Every nuclear plant you have ever driven past leans on the same visual language: cooling towers, a containment dome built to shrug off an airliner, a security perimeter measured in city blocks. On August 25, a Swedish company called Blykalla asked its government to sign off on the opposite. The company wants to stand up to eight reactors at Untra, a river site about 1.5 hours north of Stockholm, and each unit occupies roughly 20 by 20 feet (6 by 6 meters), the footprint of a two-car garage.<\/p>\n
Together the eight units add up to 440 megawatts, which the company puts at about 18 percent of the new nuclear capacity Sweden wants running by 2035. Each reactor is a SEALER, short for Swedish Advanced Lead Reactor, and it generates 55 megawatts of electricity from a core bathed in molten lead. Nobody refuels it for 25 years.<\/p>\n
Blykalla also plans to build its first reactor on American soil, not Swedish.<\/p>\n
Molten lead boils at 3,092\u00b0F (1,700\u00b0C), per the company’s own spec sheet<\/a>, and the SEALER core runs nowhere near that. So the coolant physically cannot flash into steam, however badly a shift goes. The primary loop sits at 1 atmosphere, the same pressure as the parking lot outside, which deletes the thick high-pressure vessel a light-water plant has to wrap around its core. Conventional reactors keep their cooling water liquid in the first place only by clamping it under enormous pressure.<\/p>\n The lead handles accidents on its own physics too. In a full blackout, hot metal around the fuel rods expands, rises to external heat exchangers, sheds its heat and sinks back down, a circuit run by gravity, with no pumps, no outside power and no human in the loop. World Nuclear News<\/a> reports each reactor’s rods sit in about 880 US tons (800 metric tons) of liquid lead, and the company’s stated design case is that the pool traps volatile fission products in a worst-case core accident, so nobody living at the site boundary would need to evacuate.<\/p>\n Sodium, the other liquid metal running today’s fast reactor projects<\/a>, burns in air and reacts violently with water. Lead does neither. It just sits there, moonlighting as radiation shielding.<\/p>\n Lead cooling is older than it sounds. Submarine reactors have run on it since the 1960s, per Blykalla, mostly on the Soviet side of the Cold War, and the metal has one expensive vice: hot liquid lead corrodes and erodes steel. Corrosion retired early lead-cooled designs and kept the whole concept out of commercial power for six decades.<\/p>\n The answer was steel. Researchers at Stockholm’s KTH Royal Institute of Technology have worked on lead-cooled systems since 1996, Blykalla spun out of that lab in 2013, and the company, now around 140 people, holds patents on three aluminum-alloyed steels: one grade for the fuel cladding, an austenitic one for the reactor vessel and a martensitic one for the pump impellers. During operation, aluminum inside the alloy migrates to the surface, meets trace oxygen held in the lead and grows an oxide film over every wetted part. Scratch the film and it heals over.<\/p>\n Fuel follows the same leave-it-alone philosophy. Each core starts on ordinary uranium dioxide, the most widely used reactor fuel on Earth, with a shift to uranium nitride planned later because it packs 40 percent more uranium into the same volume. The SEALER’s 25-year core has company in the filing cabinet too: a French startup just filed for a compact reactor<\/a> meant to run 20 years on a single load.<\/p>\n Untra sits in Tierp municipality, Uppsala County, inside the SE3 bidding zone, where Swedish electricity demand runs highest. Two hydropower stations already work the Dal\u00e4lven river there, at Untra and S\u00f6derfors, and the Swedish firm’s pitch parks its always-on reactors next to hydro turbines<\/a> that can throttle up and down to follow demand. Svenska kraftn\u00e4t, the national grid operator, is stringing new 400-kilovolt lines through the same municipality under a regional buildout called the Uppsalapaketet.<\/p>\n Blykalla CEO Jacob Stedman said the reactors let the company build “closer to industry, in new municipalities and inland locations” that traditional plants never reached. Factory-built modules move by ordinary road and rail, which is the entire reason an inland river site works at all.<\/p>\n Untra is application number two. Blykalla filed its first in May 2026, for a six-unit, 330-megawatt park at Norrsundet in G\u00e4vle municipality, about two hours north of Stockholm, and billed that one as the first commercial application for an advanced reactor park in the country. The two parks together come to 770 megawatts.<\/p>\n Sweden runs six large reactors today, split across Forsmark, Oskarshamn and Ringhals, and nuclear covered 29 percent of the country’s electricity in 2024, according to IAEA data. The Riksdag wants national output near 300 terawatt-hours by 2045, roughly double what the country produces now. The government’s plan calls for 2,500 megawatts of new nuclear by 2035 and 10,000 megawatts by 2045. Parliament also adopted a new review framework for nuclear plants in 2026, and the two filings run straight through it: the government rules first, then the Swedish Radiation Safety Authority, then the Land and Environment Court, then Tierp’s own municipal council. Any one of the four can kill the project. The plant produces first power in the first half of the 2030s only if all four say yes.<\/p>\n A state-aid act in force since August 1, 2025, offers government loans for new nuclear, capped nationwide at the equivalent of four large reactors, about 5,000 megawatts, with two-way contracts for difference once a plant is licensed at full output. The act only covers sites with at least 300 megawatts installed in one place, and Norrsundet’s 330 megawatts and Untra’s 440 both clear that bar. Blykalla announced on June 5 that it had applied for the financing, and three other companies are already in line for it, including one proposing two full-size reactors at Barseb\u00e4ck, a site where two old units are being decommissioned.<\/p>\n Blykalla’s first actual reactor, a demonstration unit the company calls FJ\u00c4LL, is planned for the United States, developed with Oklo, the California fast-reactor firm. The Swedes opened formal pre-application engagement with the Nuclear Regulatory Commission<\/a> on June 18, 2026, the standard first move before anyone files for a US license. The 2024 ADVANCE Act ordered the NRC to license advanced reactors faster, and federal actions in 2025 set a goal of quadrupling US nuclear capacity to 400 gigawatts by 2050. The demo is aimed at exactly that market.<\/p>\n Oklo put roughly $5 million into Blykalla’s funding round in September 2025, and the two companies expanded the deal in March 2026. Under the wider agreement, the Swedish side plans to deploy $100 million to $200 million and 30 to 40 engineers in the US, subject to final planning and approvals, while feeding technical analyses into Oklo’s DOE-authorized reactor pilot. The Stockholm firm’s American office sits at 190 Bowery in Manhattan.<\/p>\n The company frames the US demonstration as the validation step before its Swedish commercial parks. So the reactors Sweden is being asked to approve at Untra depend on a first-of-a-kind unit running on American soil. An electric, non-nuclear prototype is already going up near Oskarshamn with the utility Uniper, backed by a $9.3 million (SEK 99 million) grant from the Swedish Energy Agency, to shake down components before any fuel shows up.<\/p>\n The Swedish government has approved nothing yet. Its ruling opens a four-gate sequence, with the radiation regulator, the environmental court and Tierp’s council behind it, and the American demo has to run somewhere in the middle of all that. Blykalla filed the Untra application<\/a> on August 25, 2026: eight reactors, 440 megawatts, one two-car garage at a time.<\/p>\n","protected":false},"excerpt":{"rendered":" Every nuclear plant you have ever driven past leans on the same visual language: cooling towers, a containment dome built … <\/p>\nSweden spent 30 years fixing the steel problem<\/h2>\n
The site comes with two hydro dams attached<\/h2>\n
Sweden’s checkbook opens at 300 megawatts<\/h2>\n
The first one gets built in America<\/h2>\n