Watts Bar Unit 2 Starts Up

Watts Bar Nuclear Plant, courtesy TVA

Watts Bar Nuclear Plant, courtesy TVA

On May 26, 2016 at precisely 2:16 a.m., what will probably be the final large unit in the Tennessee Valley Authority (TVA) nuclear fleet – Watts Bar Nuclear Plant, Unit 2 – achieved its initial criticality.  This event opens the final chapter of the extended construction history of this unit, and paves way for another gigawatt of generating capacity (in nameplate rating) to be added to TVA’s generating portfolio.

Much news has been made of the protracted construction process of this plant, which was ordered in August of 1970.  Due to the fact that the predicted increase in demand for power did not occur, TVA decided to slow down the progress of the plant during construction. While a number of plants were cancelled, Watts Bar continued along in construction at a pedestrian speed.  Unit 1 was not placed into operation until 1996, and Unit 2 was essentially mothballed.

Not until April 2012 did TVA decide to complete Unit 2.  From there, work proceeded at a deliberate pace, and was prioritized over the incomplete Bellefonte Nuclear Plant (which is now cancelled).  By December 2015 the reactor was ready to receive fuel for the first time, setting the stage for this month’s notable achievement – the first criticality.  (This simply means that the reactor was made to sustain a nuclear chain reaction.)

Much other work has gone on at the site as well — Watts Bar was the first US nuclear plant to complete the mandated post-Fukushima modifications (the “FLEX” program) and pass NRC inspection.

With the initial startup of Unit 2, a (so far) 46 year history of the Watts Bar site will finally culminate into a two-unit plant, as originally intended.  TVA takes justifiable pride in describing Unit 2 as “the nation’s first new nuclear unit in the 21st century,” and historically this marks the last incomplete nuclear unit in the United States left from the “First Nuclear Era” which has any chance of being completed.  A chapter in history has closed, and another has opened!

  • For a history of TVA’s nuclear program at ANS Nuclear Cafe, click here.
  • For a history of the Watts Bar Unit 2 project since 2012, click here.
  • For the announcement of initial criticality at Watts Bar Unit 2, click here.


Will DavisWill Davis is Communications Director and board member for the N/S Savannah Association, Inc. He is a consultant to the Global America Business Institute, a contributing author for Fuel Cycle Week, and he writes his own popular blog Atomic Power Review. Davis is also a consultant and writer for the American Nuclear Society, and serves on the ANS Communications Committee and will serve on the Book Publishing Committee beginning in June. He is a former US Navy reactor operator and served on SSBN-641, USS Simon Bolivar.

7 thoughts on “Watts Bar Unit 2 Starts Up

  1. Pau Sabaté

    Watching the “Current Status Report” on the NRC website, I can observe that Watts Bar 2 power rages smoothly from 46 to 47 % during all these weeks.
    a) Does this mean that you are making electrons to the line but not officially producing electricity?
    b) Does this mean that you are still in the Power Ascension testings, as it is said on TVA Timeline? https://www.tva.gov/Newsroom/Watts-Bar-2-Project/Timeline

    I would be glad to know that the unit is at full power, but I also know that you are coming up with the issues of starting a new unit.


  2. James Greenidge

    Re: “…But using NuScale reactors placed inside cities to provide both electric power and low-grade heat would decarbonize a much larger fraction of US energy much faster than large PWRs can.”

    The unchallenged New York media helped frighten the public and city council enough to help boot a tiny research reactor out of Columbia U, and the same happened to Brookhaven near here too. I’d eat my hat if any U.S. city allowed any NPP even near their borders in the next five lifetimes.

    James Greenidge
    Queens NY

  3. Ike Bottema

    OK thanks. Yes I was asking as to when 100% might be achieved. The NCR reports don’t extend into the future i.e. they don’t show any planned or forecasted dates of any sort.

  4. EntrepreNuke

    Will, a few correction items: The Watts Bar Unit 2 completion project began in October 2007, basically right after Browns Ferry Unit 1 was re-started. The board decision to complete Unit 2 was made in August 2007 (https://www.tva.gov/file_source/TVA/Site%20Content/News/wb2/wb2_11th-q_summary.pdf).
    When the project was started, the estimate to completion was “only” $2.5 billion. April 2012 was when the range of the total estimate was raised to $4.0 to 4.5 billion, and authorization was grated for that. In later 2015 (if I remember correctly), authorization was granted for the total cost to be up to $4.7 billion.

    Ike, depends on what you mean by “full production”. The first electrons sent to the grid should be this weekend and first time to 100% reactor power should be in the near future (can check that on the NRC Power Reactor Status report here), but there is still testing to be completed prior to the plant operating at 100% for a steady period of time and then being officially certified as having entered “commercial operation”.

  5. Ike Bottema

    Any idea when Watts Bar 2 will be going into full production? The date I have (prolly based on a schedule set a few years ago) is for the end of September this year.

  6. Engineer-Poet

    I wouldn’t mind seeing Watts Bar #2 and the Vogtle and Summer units as the last GW-scale reactors built in the USA, ever.

    NuScale appears to have the potential to build nuclear out on a schedule closer to wind farms (2 years); perhaps mPower does too, if it’s ever pushed.  There are other reactor technologies which also lend themselves to small size and assembly-line construction in central factories, though they are much further from commercial use.  But using NuScale reactors placed inside cities to provide both electric power and low-grade heat would decarbonize a much larger fraction of US energy much faster than large PWRs can.

    A facility built for a NuScale would be much bigger than a LMFBR or molten-salt reactor would require, but it could probably be retrofitted for the new technology when it became available.  Voila, a 100-year solution.

  7. James D. Freels

    Isn’t your date incorrect ? Today is 5/25/2016. I think the initial criticality was 5/23/2016.

Leave a Reply

Your email address will not be published.

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>