start automatically and provide power to the b us. The operator may manually synchronize the sec ond offsite power source to the ESF bus.

Each 4160-volt n on-safety-related bus has a feed from (1) the respective unit's system aux iliary trans former, (2) the respective unit's un it auxiliary transfo rmer, and (3) the respective ESF bus.

These buses are nor mally fed from either the UAT or SAT. Automatic transfer from the UAT to the SAT, or vice versa, is provided in the event of loss of e ither power source.

If both the UAT and SAT are lost, the cross-tie breaker to the 4160-volt ESF bus can be manually closed (by operator action) to provide power to certain non-safety-related, b ut essential loads within the capability of the diesel generator.

Unit Class 1E A-C Power System All of the ESF equipme nt required to shut down the reactor safely and to remove r eactor decay heat for extended periods of time following a loss of offsite power and/or a loss-of-coolant accident are supplied with a-c power from th e Class 1E a-c power system. The unit Class 1E a-c power system is divided into two divisions (Divisions 11 and 12 for Unit 1; Divisions 21 and 22 for Unit 2), each of which is supplied from a

B/B-UFSAR 8.1-7 REVISION 7 - DECEMBER 1998 4160-volt bus (141 a nd 142, for Unit 1, respectively; 241 and 242 for Unit 2, respectively).

Each ESF group of ea ch unit is supplied stan dby power from an individual diesel-gene rator unit. With this arrangement, alternate or redundant c omponents of all ESF systems are supplied from separate switch groups so that no single failure can jeopardize the p roper functioning of r edundant ESF loads.

The assignment of ESF loads to the two elect rical divisions for each unit is indicat ed in Table 8.3-5. The division of the ESF loads among the system b uses is such that the total loss of one of the two electrica l divisions cann ot prevent the safe shutdown of the reactor u nder any normal or abn ormal design condition.

In the event of a loss of offsite po wer, 4160-volt ESF bus undervoltage relays au tomatically trip the bus's offsite supply circuit breakers and non-safety-related 4160-volt bus tie breaker, shed all significant ESF loads, and automatically start the diesel-gen erator. The diesel-generator supply circuit breaker closes a utomatically when the diesel-generator is up to rated speed and voltage, provided all other source breakers are open.

Provisions are made for sequential starting of required ESF loads within the diesel-generator's capability.

Unit Class 1E D-C Power System A 125-volt battery is provided for each ESF division in each unit to supply c ontrol power to the re actor trip switchgear, MCB ESF sections, ES F switchgear control systems, and other safety-related systems r equiring d-c power.

Each unit is provided with two physically separate and electrically isolated so urces of 125-Vdc ESF power (each with its own battery, battery charger, and distri bution bus).

Drawings 6E-0-4001 and 20E-0-4001 show the si ngle-line of the Unit 1 and 2 125-Vdc systems.

Unit Non-Class 1E D-C System One 48-Vdc system is required for operat ion of equipment at the river screen house.

The control power for the 345-kV switchyard breakers is supplied by two 125-volt batteries (not safety-re lated) located in the switchyard relay house.

The two feeds f rom each battery to the switchyard breakers are supplied by separate cables to establish two separate trip circ uits for each br eaker; i.e., each breaker has two trip coils. E ach trip coil is opera ted from a separate protective relay package.

B/B-UFSAR 8.1-8 REVISION 7 - DECEMBER 1998 Each unit is provided with a 250-Vdc system for use with essential non-safety-related auxiliaries as described in Subsection 8.3.2.1.

Identification of Class 1E Loads Nuclear safety-related systems and compo nents that require electrical power to perform their nuclear safety function are defined as Class 1E loads.

8.1.1 Independence

Between R edundant Standby (Onsite) Power Sources and Between Their Distribution System An acceptable degree of independence bet ween redunda nt standby (onsite) power sources a nd between their dis tribution system is described in the fol lowing subsections.

a. Independent Load Assignment Each Class 1E Load (a-c or d-c) is a ssigned to an ESF Division 11 or 12 (21 or 22) load group.

Assignment is determin ed by the nuclear safety functional redundancy of the load. The loss of a single division does not prevent the performance of the minimum safety functions required for a safe shutdown.

b. Independent Class 1E A-C Sources Each ESF division a-c lo ad group has a feed from two auxiliary transf ormers (offsite) and from one diesel generator (onsite) as shown in Drawings 6E-0-4001 and 20E-0-4001.

The diesel-generator circuit breaker will not close automatically unless other s ource circuit breakers to that load gro up are open as s hown in Drawings 6E-1-4030DG01, 20E-1

-4030DG01, 6E 4030DG02, and 20E-1-4030DG02.

c. Independence of Class 1E D-C Sources Each ESF division d-c lo ad group has a feed from one battery charger and one battery as shown in Drawings 6E-0-4001 and 20E-0-4001.

The redundant d-c load groups cannot be connected to each other. The d-c battery-charger combination of one ESF divis ion cannot be connec ted to another ESF redundant division.

Each d-c lo ad group of one unit can be connected to the corresponding nonredundant d-c load group of the second unit and satisfy the design load.

B/B-UFSAR 8.1-9 REVISION 9 - DECEMBER 2002 d. Independence of Standby Sources The diesel-generator circuit breaker will close to its associated load group au tomatically only if the other source circuit breakers to the load group are open. When the diesel-generator circuit breaker is closed, no other source breaker will close automatically. The redu ndant buses independent configuration ensures that no means exist for connecting redundant load groups with each other.

Each of the redundan t load groups is fed from only one diesel generator. No means are provided for transferring loads betwe en the redundant diesel generators.

Paralleling of the redundant die sel generators by manual breaker actuati on can only be accomplished if the disconnect link between the SATs is installed.

Therefore, the proba bility of paralleling of the redundant diesel generator manually by an operator error during loss of offsite power is very remote.

e. Prime Mover Division 11 and 12 (21 a nd 22) diesel-generators are provided with only o ne prime mover for each generator.

Compliance with Regulato ry Guide 1.6 is discus sed in Appendix A.

8.1.2 Selection

of Diesel-Gene rator Set Capaci ty For Standby Power Supplies

Diesel-generator sets are select ed as the onsite standby power supply with sufficient capacity and margin to assure that acceptable fuel desi gn limits and desi gn conditions of the reactor coolant pressure boundary are not exceeded, that the core is cooled, and th at containment integri ty and other vital functions are maintained in postulated accidents.

The diesel generator load rating for continuous duty is 5500 kW (6875 kVA, 0.8 p ower factor).

The 2000-hour rating of each standby die sel generator is 5935 kW (7419 kVA, 0.8 power factor), and the 2-hour rating is 6050 kW.

Table 8.3-5 shows the loads for each of the diesel generator sets, for LOCA conditi ons, and for safe shutdown conditions.

Actual diesel ge nerator loading during a LOOP coincident with a LOCA condition, howeve r, is monitored by the Electrical Load Monitoring System for Alternat ing Current Loads (ELMS-AC).

B/B-UFSAR 8.1-9a REVISION 7 - DECEMBER 1998 During preoperational te sting, the predicted standby diesel generator loads for each ESF div ision is verified, as well as the capability of the diesel generators to carry these loads.

B/B-UFSAR 8.1-10 Acceleration requireme nts, voltage and f requency dips, etc., were incorporated in the die sel generator specification.

During preoperational testing, it was ve rified that the diesel generators are c apable of starting and accelerating to rated speed, and accep ting, in the required sequence, all the needed ESF and emergency shut down loads, while maintaining the voltage and frequency within the specified limits.

During these tests, the overspeed limits were verified.

The suitability of each standby diesel-gener ator was confirmed by prototype qualifi cation test data a nd by preoperational tests. Compliance with Regulato ry Guide 1.9 is discus sed in Appendix A.

8.1.3 Periodic

Testing of Protecti on System Actuat ion Functions (Regulatory Guide 1.22)

The protection system, including the act uation devices and actuated equipment, is d esigned to permit periodic testing.

All safety actuation c ircuitry is provided w ith a capability for testing with the reactor at power with the follo wing exceptions:

a. generation of a reactor trip by tripping the reactor coolant pump breakers, b. generation of a reactor trip by trip ping the turbine, c. generation of a reactor trip by use of the manual trip switch, d. generation of a reactor trip by manually actuating the safety inj ection system,

e. generation of safety i njection signal by use of the manual safety inject ion switch, and

f. generation of containment spray signal by use of the manual spray act uation switch.

Exception to testing the dev ices listed above is taken, where it has been de termined that:

a. The present position is that it is not a "practicable system design" to provide equipment to b ypass a device such as a reactor coolant pump breaker solely to test the device. In the ca se of testing the manual initiation switches, the design for test capability would require that s witches be provided

B/B-UFSAR 8.1-11 on a train or sequential basis. This complicates the operator action required to actuate the function manually.

b. The probability that the protect ion system will fail to initiate the ope ration of the equipment is, and can be maintained, a cceptably low without testing the equipmen t during reactor operation.

Probabilities have been established by the use of general failure data based on continuous operation.

Specific probability analyse s can be provided on a plant basis at the reque st of the Commission.

c. The equipment can rout inely be teste d when the reactor is s hut down.

In all the cases dis cussed, it is only t he device function which is not tested. The logic associated with the devices has the capability for tes ting at power.

Further information related to the s ubject of periodic testi ng of protection system actuations functions is presented in Section 7.1.

Compliance with Regulato ry Guide 1.22 is discu ssed in Appendix A.

8.1.4 Seismic

Design Classification Information concerning t he seismic design classification of electrical systems a nd components of the Byron/Braidwood Stations, intended to withst and the effects of the safe shutdown earthquake (SSE), is presented in S ection 3.10.

Compliance with Regula tory Guide 1.29 is dis cussed in Appendix A. 8.1.5 Quality Assurance Requir ements for the Installation, Inspection and Testi ng of Instrumentat ion and Electric Equipment Quality assurance re quirements for tes ting, inspection, and proper installation of e lectrical and instru mentation equipment are described for various su bsystems in Section 8.3.

Preoperational tests that demonstrate fu nctional performance are identified in Chapter 14.0.

Startup tests are also covered in Chapter 14.0. Each of these tests on safety-related equipment complies with the test and evaluation requireme nts of Commonwealth Edison's Quality Assurance Manual.

Compliance with Regulato ry Guide 1.30 is discu ssed in Appendix A.

B/B-UFSAR 8.1-12 REVISION 8 - DECEMBER 2000 8.1.6 Use of IEEE Standard 308-197 1, "Criteria for Class 1E Electric Systems for Nuclear Power Generating Stations" IEEE 308-1971 provides criteria that may be used in establishing some of the bases fo r the design of elec tric power systems, except that conflicts wi th General Design Criterion 17 should be resolved by:

a. provision of one immedia te access and one delayed access circuit from the tran smission network; and

b. the capacity of the batt ery charger supply should be based on: the largest combined demands of the various steady-state loa ds and enoug h charging capacity to restore the batt ery from the minimum design charge state to a fully charged state, irrespective of the st atus of the plant.

At least two physica lly independent 345-kV transmission lines occupying separate rights-of-way are available to ea ch of the two reactor units. One circuit is norma lly connected to the 4.16-kV ESF buses, and the other circuit is available as a delayed access circuit from the system auxiliary transforme rs of the opposite unit. No single event, such as a breaker failing open, a bus fault in the switchyard, or a fa ilure on a tra nsmission tower, will cause simultaneous loss of both offsite power sources.

Switchyard power is available to both units as long as at least one 345-kV transmission line is available at the switchyard (Section 8.2).

The time schedule for performing inspections and measurements is established in accordance with the req uirements of I EEE Standards 450-1995 and 308-1971. The batt eries will be discharge tested periodically in accord ance with the recommen dations of Regulatory Guide 1.129 and the re quirements of Technica l Specifications.

Compliance with Regulato ry Guides 1.32 and 1

.93 is discussed in Appendix A.

8.1.7 Qualification

Te sts of Continuous-Duty Motors Installed Inside the Containme nt of Water-Cool ed Nuclear Power Plants To the extent pr acticable, motors and auxiliary equipment that are part of the installed motor assembly have been qualified in accordance with IEEE 334-1971.

The qualification tests have simulated as clos ely as practicable all design-basis events which affect operation of the motors and auxiliary equipment.

Compliance with Regulato ry Guide 1.40 is discu ssed in Appendix A.

B/B-UFSAR 8.1-13 REVISION 10 - DECEMBER 2004 8.1.8 Preoperational Testi ng of Redundant Onsi te Electric Power Systems to Verify Prop er Load Group Assignments An acceptable testin g program to verify the existence of independence among red undant onsite power so urces and their load groups was insti tuted through preope rational testing conducted for both energized and d eenergized conditions of the load group not under test (Chapter 14.0).

Compliance with Regulato ry Guide 1.41 is discu ssed in Appendix A.

8.1.9 Bypassed

and Inoperable Status Indication for Nuclear Power Plant Safety Systems (Regulatory Guide 1.47)

Bypass or test of reac tor trip system or ESF AS logic channels is automatically indicated on the main control board (trip status and bypass permissiv e lights), except for the containment ventilation radi ation monitor.

Compliance with Regulato ry Guide 1.47 is discu ssed in Appendix A.

8.1.10 Application of t he Single-Failure Criterion to Nuclear Power Plant Prot ection System (Regulatory Guide 1.53)

It is shown in Chapter 7.0 that the reac tor protection system complies with the requirements of Section 4.2 of IEEE 279-1971 (also designated ANSI N42.7-1972) and IEEE 379-1972 with respect to satisfying the single-failure criteria.

Where a single failure c an result in c omponents performing undesirable mechanic al motion of manua lly controlled electrically-operated valves, administra tive controls or operator action provisio ns are provided to disconnect power to the valve or the valve

's electric system.

For the safety injecti on (SI) system v alves (except for SI8808A-D) listed in Table 8.1-2, operator action is required to close a feeder contactor by means of a manually operated control switch at the main con trol board. Elect ric power will then be restored to the line side of v alve motor starters and in the event valve operation is necessary, power will be available.

Redundant valve position indicat ion is provided for the operators assistance in meeting the ti me requirements for the plant condition.

This design utilizes a power lockout " circuit breaker-starter" in series with the " circuit breaker-starter" for each of the SI MOV valves. This po wer lockout starter can be controlled from the main control room.

B/B-UFSAR 8.1-14 REVIS ION 10 - DECEMBER 2004 Example: Motor-oper ated valve 1SI8802B

1. The power lockout feature is the starter at MCC 132X4, compartment K2 (which is the upstream starter for MOV 1SI8802B), see key diagrams 6E-1-4008AA and 20E-1-4008AA.

2. This starter contact c an be opened or closed by the selector switch at t he main control room panel 1PM06J (see schematic drawings 6E-1-4030 S I34 and 20E-1-40 30 SI34). This feature meets Branch Technical Position ICSB-18, paragraph B.3. 3. The starter for MOV 1SI8802B is at MCC 132X4 A, compartment L2 which is downstream of the power lockout starter as mentioned in Item 1 (see drawings 6E-1-4008AA and 20E-1-4008AA).

4. When the power l ockout starter contact o pens (as mentioned in Item 2) there is no electrical power supply furnished to valve motor 1SI8802B (see drawings 6E-1-4008AA and 20E-1-4008AA) or there is no power supply furnished to the control transformer which suppli es the power supply to the control circuit.

5. During power loc kout, if any signal is present, it will not change the valve posit ion since there is no power to the motor or control circuit.

Also if the 3-phase starter cont act (O) gets stuck in the close position, the valve will not change position since there is no electric pow er to the valve motor.

Because of the d esign which is explained in Items 1 through 5, there is no need to rack the cir cuit breaker out or separate the control circuit.

However, for the reactor coolant loo p stop valves (RC8001A-D and RC8002A-D), the safety injection system accumula tor isolation valves (SI8808A-D), and the cont ainment purge is olation valves (VQ001A-B and VQ002A-B) listed in Table 8.1-2, the individual breaker for each valve (located at the respective MCC compartment) is mainta ined manually deen ergized (opened) and administratively control led. This precautio n assures that these valves always remain in the correct position during Modes 1, 2, 3, and 4 for the RC and VQ valves and during Modes 1, 2, and 3 for the safety injecti on system accumulator isolation valves.

The individual breakers for the essential se rvice water (SX) return valves, in Brai dwood Table 8.1-2, are also maintained manually deenergized and adminis tratively cont rolled. This method of power lockout is acceptable becaus e the RC, SI8808A-D, VQ, and SX valves are not "activ e" valves as d efined in Branch Technical Position ICSB-18.

All motor-operated val ves that require power lockout to meet Branch Technical Position ICSB-18 are listed in Table 8.1-2.

B/B-UFSAR 8.1-14a REVIS ION 10 - DECEMBER 2004 Technical Specification surveillances verify t hat each valve is in the required position, with the exc eption of the Braidwood SX165A/B valves, which were re moved from the Technical Specifications by Brai dwood Amendment 62.

Conformance to Regulatory Guide 1.53 is discus sed in Appendix A.

B/B-UFSAR 8.1-15 REVISION 10 - DECEMBER 2004 8.1.11 Manual Initiation of Protective Actions (Regulatory Guide 1.62) Manual initiation of e ach protective action at the system level is provided in a manner such that initiation accomplishes all action performed by auto matic initiation, an d that protective action at the system goes to completion once manually initiated. Manual i nitiation is performed by readily accessible switches located in the control room and a m inimum of equipment is used in common wi th automatically initiat ed protective action.

For additional discussion on this subject, s ee Subsection 7.1.2.

8.1.12 Electric al Penetrations The Byron/Braidwood Stations' electrical penetrations are designed to withstand, without loss of mecha nical integrity, the maximum possible f ault current versus time conditions (which could occur due to a single random failure of a circuit overload protection device) with in the two l eads of any one single-phase circuit or the three leads of any one three-phase circuit. The penetratio ns are designed with oversized conductors through the penetration seals such that they can withstand the maximum fault current ve rsus time condition from the time the fault occurs through the time required for ope ration of the backup protection device if not interrupted by the primary protective device.

The Byron/Braidwood de sign specification (Construction Permit was issued December 31, 1975) requires the penetration vendors to meet all requirements of Regu latory Guide 1

.63, Rev. 0.

Each type of typical circuit s that penetrate the reactor containment is identified in the following paragraphs with a description of the pri mary and backu p protection systems provided for the circuits and the fault-current-versus-time that the penetrations are qualified to.

Both the primary and backup protection devices a re selected and set to clear faults, up to the maximum calculated fault current, wi thout exceeding the current and related time interval for which the pene trations are qualified to for maintaining m echanical integrit

y. In addition, the primary and secondary protection devices are selected with time-current tripping characteristics that will provide time-current thermal protection for the penetration conductors up to the maximum calculated fault current.

The Byron/Braidwood Unit 1 e lectrical penetrations are manufactured by Conax Co rporation, whereas Byr on/Braidwood Unit 2 electrical penetrati ons are manufactured by either Conax Corporation, Bunker Ramo (Amphenol SAMS) or Bu nker Ramo (Amphenol SAMS) with Conax adaptor modules.

It must be noted that there is no need to maintain the Conax penetrations pressurized during normal operation to en sure electrical fu nctionality during a LOCA. However, there is a need to m aintain the Bunker Ramo penetrations pressurized during normal operation to assure electrical functiona lity during a LOCA.

B/B-UFSAR 8.1-15a REVISION 10 - DECEMBER 2004 1. Medium Voltage (6.9-kV) Power Se rvice Penetrations The primary protection consists of the 6 900-V feeder air circuit breaker that feeds the penetrati on directly. This breaker utilizes Westi nghouse COM-5 and COM-11 relays for its penetration prot ection scheme.

B/B-UFSAR 8.1-16 REVISION 10 - DECEMBER 2004 The backup protection co nsists of the 6900-V m ain bus (to which the penetration feeder b reaker is connected) supply air circuit breaker. This break er utilizes two West inghouse CO-6 or CO-9 relays for its p enetration pro tection scheme.

Both Conax and B unker Ramo (Amphenol SAMS) penetrations have been qualified and can withstand a short circuit of 44,000 amperes symmetrical for a peri od of 0.5 seconds or a short circuit of 40,840 amperes symmetric al for a period of 0.845 second.

2. Low Voltage Power Service Penetrations These penetrations are further subdivided in to the following:

a. Circuits energized direc tly from 480-V E SF substations The primary protection consists of the 480-V feeder circuit breaker that feeds the penet ration directly.

The backup protectio n consists of th e 4160-V supply air circuit breaker that fee ds the entire 480-V substation. This breaker utilizes three Westinghouse CO-9 relays for its penetrat ion protection scheme.

The Byron/Braidwood Unit 1 penetrations (500 MCM conductors) have been qualif ied and can withstand a short circuit of 22, 000 amperes (symme trical) for 0.5 second or a short circ uit of 21,500 amperes (symmetrical) for a peri od of 0.52 second.

B/B-UFSAR 8.1-16a REVISION 8 - DECEMBER 2000 The Byron/Braidwood Unit 2 penetrations (500 MCM conductors) have been qualif ied and can withstand a short circuit of 42, 000 amperes (symme trical) for 0.5 second or a short circ uit of 21,500 amperes (symmetrical) for a peri od of 1.9 seconds.

B/B-UFSAR 8.1-17 REVISION 10 - DECEMBER 2004

b. Circuits energized from 480-V pressurizer heater distribution cabinets The primary protection consists of a 480-V feeder molded case air circuit brea ker that feeds the penetration directly.

The backup prote ction consists of another molded case air circuit breaker similar (and connected in series) to that provided for primary protection.

The Byron/Braidwood Unit 1 penetrations (#2 AWG conductors) have been qualif ied and can withstand a short circuit of 12,000 ampe res (symmetrical) for a period of 0.19 second or a short circuit of 11,211 amperes (symmetrical) for a period of 0.2 second.

The Byron/Braidwood Unit 2 penetrations (1/0 AWG conductors) have been qualif ied and can withstand a short circuit of 27,000 ampe res (symmetrical) for a period of 0.075 seco nd or a short circuit of 11,211 amperes (symmetrical) for a period of 0.435 second.

c. Non-safety-related cir cuits energized from 480-V substations The primary protection consists of the 480-V load circuit breaker that feeds the penet ration directly.

The backup protection co nsists of the 480-V main bus (to which the penetratio n feeder breaker is connected) feeder circuit br eaker or by use of fuses in series with the load circuit breaker.

The Byron/Braidwood Unit 1 penetrations (500 MCM conductors) have been qualif ied and can withstand a short circuit of 22,000 ampe res (symmetrical) for a period of 0.5 second or a short circuit of 8203 amperes (symmetrical) for 3.6 seconds.

B/B-UFSAR 8.1-18 REVISION 10 - DECEMBER 2004 The Byron/Braidwood Unit 2 penetrations (500 MCM conductors) have been qualif ied and can withstand a short circuit of 42,000 ampe res (symmetrical) for a period of 0.5 second or a short circuit of 8203 amperes (symmetrical) for 13 seconds.

d. Circuits energized dir ectly from 480-V ESF motor control centers The primary protection consists of a 480-V feeder circuit breaker that feeds the penet ration directly.

The backup prote ction consists of another molded case air circuit breaker similar (and connected in series) to that prov ided for primary protection.

The overload heater at t he starter (where furnished) also provides bac kup protecti on for low magnitude fault currents.

The Byron/Braidwood Units 1 and 2 pene trations have been qualified and have the fault current versus time capabilities sh own in Table 8.1-3.

e. Non-safety-related cir cuits energized directly from 480-V motor control centers The primary protection consists of a 480-V feeder molded case air circuit brea ker that feeds the penetration directly.

The backup prote ction consists of another molded case air circuit breaker similar (and connected in series) to that prov ided for primary protection.

The overload heater at the starter (where furnished) also provides backup pro tection for low-magnitude fault currents.

B/B-UFSAR 8.1-19 REVISION 10 - DECEMBER 2004 The Byron/Braidwood Units 1 and 2 pene trations have been qualified and have the fault current versus time capabilities sh own in Table 8.1-3.

3. Low Voltage Control Service Penetrations These penetrations are further subdivided in to the following:

a. Circuits energized d irectly from 120/208-Vac distribution pan els at 480-V MCCs The primary protection consists of a 120-V feeder molded case air circuit brea ker that feeds the penetration directly.

The backup prote ction consists of another molded case air circuit breaker similar (and connected in series) to that provided for primary protection.

The Byron/Braidwood Unit 1 penetrations (#14 AWG conductors) have been qualif ied and can withstand a short circuit current of 120 0 amperes (symmetrical) for a period of 0.032 se cond, or a short circuit current of 554 a mperes for a per iod of 0.15 second.

The Byron/Braidwood Unit 2 penetrations (#14 AWG conductors) have been qualif ied and can withstand a short circuit current of 1,6 00 amperes (symmetrical) for a period of 0.03 sec ond or a short c ircuit current of 554 amperes for a period of 0.25 second.

B/B-UFSAR 8.1-20 REVISION 10 - DECEMBER 2004 b. 120-Vac control circui ts energized from the 480-120 V control power transformers in the motor control centers The primary protection consi sts of a nonrenewable cartridge-type fuse in the control t ransformer's 120-V secondary leads that feed th e penetrations directly.

The backup protectio n consists of anot her fuse similar (and connected in series) to that provid ed for primary protection.

The Byron/Braidwood Unit 1 penetrations (#14 AWG conductors) have been qualif ied and can withstand a short circuit current of 120 0 amperes (symmetrical) for a period of 0.032 second, or a short circuit of 40 amperes for a per iod of 28.8 seconds.

The Byron/Braidwood Unit 2 penetrations (#14 AWG conductors) have been qualif ied and can withstand a short circuit of 1600 amperes (symmetrical) for a period of 0.03 second, or a short circuit of 40 amperes for a per iod of 48 seconds.

4. Low Voltage Shielded Instrumentation S ervice Penetrations The short circuit current through these penetrat ions will not exceed their continu ous current rating.

5. Neutron Monitoring Service Penetrations The short circuit current through these penetrat ions will not exceed their continu ous current rating.

6. Circuits Energized from 125 Vdc Distribu tion Panels The 125-Vdc emergency li ghting cabinet is the only such load.

The primary protection c onsists of a 125-Vdc molded case air circuit breaker that feeds the penetrati on directly. The backup protection cons ists of another molded case air circuit breaker similar (and con nected in series) to that provided for primary protection.

B/B-UFSAR 8.1-21 7. Circuits (Solenoid Operated Valves) Energized From 125 Vdc Distribution Panels The primary protection c onsists of a nonrenewa ble cartridge-type fuse that feeds the pe netration directly.

The backup protection consists of another fuse similar (an d connected in series) to that provided for pr imary protection.

8. Rod Control System Lift and Gripper Coil Circuits

The primary and backup protection for the rod control system lift and gripper coil circuits c onsists of fuses connected in series. 9. Rod Position Ind ication Data Circuits The primary and backup p rotection for the ro d position indication data cabinets consists of two 120-Vac molded case air circuit breakers connected in series.

10. There are no pro visions for periodic t esting of penetration or fuses under simulat ed fault conditions be cause such testing would be detrimental to the penetration and fu ses. The circuit breakers that provide the primary and backup pro tection will be periodically tested un der simulated fault conditions to demonstrate that the overall coo rdination scheme remains within the specified limits.

The test interval will be at l east once every 18 months during refueling outages.

Conformance to Regulatory Guide 1.63 is discus sed in Appendix A.

8.1.13 Qualificatio n Tests of Electric Valve Operators Installed Inside the Contain ment of Nuclear Power Plants

To the extent pr acticable, the e lectric and mechanic al components integral to the electric valve operator mechanism and required to operate and control valve action ins ide the containment have been tested in accordance with IEEE 382-1972.

Although in some instances, stem mounted switches are not environmentally tested a long with the valve-motor operator, they are still tested in accorda nce with the sub ject standard.

Compliance with Regulato ry Guide 1.73 is discu ssed in Appendix A.

8.1.14 Physical Independenc e of Electric Systems The physical independe nce of the circuits and electrical equipment comprising or associated with Class 1E power systems, protection systems, sy stems actuated or controlled by the protection system, and auxiliary or su pporting systems that

B/B-UFSAR 8.1-22 REVISION 8 - DECEMBER 2000 must be operable for the prote ction systems to perform their safety-related function are discussed in Subsection 8.3.1.4.

The physical identif ication of safety-re lated equipment is discussed in S ubsection 8.3.1.3.

Compliance with Regula tory Guide 1.75 is dis cussed in Appendix A. 8.1.15 Shared Emergen cy and Shutdown El ectric systems for Multi-Unit Nuclear Power Plants The criteria followed in designing the two u nit station is that each unit shall operate independently of the other and malfunction of equipment or operator error in one unit will not initiate a malfunction or error in the other unit nor affect the continued operation of the other unit.

Compliance with Regulato ry Guide 1.81 is discu ssed in Appendix A.

8.1.16 Qualification of Class 1E Equipm ent for Nuclear Power Plants With regard to environ mental qualification of instrumentation, control, and electri cal equipment impo rtant to safety, the Licensee complies with the intent of IEEE 323-19

74. Additional information is provided in Section 3.11.

Compliance with Regula tory Guide 1.89 is dis cussed in Appendix A. 8.1.17 Availability of Electric Power Sources During abnormal electr ic power source co nfigurations, plant operations are limit ed as described in the Technical Specifications.

Compliance with Regulato ry Guide 1.93 is discu ssed in Appendix A.

8.1.18 Conformance to IEEE 338-1975 (Periodic Testing of Nuclear Power Generating Sta tion Class 1E Power and Protection System)

Conformance to this standard is addressed in Subsection 8.3.1.2.

8.1.19 Conformance to I EEE 344-1971 (Recommen ded Practices for Seismic Qualification of Class 1E Equi pment for Nuclear Power Generating Station)

Conformance to this stan dard is addressed in Section 3.10.

B/B-UFSAR 8.1-23 8.1.20 Conformance to IEEE 387-1972 (Criteria for Diesel Generator Units Appl ied as Standby P ower Supplies for Nuclear Power Genera ting Stations)

Vendor qualification tests, preoperation al testing, and periodic testing during normal plant o peration conform to those procedures described in this standard, except as noted in Subsection 8.3.1.2, Chapter 14.0, and the Technical Specifications.

8.1.21 Conformance to I EEE 420-1973 (IEEE Trial-Use Guide for Class 1E Control Swi tchboards for Nuclear Power Generating Stations)

Class 1E control switchboards co nform to this st andard with the following clarification to Paragraph 4.6.1.2

Splices may be used on individual c onductors of external field run cables within switchboards for the pu rpose of extending individual conductors to their point of termination.

B/B-UFSAR

8.1-24 TABLE 8.1-1 LISTING OF APP LICABLE CRITERIA CONFORMANCE CRITERIA TITLE DISCUSSED IN 1. 10 CFR Part 10

a. 10 CFR 50.34 Contents of Applications: Technical All Chapters of Information UFSAR

b. 10 CFR 50.36 Technical Specifications Technical Specifications

c. 10 CFR 50.55a Codes and Standards See Response of IEEE Standard 279 Below

2. General Design Criteria (GDC),

Appendix A to 10 CFR Part 50

a. GDC-1 Quality Standards and Records Section 3.1 b. GDC-2 Design Bases for Protection Against Natural Section 3.1 Phenomena

c. GDC-3 Fire Protection Section 3.1

d. GDC-4 Environmental and Missile Design Bases Section 3.1

e. GDC-5 Sharing of Structure s, Systems, and Section 3.1 Components

f. GDC-13 Instrumentation and Control Section 3.1

B/B-UFSAR

8.1-25 TABLE 8.1-1 (Cont'd)

LISTING OF APP LICABLE CRITERIA CONFORMANCE CRITERIA TITLE DISCUSSED IN g. GDC-17 Electric Power Systems Section 3.1 h. GDC-18 Inspection a nd Testing of Electrical Power Section 3.1 Systems

i. GDC-21 Protection System Reliability and Section 3.1 Testability j. GDC-22 Protection System Independence Section 3.1 k. GDC-33 Reactor Coolant Make-up Section 3.1 l. GDC-34 Residual Heat Removal Section 3.1 m. GDC-35 Emergency Core Cooling Section 3.1

n. GDC-38 Containment Heat Removal Section 3.1 o. GDC-41 Containment Atmospheric Clean-up Section 3.1 p. GDC-44 Cooling Water Section 3.1 3. Institute of Electrical and Electronics Engineers (IEEE) Standards: a. IEEE Std. 279 Criteria for Protect ion Systems for Nuclear Subsections 8.1.11, (ANSI N42.7) Power Generating Systems 8.3.1.2 and 8.3.1.4.1 b. IEEE Std. 308 Criteria for Cla ss 1E Electrical Systems See Response to for Nuclear Power Generating Stations R.G. 1.32 below

B/B-UFSAR

8.1-26 TABLE 8.1-1 (Cont'd)

LISTING OF APP LICABLE CRITERIA CONFORMANCE CRITERIA TITLE DISCUSSED IN c. IEEE Std. 317 Electric Penetra tion Assemblies in See Response to Containment Structures for Nuclear Power R.G. 1.63 below Generating Stations

d. IEEE Std. 323 Standard for Qua lifying Class 1E Equipment See Response to for Nuclear Power Generating Stations R.G. 1.89 below.

A lso see Subsection 8.3.1.2 e. IEEE Std. 334 Standard for Type Te st of Continuous Duty See Response to Class 1E Motors for Nuclear Power Generating R.G. 1.40 below. Stations Also see Subsection 8.1.19

f. IEEE Std. 336 Installation, In spection and Testing See Response to (ANSI N45.2.4) Requirements for Instrumentation and R.G. 1.30 below Electric Equipment During the Construction of Nuclear Power Generating Stations

g. IEEE Std. 338 Criteria for the Periodic Testing of See Response to Nuclear Power Generating Station Protection R.G. 1.118 below. Systems Also see Subsections 8.1.18

and 8.3.1.2

h. IEEE Std. 344 Guide for Seismic Qualification of Class 1 See Response to (ANSI N41.7) Electrical E quipment for Nuclear Power R.G. 1.100 below. Generating Stations A lso see Subsection 8.1.19

i. IEEE Std. 379 Guide for the Ap plication of the Single See Response to (ANSI N41.2) Failure Crit erion to Nuclear Power R.G. 1.53 below Generating Station Protection System B/B-UFSAR

8.1-27 REVISION 5 - DECEMBER 1994 TABLE 8.1-1 (Cont'd)

LISTING OF APP LICABLE CRITERIA CONFORMANCE CRITERIA TITLE DISCUSSED IN j. IEEE Std. 382 Trial-Use Guide for the Type-Test of Class See Response to 1 Electric Valve Operators for Nuclear R.G.

1.73 below Power Generating Stations (ANSI N416)

k. IEEE Std. 383 Standard for Typ e-Test of Class 1E Electric Subsections Cable Field Splices, and Connections for 8.3.1.4.1.2 and Nuclear Power Generating Stations 8.3.3 l. IEEE Std. 384 Criteria for S eparation of Class 1E See Response to (ANSI N41.14) Equipment and Circuits R.G. 1.75 below

m. IEEE Std. 387 Criteria for Diesel-Generator Units Applied Subsections 8.1.20 (ANSI N41.13) as Standby Power Supplies for Nuclear Power and 8.3.1 Stations

n. IEEE Std. 415 Planning of Pre-Operational Testing Chapter 14.0 Programs for Class 1E Power Systems for Nuclear Power Generating Stations, IEEE Guide for o. IEEE Std. 420 Trial-Use Guide for Class 1E Control Subsection 8.3.1 Switchboards for Nuclear Power Generating Stations (ANSI N41.7)

p. IEEE Std. 450 Recomm ended Practice for Maintenance, See Response to Testing and Replacem ent of Large Stationary R.G. 1.129 below Type Power Plant and Substation Lead Storage Batteries

q. IEEE Std. 484 Recommended Prac tice for Installation See Response to Design and Insta llation of Large Lead R.G. 1.128 below. Storage Batteries for Nuclear Power Plants A lso see Subsection 8.3.2 B/B-UFSAR

8.1-27a REVISION 5 - DECEMBER 1994 TABLE 8.1-1 (Cont'd)

LISTING OF APP LICABLE CRITERIA CONFORMANCE CRITERIA TITLE DISCUSSED IN r. IEEE Std. 485 Recommen ded Practice for Sizing Large Lead Subsection 8.3.2 Storage Batteries for Generating Stations and Substations

s. IEEE Std. 946 Recommen ded Practice for the Design of DC Subsection 8.3.2 Auxiliary Power Systems for Generating Stations

B/B-UFSAR

8.1-28 TABLE 8.1-1 (Cont'd)

LISTING OF APP LICABLE CRITERIA CONFORMANCE CRITERIA TITLE DISCUSSED IN 4. Regulatory Guides (RG)

a. RG 1.6 Independence Between Redundant Standby Appendix A (Onsite) Power Sources and Between Their Distribution Systems

b. RG 1.9 Selection of Diesel Generator Set Capacity Appendix A for Standby Power Supplies c. RG 1.29 Seismic Design Classification Appendix A

d. RG 1.30 Quality Assurance Re quirements for the Appendix A Installation, Inspection, and Testing of Instrumentation and Electric Equipment

e. RG 1.32 Use of IEEE Std. 308, "Criteria for Class Appendix A 1E Electric Systems for Nuclear Power Generating Stations" f. RG 1.40 Qualification Tests for Continuous-Duty Appendix A Motors Installed Inside the Containment of Water Cooled Nuclear Power Plants

g. RG 1.41 Preoperation al Testing of Redundant Onsite Appendix A Electric Power Systems to Verify Proper Load Group Assignments

h. RG 1.47 Bypassed and Inopera ble Status Indications Appendix A for Nuclear Power Plant Safety Systems i. RG 1.53 Application of the Single-Failure Criterion Appendix A to Nuclear Power Plant Protection Systems B/B-UFSAR

8.1-29 TABLE 8.1-1 (Cont'd)

LISTING OF APP LICABLE CRITERIA CONFORMANCE CRITERIA TITLE DISCUSSED IN j. RG 1.63 Electric Penetration A ssemblies in Contain- Appendix A ment Structures for Water-Cooled Nuclear Power Plants

k. RG 1.68 Preoperation al and Initial Start-up Test Appendix A Programs for Water-Cooled Power Reactors

l. RG 1.70 Standard Format and Content of Safety Appendix A Analysis Reports for Nuclear Power Plants m. RG 1.73 Qualification Tests of Electric Valve Appendix A Operators Installed Inside the Containment of Nuclear Power Plants

n. RG 1.75 Physical Independence of Electric Systems Appendix A

o. RG 1.81 Shared Emergency and Shutdown Electric Appendix A Systems for Multi-Unit Nuclear Power Plants p. RG 1.89 Qualification of Class 1E Equipment for Appendix A Nuclear Power Plants

q. RG 1.93 Availability of Electric Power Sources Appendix A

r. RG 1.100 Seismic Qualification of Electric Equipment Appendix A for Nuclear Power Plants

s. RG 1.106 Thermal Overload Protection for Electric Appendix A Motors on Motor-Operated Valves

t. RG 1.108 Periodic Testing of Diesel Generators Used Appendix A as Onsite Power Systems at Nuclear Power Plants B/B-UFSAR

8.1-30 REVISION 5 - DECEMBER 1994 TABLE 8.1-1 (Cont'd)

LISTING OF APP LICABLE CRITERIA CONFORMANCE CRITERIA TITLE DISCUSSED IN u. RG 1.118 Periodic Testing of Electric Power and Appendix A Protection System v. RG 1.120 Fire Protection Guidelines for Nuclear Appendix A Power Plants w. RG 1.128 Installation Des ign and Installation of Appendix A Large Lead Storage Batteries for Nuclear Power Plants x. RG 1.129 Maintenance, Testing and Replacement of Appendix A Large Lead Storage Batteries for Nuclear Power Plants y. RG 1.155 Station Blackout Appendix A

5. Branch Technical Positions (BTP) ICSB a. BTP ICSB 2 Diesel-Generator Reliabi lity Qualification Subsections 8.1.20 (PSB) Testing and 8.3.1

b. BTP ICSB 6 Capacity Test Requirements of Station Technical (PSB) Batteries-Technical Specifications Specifications c. BTP ICSB 8 Use of Diese l-Generator Sets for Peaking Subsections 8.1.20 (PSB) and 8.3.1 d. BTP ICSB 11 Stability of Offsite Power Systems Subsection 8.3.1 (PSB) e. BTP ICSB 15 Reactor Coolant Pump Breaker Qualification Subsection 8.1.16 (PSB)

B/B-UFSAR

8.1-31 TABLE 8.1-1 (Cont'd)

LISTING OF APP LICABLE CRITERIA CONFORMANCE CRITERIA TITLE DISCUSSED IN f. BTP ICSB 17 Diesel Generator Protective Trip Circuit Table 8.3-7 and (PSB) Bypasses Subsection 8.3.1

g. BTP ICSB 18 Application of the Single Failure Criterion Subsection 8.1.10 (PSB) to Manually-Controlled Electrically- Operated Valves

h. BTP ICSB 21 Guidance for Application of RG 1.47 Subsection 8.1.9

BYRON-UFSAR

8.1-32 TABLE 8.1-2 MOTOR-OPERATED VALVES RE QUIRING POWER LOCKOUT

All motor-operated valves within the (total) scope of design that require power lockout to meet the B ranch Technical Position ICSB-18 are listed as follows:

VALVE NO. VALVE NO.

SI8840 SI8808B SI8835 SI8808C

SI8806 SI8808D

SI8809A SI8809B

SI8802A SI8813

SI8808A SI8802B

RC8001A VQ001A RC8001B VQ001B RC8001C VQ002A

RC8001D VQ002B

RC8002A RC8002B RC8002C RC8002D BRAIDWOOD-UFSAR

8.1-33 TABLE 8.1-2 (Cont'd)

MOTOR-OPERATED VALVES RE QUIRING POWER LOCKOUT

All motor-operated valves within the (total) scope of design that require power lockout to meet the B ranch Technical Position ICSB-18 are listed as follows:

VALVE NO. VALVE NO.

SI8840 SI8808B SI8835 SI8808C

SI8806 SI8808D

SI8809A SI8809B

SI8802A SI8813

SI8808A SI8802B

RC8001A VQ001A RC8001B VQ001B RC8001C VQ002A

RC8001D VQ002B

RC8002A SX165A

RC8002B SX165B

RC8002C RC8002D

B/B-UFSAR

8.1-34 REVISION 10 - DECEMBER 2004 TABLE 8.1-3 PENETRATION CONDUCTOR AND FAULT CURRENT DATA

UNIT 2 UNIT 1 (CONAX) PENETRATION (BUNKER RAMO) PENETRATION FAULT CURRENT VERSUS FAULT CURRENT VERSUS FIELD TIME CAPABILITIES TIME CAPABILITIES CABLE (SHORT CIRCUIT CONDUCTOR (SHORT CIRCUIT CONDUCTOR SIZE SYMMETRICAL AMPS) SIZE SYMMETRICAL AMPS)

SIZE #10AWG 5,200A for 0.5 sec. #2AWG 27,000A for 0.03 sec #2AWG or or 3,026A for 1.5 sec 3,026A for 2.4 sec

1. 6AWG 5,200A for 0.5 sec #2AWG 27,000A for 0.03 sec #2AWG or or 6,407A for 0.33 sec 6,407A for 0.53 sec

1. 2AWG 12,000A for 0.19 sec #2AWG 27,000A for 0.075 sec 1/0 AWG or or 8,135A for 0.4 sec 8,135A for 0.826 sec

1. 2AWG 9,500A for 0.5 sec 2/0 AWG 27,000A for 0.075 sec 1/0 AWG or Or 10,094A for 0.44 sec 10,094A for 0.53 sec

1. 10AWG 8,000A for 0.1 sec #4AWG 27,000A for 0.03 sec #2AWG or or 3,984A for 0.4 sec 3,984A for 1.37 sec

1. 6AWG 8,000A for 0.1 sec #4AWG 27,000A for 0.03 sec #2AWG or or 7,119A for 0.126 sec 7,119A for 0.43 sec

B/B-UFSAR

8.1-35 REVISION 10 - DECEMBER 2004 TABLE 8.1-3 PENETRATION CONDUCTOR AND FAULT CURRENT DATA

UNIT 2 UNIT 1 (CONAX) PENETRATION (BUNKER RAMO) PENETRATION FAULT CURRENT VERSUS FAULT CURRENT VERSUS FIELD TIME CAPABILITIES TIME CAPABILITIES CABLE (SHORT CIRCUIT CONDUCTOR (SHORT CRICUIT CONDUCTOR SIZE SYMMETRICAL AMPS) SIZE SYMMETRICAL AMPS) SIZE #2AWG 12,000 for 0.19 sec #2AWG 27,000A for 0.075 sec 1/0 AWG or or 9,836A for 0.28 sec 9,836A for 0.56 sec 1/0 AWG 14,200A for 0.5 sec 2/0 AWG 27,000A for 0.12 sec 2/0 AWG or or 13,180A for 0.58 sec 13,180A for 0.5 sec #10AWG 8,000A for 0.1 sec #4AWG 27,000A for 0.03 sec #2AWG or or 3,984A for 0.4 sec 3,984A for 1.37 sec #6AWG 8,000A for 0.1 sec #4AWG 27,000A for 0.03 sec #2AWG or or 4,444A for 0.32 sec 4,444 for 1.1 sec 4/0 AWG 18,600A for 0.5 sec 250 MCM 27,000A for 0.3 sec 4/0 AWG or or 12,163A for 1.17 sec 12,163A for 1.48 sec 350 MCM 22,000A for 0.5 sec 500 MCM 42,000A for 0.5 sec 500 MCM or or 10,924A for 2 sec 10,924A for 7 sec

BYRON-UFSAR 8.2-1 REVISION 4 - DECEMBER 1992 8.2 OFFSITE (PREFERR ED) POWER SYSTEM

8.2.1 Description

Electric energy generated at t he station is transformed from generator voltage to a nomin al 345-kV transmis sion system voltage by the main po wer transformers.

The main power transformers are connected via intermediate tran smission towers to the station's 345-kV transmission ter minal. A one line diagram of the 3 45-kV bus arrangement is sho wn on Figure 8.2-1.

The 345-kV overhead lines exit the station transmission terminal on three separate rights-of-way as shown on Figure 8.2-2.

The transmission line structures are designed for heavy ice loadings, high wind, and broken wire l oadings. Dampers are installed on all conductors and static wires to control high frequency vibration. Figure 8.2

-3 shows the transmission line routing on the site pr operty, and Figure 8.2-2 indicates the general routes and lengths of transmis sion lines from the station to major subst ations on the Comm onwealth Edison grid.

No other transmission lines cross over these lin es and as the lines enter the station via three separa te rights-of-way a structural failure in any one li ne will not resu lt in the loss of the transmission li nes entering the s ite via the other two rights-of-way.

The preferred power system is co nsidered as having three major sections, each of which must provide two phy sically separate and electrically independent circuit pat hs between the o nsite power system and the trans mission network (the transmission network excludes the station switchyard).

The three sections are:

1. The transmission lines e ntering the station switchyard from the transmission network.

2. The station switchya rd. (A common s witchyard is allowed by GDC 17).

3. The overhead tra nsmission lines, SATs, buses between the switchyard, and the on site power system.

The station's 345-kV s witchyard ring bus es are continuously energized and serve as the power source for the station's safety loads. The two power circuits from the 345-kV switchyard ring buses to each unit's Class 1E di stribution system enter through two physically separate rights of way with independent transmission line stru ctures. These lines enter the switchyard from the opposite sides to the lines leaving the switchyard and terminate at transformers located on the opposite sides of the reactor buildings. Th ere are no other l ines crossing these preferred power lines.

A single event will not simultaneously

BYRON-UFSAR 8.2-1a REVISION 4 - DECEMBER 1992 affect both circuits in such a way that neither can be returned to service within the time lim it to exceed any design limits.

The system auxiliary t ransformers step the 3 45-kV system voltage down to the station 4160-volt and 6900-volt po wer systems. Each pair of system a uxiliary transformers is siz ed to provide the total auxiliary power for one unit plus the ESF auxiliary power for the other unit.

The transmission terminal 345-kV circuit breakers are configured to afford optimum protection for the bus in the event of a transmission line, gen erator, or bus fault.

Relay tripping of the breakers over a microwave co mmunication system is used for line protection. Should a break er fail to ope rate or primary relaying fail to trip a breaker, local breaker b ackup (LBB) will operate the adjacent breaker. The o peration of the

BYRON-UFSAR 8.2-2 REVISION 10 - DECEMBER 2004 adjacent breaker still provides maximum reli ability of power supplied to the bus as it will o nly isolate an additional bus section. For instance, the ring bus is conf igured so that a generator trip from the backup protection system will not jeopardize the a vailability of the system auxiliary transformer or one of the two tr ansmission feeds to the ring bus for the unit. Control p ower for operation of the 345-kV breakers is provided by two 125-volt batteries located in the switchyard.

The 345-kV switchyard relay house houses the 125-volt batteries and the protective relay

s. A single line di agram of a typical d-c control system for operation of the brea kers is shown on Figure 8.2-4.

The only remote source of fire, explosion, or missiles in the area of the transmis sion terminal would be the circuit breakers. The worst possible failure of any circuit breaker and the microwave tower will not result in t he total loss of offsite power.

Further discussion c oncerning the rela tionship between the station's offsite po wer system and its o nsite auxiliary power system is found in Subsection 8.3.1.

BRAIDWOOD-UFSAR 8.2-3 REVISION 8 - DECEMBER 2000 8.2 OFFSITE (PREFFER RED) POWER SYSTEM

8.2.1 Description

Electric energy generated at t he station is transformed from generator voltage to a nomin al 345-kV transmis sion system voltage by the main po wer transformers.

The main power transformers are connected via intermediate tran smission towers to the station's 345-kV transmission ter minal. A one line diagram of the 3 45-kV bus arrangement is sho wn on Figure 8.2-5.

The 345-kV overhead lines exit the station transmission terminal on three separate rights-of-way as shown on Figure 8.2-6.

The transmission line structures are designed for heavy ice loading, high wind, and broken wire loadings. Dampers are installed on all conductors and static wires to control high frequency vibration. Figure 8.2

-7 shows the transmission line routing on the site pr operty, and Figure 8.2-6 indicates the general routes and lengths of transmis sion lines from the station to major subst ations on the Comm onwealth Edison grid.

As the lines enter t he station via three sep arate rights-of-way a structural failure of any one line will not result in the loss of transmission lines entering the site via the other two rights-of-way. The transmission lines that are exposed to a crossover are the two lines to East Frankfort which pass under one 765-kV line and the lines from La Salle wh ich pass under one 345-kV line.

The preferred power system is co nsidered as having three major sections, each of which must provide two phy sically separate and electrically independent circuit pat hs between the o nsite power system and the trans mission network (the transmission network excludes the station switchyard).

The three sections are:

1. The transmission lines e ntering the station switchyard from the transmission network.

2. The station switchya rd. (A common s witchyard is allowed by GDC 17).

3. The overhead tra nsmission lines, SATs, buses between the switchyard, and the on site power system.

The station's 345-kV s witchyard ring bus es are continuously energized and serve as the power source for the station's safety loads. The two power circuits from the 345-kV switchyard ring buses to each unit's Class 1E di stribution system enter through two physically separate rights of way with independent transmission line stru ctures. These lines enter the switchyard from the opposite sides to the lines leaving the switchyard and terminate at transformers located on the opposite sides of the

BRAIDWOOD-UFSAR 8.2-3a REVISION 4 - DECEMBER 1992 reactor buildings. Th ere are no other l ines crossing these preferred power lines.

A single event will not simultaneously affect both circuits in such a way that neither can be returned to service within the time lim it to exceed any design limits.

The system auxiliary t ransformers step the 3 45-kV system voltage down to the station 4160-volt and 6900-volt po wer systems. Each pair of system a uxiliary transformers is siz ed to provide the total auxiliary power for one unit plus the ESF auxiliary power for the other unit.

The transmission terminal 345-kV circuit breakers are configured to afford optimum protection for the bus in the event of a transmission line, gen erator, or bus fault.

Relay tripping of the breakers over a microwave co mmunication system is used for line protection. Should a b reaker fail to operate or

BRAIDWOOD-UFSAR 8.2-4 REVISION 10 - DECEMBER 2004 primary relaying fail to trip a breaker, local b reaker backup (LBB) will operate t he adjacent breaker.

The operation of the adjacent breaker still provides maximum reli ability of power supplied to the bus as it will o nly isolate an additional bus section. For instance, the ring bus is conf igured so that a generator trip from the backup protection system will not jeopardize the a vailability of the system auxiliary transformer or one of the two tr ansmission feeds to the ring bus for the unit. Control p ower for operation of the 345-kV breakers is provided by two 125-V ba tteries located in the switchy ard. The 345-kV switchyard relay house houses the 125-volt batteries and the protective relays.

A single line diagram of a typical d-c control system for operation of the brea kers is shown on Figure 8.2-4. The only remote source of fire, explosion, or missiles in the area of the transmis sion terminal would be the circuit breakers. The worst possible failure of any circuit breaker and the microwave tower will not r esult in the total loss of offsite power.

Further discussion c oncerning the rela tionship between the station's offsite po wer system and its o nsite auxiliary power system is found in Subsection 8.3.1.

B/B-UFSAR 8.2-5 REVISION 10 - DECEMBER 2004

8.2.2 Analysis

The probability of los ing the offsite electr ic power supply has been minimized by th e design of the Co mmonwealth Edison transmission system and the Exelon Generatio n Company system.

Increased reliability is provided through interconnections to neighboring systems. At the beg inning of 1985, the Commonwealth Edison transmission syst em consisted, in par t, of ninety-two 345-kV lines totaling 23 35 miles, and three 76 5-kV lines totaling 90 miles. The t ransmission system is interconnected with neighboring electric utilities at 28 points, 9 at 138-kV, 18 at 345-kV, and 1 at 765-kV.

The interconnections b etween Byron and Braidwood generating stations and the Commonwealth Edison grid and the MAIN, ECAR, and MAPP grids are shown in Figures 8.2-2 and 8.2-6.

Commonwealth Edison is a member of Mid-American Interpool Network (MAIN). In general, all elect rical utilities in Illinois, the eastern part of Missouri, Upper Mi chigan, and the eastern half of Wisconsin are members of MAIN. At the beginning of 1985, the transmission with in MAIN consisted of 153 345-kV lines totaling 4913 miles and three 765-kV l ines totaling 90 miles. One of the fun ctions of MAIN is to ensure that the transmission system is reliable and adequa te. Power flow and transient stability studies are conducte d on a regular basis using the criteria stated in MAIN Guid e No. 2 (Reference 1).

The relevant part of MAIN Guide No. 2 is given below:

"Extreme Disturbance Testing" "The reliability and strength of the MAIN interconnected system shall be tested by sub jecting the system to simulated extreme disturbances. It should be ab le to withstand se vere outages without resulting in an uncontrolled widespr ead tripping of lines and/or generators with resulting loss of load over a large area.

"In planning and operating a bulk power transmis sion system to have a high degree of reliability, condition s should be avoided which could cause an uncontrolled break-up or collapse of the interconnected system ev en for extremely imp robable but credible contingencies. Providing 100% reliability is, of course, impossible, but it is possible to build an interconnected bulk power system in which uncontrolled wides pread interruptions would be very unlikely even during improbable disturbances.

"Also, it is impossi ble to anticipate and test for all combinations of cont ingencies that cou ld occur on an interconnected network.

B/B-UFSAR 8.2-5a REVISION 8 - DECEMBER 2000 Therefore, reliabili ty testing should be such as to thoroughly search out t he maximum

B/B-UFSAR 8.2-6 credible contingencies for examination with good assurance that the many possible contingencies not studied are less severe.

"Due to the individu al characteristics of the various systems in the interconn ected network, each system should be tested for the mos t severe of the following contingencies:

A. At peak load, wi th reasonable increm ental interchange above projected base case schedules between the two systems most affected by the disturbance:

1. Sudden outage of all generating capacity at any plant. 2. Sudden outage of any transmission station, including all generating cap acity associated with such a station.

3. Sudden dropping of a large load or a major load center. 4. Any other credible c ontingency of the same degree. B. At peak load, with i nterchange equal to *First Contingency Incremental Transfers Capability (FCITC) between the two syst ems most affected by the disturbance:

1. Sudden outage of any tra nsmission tower line at a time when any other ci rcuit is out of service.

2. Sudden outage of all transmission circuits on the same right-of-way.

3. Sudden outage of any single or d ouble circuit transmission tower line associated with a station which has two generating units already out of service.

• Notes: i. If the results of Extreme Dist urbance Testing show severe problems whic h might jeopardize the system, this should be noted and the tests repeated to determine an acceptable lower level of transfer.

ii. A further analysis should be made to ensure that, as a result of the distu rbance, the outage of any facility due to over loading will not c ause instability or cascading.

B/B-UFSAR 8.2-7 REVISION 8 - DECEMBER 2000 "The studies conduct ed to test the eff ect of the above contingencies should give due consider ation to the following:

A. Steady-state, transient and dy namic stability consideration, including thr ee-phase faults at the most critical locations.

B. The effect of slow cle aring as a conse quence of improper relay operation or failure of a circuit breaker to open.

C. Possible occurrence of t he above contingencies not only on the intercon nected MAIN networ k, but also on the network of adjacent power systems, where a major contingency might involve MAIN or portions thereof in a cascading incident." The Exelon Generation Company generation sys tem and transmission system at Commonwealth Edison is designed to meet the above criteria.

The reliability of the transmission grid is demonstrated by the performance data of the 345-kV transmission li nes. The average 345-kV line in the MAIN grid experienced 1.5 forced outages per year, with an average duration of 24 hou rs per force d outage during 1984 covering 1 52 line years of exposur

e. For the 17 years between January 1, 1965 and December 31, 1981, the average Commonwealth E dison 345-kV line experienced 1.8 forced outages per year, with an average duration of 15.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> per forced outage. This 1 7-year period represen ts 826 line years of experience. The ca uses of the forced line outages may be summarized as follows:

% of Forced Outages

a. Terminal Related 1. Storm Damage 1.4 2. Equipment Failure 16.0 3. Human Error 7.8 4. False Trip 8.4 5. Other 7.7

b. Line Related 1. Storm Damage 23.5 2. Equipment Failure 5.9 3. Contamination 8.4 4. Other 6.0 c. Unknown 14.9 100% The ability of the Com monwealth Edison trans mission system to withstand the loss of transmission lines

B/B-UFSAR 8.2-8 REVISION 11 - DECEMBER 2006 connecting the B yron and Braidwood 345-kV switchyards to the network has been investigated through separa te stability studies for each station to de monstrate adequacy of the transmission system.

Conditions were studied for the year 1987 for Byron and 1988 for Braidwood. Both Uni ts 1 and 2 were operat ing at their net capabilities of 1120 MW. The electric s ystems in Wisconsin, Iowa, Illinois, and In diana were all rep resented in detail, while the systems in other a djacent states w ere represented in lesser detail.

The studies demonstrate the adequacy of the tran smission system under various line c ontingencies on the Byron and Braidwood 345-kV lines. Contingen cies studied were th ree phase faults near the 345-kV switchyard which are the most severe as concerns the stability of the units. Included were three p hase line faults with normal clearing of the line protect ive systems and also phase-to-ground faults with abnormal cle aring involving the failure of a relay or circuit br eaker. Double line tower faults were also studied. ComEd Tr ansmission Planning Department had conducted transient and dynamic stability studies for the addition of MWs at Byron and B raidwood stations as a result of Power Uprate and the addition of new generation by Independent Power Producer at Lee Co unty station. Lee C ounty Station is added between Byron and Nelson switchyards.

Therefore line no.

from Byron to new substation

1. TSS937 at Lee County will be revised to L0627 and the line no.

between TSS937 and TSS155 (at Nelson) will be left with the old line n

o. L15501. This will revise UFSAR fig ures 8.2-1, 8.2-2 and 8.

2-3. Stabil ity studies have added some more contingencies and a Power System Stabilizer to Byron Unit-2. All these ch anges will be impl emented prior to Power Uprate is effective (in year 2001 at B yron). Due to its unique position in Transmission Network Brai dwood station does not have same changes as Byron except some L BB timer setting changes.

All units remained stable thro ughout all of the line outages mentioned above.

Studies were also ma de for more severe, though less likely, contingencies. To m inimize the possibil ity of instability, provisions have been made to automatic ally trip one unit at Byron for some severe, infrequent contingenc ies. These include multiphase faults wi th abnormal clearing or simultaneous outage of two lines on different rights of way.

With the t ransmission connections at Braidwood, a un it trip is not required for similar conditions.

The expected operating voltage ranges on the 345-kV buses at Byron and Braidwood are 352-356kV and 358-36 2kV, respectively.

There will be no intentional r eduction of tran smission system overload condition. Overload re lief is achiev ed by reducing distribution voltage l evels alone. The nucl ear plant operator is provided with operating inst ructions on 345kV bus voltage levels, including maximum and minimum li mits. These v oltage levels are B/B-UFSAR 8.2-8a REVISION 11 - DECEMBER 2006 developed through system prote ction department s tudies and are communicated to the op erator through the bulk power operations and generating station departments. Low er voltages than indicated above may be experienced under certain transmission system conditions (e.g., some ge neration and transmission line outages). These conditions and their probability of occurrence are discussed below.

Their effects on the voltages of safety-related buses are discussed in Subsection 8.3.1.

The frequency of the offsite power supply will be in the range of 59.9 to 60.1 Hz even under the types of system disturbances referred to below. This rather small frequency band is inherent in the large interco nnected grid control, including an incident involving the sudden loss of the largest generating station.

Frequencies outside this range c an only occur if a system separation occurs as discussed below.

B/B-UFSAR 8.2-9 REVISION 5 - DECEMBER 1994 1. The nuclear plant operat or is provided with operating instructions on 345-kV bus voltage l evels, including maximum and minimum limits. T hese voltage levels are developed through syst em protection department studies and are commun icated to the op erator through the bulk power operations and generating station departments. The operat ing voltage instructions are available with other sta tion operati ng material located in the control room.

Grid system frequenc y is primarily under the control of the bulk power operat ions and is not directly under the plant operator's control. However, a frequency meter is located in the control room to allow the operator to observ e the actual grid system frequency and to take approp riate emergency action, which may be required.

2. Recommended generator operating voltages are selected as a function of sy stem load. In general, it is necessary to operate generator s at a minimum voltage during light sys tem loads and a maximum voltage during heavy sys tem loads to obtain acceptable voltages throughout the gri

d. The maximum and minimum levels vary for different plants depending on their locat ion in the system and are always selected to be within equ ipment limitations.

At light system load s, the generator excitation is reduced to reach the m inimum voltage, thereby somewhat reducing stability margins.

However, the overall system desig n has sufficient margin to ensure stability following a system disturbance for this mode of operation.

At high system l oads, the genera tor excitation is increased to reach the maximum volta ge, which in turn enhances stability.

Counteracting this benefit is the high tran smission system loading.

Stability design margins are also adequate to compensate for this effect.

The normal slight freque ncy deviation from 60 Hz of

+/- 0.1 Hz has a negligible ef fect on system stability.

Significant departures from 60 Hz can only occur if a portion of the s ystem becomes separa ted from the interconnected grid.

Protective schemes are used to arrest the frequency dev iation both for over- and underfrequency conditi ons to satisfactory levels.

3. There are no specific restrictions on the power grid system, which req uires specific spinning reserve within a ded icated distance of Byron and

B/B-UFSAR 8.2-10 Braidwood Stations bey ond the average general requirements included in MAIN Guide #5, "Minimum Operating Reserve of Generating Capacity." Power grid frequency decay rates expected at Byron and Braidwood as a result of disturbances in the grid system have been evalua ted. Frequency levels below 59.9 Hz will occur onl y in the event that the plant and an extensive p art of the C ommonwealth Edison bulk power system bec omes separated from the MAIN, ECAR, and MAPP grid systems creating an isolated island. Such an island would result following the loss of many transmission rights-of-way.

The probability of this event is considerably less than 10-6 per year.

For the Byron plant, the maximum decay rate under an islanding event is ex pected to be about 2.0 Hz/sec, requiring the co ncurrent outage of six rights-of-way. The Braidwood plant, because of its location with respect to oth er generating plants in the grid, cannot reaso nably be involved in a relatively small area island with load exceeding generation. If Braidwood is included in the islanding of a multistate geog raphical area, w hich is extremely unlikely, the maximum freque ncy decay rate is expected to be approximately 2 Hz

/sec, assuming a generation deficiency of the larg est plant in the area.

The possibility of a load di spatch system failure causing an incident at t he generating station or interfering with the reactor protection system has been evaluat ed below.

The economic generating control (EGC) can affect only the turbine digital ele ctrohydraulic control system (DEH) and, thus, the turbine throttle valve and governor valve. The EGC contains a load limiting function which maintains saf e operating conditions independently of the rea ctor control system.

Under no circumstances can the load dispatcher or control systems caus e the unit to change output at a rate exceeding the pre determined internally set rates. These rates are set so as to be compatible with limiting ra tes of the NSSS.

The reactor protection s ystem and the turbine protective system are entire ly independent of the EGC and the DEH control system.

Therefore, a malfunction of the EGC system will n ot affect th ese safeguards.

B/B-UFSAR 8.2-11 REVISION 9 - DECEMBER 2002 The control power for the 345-kV switchyard breakers is supplied by two independent, 125-volt batteries (non-ESF) located in the swi tchyard relay house. The design of the 345-kV transmission line control is such that the loss of either battery or the loss of both batteries and associated feeder cables will not caus e the loss of the offsite power sources. As indicated on the schematic and relay house physical drawi ngs, two protect ive relay systems are used on each transmissio n line, and two trip coils are used on each circuit break er to assure tripping of faulted equipment.

The physical design of the switchyard control power supplies incorporates the following features:

a. two control power su pplies, each consisting of a battery, ba ttery charger, and distribution cabinets (one supply is located at each end of t he relay house).

b. two separate cable p an systems in the relay house.

c. two separate access ducts for cables to exit the relay house b asement (one at each end of the building).

d. two separate concret e trough systems for feeder cable distribution in the switchyard proper. As indicated in the station single l ine diagram, 6E 4001 and 20E-0-4001, o ne unit and its normal power source are connected to one 345-kV ring bus and the second unit and its normal power source are connected to another 345-kV ring bus. The normal 345-kV source to each un it supplies two system auxiliary transformers (SATs). The 4-kV winding on each SAT is the normal source to an ESF bus and also supplies some non-ESF station loads. The reserve source to any ESF bus is then suppli ed from the corresponding ESF bus of the alterna te unit.

Therefore, the norma l source to one unit becomes the reserve source to the other unit.

The analysis of the sw itchyard break er control system, power supply, and breaker arrangement indicates that there is no single event which could cause simultaneous failure

B/B-UFSAR 8.2-12 REVISION 9 - DECEMBER 2002 of both power circui ts to a unit.

However, if the initiating event is a highly improbable failure of breaker (BT 6-7) and another breaker (BT 12-13) failed to open in cleari ng the fault, the local breaker backup (LBB) protection woul d open the next breaker downstream a nd the normal an d reserve source of power would not be availa ble to the ESF buses.

The units should not tri p, however, since the equipment required to op erate the plant would be quickly transferred from the system auxiliary transformers to the unit aux iliary transformers. A manually operated disconnect switch on each side of each of these automa tically operated c ircuit breakers would facilitate quick i solation of this low probability event. This is the second of five levels of electrical po wer degradation in the Regulatory Guide 1.93 evaluation.

Technical Specification 3.8.1, therefore, requires at least one of these two sources to be reestabl ished within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

8.2.3 References

1. MAIN Guide Number 2, "Criteria for Simulation Testing of the Reliability and Adequacy of the MAIN Bulk Power Transmission System."