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Made Like New TVA’s Watts Bar Unit 2 is on track to be the first new nuclear generation in the United States in the 21st Century. SAFE
The work to complete the unit is building on proven technology, using established engineering and design standards, and taking advantage of the extensive operating and construction experience available in TVA and the nuclear industry. TVA’s work will provide a two-unit nuclear power plant with • consistent licensing and design bases for both units; • construction and operational similarities between the units with minimal, known differences that are addressed through comprehensive training; and • a second unit that is made like new through a comprehensive refurbishment effort that rebuilds or replaces systems, structures, and components using modern materials and current technology. The skilled workers performing the work rigorously adhere to – and deliver – high standards of safety and quality. And systems are being completed, tested, and made operationally ready according to a logical schedule that supports key milestones that must be achieved to be ready to load fuel in the reactor and eventually reach commercial operation. Ultimately, the safe and quality completion of Watts Bar Unit 2 – and its successful transition into TVA’s operating nuclear fleet – will provide an additional 1,150 megawatts of safe, clean, and reliable energy to fuel jobs, businesses, and homes across the region.
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WAT T S B A R U N I T 2
Containment Systems, structures, and components associated with nuclear safety and reactor cooling have been rebuilt, refurbished, or replaced.
New reactor coolant pumps
Rebuilt reactor coolant pump motors
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New safety injection system vent valves will reduce radiation dose to employees performing routine jobs while the unit is online.
New wiring on pressurizer heater
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WAT T S B A R U N I T 2
Auxiliary Building Systems, structures, and components associated with nuclear safety and reactor cooling have been rebuilt, refurbished, or replaced. Refurbished and rebuilt residual heat removal system pumps
Replaced residual heat removal system heat exchanger
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Refurbished safety injection system pumps
New primary water pumps and motors
Replaced switches on chemistry sample valve junction box
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WAT T S B A R U N I T 2
Digital Upgrades Many instruments and controls that monitor operation of key components of the secondary plant have been replaced and upgraded with digital controls for greater reliability and enhanced monitoring capability.
New digital, dual channel voltage regulator for main generator and exciter
WAT T S B A R U N I T 2
New digital supervisory instrumentation for main turbine
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New local instrument control panel for generator stator cooling hydrogen
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WAT T S B A R U N I T 2
Control Building Panels, Boards, and Auxiliary Controls Electrical systems connecting the main control room and the plant equipment have been upgraded and refurbished with digital components and new cabinets.
Relay panel for common station service transformer
6.9 kV shutdown boards for supplying electrical power to safety-related equipment
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Relay panel for the 500 kV switchyard – supporting reliable generation and grid reliability
Auxiliary control room remote shutdown panel controls have been replaced or reconditioned.
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WAT T S B A R U N I T 2
Local Controls in the Turbine Building Controls for non-nuclear equipment have been upgraded and refurbished to better ensure reliable power generation. New hydrogen gas dryer in the generator cooling system
Panel for component controls in the Turbine Building heater drains and vents system
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Instrument control panel for components in the raw cooling water system
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Local Controls in the Turbine Building
Turbine Building motor operated valve motor control center
The condenser circulating water motor control center (MCC) breakers were replaced. The MCC controls the system’s refurbished motors and pumps. Unit identification was maintained by painting common controls white and Unit 2 controls blue.
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WAT T S B A R U N I T 2
Main Control Room Unit 2 main control room recorders and indicators were replaced and switches reconditioned while minimizing differences between the units. New, digital instrumentation and reorganized control panels provide operators more information and improved ease of operation.
New control panels for steam generator indicator/recorder and upgraded digital instrumentation for common qualified post accident sampling (Common Q) for monitoring reactor water level
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Digital control system display
New Westinghouse in-core information surveillance and engineering (WINCISE) system
Unit 2 main control room upgrades required more than 15 miles of electrical wiring.
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Secondary Systems Supporting Steam Supply and Power Conversion Pumps, motors, controls, and other components of non-nuclear systems in the Turbine Building that work together to safely and reliably generate electricity have been made like new with the same diligence that has been given to nuclear cooling and safety-related systems.
The condenser circulating water system uses four large refurbished pumps driven by these refurbished electric motors to circulate water from the cooling towers to the condensers and back. Each pump is capable of circulating 100,000 gallons of water per minute.
Replaced original moisture separator reheater high pressure by-pass valves with more reliable, larger valves
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WAT T S B A R U N I T 2
Secondary Systems Supporting Steam Supply and Power Conversion The standby main feedwater pump in the feedwater system was refurbished offsite by vendor and reinstalled.
New, corrosion-resistant feedwater piping
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Level control isolation valve refurbished – removed original packing containing asbestos, disassembled, refurbished, reassembled, and tested
New stator coolant heat exchangers in the generator cooling system
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WAT T S B A R U N I T 2
Moisture Separator/Reheaters Moisture separator/reheaters (MSRs) ensure the humidity and temperature of the steam going into the turbine meet design criteria. The Unit 2 MSRs are an upgraded design to support the new main turbine. The original Unit 2 MSRs have been removed, refurbished, and used on Unit 1.
Installation of a new moisture separator/reheater
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Enhanced covers over outdoor control valves help minimize heatrelated failures.
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WAT T S B A R U N I T 2
Main Turbine and Generator The Unit 2 turbine has been upgraded to improve efficiency and power output. The newer design offers increased margin in operating parameters for Watts Bar operators.
Reconditioned main generator
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New low pressure turbine rotors
Main turbine oil tank – cleaned and coated inside and out
The electric hydraulic control fluid tank in the turbine/ generator control system was refurbished by the vendor.
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WAT T S B A R U N I T 2
Transformer Yard Upgrades and Painting Inspected, upgraded, and refurbished the two station service transformers, three main bank transformers, and associated electrical buses and ducts
Bus ducts and bus duct cooling cabinets
Painted bus ducts from the Turbine Building
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Station service transformer instrumentation was refurbished.
Station service transformer 2A
Painting a main transformer
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WAT T S B A R U N I T 2
Fukushima Response Modifications The FLEX concept for Fukushima modifications provides additional response capability – such as portable generators, water pumps, hoses, and batteries – to add layers of defense against unlikely events that are considered outside the scope of what a plant should be designed or regulated to withstand.
The new FLEX Equipment Storage Building is built to withstand tornadoes, floods, and earthquakes. It contains portable pumps, generators, valves, pipes, and other emergency response equipment.
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Portable water pumps ensure flexible options for cooling
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WAT T S B A R U N I T 2
Fukushima Modifications Fukushima modifications include FLEX equipment such as additional pumps, generators, batteries, and other equipment located in diverse locations throughout the plant site.
Specially built tornado and seismically protected enclosures on top of the Auxiliary Building house auxiliary generators.
One of four new diesel-powered auxiliary generators
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Breaker/switch panel connects auxiliary generators to battery chargers.
A new, seismically protected 500,000 gallon auxiliary feedwater supply tank provides additional water for the auxiliary feedwater system.
Lifting an auxiliary generator
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Fukushima Modifications New pipes, valves, and instruments have been installed that connect FLEX equipment to existing systems to provide additional cooling water, electrical power, information, and controls.
Nitrogen bottle storage station Example of a new tap
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Auxiliary feedwater supply tank feeds to auxiliary feedwater supply
New instrumentation monitors spent fuel pool water level and temperature.
Essential raw cooling water system
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Watts Bar Unit 2 Guiding Principles • Ensure the public’s health and safety • Protect the safe operation of Watts Bar Unit 1 • Maintain a consistent, predictable, and transparent process for completing and licensing Watts Bar Unit 2 • Establish design basis fidelity with Watts Bar Unit 1 • Make systems, structures, and components like new
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www.tva.com/wattsbar2 SAFE
CLEAN
PROGRESS
14-337 10/14