SPECIAL REPORT | ALARA
What future for the ALARA principle?
Influential UK and US stakeholders say the ALARA principle has been a substitute for holistic decisionmaking and the ‘realistically achievable’ threshold has not had enough regard for cost. Should it be re-examined?
THE AIM TO KEEP RADIATION doses from the nuclear industry as low as reasonably achievable (ALARA) is enshrined in the fundamental principles of the International Commission on Radiation Protection (ICRP). US President Donald Trump raised eyebrows when his Executive Order on reforming the US Nuclear Regulatory Commission (USNRC) called for reliance on this principle to be revisited. But a new UK Nuclear Regulatory Review (NRR) produced for the Department for Energy Security and Net Zero (DESNZ), which provides advice to government on how to reduce regulatory barriers to fast deployment of nuclear power, has also called the principle into question – at least in its practical application. Is this fundamental principle under threat? When President Trump tasked the USNRC with revisiting
its approach to radiation safety, he including reconsidering its reliance on the linear no-threshold (LNT) model and the ALARA principle. Instead, the NRC is directed to explore the adoption of “determinate, data-driven radiation limits” in consultation with the Department of Defense and Department of Energy, and the Environmental Protection Agency (EPA).
LNT is a fundamental of the ICRP’s system, adopted in the
International Atomic Energy Agency’s (IAEA’s) regulations. It assumes that any amount of ionising radiation carries some risk of causing harm (typically cancer) and the risk increases linearly with dose. The NRR says that the reality of radiation exposure is more complex, and some critics say the LNT model over-estimates the risks at low doses or argue that there is a threshold for harm. The NRR notes that the ICRP itself states that the LNT
model carries “uncertainty on health effects at low doses”, underscoring the need for a proportionate approach with cautious application at very low doses. But the broader international radiological protection community, including the ICRP and the UK, continue to support its use as the best available tool for public health policy and radiation protection.
The argument over the role of the LNT model is a
longstanding one. It was revisited recently in a paper (Reevaluation of Radiation Protection Standards for Workers and the Public Based on Current Scientific Evidence) published by Idaho National Laboratory in July 2025 with the support of the US DOE. Lead author Dr John C Wagner is the director of INL and president of Battelle Energy Alliance. Wagner and his co-authors say, “the preponderance
of available evidence suggests that current radiation protection frameworks may be overly conservative”. They say studies do not show statistically significant adverse health effects at doses below 10,000 mrem delivered at low dose rates and this is born out by studies of populations where natural background radiation is high. They add, “Multiple major professional organizations acknowledge significant limitations and uncertainties” in LNT. The INL paper supports a numerical exposure limit. The authors suggest maintaining an annual occupational whole-body dose limit of 5,000 mrem/yr, as currently applies, and eliminating all ALARA requirements and limits below this threshold. They suggest future consideration of a higher limit, 10,000 mrem/yr, which “may maintain sufficient safety margins while further reducing protection costs”. The INL concern is over the elements of a “multifaceted
system” that solidifies the outcomes of ALARA. Regulatory guides include recommendations for optimising facility layout and equipment design, remote-handling, ventilation systems, reducing source terms, decontamination and radiation monitoring. They say, “Collectively, this regulatory framework transforms ALARA from a philosophical aspiration into a binding legal requirement. Licensees must reduce doses below the 5,000 mrem limit regardless of economic impact because ALARA implementation is an explicit regulatory obligation rather than simply a goal or ideal.”
They say that this is “overly effective” because it results in doses “well below the regulatory limit” – 58 per cent of
The ICRP’s Fundamental Principles of Radiation Protection Justification:
Optimisation:
No practice involving exposure to radiation should be adopted unless it produces a net benefit.
Radiation doses should be kept as low as reasonably achievable (ALARA), taking into account economic and societal factors.
Dose limitation: Individual doses must not exceed prescribed limits.
14 | December 2025 |
www.neimagazine.com
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