Small modular reactor
Small reactors were first designed mostly for military purposes in the 1950s to power ballistic missile submarines and ships (aircraft carriers and ice breakers) with nuclear propulsion.
[4][5] Working with Oregon State University (OSU), NuScale Power developed the first Nuclear Regulatory Commission approved model for the US market in 2022.
[10] NuScale Power partnered with OSU to become the first to apply this manufacturing strategy starting in 2006[11][12] Proponents claim that SMRs would be less expensive due to the application of standardized modules that could be industrially produced off-site in a dedicated factory.
[17] In its pathway to reach global net zero emissions by 2050, the International Energy Agency (IEA) considers that worldwide nuclear power should be multiplied by two between 2020 and 2050.
[2][20] Several fleets of SMRs of exactly the same type, industrially manufactured in large numbers, should be rapidly deployed worldwide to significantly reduce emissions of CO2.
Helium is often elected as a gas coolant for SMRs because it yields a high plant thermal efficiency and supplies a sufficient amount of reactor heat.
There was a large focus on sodium during early work on large-rated reactors which has since carried over to SMRs to be a prominent choice as a liquid metal coolant.
[33] SMRs have lower cooling water requirements, which expands the number of sites where a SMR could be built, including remote areas typically incorporating mining and desalination.
Reactor designs using liquid metal coolants (molten sodium, lead, lead-bismuth eutectic, LBE) also become radioactive and contains activated impurities.
If higher concentrations of fissile materials subsist in the spent fuel, the critical mass needed to sustain a nuclear chain reaction is also lower.
Given the potential technical and economical importance of SMRs to supply zero-carbon electrical energy needed to fight climate change and the long-term and social relevance of the study to adequately manage and dispose of radioactive waste without imposing a negative burden onto the future generations, the publication of Krall et al. (2022) in the prestigious PNAS journal has attracted many reactions ranging from criticisms on the quality of their data and hypotheses[50] to international debates on radioactive waste produced by SMRs and their decommissioning.
[51] In an interview with François Diaz-Maurin, the associate editor of the Bulletin of the Atomic Scientists, Lindsay Krall, the lead author of the study and a former MacArthur postdoctoral fellow at Stanford's Center for International Security and Cooperation (CISAC) answered to questions and criticisms, amongst others, those raised by the NuScale reactor company.
As previously stressed by Krall and Macfarlane (2018),[53] some types of SMR spent fuels, or coolants, (highly reactive and corrosive uranium fluoride (UF4) from molten salt reactors, or pyrophoric sodium from liquid metal cooled fast breeders) cannot be directly disposed of in a deep geologic repository because of their chemical reactivity in the underground environment (deep clay formations, crystalline rocks, or rock salt).
[54] A report by the German Federal Office for the Safety of Nuclear Waste Management (BASE) found that extensive interim storage and fuel transports are still required for SMRs.
Once the fuel has been irradiated, the mixture of fission products and fissile materials is highly radioactive and requires special handling, preventing casual theft.
In the United States and IAEA adhering countries, the licensing is based on a rigorous, independent analysis and reviewing work of all structures, systems and components critical for the nuclear safety under normal and accidental conditions on the whole service life of the installation including the long-term management of radioactive waste.
Some adaptations of the original licensing process by the US's Nuclear Regulatory Commission (NRC) have been repurposed to better correspond to the specific characteristics and needs of the deployment of SMR units.
[71][72][73] While deploying identical systems built in manufacturing plants with an improved quality control can be considered an advantage, SMRs remain nuclear reactors with a very high energy density and their smaller size is not per se an intrinsic guarantee for a better safety.
[74] In July 2024, the ADVANCE Act directed the United States Nuclear Regulatory Commission to develop a process to license and regulate microreactor designs.
Additionally, this flexibility in a standardized SMRs design revolving around modularity could allow for a faster production at a decreasing cost following the completion of the first reactor on site.
This includes "desalination, industrial processes, hydrogen production, shale oil recovery, and district heating", uses for which the present conventional larger reactors are not designed.
[86] GE Hitachi Nuclear Energy Executive Vice President Jon Ball agreed, saying the modular elements of SMRs would also help reduce costs associated with extended construction times.
[86] In October 2023, an academic paper published in Energy collated the basic economic data of 19 more developed SMR designs, and modeled their costs in a consistent manner.
[77] Before its cancellation, the project received a $1.355 billion cost-share award toward construction costs from the US government in 2020[88] plus an estimated $30/MWh generation subsidy from the Inflation Reduction Act of 2022.
SMRs are expected to require less land, e.g., the 470 MWe 3-loop Rolls-Royce SMR reactor should take 40,000 m2 (430,000 sq ft), 10% of that needed for a traditional plant.
[147] This unit is too large to meet the International Atomic Energy Agency's definition of a SMR being smaller than 300MWe[148] and will require more on-site construction, which calls into question the claimed benefits of SMRs.
[170] In February 2022, NuScale Power and the large mining conglomerate KGHM Polska Miedź announced signing of contract to construct a first operational reactor in Poland by 2029.
The power plant is expected to generate 462 MWe, securing the consumption of about 46.000 households and would help to avoid the release of 4 million tons of CO2 per year.
[181] The US Department of Energy had estimated the first SMR in the United States would be completed by NuScale Power around 2030,[182] but this deal has since fallen through after the customers backed out due to rising costs.
[77] NuScale said in January 2023 the target price for power from the plant was $89 per megawatt hour, up 53% from the previous estimate of $58 per MWh, raising concerns about customers' willingness to pay.
