A US court rejected environmental groups’ challenge that the Nuclear Regulatory Commission (NRC) acted arbitrarily by failing to discuss in greater detail the aging or climate-related inputs in its severe-accident risk analysis (SAMAs).
The NRC was sued by Beyond Nuclear and the Sierra Club over a 2024 rule changing the number and scope of environmental issues considered during the renewal process.
The petitioners argued that the NRC and industry did not adequately consider how aging components and climate change would affect the risk of severe accidents involving reactor-core damage. “Of greatest concern is the extension of operating the licenses of the country’s already aging nuclear power plants well beyond the initial 40-year licensing period and the NRC’s refusal to view the more extreme conditions caused by climate change as risk factors to future safe operation.”
The nuclear power plant accident risk review was unanimously upheld by three judges of the US Court of Appeals in the District of Columbia on July 21, 2026.
The court rejected the claims that the nuclear regulator’s updated process for renewing licenses for commercial nuclear reactors failed to adequately consider the effects of climate change and aging plant components.
The court said the agency’s review was reasonable under the National Environmental Policy Act (NEPA) while upholding NRC’s challenged rule.
“We find no basis to conclude that the Commission acted arbitrarily by failing to discuss in greater detail the aging or climate-related inputs in its severe-accident risk analysis. We also reject the Environmental Groups’ related challenge to the Commission’s treatment of SAMAs,” the court said.
The court said the Commission’s treatment of the effect of aging on accident risks was reasonable. The Commission acknowledged the risk that aging reactor components can increase the likelihood of severe accidents. But it explained that this risk did not meaningfully affect its environmental assessment.
The environmental groups commented that the Commission should have considered “the effects of climate change on accident risk” and stated that climate change can heighten accident risk by increasing storm frequency—specifically noting severe windstorms—and by worsening flood-related hazards.
The Commission said several sections of the Generic Environmental Impact Statement (GEIS) address “climate change and its possible environmental effects.”
To organise and streamline its environmental reviews, the Commission relies on a Generic Environmental Impact Statement (GEIS). The Commission first issued a GEIS in 1996, revised it in 2013, and in 2024 finalised the revision which was the point of contention.
As part of its “holistic assessment of the environmental impacts of severe accidents”, the NRC acknowledged the types of climate-related events the environmental groups are concerned about: “high winds, floods, tornadoes, and other external hazards.” But it explained that those risks generally contributed much less to plant risk than seismic and fire events, and it considered external events as part of an all-hazards assessment.
The Commission informed the court that existing safety regulations supported its conclusion that further study of climate change’s effect on storm frequency was unnecessary.
The Commission explained that “adaptation of nuclear power plants to climate change is addressed through . . . existing regulations” requiring certain plant features to withstand natural phenomena without losing their safety functions. Instead, it reasonably invoked relevant regulations as one reason why the GEIS need not separately assess the possible impact of climate change on storm frequency.
In essence, the Commission declined to expend further resources on an attempt to model the future effects of climate change on severe storms. It did so because its assessment based on current data showed the risks from such storms to be minimal compared to other risks, because its overall analysis already included a large buffer that could account for these types of uncertainties, and because regulatory mechanisms exist to address the issue should circumstances change, the order read.
The decision is a loss for environmental groups who say that the NRC should have done more to evaluate harm.
Beyond Nuclear said “the court’s decision effectively allows the US Nuclear Regulatory Commission to ignore future (or even the clearly present) harsher and more violent climate change impacts on the safe operation of nuclear power plants, to which the NRC is presently awarding license extensions out to 60, 80 and even possibly 100 years.”
NRC renewed licenses for 13 reactors in 2025. In a Facebook post, December 23, 2025, the NRC talked about the process to ensure safety of older nuclear reactors. The post said that NRC inspect systems and evaluate safety programs and renew licenses only when the commission is confident the reactor can operate safely for 20 more years.