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LeadCold is a company developing lead-cooled small nuclear reactor technology founded in 2013 by Janne Wallenius, Jesper Ejenstam and Peter Szakalos.

LeadCold Reactors is a lead-cooled small nuclear reactor technology company. To overcome issues that have previously hindered the commercial implementation of lead-cooled reactors LeadCold have developed novel aluminum steel alloys that are highly corrosion-resistant in contact with liquid lead.

Lead-cooled reactors offer fuel cycle and safety advantages, including:

  • No violent exothermic reaction with water
  • A very high boiling temperature, reducing the risk for loss of coolant
  • Excellent potential for decay heat removal by natural convection
  • Chemical retention of iodine and cesium, should a fuel failure occur
  • Inherent shielding of gamma radiation from fission products

SEALER (Swedish Advanced Lead Reactor) the company’s lead-cooled reactor can generate 3-10 MWe over a 10-30 year period without refueling. It is designed to operate at a much lower power density which allows a lower temperature reducing corrosion rates and extending the lifetime of the fuel.

LeadCold's SEALER reactors are being developed for use in Canada's Arctic regions. These areas are not connected to the countries power grid and diesel fuel can only be shipped during the summer months. Small nuclear reactors for power production address the need for less costly, reliable and sustainable power in these off-grid communities.

LeadCold is also developing its technology for the United Kingdom and the Swedish nuclear market.


LeadCold Reactors (Blykalla Reaktorer) was founded in 2013 by Janne Wallenius, Peter Szakalos and Jesper Ejenstam as a joint-stock company, with its headquarters in Stockholm. Its Canadian subsidiary is registered in Alberta, the Northwest Territories, and Nunavut. The company is a spin-off from the KTH Royal Institute of Technology in Stockholm, where Janne Wallenius has carried out research on the design and safety analysis of lead-cooled reactor systems since 1996.


Seed funding was provided to LeadCold by KTH Innovation in 2013. In December 2014, the company was awarded a grant from VINNOVA (The Swedish Innovation Agency) and in December 2015 KIC InnoEnergy became investors. Essel Group Middle East a subsidiary of Indian multinational conglomerate Essel Group invested $18M in October 2016 and a further $200M in January 2017. This investment allows the company to license and construct its first lead-cooled nuclear power plant.

The company was awarded a contract from the UK government in June 2018 to produce a feasibility study for serial production of its SEALER-UK concept. In November 2019, LeadCold entered a collaboration with NewClearEnergy to benefit from sales of Nuclear Electricity sales in Sweden.


Funding rounds



Anders Blennermark

Board Director

David Malcolm

Board Director, Canada

Janne Wallenius

Founder & Reactor Physics

Lars Franzén

Board Director

Magnus Sjöland

Board Director

Peter Szakalos

Founder & Materials

Staffan Qvist

Core Design

Further reading


Documentaries, videos and podcasts





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