NRC Licensing Pathways

The NRC licensing process was designed for 1,000 MW light-water reactors built by GE and Westinghouse. It was not designed for 50 MW microreactors or molten salt designs. Fitting new technology through an old regulatory pathway is one reason advanced nuclear moves slowly.

Two licensing pathways exist. Part 52 (combined construction and operating license) was created in 1989 to streamline what had been a two-step process. The applicant gets a single license before construction begins, reducing the risk of mid-build regulatory changes that plagued 1970s-era projects. NuScale's small modular reactor received the first Part 52 design certification for an advanced reactor in 2023 (before the project was cancelled for cost reasons). Part 53, proposed in 2023, would create a technology-neutral, risk-informed framework specifically for advanced reactors that do not fit the light-water assumptions embedded in Part 52.

The problem with existing pathways: Part 52's safety analysis requirements assume large light-water reactor failure modes (loss of coolant, containment breach). A molten salt reactor that operates at atmospheric pressure and cannot melt down must still demonstrate compliance with criteria designed for a different technology.

Licensing timelines. NuScale's design certification review took roughly 6 years. Kairos Power's molten salt test reactor received a construction permit in 2023 but under a limited Part 50 test reactor license, not the full Part 52 process.

If Part 52 does not fit advanced reactors, why not just use Part 53?

Part 53 is not yet finalized. The NRC has been developing it since 2019 with no completion date certain. Developers must choose between a pathway that does not fit (Part 52) and one that does not yet exist (Part 53).

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