radiation

July 31 (Asia Today) — Nearly half of the North Korean defectors tested last year after living near the Punggye-ri nuclear test site showed chromosomal changes above a minimum detection threshold, South Korea’s Unification Ministry said Friday.

The ministry cautioned, however, that the findings did not establish a connection between the individuals’ radiation exposure and North Korea’s nuclear tests.

The Korea Institute of Radiological and Medical Sciences conducted biological radiation tests on 59 defectors from eight cities and counties near Punggye-ri in North Hamgyong Province.

The group included former residents of Kilju, Hwadae, Kimchaek, Myonggan, Myongchon, Orang, Tanchon and Paekam.

Tests found stable chromosomal abnormalities above the minimum detection level in 26 people, or 44.1% of those examined.

Stable chromosomal abnormalities can reflect radiation accumulated from birth until the date of testing. The measurement can include exposure from natural sources, medical procedures and work environments.

The institute said the test cannot determine when the exposure occurred or identify its source.

Age, smoking, alcohol use, heavy metals and other factors can also affect the results, it said.

Researchers conducted an additional test for unstable chromosomal abnormalities among the 26 people whose initial readings exceeded the detection threshold.

That second test, which is more useful for identifying relatively recent radiation exposure, produced above-threshold results in six people.

Older age complicates findings

The average age of the 26 people with elevated results was 52.8, or 13.2 years older than the average age of the 33 participants whose results remained within the normal range.

The group with elevated readings had also spent less time near Punggye-ri than the group with normal results.

Researchers found differences in drinking-water sources as well. Piped water was more common among participants with elevated readings, while a greater share of the normal group reported using water from mountain streams.

The findings did not demonstrate that the 26 participants were exposed to radiation from underground nuclear explosions, the institute said.

“There are limitations to interpreting the stable chromosome-aberration test results as exposure caused by past nuclear tests,” the institute said.

It said the participants with elevated readings were older on average and had several possible contributing factors, including medical radiation exposure.

The institute recommended continued health examinations and long-term monitoring for participants whose biological dose assessments exceeded the minimum detection level.

It said the results should be interpreted carefully because of possible confounding variables.

More environmental information would be needed to conduct a reliable assessment, including radiation measurements around former residential areas, drinking-water tests and radioactivity measurements from local food, the institute said.

No cancer cases identified

The Unification Ministry also provided detailed medical examinations to five defectors whose radiation tests conducted from 2017 through 2024 had produced readings above the detection threshold.

The ministry said no confirmed or suspected cancer cases were identified among the people examined during the latest program.

South Korea conducted similar examinations of defectors from areas near Punggye-ri in 2017, 2018, 2023 and 2024 after concerns were raised about possible radiation leakage from the test site.

Across tests conducted since 2017, researchers have identified chromosomal abnormalities in some former residents of the region, but they have not established that North Korea’s nuclear tests caused them.

North Korea carried out six underground nuclear tests at Punggye-ri between 2006 and 2017.

The country has not allowed international nuclear inspectors to conduct an independent environmental assessment at the site.

North Korea has maintained that its nuclear tests were conducted safely and did not release radioactive material into surrounding communities.

— Reported by Asia Today; translated by UPI

© Asia Today. Unauthorized reproduction or redistribution prohibited.

Original Korean report: https://www.asiatoday.co.kr/kn/view.php?key=20260731010011734

The Nuclear Regulatory Commission is proposing to eliminate a foundational safety principle that has for 50 years minimized the radiation people in the United States are exposed to and that has been adopted around the world.

Currently, facilities such as nuclear plants, hospitals or academic institutions that use radioactive materials must ensure radiation exposures are kept “as low as reasonably achievable” — the ALARA principle. The NRC proposal would abandon that philosophy while keeping a separate standard on maximum radiation exposure.

The two standards have worked together in radiation safety. Dose limits set the maximum amount of radiation the public and radiation workers can be exposed to, while ALARA kept radiation exposure as low as practical under those limits. Research shows radiation exposure increases a person’s chance of getting cancer, a risk that increases as the dose increases.

The dose limits are not changing. But the NRC, which regulates civilian nuclear energy technologies and radioactive materials, now wants to replace ALARA with a “graded approach” that includes several actions facilities must take depending on the potential dose of radiation to workers. More rigorous radiation protection measures would be required when approaching dose limits to ensure they aren’t exceeded.

This comes as President Trump attempts to quadruple domestic nuclear energy production because of surging electricity demand amid a data center and artificial intelligence boom. Reforming the NRC is one way Trump is trying to speed up nuclear reactor development. He instructed the federal agency in an executive order last year to “adopt science-based radiation limits.”

The Energy Department, which oversees national energy policies, has already stopped using ALARA. The NRC expects to finalize its radiation protection regulations in the coming months.

NRC Chairman Ho Nieh said the commission is not lowering the bar on safety.

“We’re just removing the ambiguity,” he said in a call with reporters. “But the standard for exposure to workers and the public, those are not changing. We’re just putting in place greater clarification.”

Nieh doesn’t expect major changes within the nation’s existing fleet of large, traditional reactors. But companies designing and building new, smaller reactors could move faster with a clearer picture of the radiation protection requirements, he said.

Could radiation doses creep higher?

The NRC said radiation exposure limits are set well below levels associated with health effects, and it expects remaining standards and industry practices to keep radiation doses far below the limits. There’s incentive to do so — it’s more expensive and time-consuming to work in areas with higher radiation because access must be restricted and more surveys are required.

The nuclear industry’s trade association agrees with the NRC.

“We will always continue to look at what can we do to reduce the dose to workers, and maintain our doses to the off-site public as low as possible,” said Doug True, chief nuclear officer at the Nuclear Energy Institute. “It’s not like we’re just going to throw open the doors and let everything run up to the limits.”

ALARA created a “moving target” for regulation, said Justin Friedman, a nuclear energy consultant who previously spent three decades at the U.S. Department of State. Getting rid of the rule would allow NRC scientists to make more rational decisions about appropriate levels of manageable risk, he added.

Some experts question cutting ALARA

Edwin Lyman, director of nuclear power safety at the Union of Concerned Scientists, cautions that some parts of the NRC proposal could raise permissible radiation doses in certain cases, while still staying below the cap. Lyman highlighted a proposed revision to radionuclide emissions standards, in particular.

Radiation exposure to the general public is limited to 100 millirem per year. A typical dose of radiation from a chest X-ray is 10 millirem.

The NRC wants to increase its radionuclide emissions standards from a conservative, 10 millirem per year dose to 25 millirem per year, based on a hypothetical person living in a house at the property line for a nuclear plant.

The NRC says actual doses to the public would remain far lower because, in reality, people live farther from nuclear sites and benefit from dispersion in air and water.

The NRC should improve, rather than eliminate, ALARA, Lyman said, to protect the public and workers. ALARA has become a political target because some people mistakenly believe radiation exposures have to be as low as possible no matter the cost, Lyman said. In reality, it allows trade-offs.

Katy Huff, a former U.S. assistant secretary for nuclear energy, said in some cases, the requirement may be challenging to regulate. Additional clarity would improve the regulatory environment without harming the public, added Huff, a professor and department chair at the University of Wisconsin-Madison.

However, Huff said, she thought the NRC was going to clarify what “reasonably” means in ALARA without scrapping it. She said she’s open to being convinced the graded approach will be just as effective.

One expert sees a mixed bag

The National Council on Radiation Protection and Measurements, chartered by Congress to provide independent scientific guidance, has not formally weighed in yet. Council President Kathryn Higley said she likes some things in the 180-page document but thinks others are problematic.

The NRC should look at the whole picture for managing risk, she said. For instance, if a worker at a nuclear power plant were to enter an area where airborne radioactive materials are present, in keeping with ALARA, they might wear full personal protective equipment with respirators, said Higley, professor emeritus at Oregon State University. That makes them move slower, potentially subjecting them to heat stress that could hurt them more than a low dose of radioactivity, she said.

A concern with the proposal, Higley said, is that it maintains the current occupational dose limit for adult radiation workers at 5 rem, or 5,000 millirem, per year. With ALARA in place, the average dose to workers has been well below that cap.

The International Commission on Radiological Protection recommends an occupational dose of 2 rem per year on average. The NRC previously found it wasn’t justified to match that, because workers were exposed to less than that and changing regulations is costly.

Higley said the U.S. may need to align with the international community if ALARA is going away.

McDermott writes for the Associated Press.