Up to eight Sealer SMR units planned for 440-MW Tierp project
Sweden-based advanced nuclear technology company Blykalla has applied to the Swedish government for a second commercial advanced reactor park at Untra in Tierp municipality, Uppsala county, the company said in a statement.
According to the statement, the proposed facility would have up to eight Sealer lead-cooled advanced modular reactors (AMRs) with combined electrical capacity of up to 440 MW.
The application follows a first submission in May 2026 for a reactor park at Norrsundet in Gävle municipality.
Blykalla chief executive officer Jacob Stedman said the company is continuing to identify locations in Sweden where advanced nuclear power could “deliver the greatest value”.
He said Blykalla’s reactor technology could allow nuclear power to be built closer to industry and in inland municipalities where traditional nuclear power has not historically been possible.
Blykalla said it chose Untra because the site is Sweden central SE3 electricity bidding zone, where Sweden’s electricity demand is highest, and close to existing hydropower plants at Untra and Söderfors.
The company said this could create a regional power cluster where dispatchable nuclear generation complements regulated hydropower. The site also has access to new 400-kV transmission infrastructure being developed by Svenska kraftnät through Tierp municipality as part of the Uppsalapaketet programme.
Blykalla says its 55-MWe Sealer AMR is a small modular reactor (SMR) that uses proven lead-cooling technology. By incorporating its proprietary and patented aluminium alloyed steels into its Sealer reactor, Blykalla has developed an AMR that it says can withstand the corrosive nature of liquid lead, enabling the commercialisation of lead-cooled fast reactors.
The company said it is targeting first operations at Untra during the first half of the 2030s, subject on approvals from the government, regulatory agencies, courts, and Tierp municipality.
Sweden has six large-scale reactor units in commercial operation at three sites: Forsmark, Oskarshamn and Ringhals. According to International Atomic Energy Agency data, nuclear energy provided 29% of the country’s electricity generation in 2024.
In May 2025, Sweden passed a law establishing a state aid framework including government-backed loans and two-way contracts for difference for companies planning to build nuclear reactors, covering projects with a total capacity of up to 5,000 MW.
In 2023, the government introduced a nuclear roadmap with plans for at least 2,500 MW of new nuclear capacity by 2035 and a major expansion by 2045. A wider electricity planning target of at least 300 TWh by 2045 was adopted by parliament in 2024.
Blykalla said the proposed Tierp facility alone would represent about 18% of the 2035 target.
