Asked and Answered:Linear No-Threshold & As Low As Reasonably Achievable

President Donald Trump signed Executive Order 14300 (EO 14300) on May 23, 2025. Among other things, the Executive Order addressed the U.S. Nuclear Regulatory Commission’s (NRC’s) regulations protecting workers and the public from harm caused by exposure to radiation. EO 14300 contended that:

The NRC utilizes safety models that posit there is no safe threshold of radiation exposure and that harm is directly proportional to the amount of exposure. Those models lack sound scientific basis and produce irrational results, such as requiring that nuclear plants protect against radiation below naturally occurring levels.

The Executive Directive mandated that the NRC:

Adopt science-based radiation limits. In particular, the NRC shall reconsider reliance on the linear no-threshold (LNT) model for radiation exposure and the ‘‘as low as reasonably achievable’’ [ALARA] standard, which is predicated on LNT. Those models are flawed, as discussed in section 1 of this order. In reconsidering those limits, the NRC shall specifically consider adopting determinate radiation limits, and in doing so shall consult with the Department of Defense (DOD), the Department of Energy (DOE), and the Environmental Protection Agency.

The questions raised in EO 14300 regarding the validity and applicability of LNT and ALARA have been asked and answered (AAA) many times over decades.

LNT Background

The linear no-threshold model assumes that the risk of harm from radiation exposure is directly related to the amount of radiation exposure: the risk of harm is doubled if the amount of exposure is doubled. Put another way, the risk of harm is halved if the amount of exposure is halved.

This post has great illustrations, citations, and links, you can read the remainer HERE.

‍ ‍

‍ ‍

‍ ‍

‍ ‍