Up & Atom


The Nuclear Regulatory Commission (NRC) has announced that it intends to issue, by the end of 2023, the final rule and associated regulatory guide that sets emergency preparedness requirements for new reactors. The rulemaking will allow small modular reactor (SMR) and advanced reactor license applicants to develop performance-based emergency preparedness programs as an alternative to the current offsite radiological emergency planning requirements. This rulemaking is a significant development toward providing flexibility in meeting the NRC’s emergency preparedness requirements.


In an August 2023 press release, the NRC announced its intent to finalize by the end of 2023 its rulemaking for “Emergency Preparedness for Small Modular Reactors and Other New Technologies.” The NRC published its proposed rule in May 2020 and, after a lengthy comment period and public meeting, finalized its rulemaking package for Commission review in early 2022. That rulemaking package includes a draft Final Rule.

Planned Final Rule

Facilities covered by the Final Rule are limited to SMRs (defined by the rule as light-water reactors generating 1,000 MW thermal power or less per module), advanced reactors (i.e., non-light-water reactors), research and test reactors, and medical radioisotope facilities. The rulemaking excludes light-water reactors licensed to produce greater than 1,000 MW thermal power, fuel cycle facilities, and existing research and test reactors, which will remain subject to existing emergency preparedness requirements.

As the NRC explained, existing emergency preparedness regulations and guidance focus on large light-water reactors, and do not account for newer reactor designs, such as SMRs or advanced reactors, like those cooled by molten salt or liquid metal. The Final Rule will apply “performance-based emergency preparedness requirements” to “address how state-of-the-art facility designs and safety research apply to future operation of small modular reactors and other new [nuclear] technologies.” The NRC described the requirements as “a technology-inclusive and consequence-oriented approach.”

The Final Rule will create a new, alternate, performance-based emergency preparedness framework in 10 CFR Section 50.160. The NRC explained that its current regulations for reactors require site-specific emergency plans designed around 16 planning standards, a deterministic structure that works well for large light-water reactors whose risks are well understood. However, because SMRs and other new nuclear technologies may use a wide range of designs and safety features, a performance-based approach would be better suited, and would reduce the administrative burden to evaluate expected exemption requests from existing regulations.

The Final Rule also amends 10 CFR Section 50.33 to provide for a scalable approach to determining the size of the emergency planning zone (EPZ). Currently, the plume exposure pathways for the EPZ and ingesting pathway EPZ are set at a 10-mile and 50-mile radius, respectively, although reactors under 250 MW thermal and gas-cooled reactors can apply for smaller zones. To account for the safety features of newer reactor designs, the Final Rule would use a consequence-oriented approach to determine the size of the exposure plume, namely the area within which the public dose would exceed 10 millisieverts over 96 hours after a release. That is, rather than setting a predetermined inflexible distance for the EPZ, the distance would be determined by the potential consequence of an accident based on factors such as accident likelihood and source term, timing of the accident sequence, and meteorology.

This new framework will include requirements for demonstrating effective responses via drills and exercises. Significantly, the facility will not need to involve local responders in these drills and exercises where the EPZ does not extend beyond the facility’s perimeter, as is being proposed by some advanced designs.

The Final Rule also clarifies that an emergency plan that satisfies the Section 50.160 requirements will also satisfy the emergency preparedness requirements for co-located independent spent fuel storage installations licensed under 10 CFR Part 72.


These long-awaited emergency planning regulations will allow flexibility, while fostering predictability in how the NRC will evaluate emergency plans. Significantly, the resource burden for drills and exercises will be significantly reduced for those reactor designs that can achieve an EPZ that does not extend beyond the facility’s perimeter. The new regulations will also potentially aid the adaption of SMRs and advanced reactor designs for uses other than traditional electric generation, such as powering commercial maritime vessels.

Morgan Lewis regularly advises on all matters related to the energy sector, including nuclear reactor licensing, regulatory compliance, and exports of radiological materials.