LWR SMRs have fuel advantages
Fast reactor designs face export controls and the need to develop new fuel types which may slow time to market
This article is based on a presentation given by Andrea Jennetta, Publisher, Fuel Cycle Week, at a conference held in July in Washington, DC, on commercializing small modular reactors.
Research for and preparation of the slides was a joint effort by myself, as a reporter for Fuel Cycle Week, and Ms. Jennetta who delivered the full presentation and responded to the Q&A from the audience. The article below is a short version.
Developers of small modular reactors (SMRs) fall in two camps as far as reactor designs and fuel types are concerned. The first are developers of downsized versions of light water reactors (LWRs). The second are developing a variety of fast reactors. It is in the second area where the greatest number of challenges occur as far as fuel is concerned and also for the back end.
Regardless of the design SMR developer is working, eventually, all the fuel will wind up in the same place until U.S. waste management policies attain some level of coherence and common sense. For now that “place” is at the reactor in wet and dry storage.
Developing the fuel for the LWRs will be straightforward and at least two of the vendors, B&W and Westinghouse, already have the capability to make their own. Developing fuel for the fast reactors will be more complicated including the potential for extended testing and qualification of fuel types to meet licensing requirements.
U.S. nonproliferation rules may make life difficult for SMRs that are fast reactors. Because fast reactor fuels tend to have higher levels of enrichment, from 9-19% U235, getting export licenses for them may be a bureaucratic nightmare.
It’s more likely that fast reactor vendors will license their technologies to wholly owned subsidiaries in the countries that want to buy them and fabricate the fuel there. The parent firms, and their investors, will still face delays due to export controls on the technologies, but at least they won’t be hamstrung by having to physically move fuel.
Business as usual for LWRs
The four leading developers of LWR type SMRs in the U.S. are working with similar fuel types and will use similar management practices for the back end of the fuel cycle. The firms and the power ratings (electrical) are;
· Babcock& Wilcox: 180 MW
· Holtec: 140 MW
· NuScale: 45 MW
· Westinghouse: 225 MW
The fuels for these reactors will be remarkably similar. They will be 5% or less U235 enrichment with 24-to-48 month fuel cycles. All of the fuel assemblies will be smaller than those used in larger LWRs and cores will range from 68-89 assemblies. Overall, there will be less fuel in the core and less demand per reactor for uranium for their fuel.
In terms of spent fuel storage, operators of these reactors will store it in pools and eventually dry casks under Part 72. Holtec casks are currently deployed at many reactor sites in the U.S. B&W will probably design and certify their own casks. Permanent disposal depends on resolution of complex political issues.
All four LWR developers are building the first-of-a-kind (FOAK) units inside the emergency planning zone (EPZ) of existing facilities. No SMR developer will need to worry about the challenges of having a customer try to build one at a greenfield site. The NRC’s policy issue about the size of the EPZ and SMRs is punted into the future at least for the FOAK units.
· B&W at Clinch River (TVA)
· Holtech at Savannah River (DOE)
· NuScale at Savannah River (DOE)
· Westinghouse at Callaway (Ameren)
Fast reactors – interesting and complicated
Unlike LWR designs, the developers of fast reactors as SMRs are unlikely to have times to market in the U.S. by the end of this decade. There are a lot of reasons, but one of the most important is that they do not use conventional LWR fuel.
Except for the Gen4Energy design, they all use spent fuel. Except for the GE PRISM design, once the fuel goes in it stays in the reactor for its complete operational life which, in some cases, can be 40-60 years. Vendors include;
· General Atomics – EM2
· GE Hitachi – PRISM
· Gen4Energy – Gen4 Module
· TerraPower – Traveling Wave Reactor
Without going through the technical details of each reactor, there are some conclusions that we can draw about all of them. Most importantly, it will take longer to license them in the U.S. Indeed, TerraPower has said it has no plans to pursue licensing in this country. Another reason is there is even more uncertainty about how to decommission one of these units and dispose of its spent fuel.
A huge problem for all of the fast reactors will be fuel qualification and testing. Because of the higher enrichment levels, it is unlike any of the units sold for export will have their fuel fabricated in the U.S. This is due to the endless multi-agency bureaucratic snarls that would be encountered by vendors seeking export licenses.
Supply chains and skilled labor to build fast reactors will also involve localization and technology licensing. Either way, a buyer will have to understand the complexity of the technology they are getting and how to manage it.
For this reason, fast reactor SMRs are not good candidates for developing nations with limited pools of manufacturers who can meet nuclear quality requirements and have the required skilled labor. This reality is a challenge to marketing claims about fast reactor SMRs that are said to be designed for “off-the-grid” applications.
The exception might be U.S. military bases overseas, but there would also be diplomatic issues associated with bringing a nuclear reactor to a U.S. defense mission on foreign soil. Tactical readiness in the U.S. might be enhanced with either an LWR or fast SMR and represents a real opportunity since the Pentagon can bypass the NRC in terms of licensing process time.
In summary, LWR SMRs have the best chances in terms of time to market to book sales with U.S. customers. Fast reactors are likely to be built overseas, but only for large nations with deep pockets, strong manufacturing bases, and the engineering and skilled trades to build them.
Post Script – What about thorium reactors?
Digging deeper into that question, you come up with the issue of competitive advantage. What is in it for a customer to go down the path of an entirely different fuel type?
Consider the fact that it would need a completely new fuel cycle, with billions spent on facilities to make the fuel that would be needed to run a fleet of thorium fueled reactors. No one is going to build just one. Then there is the question of whether a utility could have any certainty that it could operate them at a profit.
For now the risks and the unknowns are too great for any commercial utility to get involved with anything other than uranium fuel.
Any company or country developing a thorium fueled reactor has to address the issues of cost competitiveness as a very high priority. Advocates of thorium reactors have for the most part talked about technology differentiation and also nonproliferation advantages.
Unless commercial utilities see a compelling business case for them, e.g. lower total cost of operations v. $6/Mbtu natural gas, there are likely to be few takers in next few years.
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