The UK’s Office for Nuclear Regulation, the Environment Agency, and Natural Resources Wales (NRW) can confirm that the Holtec SMR-300 nuclear reactor design has successfully completed Step 2 of the Generic Design Assessment (GDA). Step 2 began in August 2024 and involved a comprehensive and rigorous examination the fundamental adequacy of the reactor design and its safety, security, safeguards and environmental protection documentation.
The assessment has concluded with the issuing of two GDA statements setting out the regulators’ conclusions on the Holtec SMR-300 and its supporting documentation. Regulators have confirmed that their assessments have identified no fundamental safety, security, safeguards or environmental protection shortfalls with the design that would prevent its deployment in Great Britain.
Tim Parkes, ONR’s head of the Holtec SMR-300 GDA, said: “Our assessment covered 21 technical topic areas, and we have not identified any fundamental shortfalls.
Saffron Price-Finnerty, the Environment Agency’s New Reactors Programme manager, said: “Based on our assessment across all topic areas, we have found no fundamental environmental protection shortfalls at this stage in the development of the SMR-300, that could prevent the design from being acceptable for future deployment in England or Wales.
“As the environmental regulator of nuclear sites and radioactive substances in England, the Environment Agency ensures that nuclear companies and the sites they operate meet high standards of environmental protection throughout the stages of design, construction, operation and decommissioning.”
In September 2025, Holtec, in partnership with EDF Energy and Tritax, announced plans to construct the SMR-300 at Cottam in Nottinghamshire, UK. At present, Holtec and its partners have not asked the regulators to carry out Step 3 of GDA, but should construction plans progress, the regulators will continue to engage with Holtec and its partners, as they prepare the design, safety, security and safeguards and environment safety case, site licence application, and environmental permit applications.
Before the Holtec SMR-300 can be deployed in Great Britain, the regulators will need to undertake a further period of detailed assessment before safety-significant construction can begin and environmental permits be issued.
