Small Modular Reactors are a required part of the net zero transition
The world is electrifying rapidly and global electricity generation is expected to grow by 65% in the next 30 years, to more than 40 000 TWh. Yet in Sweden alone, the expected electricity usage far surpasses the expected electricity production, pointing to an electricity investment gap of more than 200 TWh in 2050. There is an urgent need to invest in more electricity capacity than current annual production.
Leadcold has developed a technology to use lead as coolant liquid. Using lead makes it possible to achieve passive safety in its most compact form – LeadCold’s reactors will be 5 meters high compared to water-cooled SMRs that are typically 20 meters high. This positions LeadCold for serial factory production of reactors. In addition to the compact size, using lead has important benefits in terms of safety and system simplifications.
Liquid lead has historically been used in SMRs on military submarines. The main inhibitor to more long-term use of liquid lead is that it may corrode and erode stainless steel structures. However, Leadcold has developed a patented, aluminum alloyed steel exhibiting perfect corrosion resistance. This will be used to protect the SMR’s fuel cladding tubes, steam generator tubes and internal surfaces of the reactor vessel against corrosion.
Our vision - safe, scalable & carbon-free baseload power
Leadcold (Blykalla) was founded in 2013 by Janne Wallenius, Peter Szakalos and Jesper Ejenstam as a spin-off from the Royal Institute of Technology in Stockholm, where Janne Wallenius carried out research on design and safety analysis on lead-cooled reactor systems since 1996.
The research brought together insights from fast reactor design, transient analysis, corrosion and materials science, nuclear fuel development, lead coolant chemistry, radiation damage, severe accident analysis, nuclear construction and operation of nuclear power plants to create a unique reactor design to provide safe, green baseload energy that is perfect to complement solar and wind energy.
Historical concerns with nuclear are addressed
Leadcold’s reactors are passively safe, which means that no supply of electricity, other means of power nor human action is required for emergency cooling of residual heat. Moreover, the lower power of SMRs as compared to larger reactors, means that less residual neat needs to be removed to ensure the integrity of the fuel cladding tubes.
SMRs are smaller in size, making them more suitable for standardized and serial production, enabling more predictable production and factory based quality controls. “As a result, construction costs are reduced by up to 60% and construction time by roughly 70% compared to that of traditional generation III nuclear power plants. This brings down financing costs and improves overall project affordability.
SMRs are suitable for remote and flexible deployment. Unlike traditional generation III nuclear power, the deployment of SMRs is not dependent on close proximity to large water areas for cooling, nor connectivity to the electricity grid. Furthermore, reactor modules may be added or removed over time to better match demand.
There are numerous advantages with using liquid lead as the choice of coolant in an SMR. For example:
- No overpressure system (1 atm)
- No exothermic reaction with structural materials nor water
- Very high boiling temperature: No loss of coolant
- Passive decay heat removal by natural convection
- Retention of volatile fission products: source term limited to noble gases
- Gamma shield: simplifies core melt management
- Passive safety can be achieved in most compact form (approved patent)
- Can be configured to run on recycled fuel
The main inhibitor to long-term use of liquid lead in SMRs is that it can corrode and erode stainless steel structures. Leadcold has developed numerous solutions to this problem: aluminium oxide forming steels
- Fe-10Cr-4Al-RE (RE = Zr, Ti, Nb) for protecting cladding tubes
- Austenitic steel for protecting reactor vessels
- Martensitic steel suited for lead pump impellers
As noted by Mark Zimny, MSc., P.Eng. CEO, Promation Nuclear Ltd: “The SEALER nuclear design is well suited to become a future leader in large-scale factory production with the use of automation and robotics. The competitive advantage stems from the reactor’s overall compactness and forecasted production volumes, which results in components that are of a size that are more optimally conducive to scalability and repeatability in production. Furthermore, design for manufacturability and automation have been elements of consideration from the onset of the SEALER design development and continue to be considered in resulting iterations.”
Fuels that have a higher uranium density can be used longer than the standard UO2 fuel. Uranium nitride features 40% more uranium per volume unit, which equals a 40% longer life for the fuel. This also leads to seven times higher thermal conductivity in the fuel, which provides better safety margins.
While this fuel is difficult to manufacture using conventional methods, Leadcold has developed a solution that enables the direct conversion of enriched UF6 in streaming NH3. Using “Spark Plasma Sintering” – current (1000 A) assisted hot pressing – pellets can be sintered in just 3 minutes at 1450°C. In comparison, this takes 8 h at 1900°C using conventional methods.
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