Microreactors show promise, but there are hurdles to clear

Replacing expensive, polluting generators with very small nuclear reactors could have a significant impact on off-grid, isolated industries and communities, but the path to commercial use is not as straightforward as the hype suggests.

A cross section of the USNC-Power Micro Modular Reactor™ (MMR™) unit. (Source: Global First Power)

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Microreactors, or very Small Modular Reactors (vSMRs), refer to any small nuclear reactor that can be delivered in one, or more, pieces, can operate away from the usual transmission infrastructure, and has a generating capacity that can be measured in tens of, rather than hundreds of, megawatts.

Many developers are promising the equivalent of a large battery for your energy needs; a factory-ready, inherently safe and transportable power source that can be plugged in at an off-grid site to deliver uninterrupted energy for decades before refueling.

The technology could potentially solve the power needs of millions of isolated industries and communities around the world, but there’s still some way to go before they can be widely adopted.

High cost of production and scarcity of the necessary fuel, strict regulation for a relatively new technology, unresolved transportation logistics, cybersecurity and public acceptance of a small nuclear reactor in your backyard are all hurdles the industry must clear, say developers and researcher in the field.

Many believe, however, that once the new generators are successfully demonstrated to work as advertised, they will be impressive enough to spawn a whole new industry of nuclear reactors.

“There are some open questions still and some of those questions are best answered by doing a demonstration project. These designs are, in many cases, leveraging existing knowledge and experience from other test reactors, or a version of these reactors that have been built all over the world,” says Ali Siddiqui, Head of Directorate for Advanced Reactors at the Canadian National Laboratory (CNL).

“Part of it is a technical question, part of it is a practical logistics question of how you build these and deploy them, and the other is regulatory and social acceptance. And, in fact, all of those can be addressed by a deployment project.”

Estimated Program Activities by Year for the U.S. Microreactor Program 

(Source: Idaho National Laboratory "A Microreactor Program Plan for the Department of Energy; An Integrated, Strategic Progam Plan for Research and Development supporting Demonstration and Deployment of Nuclear Microreactors.")  

Proof in the building

In Canada, where distant oilsands, isolated mines and far-flung indigenous communities currently rely on diesel to fuel the local generator, a reliable, clean power source during the long, harsh winters could make all the difference.

In a study conducted by CNL, Ontario Power Generation (OPG), and Mining Innovation, Rehabilitation, and Applied Research Corporation (MIRARCO), it was found very small modular reactors could reduce or even completely eliminate the need for diesel in mines in the country’s far north.

The feasibility study found that the most economical energy mix was for vSMRs to provide 90% of baseload power required for mining operations and associated uses, with diesel only being applied during peak demand, reducing emissions by 85%.

A 5-MW electricity (15-MW thermal) reactor, the Micro Modular Reactor (MMR), presented in a joint venture (Global First Power) between the Ultra Safe Nuclear Corp.’s (USNC’s) subsidiary USNC Power and OPG, was the first SMR to enter into a formal licensing review with the Canadian Nuclear Safety Commission (CNSC) in May.

A full-scale version of the reactor will be built and run at the CNL-operated Chalk River site in Ontario and is expected to produce its first power by 2026.

The MMR consists of two parts; a reactor core contained in a reactor vessel and connected to an intermediate heat exchanger, which transfers heat from the helium coolant to a molten salt loop and; the adjacent power plant, which transfers heat from the molten salt loop to a steam loop for direct use as process heat or for electrical conversion.

“We want to demonstrate that the plant can be built and licensed and, in seeing it be built, we hope to generate some social acceptance. Then government, stakeholders, communities, and private sector companies can come and kick the tires and see that this thing can operate safely and economically,” says Siddiqui.

Getting it right

The technology for the MMR is proven, says Robby Sohi, President and CEO of Global First Power (GFP), though work still needs to be done on sowing social acceptance for the reactor in the regions they hope to operate.

“There are two things that if we don’t get right, it won’t happen. First, if you don’t have a good positive relationship with the Indigenous communities, there's no point in building a commercial demonstrator because you’re not going to be deploying anything. And, secondly, is the cost,” Sohi says.  

GFP’s goal is around CAN$270-320/MWh ($218-$259) which, says Sohi, when the high cost of diesel, including shipping, and implied cost of carbon emissions are considered, is competitive with current remote community power costs.

The right fuel will also be key and CNL’s announcement in April that it successfully fabricated Fully Ceramic Microencapsulated (FCM) fuel pellets, designed by USNC for use in the MMR, is a major step for GFP.  

“We’re trying hard to make sure, if nothing else, we establish the supply chain for fuel. The fuel is where it’s at. You can put out as many reactors as you want, but it doesn’t matter; you have to get fuel from somewhere,” says Sohi.

The FCM pellets are the first time Tristructural-Isotropic (TRISO) based fuel has been manufactured in Canada and, with each poppy-seed-sized particle having a dense fuel kernel coated with layers of graphite and silicon carbide making them able to withstand intense heat and pressure, the pellets have been proposed for more than one small and advanced reactor designs in the works.  

CNL’s production of the fuel pellets could mean the country will soon start exporting FCMs to other operators much in the same way it has successfully exported its own reactor technology, the Canada Deuterium Uranium or CANDU.

“What we did with CANDU, we’re about to do the same thing for TRISO-based fuel,” says Sohi.

By Paul Day