While some companies seem to be having trouble building new nuclear power capacity, the Tennessee Valley Authority (TVA) seems to have it down pat.
To increase nuclear power in this country, you can build a new reactor. Or you can upgrade and complete reactors that were never finished. Or you can increase the power output of existing reactors. TVA is on track for all three.
TVA submitted the first-ever permit application to the NRC for a new design small modular nuclear reactor (SMR). Their Watts Bar 2 Nuclear Generating Station, an upgraded and completed partially-constructed plant from the 1980s, became the first new nuclear power plant this century in the United States.
The third method, increasing the power output of existing reactors, called uprating, is what TVA is starting at their Browns Ferry Nuclear Plant. TVA just received approval from the Nuclear Regulatory Commission to significantly increase the generating capacity of the three nuclear reactors at Browns Ferry, located in Athens, Alabama.
Significant indeed – this uprate will add almost 500 MW of nuclear capacity. This will generate an additional 4 billion kWhs each year of exceptionally low-carbon electricity. This is more low-carbon power than 1,200 new MW wind turbines and twice as much as the biggest solar array in the world.
And for only $0.5 billion, a fraction of the price for the wind or solar path. 1,200 new MW wind turbines would cost about $2.5 billion. A 1,500 MW solar array would cost over $10 billion.
‘The real advantage of the Browns Ferry investment is that we are maximizing the capability of an existing generation asset that already produces our lowest-cost, most reliable form of carbon-free baseload power,’ TVA spokesman Jim Hopson said. ‘It's a true win-win.’
The NRC staff determined that TVA could safely increase the reactors’ output at Browns Ferry primarily by upgrading certain plant systems and components. NRC staff also reviewed TVA’s evaluations showing the plant’s design can handle the increased power level.
Utilities have used power uprates for a long time as a way to generate more electricity from their nuclear plants. So far, NRC has approved over 8,000 MW of uprates, equivalent to building eight new nuclear power plants.
To increase the power output of a reactor, a utility will refuel with either slightly more enriched uranium fuel or use a higher percentage of new fuel in the core. These produce more thermal energy and more steam, driving turbines to generate more electricity.
Components such as pipes, valves, pumps, heat exchangers, electrical transformers and generators must be able to accommodate the higher power level with its increased flows and heat.
For an extended power uprate like Browns Ferry, the NRC staff issued a draft environmental assessment for a 30-day public comment period, and considered and addressed all comments before finalizing the environmental assessment.
The NRC’s safety evaluation of the proposed uprate for Browns Ferry focused on areas such as the nuclear steam supply systems, instrumentation and control systems, and accident evaluations. NRC itself conducted independent confirmatory calculations and audits.
Claims by anti-nuclear groups that the higher core temperatures would make the plant less safe, and increase the chance for a meltdown or radiation leak, proved baseless.
This power uprate for Browns Ferry authorizes an increase of maximum power level by about 155 MW for each unit. The uprates for the three reactors will occur during their planned refueling outages over the next two years.
The uprate is just the latest move by TVA to increase its energy diversity and reliability while cutting carbon emissions. Besides the Watts Bar start-up last year, TVA started their large solar power program and have ramped up efficiency dramatically. It’s why TVA has cut carbon emissions by 30% since 2005, a reduction that should rise to 60% by 2020.
The new Watts Bar 2, like the power uprate at Browns Ferry, is quite important to grid reliability needs as well. ‘With the drought conditions we experienced in the first half of the year, which limited power production from our dams, Watts Bar Nuclear Unit 2 played an important role in keeping costs low,’ says TVA President Bill Johnson. ‘TVA’s generation fleet continues to become more diversified and this is helping us provide low-cost energy in a reliable and efficient manner.’
Although not planned, more of its nuclear fleet could be uprated in the future if additional power demands are higher than expected.
Last year, TVA generated 155 billion kWhs of electricity that sold for $10.5 billion. To produce this energy, 10,000 employees operated a mix of sources that included 37% nuclear, 24% coal, 20% natural gas, 9% hydro, 3% wind & solar and 7% energy efficiency.
It’s nice to see that being 84 years old hasn’t slowed TVA down.
