Browns Ferry Nuclear Pla Nuclear Power Plant Orientation Introduction to BWR Systems
Jan 03, 2016
Browns Ferry Nuclear Plant
Nuclear Power Plant Orientation
Introduction to BWR Systems
TVAN Technical TrainingHealth Physics (RADCON) Initial Training Program
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Introduction
• During this phase of the training we will discuss the basic operation of a Boiling Water Reactor (BWR) Plant, including:– the major design concepts of the Browns Ferry
BWR-4 and its Mark I containment
– the importance of nuclear safety.
• We will also discuss several of the systems associated with BFN’s operation.
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Enabling Objectives
Identify the major components and flowpaths in the steam cycle.
Recognize the functions of water in a BWRRecognize the functions of the control rods in a
BWR
Recognize the capability and purpose of nuclear
instrumentation
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Enabling Objectives
Identify alternate sources of emergency cooling
water to the reactor vessel
Relate major concepts employed in containment
design
Identify inherent safety features of a BWR
Compare advantages and disadvantages of a
BWR to that of a PWR
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$
Tennessee River
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BWR Design
• Selected by GE due to its inherent advantages in control and design simplicity.
• Single loop system; steam and associated secondary systems are radioactive.
• Operating pressure is approximately half that of a PWR at 1,000 psi.
• Capacity of units two and three is ~1,100 Mwe each.
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BWR Internal Flow
• Feedwater enters downcomer.
• Recirculation loops provide forced circulation.
• Moisture removed by separators and dryers.
• Steam exits steam dome.
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BWR Internal Flow
Core
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Recirculation System Flow Path
Recirc Pump Suction
Recirc Pump Motor
Ring Header
Risers
Jet Pump
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Steam Dryer installed in Reactor Pressure Vessel
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Steam Dryer stored in Equipment Pit
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Fuel Transfer Canal
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Plant Layout
• The entire Reactor Coolant System (RCS) and other primary support systems are located within containment (the drywell) and reactor buildings.
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Main Steam, Condensate and Feedwater (all radioactive) are housed within the turbine building.
The reactor is operated remotely from the control building.
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Main Steam System• Steam generated by the reactor is admitted to four main
steam lines.• One high pressure and three low pressure turbines
convert thermody- namic energy into mechanical energy to drive the main generator.
• Safety objective is to prevent overpressurization of the nuclear system.
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Main Steam System Flow Path
To HP and LP Turbines
RPV
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Condensate and Feedwater Systems
• Once the steam has passed through the high and low pressure turbines, it must be condensed and then pumped back to the reactor so that the cycle can be repeated.
• These systems will collect, pre-heat, and purify feedwater prior to its return to the reactor plant.
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Makeup FromCST
RejectControl
To 9 Cond.Demins
MakeupControl
To29A & B
Reject toCST
To SealInjectionPumps
Condensate System Flow Path
A
B C
LP FW Heaters
B
C
A
A B C
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Feedwater System Flow Path
Reactor Feed Pumps
HP FW Heaters
Primary Containment
Reactor PressureVessel
RPV
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Fuel Cell
• Currently, Framatome is
the supplier of fuel for
BFN.
• Four fuel bundles per
cell.
• 764 bundles per
reactor.
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Fuel Cell
Control Rod Blade
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Control Rods
• Rods contain boron as the neutron absorber.
• Tubes held in cruciform array by a stainless steel sheath.
• 185 control rods per reactor.
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Control Rod Blade
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Control Rod Blades
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Nuclear Instrumentation
• Source range - 0.1 to 106 cps
• Intermediate range - 104 cps to 40% power .
• Power range - 1 to 125% power.
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Three ranges of neutron monitoring; all in-core.
Nuclear Instrumentation
IN-CORE HOUSING GUIDE TUBE
CORE SUPPORT
REACTOR SUPPORT STRUCTURE
LENGTH OFACTIVE FUEL
DETECTOR CHAMBERSBOTTOM OF TOP GUIDE
REACTOR VESSEL
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EMERGENCY CORE COOLINGSYSTEMS (ECCS)
• Prevent fuel cladding fragmentation for any failure including a design basis accident.
• Independent, automatically actuated cooling systems.
• Function with or without off-site power.• Protection provided for extended time
periods.TP-26
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EMERGENCY CORE COOLINGSYSTEMS (ECCS)
• High Pressure Coolant Injection (HPCI)
• Low Pressure Coolant Injection (LPCI)
• Core Spray
• Automatic Depressurization System
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CondensateStorage Tanks
~2,000,000 gal
Torus~950,000 gal
Reactor
Tennessee River
Normal SystemsCONDENSATEFEEDWATERCONTROL ROD DRIVE
Emergency SystemsHIGH PRESSURE COOLANT INJECTIONCORE SPRAYLOW PRESSURE COOLANT INJECTION
RHR SVC WATERFIRE PROTECTION
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Emergency Core Cooling Water Sources
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Primary and Secondary Containment
• Primary Containment consists of the Drywell and Suppression Pool (Torus).
• Secondary Containment consists of the Reactor Building.
• Designed to contain the energy and prevent significant fission product release in the event of a loss of coolant accident.
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TVAN Technical TrainingHealth Physics (RADCON) Initial Training Program
HPT001.014DRev. 0Page 30 of 34Containment Design
• Structural Strength - steel structure with reinforced concrete able to withstand internal pressure.
• Pressure Suppression - large pool of water in position to condense steam released from LOCA.
• Designed to contain the energy and prevent significant fission product release in the event of a loss of coolant accident.
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Primary and SecondaryContainment
Drywell
Torus31
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HPT001.014DRev. 0Page 32 of 34Advantages of BWRs
• Single loop eliminates steam generator
• Bottom entry control rods reduce refueling outage time/cost; also provide adequate shutdown margin during refueling.
• Lower operating pressure lowers cost to obtain safety margin against piping rupture.
• Design simplifies accident response.
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TVAN Technical TrainingHealth Physics (RADCON) Initial Training Program
HPT001.014DRev. 0Page 33 of 34Disadvantages of BWRs
• More radiation/contamination areas; increased cost associated with radwaste.
• Piping susceptible to intergranular stress corrosion cracking (IGSCC).
• Off-gas issues (e.g. - H2 gas presents
explosion potential, low levels of radioactive noble gases are continuously released).
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TVAN Technical TrainingHealth Physics (RADCON) Initial Training Program
HPT001.014DRev. 0Page 34 of 34Summary
• A Boiling Water Reactor plant is comprised of many different and complex systems, all of which support the overall goal of safely producing electricity.
• The design challenge of a BWR is to incorporate all the criteria of power generation and safety in non-conflicting ways in order to meet the load demand of the public and satisfy the requirements set forth by
the Nuclear Regulatory Commission (NRC).
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