|Fig. 1: The Watts Bar nuclear plant. (Source: Wikimedia Commons)|
The Watts Bar Nuclear Plant (see Fig. 1) is a Tennessee Valley Authority (TVA) nuclear power plant located near Spring City, Tennessee, between the cities of Chattanooga and Knoxville. Watts Bar is comprised of two nuclear reactors, designated as Unit 1 and Unit 2. The plant is significant, due to the fact that Unit 2 of the plant is the first and only reactor to come online in the United States during the 21st century, illustrating Americas shift away from adding nuclear power to its electric grid.  Though there are a number of reasons for this trend, the cost of construction associated with building a nuclear power plant is one of them, and the Watts Bar Nuclear Plant serves as an example of how expensive building and bringing a nuclear plant online can be. Though construction of the Watts Bar Nuclear Plant began in 1973, Unit 2 was not operational until 2016, and the total cost of construction exceeded $12 billion.
The Watts Bar Nuclear Plant underwent a long and arduous path to completion. Construction of both Unit 1 and Unit 2 of the plant began in 1973 but was halted by TVA in 1988 due to safety concerns over the utilitys entire nuclear program. Construction of Unit 1 was completed in 1996 and the plant came online in that same year.  Unit 1 of the Watts Bar Nuclear Plant acts as the last nuclear reactor to come online in the United States during the 20th century.  Having been listed as under construction for 43 years, Unit 2 holds the world record for longest gestation for a nuclear power plant.  Nearly 42 years after initial construction began, construction on Unit 2 wrapped up in 2015 and the plant went online for the first time in October 2016, making Unit 2 the first and only new reactor to go online in the United States during the 21st century. This accomplishment was somewhat short-lived, as just over 5-months later, the plant went offline to undergo repairs to address a failed support beam on one of the plants condensers.  Unit 2 resumed generation in August of 2017. 
Both Unit 1 and Unit 2 of the plant are Westinghouse-manufactured pressurized water reactors (PWR) that have the ability to generate about 1,150 MW of electric power. The process of generating electricity at the Watts Bar plant begins with fission, or the splitting of uranium atoms, in the reactor core. Fission in the reactor produces heat, which is used to heat water in a pressurized water reactor. From there, the hot water is piped from the reactor vessel to a steam generator, where the energy from the heated water is transferred to boil water and make steam in a second system.  After transferring its energy, the water is pumped back to the reactor vessel to be reused. Meanwhile, the steam from the steam generator spins turbines that drive the generator of the plant to produce electricity. Once used in the turbine, the steam is then drawn into a condenser, converted back into water, and is pumped back into the steam generator where it is reused.  Together these two reactors provide carbon-free electric power for 1.3 million homes in the seven-state service territory of the Tennessee Valley Authority. 
As of now it seems that Unit 2 of Watts Bar may be the last nuclear reactor to come online in the United States, as the recent trend in the United States has been to shut off nuclear power plants, rather than bring them online. For example, in California, Pacific Gas and Electric has scheduled the shutdown of the two reactors at the Diablo Valley Canyon power plant by 2025, which would mark the end of nuclear power in the state. The trend away from nuclear energy is alarming as nuclear power acts as a reliable source of consistent carbon free baseload power. Unfortunately, instead of acting as stimulus for further nuclear projects, the completion of the Watts Bar Nuclear Plant acts as cautionary tale and a deterrent against further development. The sheer cost and extended time it took to bring the plant online makes it unlikely that developers will look to follow suit in the future. That being said, the completion of the plant and the consistent generation it now provides has prompted TVA to consider shutting down two of the utilitys coal plants, the Bull Run Fossil Plant of Oak Ridge, Tennessee and the Paradise Coal Plant of Kentucky.  Doing so would further reduce the carbon footprint of TVA and demonstrate that nuclear power can act as a reliable replace to greenhouse gas emitting energy sources.
© Spencer Rogers. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
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