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Woes hit the nuclear industry too, what are the different advanced nuclear technologies and their outlook?

Nov 15, 2023

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Fine Tubes manufactures precision, heat resistant tubes for critical nuclear fuel cans — Metek

With inflation and higher interest rates most notably impacting the wind industry in recent months, nuclear has not come out unscathed itself. NuScale, a startup out of Oregon State University/Idaho National Laboratory whose initial research was funded primarily by the DOE before later received private funding and eventually going public via SPAC in 2021 has just hit a snafu. The company had an agreement to contract multiple small module reactors (SMRs) in Utah which fell through last week (along with hopes of a nuclear renaissance according to some analysts).

I’m no stranger to writing about nuclear which is often in a positive light, but this is objectively a blow for the introduction of new and advanced nuclear power in the US. Higher material costs, new supply chains effected by shifting geopolitical environments, and more expensive capital markets via higher interest rates dictated by central banks are all reasons why new technologies are struggling to takeoff. Is advanced nuclear doomed like its traditional predecessor and merely a pipe dream with a new label? What other reactor designs are there and what does this mean for advanced nuclear in the US moving forward?

Current Technology

70% of current nuclear reactors are pressurized light water reactors (PWR/LWR). The rest is primarily boiling water reactors (BWR) and pressurized heavy water reactors(PHWR). Its not vital to know the intricacies of each, but generally water is used to cool the nuclear fission reaction occurring in the reactor. The water (steam) is then used to power a turbine to create electricity.

One of the downsides of this design is the cooling at high pressure must be monitored well and there have been issues in the past which have caused severe hesitation with the public. There has not been a major meltdown since 2011 and the industry has some of the best safety track records of any energy production in the long run though. Further, a stable water source is vital to supply cooling to the reactor. In times of draught, nuclear reactors may not be able to run at maximum capacity if they rely on river water for cooling. Finally, large reactors are often specialized designs and have tremendous up front cost. Specialized designs, permitting, and regulations have driven up costs and delay a PWR in the US compared to China where they are made cheaper and on schedule.

Advanced Nuclear

SMRs are a class of reactors most easily described as a smaller version of the PWR we are used to. Sometimes all of the advanced reactors below ~300MW are considered SMRs, so be mindful there is a distinction depending on the source. While they pack less energy in each module, they allow for cost savings through standardization of components and manufacturing. This allows for economies of scale to offer cost savings as companies grow compared to traditional nuclear. For context, the traditional PWR today is ~1000MW whereas the NuScale SMR is 77MW. NuScale was the furthest along on their demonstration project of any advanced design, which is why it poses questions about the future of the space. Westinghouse, Holtec, and GE Hitachi also have SMR designs and are seeking the US as a potential market.

Liquid metal fast reactors (LMFRs) use a metal like sodium or lead as the coolant instead of water. Using different materials as the coolant gives its own advantages and disadvantages in terms of technology and supply chain for example. There are two medium sized LMFRs currently operational in Russia. Terra Power which features Bill Gates as a noteworthy investor, has purchased land in WY for demonstration of its Natrium reactor which uses sodium metal as the coolant and is expected to run in 2030. This reactor requires high assay low enriched uranium (HALEU) which is a more enriched form of uranium. They also claim their 345MW reactor can ramp up to 500MW and adjust to grid loads better than traditional nuclear plants.

Molten salt reactors (MSRs) are another design using HALEU. The main difference here is again the cooling agent is a salt instead of water or metal. Like LMFRs, MSRs don’t require high pressure and the expenses that come along with it. The ability to run at higher temperature and low cooling pressure (not limited by the boiling point of water) allows for better safety, efficiency, and the ability to produce hydrogen/heat/electricity depending on the application. The molten salts used can be highly corrosive which means that there needs to be special alloyed steel or additives to overcome this challenge. Terra Power, Kairos, and Terrestrial Energy are working on molten salt designs in the US.

High-temperature gas cooled reactors (HTGRs) are again differentiated by their coolant and use HALEU. As you probably guessed, a gas which is most commonly helium is used instead of water, metal, or salt as the coolant. China currently operates two HTGRs and Japan one. These designs also allow for the high temperature operation and the expanded applications offered by it. X-energy, BWX Technologies, General Atomics, and Ultra Safe Nuclear Corporation have HTGR designs and are located in the US.

To find an in depth report on advanced nuclear in the US including the companies and designs, see the congressional research service report here.

Thorium reactors change the fission source from uranium to thorium, but require advanced designs to be feasible. In the 1960s, Oak Ridge National Laboratory successfully developed a thorium molten salt reactor that ran for 4 years. In the 70s the US government decided not to continue thorium research in favor of the more efficient and commercially desirable uranium. There are some benefits of thorium including greater natural abundance, inability to generate weapons(unless your the gov and this may be a con), ability to harvest existing weapons into thorium fuel, no enrichment needed, less waste, and safer mining.

Challenges and opportunities

Most of these advanced designs have significantly better inherent safety properties, meaning it in theory would be easier to get public sentiment and regulators over this hurdle. Another fundamental advantage that many advanced designs are considered “fast reactors” and can recycle traditional nuclear waste and have greater fuel usage.

Many reactors under development are so-called 'fast' reactors, where the neutrons from the nuclear chain reaction are not slowed down, unlike in conventional reactors where the reaction is moderated by water and/or graphite. Fast reactors represent a technological step forward and will be capable of recycling nuclear wastes from current nuclear reactors, and radically increasing the amount of energy we can get from nuclear fuel – from approximately 5% today to 90%+. Source: World Nuclear Association

Currently, HALEU comes from down-blending existing high enriched uranium stockpiles and imports from Russia which have become problematic. This is clearly unsustainable and the US DOE, Infrastructure Bill, and Inflation Reduction Act provide funding to developing a domestic HALEU supply. While HALEU may be a challenge in terms of supply chain development, it offers unique advantages like longer times between refueling the reactor.

There are plenty of utilities looking to adopt advanced nuclear when the time is right including Duke Energy and the Tennessee Valley Authority. The Utah utility which just blocked NuScale did not rule out other locations for their SMRs. Other companies are still moving forward and getting attention around the US and world. The NuScale news is not cause to panic over the fate of nuclear, albeit a headwind.

The timeline for advanced nuclear is longer which is one reason the current energy transition favors wind and solar since these technologies are easily digestible by regulators and can be deployed very quickly. Especially if you think climate change is an immediate emergency, advanced nuclear may not be ready to save the day in such a short timeframe. It is going to take years before these companies build their demonstration projects, get the relevant data, convince regulators to accept their license, and get to higher production capabilities.

There’s a lot of work going on outside the US as well, enough that I couldn’t expand the scope of this piece to touch on each respective technologies around the world. All in all, advanced nuclear is one of the most promising long term solutions to reduce emissions and provide cheap commercial energy. It happens to fall just outside the timeline that is so eagerly pursued by policymakers seeking to abate climate change and currently suffers from some of the same economic challenges as other industries. With time, we will see demonstration projects success/failure to determine which designs will be most favorable and how important advanced nuclear will be in the future. While I have no direct experience in this field, my intuition is that advanced nuclear will be very important in the long run for commercial energy generation. Until next week,

-Grayson

*smh = shaking my head for all the boomers out there…

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