Advanced Nuclear Needs Modern Siting Regulations

The NRC has an important opportunity and a statutory obligation under the ADVANCE Act to

modernize how it evaluates population density in nuclear reactor siting. The Nuclear Energy Innovation and Modernization Act (NEIMA) of 2019 directed the Nuclear Regulatory Commission (NRC) to develop risk-informed, performance-based licensing approaches for advanced reactors. This directive explicitly included to modernize the legacy NRC approach to siting large light-water reactors, including restrictions based on the population density of areas surrounding proposed sites. But, despite these clear directives, the NRC failed to codify new regulations that align with the safety needs of advanced reactors—something that the commission agreed was necessary on multiple occasions. The ADVANCE Act reinforced the directive from Congress by directing the NRC to consider limitations of siting new reactors.

Last week, the Breakthrough Institute submitted a letter to the commission requesting that the NRC treat this issue as a delayed action—rather than a new proposal—and move swiftly to amend their population density criteria to be appropriate with the level of risk of advanced reactors.

As detailed in the letter, current criteria are based on decades-old assumptions developed for large light-water reactors and no longer reflect the safety case or deployment realities of advanced nuclear technologies. These prescriptive thresholds risk delaying projects, imposing costs without delivering commensurate public safety benefits, and excluding viable sites such as existing nuclear power facilities.

Time and again, the NRC has acknowledged that advanced reactors warrant a different approach. And yet, updated rules continue to rely on static population limits and distance-based instead of safety-based metrics that do not account for passive safety systems, reduced source terms, or site-specific risk modeling.

BTI urges the NRC to proactively revise its population density regulations and guidance. These

changes are essential to enabling a clean energy future that is affordable, secure, and aligned with the NRC’s updated mission to serve the public good.