Driven by the surging energy demands of artificial intelligence, America is resurrecting its nuclear past. Earlier this month, the Department of Energy finalized a $1.9 billion loan to restart Iowa’s Duane Arnold Energy Center, idle since 2020, so it can power Google’s expanding AI operations.
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Yet, as the United States prepares for this nuclear revival, regulators are rethinking a principle that has governed radiation protection for more than a half century. In July, the Nuclear Regulatory Commission (NRC) proposed eliminating the requirement that radiation exposure remain “as low as reasonably achievable” — what is known as the ALARA standard. That would leave some limits on radiation exposure in place, but it would remove the expectation that the operators of nuclear plants continually work to reduce unnecessary exposure.
Supporters argue that this change simply does away with a standard that added little value. NRC Chairman Ho Nieh compared ALARA to setting a 55-mile-per-hour speed limit and then telling drivers to go “as slow as reasonably achievable.” If regulators have already set a safe limit, why insist that workers stay even further below it?
The analogy is persuasive — and historically misleading.
During the 1950s and 1960s, regulators employed a system with only a limit on exposure. And as Americans learned that staying under it didn’t necessarily keep people safe, they demanded more stringent limits and lost faith in regulators and the safety of nuclear reactors.
ALARA emerged to assuage such fears, and it has successfully reduced exposure in the half century since. History suggests that eliminating it will hinder the public’s willingness to go along with a nuclear power revival.
The question of how much radiation exposure is too much emerged almost as soon as radiation entered modern life. Physicians who embraced the diagnostic power of X-rays in the late 19th century quickly discovered their dangers, as doctors, technicians and researchers suffered burns, tissue damage and cancers after prolonged exposure. Clarence Dally, an assistant to Thomas Edison who tested X-ray tubes on his own hands for years, had both arms eventually amputated and died of cancer in 1904.
Rather than abandon the promising technology, however, experts tried to determine how much radiation the body could tolerate. By 1934, the International X-ray and Radium Protection Committee had settled on numerical “tolerance doses,” premised on the belief that a threshold existed below which radiation caused no harm.
The Atomic Age tested that confidence. The Manhattan Project turned radiation from a specialized medical hazard into an industrial one, as thousands of workers handled uranium, plutonium and other radioactive materials. At the same time, geneticist Hermann Muller and others warned that radiation could damage genes in ways that might not surface for years or generations.
Given these warnings, and the newly expanded pool of people facing the risks of radiation, confidence in the ability of experts to set a safe limit for radiation exposure collapsed.
In 1934, the protection committee had set a tolerance dose of roughly 0.2 roentgens a day. Within two decades, fear of risk had driven that number down by three-quarters. But even this lower figure came with no claim of safety. Authorities had stopped believing any single number could mark a clean line between safe and unsafe exposure.
They also understood the perils of public concern continuing to rise. An internal Atomic Energy Commission memo from 1948 flagged the risk of a “shattering effect on morale” should employees learn how uncertain the safety standards were. Accordingly, the agency kept much of the research quiet.
Instead of trying to reduce risk, regulators tried to reframe how people thought of radiation risks. They scrapped the language of “tolerance doses” and instead focused on the concept of a “maximum permissible dose.”
The shift sounded technical, but it marked a real change in thinking: no longer would authorities guarantee that a permissible dose was a safe dose. Rather, as historian Shannon Cram has written in her history of U.S. radiation-worker regulation, officials were setting a level that they judged to involve an acceptable risk, given radiation’s benefits and the practical costs of reducing exposure further.
The limits of that guarantee became clear in the uranium mines that supplied the Manhattan Project and, later, civilian reactors. For years, miners worked under exposure guidelines that officials considered acceptable, though no binding federal limit applied. By the early 1960s, however, a Public Health Service study of Colorado Plateau miners found lung cancer rates several times higher than expected, rising sharply with cumulative exposure.
The lesson was blunt: the exposure level deemed permissible had not protected miners, and those who set it knew the ground under that number was shakier than they let on. In 1967, amid press exposure and growing unrest among miners, Secretary of Labor W. Willard Wirtz proposed a binding federal radon limit; it did not take effect until 1971.
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As nuclear power grew rapidly throughout the 1960s and 1970s, the concerns about radiation exposure spread from miners and industrial workers to the general public. People in areas around nuclear plants wondered if only having a maximum exposure limit truly protected them adequately.
In 1969, Northern States Power sought to open its new Monticello plant on the Mississippi River. But in response to public concern, Minnesota’s Pollution Control Agency tried to impose radioactive-release limits tighter than the AEC allowed.
The dispute sparked a court fight, in which 20 states sided with Minnesota. The battle became a flashpoint for the burgeoning environmental movement. Activists had doubts about whether the federal ceiling on releases was protective enough for the communities living near reactors.
In 1971, recognizing the need to reassure the public, theAEC responded by requiring plants to keep releases “as low as practicable.” A few years later, the NRC, the successor to the AEC, refined that standard into ALARA: exposures should stay “as low as reasonably achievable.”
The word “reasonably” did real work. As historian J. Samuel Walker has explained, ALARA never demanded eliminating every conceivable exposure regardless of cost; it accepted that nuclear work carried risk. What it rejected was the idea that staying under a number settled the question of safety.
The importance of this new standard was evident on shop floors. The earlier “maximum permissible dose” had simply told plants when they crossed legal lines. ALARA, by contrast, made managers ask a harder question: can this job be done with less exposure?
Plants started engineering exposure away, shielding jobs in advance, sending in robots instead of people and timing shifts so no one lingered in a hot zone. Compliance stopped being enough on its own.
ALARA has been successful: even as the maximum permissible dose never moved, the average dose of radiation exposure for workers has fallen. Regulators didn’t lower the bar; plants just kept clearing it by more.
The nation’s most infamous nuclear accident illuminated the importance of ALARA: during the 14-year, billion dollar operation to clean up the 100 tons of ruined fuel from the contaminated plant at Three Mile Island, workers were never exposed to more radiation than they’d have encountered operating ordinary reactors.
This history exposes the problem with Nieh’s analogy. A dose limit marks the point at which regulators judge the risk to workers unacceptable, not the point at which risk begins. The NRC itself still relies on a radiation-risk model that assumes any dose carries some risk. ALARA is the rule that acts on that assumption, requiring plants to use available technology to cut exposure wherever the cost is reasonable.
At a moment when the U.S. faces rising energy demands thanks to AI, and nuclear power offers a way to meet them without driving up carbon emissions, maintaining ALARA is important. The regulation was crucial for reassuring skeptical Americans that nuclear power could be safe.
Abandoning ALARA would mean returning to a system in which meeting the limit is the whole obligation, and in which Americans see compliance as a guarantee of safety. No regulator can honestly make that guarantee. History suggests that letting people believe otherwise risks destroying regulators’ credibility and turning workers and communities against nuclear operations. As the industry works to meet America’s growing demand for power, that is a bet it can ill afford.
Thomas Bishop is a senior lecturer in American and environmental history at the University of Lincoln and author of “Every Home a Fortress: Cold War Fatherhood and the Family Fallout Shelter” (2020). He is currently writing “A People’s History of the Permissible Dose,” a history of radiation risk and worker activism in the United States.
Made by History takes readers beyond the headlines with articles written and edited by professional historians. Opinions expressed do not necessarily reflect the views of The Inquirer.
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