Last Energy’s modular PWR-20 microreactors are designed for efficient factory fabrication, rapid on-site assembly, and flexible deployment.

Last Energy has formally launched the UK’s nuclear site licensing (NSL) process for plans to develop four 20-MWe microreactors in South Wales, becoming the first small modular reactor (SMR) developer to make the move.

The UK Office for Nuclear Regulation (ONR) on Feb. 17 confirmed the U.S.-based nuclear technology firm’s entry into the critical licensing process, which is set out under the country’s Nuclear Installations Act 1965 (NIA65). A nuclear site license is a legal document ONR issues for the full lifecycle of a nuclear installation from design and construction to operation and decommissioning. It includes the storage of radioactive waste and spent fuel. The license contains site-specific information, defines permitted installations, and includes 36 standard license conditions covering various aspects of nuclear safety.

More granular than the Generic Design Assessment (GDA)—a four-step technology-neutral assessment focused on reducing project risk through generic design evaluation—the process of obtaining the NSL is envisioned as a site-specific safety review, involving a population density review and verification there are no defense, civil aviation, or seismic issues. The process is required before construction can begin, which requires separate ONR regulatory approval. “The [NSL] licensing process is fundamental in ensuring that prospective licensees of a nuclear site are ready and able to meet their obligations under the nuclear site licence to protect their workforce and the public,” an ONR spokesperson explained.

South Wales Project Aims for 2027 Delivery of First Unit

The milestone marks a big step for Last Energy, which unveiled plans in October 2024 to deploy four 20-MWe pressurized water reactor (PWR) power plants at the vacant site that housed the Llynfi Power Station, a coal-fired power plant in South Wales that operated from 1951 to 1977. Last Energy is working to deliver its first microreactor in Wales in 2027, pending the licensing, permitting, and planning processes.

The “Prosiect Egni Glan Llynfi” project under development by Last Energy subsidiary Last Energy UK will deploy the PWR-20, which is a 20-MWe (80-MWth) single-loop PWR that has a 300C continuous output. The “plug-and-play” design uses standard full-length PWR fuel enriched to 4.95% and closed-cycle air cooling. Last Energy has said it can deploy modules within a construction timeframe of between six and 24 months.

Last year, the company said the overall capital investment for the Welsh project, estimated at £300 million ($393 million)—including for equipment, services, and other development activities—is expected to be fully privately funded and will not require public funding. In December 2024, the U.S. Export-Import Bank issued a letter of intent confirming its willingness to provide $103.7 million in debt financing to cover end-to-end delivery for its first installation, pending final commitment. In January, the company accepted a grid connection offer from National Grid Electricity Distribution—the UK’s largest electricity distribution network that serves nearly 8 million customers across the Midlands, South West, and Wales—for 22 MW of export capacity and 3 MW of import capacity for its first unit in South Wales.

ONR’s NSL acceptance notice, which became effective on Jan 1, 2025, “follows seven months of early engagement with Last Energy and is a critical accelerator for the company’s deployment progress in the UK,” Last Energy said in a statement. “Last Energy’s entry into licensing also underscores the viability of privately-financed projects, and puts the UK on a near-term path toward its first-ever commercial nuclear microreactor.”