The US Nuclear Regulatory Commission (NRC) on 5 June published in the Federal Register a proposed ruling on Emergency Preparedness for Small Modular Reactors (SMRs) and Other New Technologies (ONTs).
The document has a comment period that ends in 48 days. The NRC is proposing to amend its regulations to include new alternative emergency preparedness requirements for SMRs and other new technologies, such as non-light-water reactors and some non-power production or utilisation facilities.
The new emergency preparedness requirements would acknowledge technological advancements and other differences from large LWRs that are inherent in SMRs and ONTs.
NRC said it plans to hold a public meeting to promote a full understanding of the proposed rule and guidance and to facilitate public comment.
NRC said the current EP requirements and guidance was developed for large LWRs and non-power reactors, referred to as research and test reactors. They "do not consider the advances in designs and safety research and their application to future operation of SMRs and ONTs," NRC said. The regulator is proposing to amend its regulations to create an alternative EP framework for SMRs and ONTs.
The new alternative emergency preparedness requirements "would adopt a performance-based, technology-inclusive, risk-informed, and consequence-oriented approach." They "would adopt a scalable plume exposure pathway emergency planning zone (EPZ) approach and address ingestion response planning," NRC said.
The new requirements and guidance would:
- continue to provide reasonable assurance that adequate protective measures can and will be implemented by an SMR or ONT licensee
- promote regulatory stability, predictability, and clarity
- reduce requests for exemptions from EP requirements
- recognise advances in design and technological advancements embedded in design features
- credit safety enhancements in evolutionary and passive systems
- credit smaller sized reactors' and non-LWRs' potential benefits associated with postulated accidents, including slower transient response times, and relatively small and slow release of fission products.
Major provisions of this proposed rule and guidance would include the addition of:
- a new alternative performance-based EP framework, including requirements for demonstrating effective response in drills and exercises for emergency and accident conditions
- a hazard analysis of any NRC-licensed or non-licensed facility near an SMR or ONT, that considers any hazard that would adversely impact the implementation of emergency plans
- a scalable approach for determining the size of the plume exposure pathway EPZ
- a requirement to describe ingestion response planning in the emergency plan, including the capabilities and resources available to prevent contaminated food and water from entering the ingestion pathway.
NRC prepared an analysis to determine the expected costs and benefits of the proposed rule. It concluded that this proposed rule would result in net averted costs to the industry and the NRC ranging from $5.89 million using a 7% discount rate to $9.71 million using a 3% discount rate.
The Department of Energy (DOE) submitted a formal comment to NRC on the proposed rule in the form of a letter to NRC chairman, Kristine Svinicki dated 22 May and signed by Rita Baranwal, Assistant Secretary for Nuclear Energy. It said DOE "fully supports" the NRC staff's rulemaking efforts for a technology-neutral, dose-based, consequence-oriented emergency preparedness framework for SMRs and other new technologies.
The letter said NRC's proposed rule is a "critical step" in determining the appropriate emergency planning zone size for SMRs using a risk-informed methodology. It "will properly credit the advanced safety and performance characteristics of these new advanced reactor designs," the letter said.
It added that current EP regulations focus on regulating the current domestic fleet of large LWRs "and do not sufficiently address the advances in designs, safety, and their application to SMRs and ONTs".
"Today, advanced SMR developers are improving their designs and have incorporated inherent, passive safety features to improve plant resistance to design basis and beyond-design–basis accidents, and to assure any potential offsite dose is minimised," DOE said.
"These features include design elements such as smaller reactor cores, lower reactor core power densities, below-ground siting, and redundant passive accident response capabilities. Due to these innovations, the probability of an accident involving a significant release of radioactive material in SMRs is expected to be considerably lower when compared to the large LWRs. Moreover, if such an event were to occur, the SMR design results in a significant time delay before any release to the environment can occur; thereby allowing for additional actions that could mitigate or preclude any release."
DOE said it "supports the underlying basis for this rulemaking" to ensure the same level of public protection as the current 10-mile EPZ boundary. "It is our opinion that a scalable EPZ is a product of improved SMR designs and safety performance and does not equate to a reduction in the health and safety of the public."
Baranwal noted that DOE had made a significant investment in the development of SMRs over the past decade "to improve the nation's energy security posture". These investments have included research and development on the viability of passive safety systems based on the use of natural circulation, improved manufacturing techniques and qualification of materials for use in SMRs, and multi-module instrumentation and control capabilities.