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New Lamps for Old: TerraPower Plans to Build an Advanced Reactor to Replace a Wyoming Coal Plant

Dan Yurman's picture
Editor & Publisher, NeutronBytes, a blog about nuclear energy

Publisher of NeutronBytes, a blog about nuclear energy online since 2007.  Consultant and project manager for technology innovation processes and new product / program development for commercial...

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  • Jun 4, 2021

On June 2, 2021, TerraPower, Wyoming Gov. Mark Gordon and PacifiCorp announced efforts to build and operate a Natrium reactor demonstration project at a former coal plant in Wyoming.

The companies are evaluating several potential locations in the state. A decision on a location is expected by the end of this year.

U.S. Department of Energy Secretary Jennifer Granholm, who spoke via video feed at the event, said, “We are ready to make investments in advanced nuclear technology so that communities all over the country can enjoy the benefits of safe and reliable and clean power that will leave them with lower energy bills and greater opportunities.”

The project at its core is a 345 MWe sodium-cooled fast reactor with a molten salt-based energy storage system (fact sheet). The storage technology can boost the system’s output to 500 MWe of power for more than five and a half hours when needed for times when electricity from renewables is not available.


Conceptual Image of Natrium Reactor / Molten Salt Storage System

This innovative addition allows a Natrium plant to integrate seamlessly with renewable resources and could lead to faster, more cost-effective decarbonization of electricity generation.

Chris Levesque, TerraPower president and CEO, said in the statement that Natrium “was designed to solve a challenge utilities face as they work to enhance grid reliability and stability while meeting decarbonization and emissions-reduction goals.”

Gary Hoogeveen, president and CEO of Rocky Mountain Power, a division of PacifiCorp., an electricity provider in six states in the western US, said in the statement the companies “are currently conducting joint due diligence to ensure this opportunity is cost-effective for our customers and a great fit for Wyoming.” PacifiCorp is a subsidiary of Berkshire Hathaway Energy.

Wyoming Governor Gordon said in the statement he was “thrilled to see Wyoming selected for this demonstration pilot project … and our experienced workforce is looking forward to the jobs this project will provide.”

Maria Korsnick, NEI president and CEO, said in the trade group’s statement that “TerraPower is leading the way by expanding the potential for advanced nuclear technologies in our energy transition.”

Location to Be Determined

The location of the Natrium demonstration plant is expected to be announced by the end of 2021. TerraPower and PacifiCorp said they are “conducting due diligence” in evaluating potential sites. The plant will replace a current coal-fired plant operated by PacifiCorp.

Gary Hoogeveen, of PacifiCorp, said in a media statement that the goal is to decide which of the utility’s four coal fired power plants will house the nuclear power plant: Jim Bridger near Rock Springs, Naughton in Kemmerer, Dave Johnston in Glenrock or Wyodak near Gillette.

coal power plants wyo

Map of location of coal-fired power plants in Wyoming. Map: Google Maps

Prior to the current announcement, TerraPower had said it was considering several locations including the Columbia Generating Station in Richland, WA, and at the Idaho National Laboratory in Idaho Falls, ID. The other ARDP demonstration reactor, X-Energy’s HTGR, is slated to be located at the Richland, WA, site.

Separately, TerraPower and GE-Hitachi are engaged by DOE in the development of the Versatile Test Reactor at the Idaho National Laboratory which is also based in part on the PRISM design.  Bechtel will be the EPC for the project.

The Wyoming demonstration project will be a fully functioning power plant and is intended to validate the design, construction and operational features of the Natrium technology.  Bechtel will be the Natrium plant’s design, licensing, engineering, procurement, and construction (EPC) partner.

According to Chris Levesque, president and CEO of TerraPower, siting a Natrium pilot at a former PacifiCorp coal plant in Wyoming is the right move because it would demonstrate that an advanced nuclear reactor can solve challenges “utilities face as they work to enhance grid reliability and stability while meeting decarbonization and emissions-reduction goals.”

Getting an NRC License is the First Key Step

The cost of the plant and the schedule to license and build it are still to be determined. As the reactor design, which is based on the GE Hitachi PRISM reactor, has not yet been submitted to the NRC for its safety design review, actual operation of the reactor is still years in the future although the DOE ARDP program calls for it to be operational by 2028. Other state and federal regulatory reviews are also in the pipeline.

Chris Levesque, of TerraPower, said the demonstration plant would take about seven years to build once its gets a license from the NRC.  According to the NRC website, the license application has not yet been submitted and the Natrium design is still in what is called “pre-licensing review” as of 05/21/21. Given that the NRC safety review takes about 3 1/2 years in a best case experience, the 2028 date looks to be a tough goal to meet.


TerraPower ARDP Schedule with Level 1 Milestones. Image: TerraPower

The NRC website notes the agency is currently engaged in pre-application activities interactions for the Natrium reactor. (Index of publicly accessible documents in NRC ADAMS)

The Natrium designs combines features from the previous GEH PRISM and TerraPower Traveling Wave designs. The proposed Natrium reactor is a 345 MWe pool type sodium fast reactor using HALEU metal fuel. In June 2017 a four company team organized an effort to license the PRISM reactor, but did not take the process to completion.

As far back as 2011 a collaboration of DOE national labs and university researchers determined that there were no technical show stoppers to licensing the Integral Fast Reactor which is the design legacy for the PRISM reactor and thus the current Natrium effort.

However, John Sackett, who was a manager for the IFR at the Idaho National Laboratory, said at the time, “”What we know now is that there are no technical gaps that would preclude a licensing application if using known technology. Gaps might arise if a developer chooses to use a new fuel which would need testing. That process could be completed faster if simulation and modeling tools could be brought to bear on the problem.” In this regard, Sackett’s comment turns out to be predictive with regard to the HALEU fuel that the Natrium reactor will use.

Fuel for Natrium?

While there is plenty of uranium in the ground in Wyoming to be mined to produce fuel for nuclear reactors, what Naturium needs is high assay low enriched fuel (HALEU) for which a reliable source of this product is not yet in place. In 2020 TerraPower established a partnership with Centrus to develop a commercial production plant to fabricate the HALEU fuel.

Currently, CNETRUS is working on a $115M contract with DOE to demonstrate that it can make the fuel. The project is expected to be complete next year. However, Centrus has told the nuclear industry trade press multiple times that it has doubts that demand for the HALEU will emerge at sufficient for it to make a profit.

The firm pointed out that after the completion of the DOE demonstration effort, there are no commitments from the government to purchase the fuel. Additionally. each reactor vendor will have to submit make the case for the safety of this type of fuel in their design as part of the NRC licensing4 process. It could turn out there will be more demand globally for HALEU fuel from Centrus than domestically until the Natrium reactor comes online by the end of this decade or in the early 2030s which is a more likely date.

Investors Face Uncertainties About Costs

TerraPower’s work on the Natrium design is funded in a cost sharing agreement with the U.S. Department of Energy to build it as a demonstration project. In October 2020, the U.S. Department of Energy (DOE), through its Advanced Reactor Demonstration Program (ARDP), awarded TerraPower $80 million in initial funding to demonstrate the Natrium technology. TerraPower signed the cooperative agreement with DOE in May 2021. To date, Congress has appropriated $160 million for the ARDP and DOE has committed additional funding in the coming years, subject to appropriations.

During its media event on June 2nd TerraPower did comment on whether outside investors would take equity stakes in the new reactor, to help cover the private sector cost share with DOE.  The first of a kind unit could cost between $1-2 billion. If the conventional formula of taking an estimated “overnight cost” for a reactor is used, and assuming the cost is $5,000/Kw, then the 345 MWe plant could cost $1.73 billion. A plus for the project is that the switchyard and regional grid infrastructure for the current coal fired power plant that is to be replaced is available. The actual real cost of the reactor is yet to be determined.

The Natrium system is a combination of TerraPower and GE Hitachi technologies. Along with PacifiCorp and GE Hitachi Nuclear Energy, members of the demonstration project team include engineering and construction partner Bechtel, Energy Northwest, Duke Energy and nearly a dozen additional companies, universities and national laboratory partners.

While the there are over a dozen “partners” on the project, it isn’t clear what portions of the “cost sharing” required by DOE under the ARDP umbrella would be allocated to each of them.

Economic Drivers Touted by Wyoming Supporters

According to media reports in Wyoming, the announcement comes as state leaders are trying to figure out how to deal with Wyoming’s bleak future for fossil fuels. Coal production has been on a steep slide as coal-burning power plants across the country close amid amid increased competition from natural gas and renewable energy.

The downturn in Wyoming’s energy sector, along with the COVID-19 pandemic, has prompted multiple rounds of cuts to the state’s budget and government services amid declines in revenues.

According to a news release from Wyoming Governor Mark Gordon, “The development of a nuclear energy facility will bring welcome tax revenue to Wyoming’s state budget, which has seen a significant decline in recent years.”

Governor Gordon stressed that the state’s pursuit of nuclear power does not mean that he was turning aside from fossil fuels like coal, oil and natural gas.

“I am not going to abandon any of our fossil fuel industry,” he said. “It is absolutely essential to our state.”

The Wyoming Mining Association also took a positive view on Wednesday’s announcement. Executive director, Travis Deti, said in a statement, “This is an exciting opportunity for Wyoming to open a new chapter in the nuclear power industry. Advanced nuclear generation clearly fits the bill for zero-emission, reliable and dispatchable electricity necessary to power our country into the future,”

“Wyoming is the nation’s leader in the production of domestic uranium. Our producers stand ready, willing and able to safely and responsibly provide the vital fuel for America’s next generation of nuclear power.”

Scott Melbye, president of Uranium Producers of America (UPA) and executive vice president of Uranium Energy Corp, also welcomed the announcement.

“The UPA’s member companies have the production capability to support the fuel needs of this program and hopefully many new advanced and small modular reactors to follow. Wyoming uranium providing energy jobs and clean, reliable nuclear electricity here in Wyoming has a wonderful ring to it.”

Maria Korsnick, CEO at NEI, said in a press release that considerable overlap exists between job functions at a coal power plant to a nuclear power plant. She emphasized that nuclear is uniquely positioned to redirect skilled workers from the coal power industry to new nuclear plants, while historically offering the highest median wage across the entire energy sector. Retaining these jobs support local communities that may otherwise be devastated by the shutdown of coal power stations.

Interest for new nuclear plants is growing beyond Wyoming as states in the western region like Montana, Nebraska, Utah, Idaho and North Dakota reevaluate the role of nuclear energy – particularly applications for advanced nuclear reactors that pair well with wind and solar. It also mirrors recent interest by utilities and technology developers like Tennessee Valley Authority and NuScale to explore the possibilities of a coal to nuclear transition.

U.S. Sen. John Barrasso, R-WY, who appeared with Gordon at the podium, has been a proponent of expanding the U.S. nuclear sector. Wyoming is the nation’s top producer of uranium, Barrasso said, and some of that material will now be used here.

“This is the future of nuclear energy in America compared to what we’ve been doing over the last 65 years, with the energy being clean, affordable, reliable, safe,” he said.

# # #

Matt Chester's picture
Matt Chester on Jun 4, 2021

According to media reports in Wyoming, the announcement comes as state leaders are trying to figure out how to deal with Wyoming’s bleak future for fossil fuels. Coal production has been on a steep slide as coal-burning power plants across the country close amid amid increased competition from natural gas and renewable energy.

This is a big part of it-- not just replacing coal power production, but also finding some economic benefits for a region to be hit hard by the transition away from coal. How much transferability do you think there might be from those who are/had been employed by coal to get involved in a nuclear future? 

Dan Yurman's picture
Dan Yurman on Jun 4, 2021

The positive effect on labor - skilled trades - hiring is going to be delayed by at least four years. TerraPower hasn't yet applied for the license from the NRC, and that process takes that long. The firm can't break ground in a substantial way without it. Once the license is in hand, the labor effect will grow rapidly up to several thousand on site over a 3-5 year period.

Joe Deely's picture
Joe Deely on Jun 4, 2021

Wyoming is definitely in a tough spot.  If you look at their current electricity generation - most of the generation goes to exports.

Note that while generation is over 42 TWh the in-state retail sales of electricity is only 16.8 TWh. To make matters worse more than half of this in-state electricity consumption goes to industrial uses - for example the mining of coal. 

Other states no longer want Wyoming's coal-based electricity.  If Wyoming doesn't switch to zero-carbon sources - these "customers" will build additional internal zero carbon generation or look to other states  - for example NV or NM - which are willing to build and export zero-carbon electricity. Note: this transition has already started and WY generation is down almost 10 TWh from 2014 peak.

If this nuclear plant actually gets built in WY - and I am betting that it will - it could generate about 3 TWh of zero-carbon electricity.  Wind generation is currently at 5 TWh and will easily double to 10TWh before 2030. Throw in the current 1 TWh of Hydro and maybe a couple of TWh of new solar generation and WY could meet its internal retail sales of electricity with close to 100% Zero Carbon sources.

3 Nuclear

10 Wind

1 Hydro

2 Solar


16 TWh 

Nathan Wilson's picture
Nathan Wilson on Jun 7, 2021

Wyoming is part of the windy central plains, so we know that their grid will soon have very low wholesale power prices for many hours in the year.  Other than hydro, which is typically only a small contributor, fossil gas plants work very well as part of windpower-rich grids, as they are the best choice when the remaining net demand has low capacity factor.  And Wyoming is in the US top ten states for gas productions (EIA).

Nuclear with storage is a great addition to a solar-rich grid (because of the predictable nightly solar outages), but it remains to be seen whether any new-build technology other than gas can co-exist with cheap windpower (the slower fluctuations in windpower result in fewer cycles per year, making storage less economical). 

Coal miners won't want to hear this, but I think the grids in the central plains will tend towards 50%/10%/40% for wind/solar/gas, absent strong policy support for other technologies.  It would help a lot to have a significant price on CO2 emissions; this may help Natrium in other countries, and things may change in the US over the next decade.

One factor which may help Wyoming/Natrium is that the GE Prism reactor it uses has a fast neutron spectrum.  So even though it will be initially licensed to run on HALEU, it could be converted to consume plutonium (for at least part of the core load). So there may be a business case for consuming stockpiles from dismantled weapons.  They could attract a federal used fuel reprocessing plant to their state, and effectively profit from other state's past nuclear power production, as a very long term industry.  With states like Nevada not wanting the business, the price for such a service could rise high enough to make it interesting for Wyoming.

Michael Keller's picture
Michael Keller on Jun 7, 2021

Sodium cooled fast reactors have an absolutely horrendous  commercial and operational record. The safety of the machines is highly suspect. The alleged advantage of the machines is to create more nuclear fuel than they use, but the cost to pull that off is staggering. Reprocessing facilities, costing tens-and-tens of billions of dollars are required and that opens up a whole can of worms from a nonproliferation standpoint.

Proponents of this type of reactor technology have been trying to foist this bad idea on the unsuspecting public for more than 50 years. The vision of the technology is badly decoupled from practical reality and there is no sound economic reason to build the machines.

This is just another in a long line of profoundly dumb, multi-billion of dollar wastes of taxpayer money unleashed by the DOE.

Matt Chester's picture
Matt Chester on Jun 7, 2021

Proponents of this type of reactor technology have been trying to foist this bad idea on the unsuspecting public for more than 50 years. The vision of the technology is badly decoupled from practical reality and there is no sound economic reason to build the machines.

If this is the case, why do you think it keeps popping back up as a proposal? What are the proponents missing?  

Michael Keller's picture
Michael Keller on Jun 9, 2021

Because there is a faction of largely academics (many in the DOE) who are enamored with the idea of a reactor creating more fuel than it uses. This has been the case for over 50 years and every single one of the sodium cooled fast reactors created have been technical and operational nightmares as well as utter commercial failures.

The academics in their ivory towers are oblivious to history and practical reality. Really good example of those ignoring history being doomed to repeat failure.

Nathan Wilson's picture
Nathan Wilson on Jun 9, 2021

If this is the case, then why do opponents put such enormous amounts of energy into fighting this technology, which by your arguments should die on its own?  In Japan, the Monju plant wasn't allowed to do the most trivial maintenance without being forced to shutdown for two years of paperwork and court battles.

Doesn't it seem strange to you that the proponents of this technology are top scientists and the opposition are generally non-technical people?  When has there ever been a positive outcome when amateurs tell experts how to do their jobs?

These non-proliferation arguments fundamentally ignore where nuclear weapons really come from: electricity and dirt (or water).  Our energy source choices have essentially no bearing on our ability or willingness to produce these weapons.  North Korea and Pakistan have shown how easy they are to make.  The way to control them is using treaties and inspections, not by sabotaging our clean energy transition.

No amount of activism and complaints can change the fundamental facts that of the three large inexhaustible energy sources we have available to us (solar, wind, and nuclear), nuclear has by far the lowest environmental footprint, the lowest amount of concrete and steel requirements, and the highest degree of grid friendliness/dispatchability.  Anti-nuclear activism has delayed the inevitable transition away from fossil fuel, and made it more costly.

And it has not been only 50 years: our first breeder reactor, EBR-1, first demonstrated the production of clean, inexhaustible electricity in 1951.  So given a few decades for a reasonable transition, fully the last 40 years of coal usage are completely the fault of anti-nuclear activist (as are  the millions of resulting American deaths from air pollutions).  Many of these same activists have tried to diminish the blood on their hands by insisting that renewables can support a non-fossil energy system; however we've been trying in earnest for 40 years, and still no major grid has been decarbonized as effectively using renewables as the French, Swiss, and Swedish grids were, using nuclear and big hydro.

Michael Keller's picture
Michael Keller on Jun 9, 2021

The sodium cooled fast reactors were shut down because they were horribly unreliable. Any small leak of sodium immediately starts a fire when the material is exposed to the atmosphere. Leaking fluids are really common in power plants, but the stuff instantly catching fire is not common. Spending billions of dollars on something that only works a few hours in a year is just plain dumb.

As a 50 year veteran of the power industry (both nuclear and fossil) I do not object to nuclear per se. I do object to spending stupefying amounts of money on nuclear technologies that are unsound financially and technically. History clearly shows the sodium fast reactor to be unsound. 


Nathan Wilson's picture
Nathan Wilson on Jun 11, 2021

As you know, the reports about fast reactor sodium leaks are always presented with a lot of negative spin, as you have just done.  As you've mentioned, leaks are normal in a real-world environment; people just ignore them until they become severe, then repair them.  Leaks in fast reactors are treated like world-ending catastrophes, even though they are not.

In modern pool-type reactors, all of the heat transfer fluid which leaves the reactor is non-radioactive intermediate coolant (a heat exchanger in the pool transfers heat from the radioactive coolant to the non-radioactive intermediate fluid), so small leaks are not dangerous (they burn-off benignly with limited heat production).  Also, in many of the modern designs, the fluid that carries the heat to the steam generators is actually not sodium at all, but non-flammable solar salt.

In Charles Till's book on the IFR and EBR-II, he talks about the benefits of double-walled heat exchangers and reports that "The EBR-II steam generators of this design operated without a single tube leak for their entire thirty-year life".

Perhaps you've also heard that they have ultra-sound imaging equipment that they can put into the pool to assist with remote maintenance (in place of optical cameras)?

It is normal for new technologies to start life with poor reliability and improve over time.  (I work in computer software, where we take this principle for granted, and build it into the schedules). 

I should also say that I am a fan of aerospace and space exploration.  In those fields, on one hand, we see "stupefying" amounts of money being spent by government contractors when the government is the only customer, but then on the other hand when we see commercial markets develop, the costs plummet and the industry is able to deliver useful products and services to the public at a reasonable price.

Why would you presume that fast reactor technology was the only tech in the world that could not be improved and come down in cost?

Michael Keller's picture
Michael Keller on Jun 11, 2021

Those who do not learn from history are doomed to repeat it. Tens of billions spent, and not a single successful commercial plant. The technology is inherently too difficult to deploy, particularly in a nuclear reactor setting, and of highly doubtful need as running out of uranium will not be much of a problem for some time. Basically, the fast reactor is a technical and economic dead end and of suspect safety.

Mark Silverstone's picture
Mark Silverstone on Jun 12, 2021

For all I know, this might be a great project with a great future.

However, you managed to talk about this project at some length without mentioning the principals: Mr. Gates and Mr. Buffett, together worth well over $200 billion. So, the "$1-2 billion" cost should be pocket change for them.  But no!  They want to build a nuclear reactor and taxpayers are giving them $80 million to help do it. 

Why is that? Seems like madness.

Dan Yurman's picture
Dan Yurman on Jun 14, 2021

The $80M initially granted to TerraPower is part of cost share program where the company must match the government money dollar for dollar.  That's prudence not madness.

Michael Keller's picture
Michael Keller on Jun 15, 2021

I am in agreement with Mark. Buffet and Gates could easily fund the effort from their petty cash. Instead, they want to mooch off of the taxpayer.

The actual cost share can vary, but the minimum is 20% from the company and 80% from the taxpayer. 

Dan Yurman's picture
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