Nuclear Power

A cooling tower from an unfinished power plant in Washington
Photo: Greg Dunlap/CC BY (Flickr)

Nuclear Power

Safety first. Now.

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What's at Stake

The Fukushima disaster of 2011 showed what can happen when a nuclear power plant's safety systems fail. The US nuclear industry responded with familiar reassurances that it can't happen here.

We know better. Nuclear accidents can happen here—but they don't have to.

Enforcing fire and earthquake regulations, addressing flood risks, and safer storage for nuclear waste are just a few of the ways we can help prevent nuclear accidents.

Since its founding in 1969, UCS has served as a nuclear safety watchdog. We focus on ensuring that existing reactors meet current safety standards set by the Nuclear Regulatory Commission (NRC) and that the NRC enforces those standards.

You can helpCheck out our action alerts, visit our citizen resource center, and speak up for better-regulated nuclear power in the United States. Together we can make this important low-carbon energy source as safe as possible.

Safety Issues

Control room in a nuclear power plant

Photo: UCS/Dave Lochbaum

While the probability of a nuclear power accident may be small, the human and environmental consequences of a radiation release can be catastrophic.

Nuclear accidents happen

Floods, fires, and earthquakes can combine with aging facilities and error-prone humans in devastating ways. Adequate understanding of these issues, along with significant safety upgrades and consistent oversight, can help safeguard the US public.

Learn more about preventing nuclear accidents >

Waste should be safely stored

Nuclear fuel emits radiation long after it’s done powering a reactor. Securing a long-term waste repository—and transferring fuel currently held in cooling pools to dry casks—is essential for long-term public safety.

Learn more about handling nuclear waste >

Security matters

Reactors and waste storage facilities make inviting targets for terrorists—but adopting robust security measures could help prevent an attack.

Learn more about nuclear power security >

The NRC must do more

The Nuclear Regulatory Commission (NRC) is charged with regulating commercial nuclear power in the United States. UCS has been advocating for better NRC enforcement of safety regulations for decades—but more must be done to make nuclear power safer.

Learn more about the NRC and other safety actors >


nuclear technology

Photo: XYNO/

Boiling water with fission

The basic principle behind a nuclear reactor is simple: the heat produced by a controlled nuclear reaction is used to create steam pressure that drives a power-generating turbine.

But the technology required to implement this principle efficiently and safely is enormously complex. The fission chain reaction must be maintained at the correct rate and quickly adjusted or stopped when necessary. Water temperature and pressure must be carefully controlled. And elaborate, redundant cooling systems are needed to prevent nuclear fuel from overheating, which can lead to a meltdown.

Learn more about how nuclear power works


Different reactor designs approach these requirements in different ways. About two-thirds of operating US reactors are pressurized water reactors (PWRs); the rest are boiling water reactors (BWRs). Both BWRs and PWRs heat ordinary water with nuclear fuel, driving turbines that generate power.

New designs

Several new reactor designs have been proposed in the United States and elsewhere. These include “small modular reactors” which proponents claim are safer and more cost-effective, but which introduce their own issues. Thorium-fueled reactors have also been proposed, though they lack clear overall advantages.

Regional Work

nuclear technology

Concerned about nuclear safety in your neighborhood? Assembled by experts at the Union of Concerned Scientists, our interactive nuclear power database details the safety record of every commercial nuclear reactor in the United States. You can find comprehensive, up-to-date information on fire protection problems, flooding and earthquake risks, recent near-misses, and other nuclear safety issues affecting individual plants and reactors near your community—or view how these issues affect the nuclear fleet as a whole.

View the database >

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