The technological breakthrough developed by KTH in cooperation with the Swedish steel industry is a new aluminum and zirconium alloyed steel (Fe-10Cr-4Al-Zr) that provides adequate long-term performance in hot lead. After 19,000 hours of exposure at 550 C, the material appears to be in like new condition. By limiting operating temperature to 450 C the designers are confident that SEALERs using the new alloy will be able to operate reliably for as long as 30 years. That confidence, of course, will be something that LeadCold will have to demonstrate to the satisfaction of the regulatory agency. On photo Lead corrosion laboratory: >19000 hour exposure of Fe-10Cr-4Al-Zr alloys at 550°C completed. Optimised alloys in perfect condition after exposure.
LeadCold and Essel Group ME have announced an agreement for a $200 million (USD) investment to build uranium-fueled power sources. Their systems, trademarked SEALER, are designed to compete with diesel generators to supply dependable power to communities and industries in remote areas of the world. SEALER (Swedish Advanced Lead Reactor) is a fast spectrum nuclear reactor that uses low enriched uranium oxide fuel (19.5%) cooled by molten lead. The companies involved describe their agreement as enabling “…LeadCold to license and construct the first privately-funded lead-cooled nuclear power plant.”
Who Are These New Players In The North American Advanced Nuclear Industry?
LeadCold is a Swedish-Canadian company spun out of the Royal Institute of Technology (KTH) in Stockholm. VINNOVA (The Swedish Innovation Agency) has been supporting applied science, materials research and systems engineering at KTH for lead-cooled systems since 1996. That long-term effort resulted in a materials breakthrough that now supports a commercial product development effort. Lead has been an intriguing nuclear plant coolant option since the beginning of the Atomic Age, but it has a few characteristics that have – up to now – limited its utility. Essel Group ME is a wholly owned subsidiary of Essel Group, a 90-year old multinational conglomerate headquartered in India with a wide array of subsidiary companies that operate in high technology, infrastructure, logistics, media and packaging. Essel Group ME focuses its investments in subsidiaries companies in natural resources, education, logistics and industrial supply in the Middle East, Europe and Africa. Their business focus gives them ample opportunities to experience both the importance of reliable power and the logistical challenge of supplying it to remote areas of the world. They know that electricity often costs ten times as much in a mining outpost in northern Canada or central Africa than it does even in high-cost grid-connected areas.
LeadCold is following a well-established path for introducing new technology and then refining that technology to lower unit costs and expand the customer base. After the technology has been refined enough so that the developers feel confident in moving it out of the laboratory, the next step is finding an early adopter market.
Early adopters are customers that need – or want – a new technology so much that they are willing to pay dearly for the special capabilities that new product brings them. They are not penny pitchers who experience remorse if a better and cheaper version becomes available in a few years because they have been addressing whatever problem they have during that time period.
Canada is shaping up to be a popular early adopter target for small nuclear power systems because they have both a capable regulator and communities or mining operations that need a new power option. The target areas have two options for electricity – high priced diesel generators burning fuel with an expensive logistics challenge or doing without power.
Solar systems are laughably inadequate in areas that often don’t see the sun for months at a time. Wind turbines don’t function with bitterly cold winds. Natural gas pipelines are nonexistent and coal has all kind of issues that has always limited its use in Arctic regions. Even long transmission lines are not an option because of cost, environmental impacts and weather vulnerability.
The Canadian Nuclear Safety Commission has a reputation as a capable regulator with many decades of experience in safe nuclear plant design review and operations oversight. It also has a process that is amenable to technologies that use nontraditional fuels and coolants.
Sweden, the original home of LeadCold, has similar remote areas and a capable regulator, but it is currently lead by a government that doesn’t support nuclear energy development.
As Senator Murkowski made clear during Governor Perry’s confirmation hearing to become the new Secretary of Energy, Alaska has communities with similar power needs. Unfortunately, the U.S. NRC has not yet implemented an acceptable process for reviewing nuclear reactor designs that use coolants other than water.
What Is A Sealer?
SEALER (Swedish Advanced Lead Reactor) is a fast spectrum nuclear reactor that uses low enriched uranium nitride fuel (19.5%) cooled by molten lead. The core of the reactor is the smallest possible physical size that will support critical operations under coolant, enrichment and neutron spectrum conditions.
The lead circulates through the system at atmospheric pressure by thermal convection, using no pumps in the primary system. The secondary system, where water is pumped into the steam generators to be converted into high-pressure steam by removing heat from the lead, relies on electricity-driven pumps.
If there is a loss of electrical power that stops the flow of water into the steam generators, the primary lead-cooled system will gradually heat up, but it will not exceed any thermal limits on the reactor fuel or cladding for several weeks.
If restoration of cooling is delayed past that coping time, designers claim that the lead will retain 99.9% of any fission products that are released from the fuel rods.
The system design criteria is that fission product retention must be sufficient so that there is no need to consider evacuation as a means of protecting people. The places where SEALERs will operate are remote; large-scale evacuation is virtually impossible.
Each identical unit will be capable of producing between 3 and 10 MW of electricity. At lower power, the fuel lasts longer. The planned core lifetime is from 10 to 30 years. At the end of life, the entire unit will be replaced with the old system being transported to a centralized recycling plant.
When a SEALER has reached the end of its operating life, the reactor is shut down and the lead solidifies. It provides most of the shielding required to protect people during transportation.
Why Lead? Why Now?
Lead has long been an option for cooling nuclear reactors and transferring fission heat into water that can then boil to make steam for driving a turbine. Like sodium, lead does not slow neutrons down. Fast spectrum reactors enable eventual fission of all uranium isotopes through the process of converting U-238 to Pu-239. The breeding ratio for a SEALER will be significantly greater than one, essentially removing all concerns about fuel resources for a few thousand years.
Compared to sodium, lead has somewhat higher heat capacity and isn’t capable of explosive reactions with air or water.
Two main drawbacks have limited its use. 1) Its melting point is substantially higher than sodium. 2) Nickel, a common alloying material in steel, is soluble in hot lead, leading to serious material concerns in a relatively short period of time.
The technological breakthrough developed by KTH in cooperation with the Swedish steel industry is a new aluminum and zirconium alloyed steel (Fe-10Cr-4Al-Zr) that provides adequate long-term performance in hot lead. After 19,000 hours of exposure at 550 C, the material appears to be in like new condition.
By limiting operating temperature to 450 C the designers are confident that SEALERs using the new alloy will be able to operate reliably for as long as 30 years. That confidence, of course, will be something that LeadCold will have to demonstrate to the satisfaction of the regulatory agency.
LeadCold expects that each SEALER will cost $75 million USD for the early adopters