Design Certification (DC) is the NRC's process for reviewing and approving a standard nuclear power plant design independent of any specific site, codified as a rule in the Code of Federal Regulations (10 CFR Part 52, Subpart B). Once a design is certified, it resolves all safety questions related to the reactor design itself, and any applicant seeking to build that design need only address site-specific issues in their Combined License (COL) application. The DC remains valid for 15 years and can be renewed. This separation of design review from site review was created to avoid the costly and time-consuming relitigating of design issues that plagued nuclear construction under the older Part 50 two-step licensing process.
NuScale Power holds the distinction of obtaining the only SMR design certification in U.S. history. The NRC certified NuScale's 50 MWe US600 design in January 2023 after a review process that began with application submittal in January 2017, spanning approximately six years and representing a total review effort exceeding one million staff-hours. NuScale subsequently pursued Standard Design Approval (SDA), a related but distinct process under Part 52 Subpart E, for its uprated 77 MWe US460 design. The SDA was granted in May 2025, completed in under two years and ahead of schedule. While SDA approves a major portion of the design, it carries somewhat less regulatory finality than a full DC, though it can still be referenced in COL applications.
No other SMR vendor has yet received a design certification from the NRC, though several are advancing through pre-application and application stages. The certification process requires extensive documentation including the Design Control Document, probabilistic risk assessment, severe accident analysis, and environmental review. For the broader industry, each new DC establishes regulatory precedent and builds the body of NRC technical expertise in advanced reactor technologies. Westinghouse's AP300 (based on the certified AP1000 design), GE-Hitachi's BWRX-300, and Holtec's SMR-300 are among the light-water SMR designs expected to pursue design certification in the coming years. The forthcoming Part 53 framework may offer an alternative, technology-inclusive licensing pathway that could reduce the time and cost of the certification process for non-light-water designs.