NRC Affirms Science Behind Radiation Standards

The Nuclear Regulatory Commission plans to issue a proposed rule that upholds the current scientific model for radiation safety but makes some changes to its implementation. The changes came in response to an executive order last year that criticized the current model as lacking “sound scientific basis.”

The agency released a draft text of its proposed rule on its radiation protection framework, which proposes continuing to use the linear no-threshold (LNT) model for radiation exposure. Under LNT, there is no safe threshold of radiation exposure, and harm, specifically increased cancer risk, is assumed to be directly proportional to the amount of exposure.

However, the proposed rule would remove language from NRC regulations that directs licensees to keep radiation exposure “as low as reasonably achievable,”also known as the ALARA standard. ALARA is based on the LNT model: because harm is directly proportional to exposure amount with no safe threshold, exposure should be kept as low as reasonably achievable.

The Department of Energy made a similar rewrite to its regulations last year, but without a public rulemaking process. DOE regulations apply to its own reactors, as well as those run by contractors outside the national lab system, including those in the DOE Reactor Pilot Program, while the NRC regulates commercial reactors more broadly. NRC regulations also affect civilian use of most radioactive materials, including at hospitals.

The related executive order was issued in May 2025 as part of a suite of orders to boost nuclear power. This order, titled “Ordering the Reform of the Nuclear Regulatory Commission,” directed the NRC to “reconsider reliance” on LNT and ALARA, adding that these models “lack sound scientific basis and produce irrational results, such as requiring that nuclear plants protect against radiation below naturally occurring levels.” It directed the NRC to consider adopting determinate radiation limits instead and consult with DOE, the Environmental Protection Agency, and the Department of Defense.

The NRC is also putting forward more than 20 other final and proposed rules in response to the order, including one published on Tuesday that would limit NRC environmental reviews for activities including reactor development.

The current planned publication date for the proposed rule is July 15,and NRC plans to hold a public meeting on the proposal. Publication was originally planned for April 30 but has been postponed several times. The proposed rule will be open for public comment for 45 days after publication.

The proposed rule states that LNT “continues to be the most appropriate model upon which to base a radiation protection framework.” It acknowledges that measuring health risk from low-dose radiation “presents longstanding scientific challenges,” and that advances in radiobiology have identified mechanisms “that complicate simple linear extrapolation.” However, there is no consensus-supported, regulation-ready alternative model to LNT, the proposed rule adds.

“In the absence of such a suitable replacement, the NRC has taken this opportunity to address the LNT model’s inherent limitations by carefully examining its unintended impact on ALARA practices,” the proposed rule states. It argues that the ALARA standard is being interpreted as “as low as possible.”The rule states that “this has at times resulted in significant economic costs and operational and licensing inefficiencies without commensurate public health and safety gains.”

Some nuclear groups have previously expressed the same sentiment. According to the American Nuclear Society, “ALARA is intended to be an optimization process in which the costs associated with any potential dose reduction are balanced against the benefits in a risk-informed decision-making process considering all appropriate factors. Unfortunately, current implementation of ALARA often results in a practice of dose minimization rather than a risk-informed optimization, which can lead to more harm than benefit.”

Others have criticized the proposed change to ALARA, saying the changes are not scientifically driven. In a press release, the Union of Concerned Scientists said there is no technical or practical basis for changing the NRC’s use of LNT or ALARA. “U.S. regulatory science must be based on scientific evidence and follow due process—not the suggestive whims of the executive branch and the desires of the companies who stand to profit from less restrictive rules,” said Chanese Forté, a scientist in UCS’s Global Security Program, in the press release.

The proposed rule states that removing ALARA terminology is intended to restore the original intent of the ALARA principle. The proposal would “replace the ALARA principle with a requirement for a graded approach to dose management,” it states. For instance, the occupational dose limit is 5 rem per year. Below that, NRC licensees would no longer be expected to minimize the dose as much as reasonably achievable, though the proposal would reinforce existing requirements for expected doses above certain limits: above 0.1 rem per year, licensees must provide radiation worker training, and above 0.5 rem per year, licensees must monitor doses to individual workers.

Also, for doses below 5 rem per year, licensees could provide cost-based justifications to show that additional radiation protection measurements are not reasonable. The proposed rule provides $5,200 per person-rem as an example threshold for reasonable cost, based on a 2022 NRC report.

The proposed rule would maintain current radiation dose limits for workers and the public, with higher dose limits permitted on a case-by-case basis. It seeks input on these proposals and a few others, including raising the limit for emissions of radioactive atoms.