Pioneering advanced fission technology

Lead-cooled Generation IV SMRs

SMRs are a
required part of the
net zero transition

SMRs produce clean and reliable energy. Their smaller size and output makes them suitable for serial, standardized production, and enables more predictable production and factory based quality controls. By targeting hard-to-abate sectors beyond electricity, such as industrial process of heat, hydrogen production, and water desalination, they help decarbonize the industrial value chain.

Blykalla is building a first of a kind lead-cooled SMR concept, using a combination of proven technology and proprietary materials. By developing a patented, aluminum alloyed steel exhibiting perfect corrosion resistance, we solved the number one challenge with using lead as a coolant in nuclear reactors.

Liquid lead

Liquid lead has historically been used in SMRs onboard submarines. The main inhibitor to more long-term use of liquid lead is that it may corrode and erode stainless steel structures. However, Blykalla has developed a patented, aluminum alloyed steel exhibiting perfect corrosion resistance. This will be used to protect the SMR’s fuel capsules against corrosion.

Lead as a coolant has a number of intrinsic advantages: it is radiation shielding, and cools the system while simultaneously ensuring that radioactive elements are retained. It has a boiling temperature of 1700°C, which enables a low pressure system and makes it possible to achieve passive safety in its most compact form.


The Swedish Advanced Lead Reactor (SEALER) is a passively safe reactor designed for commercial power production in a highly compact format. Its fuel is never replaced during operation, which minimizes costs related to fuel management. The integrity of steel surfaces exposed to liquid lead is ensured by use of alumina forming alloys.

Passive safety is ensured by removal of decay heat from the core by natural convection of the lead coolant. In the event of a core disruptive accident, volatile fission products are retained in the lead coolant and no evacuation of persons residing at the site boundary would be required.

Commercialization is centered around three proprietary assets

Three different corrosion tolerant steels

The main inhibitor to long-term use of liquid lead in SMRs is that it can corrode and erode stainless steel structures. Historically, lead-cooled reactors have been used for a short amount of time before they have had to be retired due to corrosion.

Blykalla has solved this problem by developing steel alloys that protect the core components from corrosion. Hence, our key innovations are three aluminium alloyed steels: a aluminium oxide forming steel for protecting cladding tubes, an austenitic steel for protecting reactor vessels, and a martensitic steel suited for lead pump impellers. The new steels exhibits perfect corrosion resistance during exposure to lead, and thereby enables the long-term use of lead as a coolant.

A compact reactor design

The SEALER only takes up 5x5 meters. It has an output of 55MW and fuel residence time of 25 years. It has no overpressure system (1 atm), no exothermic reaction with structural materials nor water, and passive decay heat is removed by natural convection.

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.

Blykalla’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 heat needs to be removed to ensure the integrity of the fuel cladding tubes.

Long-life uranium nitride fuel

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 better safety margins (operating at > 1,500°C below its melting point), with seven times higher thermal conductivity in the fuel.

While this fuel is difficult to manufacture using conventional methods, Blykalla 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.

We are building our first project in Oskarshamn

Together with Uniper, OKG, and the Swedish Energy Agency, we are constructing an electric research reactor in Oskarshamn. Uniper is one of the world’s largest power producers and currently operates roughly 22.5 GW of generation capacity in Europe, making them the ideal partner. Together, Blykalla and Uniper have received a grant of 99 MSEK from the Swedish Energy Agency and will initiate construction during 2024. The project is also carried out in close collaboration with The Royal Institute of Technology in Stockholm.

From research to commercialization

Blykalla is the result of 25 years of research on reactor physics and material sciences. After groundbreaking research findings, Janne Wallenius, widely recognized as one of the world’s leading reactor physicists, Jesper Ejenstam, and Peter Szakalos, an expert in surface and corrosion science, co-founded Blykalla to take their product to market. The last couple of years have marked the shift from research to commercialization. Now, Blykalla is working toward criticality by 2029.