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Key Insights
Last Energy's PWR20 microreactor design successfully completed a Preliminary Design Review by UK nuclear regulators, a first for a microreactor developer in the nation.
This milestone validates the design's regulatory pathway, supporting Last Energy's ambitious target to achieve nuclear site licensing by December 2027 for its South Wales project.
The project involves deploying four 20 MWe microreactors at a former coal plant site, backed by a $103.7 million Letter-of-Intent from the U.S. Export-Import Bank.
The PDR provides crucial tailored regulatory guidance, preparing Last Energy for the more rigorous Generic Design Assessment process and accelerating commercial deployment.
Last Energy, a U.S.-based micro-nuclear technology developer, announced that its PWR20 power plant design has successfully completed a Preliminary Design Review (PDR), marking a significant first for a nuclear developer in the United Kingdom. The review, conducted jointly by the UK’s Office for Nuclear Regulation (ONR), the Environment Agency, and Natural Resources Wales (NRW), concluded in June 2025, confirming initial confidence in Last Energy’s approach to regulatory expectations across organizational plans, environmental considerations, and safety analysis.
This milestone follows over a year of early engagement and five months of intensive PDR-specific review, which included design workshops and technical submissions. The PDR specifically evaluated Last Energy’s fully-passive, walk-away-safe design approach. While the ONR emphasized that the review is not a substitute for formal generic or site-specific design assessment, it provides crucial tailored regulatory guidance, which Last Energy views as confirming a pathway to complete nuclear site licensing by December 2027.
Last Energy formally entered nuclear site licensing in January 2025 for its plans to develop four 20 MWe microreactors at the former Llynfi Power Station site in South Wales. The company secured site control in October 2024, followed by a Letter-of-Intent (LOI) for $103.7 million from the U.S. Export-Import Bank (EXIM) to support the financing of the first installation. This EXIM support, pending final commitment, would cover the entire costs for a single power plant installation, following EXIM’s review of Last Energy’s technology, business model, and fuel access.
In January 2025, Last Energy UK Limited, developing the project under the name Prosiect Egni Glan Llynfi, also accepted a grid connection offer from National Grid Electricity Distribution (NGED) for 22 MW of export capacity. The company estimates an overall capital investment of £300 million for the four units, without requiring public funding. This implies an ambitious cost target of approximately $3,750/kW for the first 20 MW PWR, significantly lower than typical new nuclear builds. Last Energy aims to source at least 10% of its needs from South Wales suppliers, representing a £30 million local economic investment.
Having raised $40 million in its Series B round in 2024, bringing total corporate financing to $66 million, Last Energy now faces the rigorous Generic Design Assessment (GDA) process with the UK Office of Nuclear Regulation. This process is historically expensive and time-consuming, with larger firms often encountering delays due to application deficiencies. Last Energy's proactive engagement through the PDR is expected to mitigate some of these risks, providing a clearer roadmap for its GDA journey and accelerating the potential deployment of its factory-built microreactors.