Swedish nuclear startup Blykalla has applied to the Swedish government for a second commercial advanced nuclear reactor park. The proposed facility, at Untra in Tierp municipality (Uppsala County), would feature up to eight lead-cooled advanced modular reactors (AMRs) with a combined electrical capacity of up to 440 MWe. This follows Blykalla’s first application submitted in May 2026 for a facility in Norrsundet, Gävle municipality.
Blykalla (formerly known as LeadCold) founded in 2013, is a spin-off from the KTH Royal Institute of Technology in Stockholm. Its SMR prototype SEALER (Swedish Advanced Lead-cooled Reactor) design is a fast compact reactor with passive safety. Each reactor will have a 55 MWe capacity, which can be increased by installing multiple units at the same location. The reactor is designed with the smallest possible core that can achieve criticality in a fast spectrum using 19.9% enriched nitride fuel. It broke ground in February 2025 for the construction of an electrical small modular reactor pilot facility near Oskarshamn to test proof of concept of its SEALER technology.
“We continue to identify locations across Sweden where advanced nuclear power will deliver the greatest value,” said Blykalla CEO Jacob Stedman. “Our reactors make it possible to build nuclear power where and when it’s needed – closer to industry, in new municipalities and inland locations where traditional nuclear power has historically not been possible.”
Blykalla selected Untra as an ideal location after a thorough site selection process that analyses multiple criteria. Untra met the company’s key criteria: a strategic position in bidding zone SE3, where Sweden’s electricity consumption is highest; proximity to existing hydropower at Untra and Söderfors, enabling a power cluster where dispatchable nuclear and regulated hydropower complement each other; and access to Svenska kraftnät’s new 400 kV transmission infrastructure being built through Tierp municipality as part of the Uppsalapaketet program. The site also offers access to nuclear expertise from Uppsala, Gävle, and Forsmark.
The application follows a new Swedish regulatory framework adopted by the government and parliament in 2026, which enables the review and approval of new nuclear facilities. Government approval represents the first step in a multi-year process involving further review by the Swedish Radiation Safety Authority (SSM), the Land and Environmental Court, and Tierp municipality.
Sweden’s Riksdag has established an ambitious energy target of 300 TWh electricity production by 2045, nearly double today’s output. The government’s plan calls for 2,500 MW of new nuclear capacity by 2035 and 10,000 MW by 2045. Blykalla’s Tierp facility alone would contribute approximately 18 percent of the 2035 target.
Blykalla has offices in both Sweden and the US and is planning its first nuclear demonstration reactor in the US. This will provide critical technology validation before commercial deployment in Sweden. Blykalla also partners with US companies including Oklo, contributing technical analyses to Oklo’s DOE-authorised reactor pilot.
