The statutory limit is 5 rem per year. Rem is a unit used to quantify potential radiation effects on the human body.

A 2017 U.S. Department of Energy standard set an administrative control level for annual dose at 2,000 millirem, or 2 rem, requiring prior approval for amounts above that. According to the Occupational Radiation Exposure Report for Calendar Year 2024, that standard also required each DOE site to establish its own administrative limit “based on historical and projected exposure” and requires approval from facility management if an individual looked like they were going to exceed it.

“There’s a statutory limit for dose rates, which is 5 rem,” McDonald said in January. “We had previously capped our administrative limits at 1 rem, for very good reasons.”

The National Nuclear Security Administration did not respond to questions about McDonald’s comments, the change itself, or the administrative limits at other DOE sites like Lawrence Livermore National Laboratory and the Savannah River Site. A spokesperson for LANL referred questions to the NNSA.

It’s “five times the danger,” said Los Alamos Study Group executive director Greg Mello.

“If they’re not going to expose people, then why is it changing?” he asked.

Moving faster

McDonald, who previously had a long career at Los Alamos National Laboratory, said during the panel discussion the nuclear enterprise is trying to overcome what he called a “risk-averse culture” and accelerate work, while still maintaining safety standards. He described the change to the administrative limit as one example where regulatory frameworks are being “right-sized” to meet the moment.

McDonald said the amount of urgency with which the pit production mission is being pursued was new in his career. That’s driven largely by a tense geopolitical situation, he added, which can be hard to keep up with.

“There’s really an effort to look at, ‘What can we do faster, while still being safe and secure?’ “ McDonald said.

But he said typically, DOE sites do not exceed limits.

“The basic principle in [the] nuclear space is ALARA — as low as reasonably achievable,” McDonald said. “When you’re an R&D facility, ALARA would dictate a low amount of dose to the worker, but the statutory limit is ... well away from where we currently are.”

In 2024, that was true. That year, the Department of Energy monitored close to 85,000 workers for radiation exposure.

For the roughly one in five Department of Energy workers who received any detectable radiation dose, the average measured dose was 1% of the 5 rem statutory limit, according to the federal agency’s annual report on worker radiation exposure.

According the report for 2024, which was completed in November 2025 and published Feb. 12, in a five-year period, just one person had received a dose of more than 2 rem across all DOE sites. A report on that 2020 incident said it occurred at LANL’s Plutonium Processing and Handling Facility, when a worker was removing his hands from the glove box he had been working in and was securing the gloves.

The glove box gloves were beginning to feel worn, but were still usable, according to the report, so they were put on the schedule for replacement. According to the report, gloves are taken out of service if they show signs of “excessive wear or imminent failure” but otherwise, they’re left in service and scheduled for replacement.

The incident occurred the day before the gloves were set to be replaced.

Due to the exposure to plutonium-238, the worker received a total effective dose that year of 3 rem, above the administrative limit but below the statutory limit of 5 rem.

Worker exposure varies by site. In 2024, five DOE sites made up 86% of the total effective dose received by workers at the 33 reporting sites. LANL was the highest contributor, followed by the Savannah River Site in South Carolina.

But the number of workers who experienced a measurable total effective dose at LANL dropped between 2023 and 2024 by 11%, or roughly 400 workers.

‘Ideological’ change

Arjun Makhijani, president of the Institute for Energy and Environmental Research, said there’s a certain “ideological” element to changing the administrative limit because typically, the average worker dose at DOE facilities is far below statutory and even administrative limits.

In 2011, the International Commission on Radiological Protection issued guidance that workers should be exposed to a maximum 2 rem of radiation, averaged over a five-year period, and no higher than 5 rem of radiation in a single year.

In lieu of lowering the nation’s statutory limit from 5 rem, Makhijani said, like other industrial countries, in the United States nuclear facilities have opted to follow ALARA — a principle to keep exposure to radiation “as low as reasonably possible,” regardless of statutory and administrative limits.

“I do not believe there is any serious reason to loosen radiation limits operationally, because generally, these radiation administrative limits and ALARA has generally been met relatively comfortably,” Makhijani said.