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General Atomics launches bid for DOE small modular reactor program with EM2

General Atomics (GA) is developing a small modular reactor (SMR) and has recently submitted a proposal to the DOE SMR initiative to help bring the reactor to market. The EM2 is a modified version of General Atomics’ high-temperature, helium-cooled reactor and is capable of converting used nuclear fuel into electricity and industrial process heat, without conventional reprocessing. Each module would produce about 240 MWe of power at 850 °C.

The core of the EM2. Click to enlarge.

The initial “starter” section of the core provides the neutrons required to convert used nuclear fuel or depleted uranium (DU) into burnable fissile fuel. First generation EM2 uranium starters (~12% U235) initiate the conversion process. The starter U235 is consumed as the used nuclear fuel/DU is converted to fissile fuel. The core life expectancy is ~30 years (using used nuclear fuel and DU) without refueling.

Substantial amounts of valuable fissile material remain in the core. This material is reused as the starter for a second generation of EM2s, without conventional reprocessing. There is no separation of individual heavy metals required and no enrichment needed. Only unusable fission products would be removed and stored. This means that all EM2 heavy metal discharges could be recycled into new EM2 reactors, effectively closing the nuclear fuel cycle and thus reducing the need for long-term repositories and minimizing proliferation risks.

The current amount of used nuclear fuel waste in storage at US nuclear plants is sufficient for 3,000 EM2 modules. The amount of available DU material in storage is sufficient for 30,000 modules. In an EM2 fuel cycle, this material can satisfy US energy demands for centuries, GA says. 400 modules could satisfy approximately 100% of the current US electricity output of nuclear reactors. Current used nuclear fuel could be removed from utility sites and be processed into EM2s.

Features include:

  • 30 years without refueling versus 18 months for current light water reactors;

  • Burns depleted uranium, spent fuel, plutonium and thorium;

  • No water for cooling, allowing much greater siting flexibility;

  • A design that achieves both increased efficiency and small size—the basic reactor reduces electricity costs by 40% relative to current reactors and produces 80% less waste; and

  • Improved safety with a gas-cooled design, utilizing GA’s innovative high-performance silicon carbide cladding that resists melting at high temperatures.

EM2 incorporates a truck-transportable high-speed gas turbine generator, an innovation that avoids the huge size and complexity of steam-generated power plants. This means lower up front capital costs for utilities, as well as lower electricity costs for consumers. EM2 will also provide three times the energy per pound of fuel compared to current technology and reduce waste by 80% utilizing just a single pass through fuel cycle, GA says.

The San Diego-based firm is working with CB&I, a global leader in energy infrastructure whose nuclear capabilities include serving as the lead construction firm for all new US reactors currently under construction. Mitsubishi Heavy Industries brings professional service to the team, with extensive experience in the nuclear industry including involvement in the construction of Japanese advanced reactors. Idaho National Laboratory offers capabilities to test the new EM2 fuel system.



A very nice design.
On the website it also shows that it can burn thorium, which is around 3 times as abundant as uranium, so it seems the lights can be kept on for a fair while!
In Europe if the German's were not insane it would be easy to plumb this into district heating systems using the waste heat, so overall efficiency would be perhaps 2-3 times present LWR reactors.


The efficiency is given here as 53%:

Of course that does not include use of the process heat.


Since the US does not have Europe's extensive district heating systems, and with the lower urban density is not likely to, the most useful thing to do with the process heat would appear to be to produce hydrogen.

At least for longer distance car travel that would appear to have the edge to power fuel cells over battery charging since it would use otherwise wasted energy.


For starters put one of these on every military installation in the country.


How about SMR-powered desalination with desal plants scattered around US coasts & arterial network of pipelines going inland? I would rather see federal government funds spent on that than rail projects.


How about a description of their technology?  The presentation on the website doesn't even come up to the level of 6th-grade science.

If that's all they will share with the public, the public should put its money on a real technology company like Babcock & Wilcox.


I'd also like to see more details on the design. What happens in the event of a loss-of-coolant incident? Flood the core with boric acid and/or water? FWIW, this particular type of reactor has to run at very high pressures which is a force for failure (alternately, one could argue that corrosion is a force for failure in MSRs).

FWIW, I'm a much bigger fan of the Hydrogen Moderated Reactor:

It's self-regulating. Could be helium cooled as well (not entirely sure why that wasn't proposed in the original patent).


Just realized the above described reactor design was licensed by Hyperion. Cool :D


I agree with E-P, they've come up short on the details while promising the moon.

Now personally I like the idea of small modular reactors. It will allow each community to choose nuclear power for their own use while rightsizing their demand to the supply they can afford instead of forcing them to buy nuclear power from a large reactor as part of a package deal from a utility that just wants to drive up demand to increase their profits. And it will lead to a decentralized grid.


I thought parts at least of this design had been tested in their GT-MHR design:

Nick Lyons

An interesting entry into the SMR sweepstakes. This is a breeder design (eek, plutonium!), with lots of less-proven technology (silicon carbide fuel cladding, gas turbine generator, etc, etc.). Looks great on paper, but there appears to be a lot of development risk. I will be surprised if the DOE chooses this entry for the next award. NuScale's more developed, low-risk design seems like a likelier winner.

I wish them luck. Anything that consumes SNF and uses up stockpiled transuranics would be a good thing.


I hope that they get to build it. It is efficient, does not require a lot cooling water, gets rid of waste, etc. We could even recycle those eyesore wind turbines into something useful:) It does create plutonium but it immediately burns it. That is where the energy comes from so you are not generating an excess of plutonium and if you use LWR waste you are actually getting rid of plutonium. Also, you could burn some of the existing weapon grade plutonium to get rid of it. there are only 2 ways to get rid of plutonium -- fast or slow and I would prefer the slow option.

Nick Lyons

@sd: I am all in favor of breeding/burning Pu--my 'eek!' was only to mimic the hysterical response any breeder design can expect from certain anti-nuclear folks.

Michael Keller

Might be interested in another SMR approach that uses a gas reactor somewhat similar to General Atomics GT-MHR and was submitted to the DOE. See for technical details. The hybrid design merges nuclear and fossil fuels and has an output of over 900 megawatts; basically a combined-cycle natural gas plant with the combustion turbine's decoupled air compressor driven by a helium turbo-compressor. Economies of scale, the low-cost nuclear fuel and the low-cost of the combined-cycle plant work together to produce a very competitive new approach to nuclear energy.

The hybrid might actually turn out to be a bridge to the EM2 which has some technical hurdles to overcome and the fact that no fast breeder has ever been licensed in the US.


I hate to be a wet blanket (okay, I lied, I really don't mind) but the Hybrid Power scheme is the worst of both worlds:

  1. It's nuclear, which attracts the reflexive opposition of both the anti-nukes and the gas industry.
  2. It cannot operate without gas, giving it a minimum level of carbon emissions that is still far too high.
If you really want a hybrid system with a helium-cooled high-temperature reactor with provision for peaking power, you'd probably be best off using nuclear heat to pre-heat a large thermal mass which can pre-heat the air for a gas-turbine peaking plant.  Most of the time, you'd operate carbon-free.

Kit P

“A very nice design. ”

More of a concept than a design.

“so overall efficiency would be perhaps 2-3 times present LWR reactors.”

So what? This is a concept that is hard for some to understand. A large coal plant need a 100 rail cars of coal per day. A 20% improvement is or 20 rail cars a day is a big deal.

A couple of truck loads loads of fuel assemblies in packing crates every year or so is hard to reduce. Consequently the amount of waste is small.

“What happens in the event of a loss-of-coolant incident? ”

Pretty much the same thing as at a coal plant. The value of the asset is lost and the cost of clean up.

The reason to develop high temperature process reactors is high temperature 'industrial process heat'.

“desalination ”

This is done with extraction steam off the turbines. A perfect application of for LWR.

“increase their profits ”

The power industry is a public service regulated. Again ai vin if you want to question the ethics of those in public service maybe you should let us know what you do besides imitate parasitical pond scum.

“you could burn some of the existing weapon grade plutonium to get rid of it ”

The US is building a facility to make MOX fuel for existing LWR. About 20,000 nuke weapons using U-235 have been destroyed in US LWR. I personally worked on those projects doing integrated safety analysis.

“Economies of scale ”

That is why we are building 1500 MWe LWRs.


Major news.


More discussion, information and links here:

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