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Nuclear Power: A Double-Edged Sword

Updated: Sep 6, 2022

The summer of 2022 was brutal. But it could have been much worse without fission, a technology with complications and vast potential.

Russia’s invasion of Ukraine has raised concerns about nuclear power. Early on, Russian troops occupied the Chornobyl (Ukrainian spelling) nuclear reactor; when they left five weeks later, the facility was missing critical equipment and software. More recently, fighting around the Zaporizhzhia Nuclear Power Plant in eastern Ukraine has intensified, raising fears of a radiation leak.


Fears of catastrophic radiation leaks are well-founded. The Chornobyl disaster in 1986 made the possibility of a nuclear meltdown a reality. The Fukushima Daiichi accident in 2011 showed that even the best-made plans aren’t always enough. And now, with Zaporizhzhia in the Russo-Ukrainian war’s crosshairs, a disaster of a different kind is frighteningly very real.


For this post, I explore the basics of nuclear power and weigh in on its greenness.


Nuclear energy 101

The heart of nuclear energy is uranium, an element present throughout nature. Named after the planet Uranus, this element has three natural forms (isotopes): U-238, U-235, and U-234. Only U-235 is suitable for nuclear fission (splitting atoms).

The first step to obtaining this isotope requires extracting uranium from the ground. This is done by mining or in-situ drilling. When mined, uranium ore is crushed and mixed with chemicals that dissolve uranium from the ore (tailings). When drilled, uranium deposits are injected with special chemicals, and the freed uranium is pumped to the surface. Processing continues with more chemicals, filtering, and drying to produce uranium oxide concentrate, better known as yellowcake.

Yellowcake is 99 percent U-238 and 0.7 percent U-235. For U-235 to be a usable fuel, reactors require a concentration of between 3 and 5 percent. So, the next step is enrichment, which requires turning yellowcake into a gas by mixing it with fluorine. Because U-238 is heavier than U-235, but only by 1 percent, the gas is spun at high speeds in centrifuges. Thousands of rotations later, the final product is a gas of mostly U-235.

From there, the enriched uranium is processed into pellets and stacked into rods, and the rods are bundled into groups called fuel assemblies. It’s now ready to power the core with seemingly endless quantities of energy.


Spent nuclear fuel

At around the five-year mark, the spent fuel assembly is removed from the reactor and held in pools of steel-reinforced concrete. Called wet storage, these pristine pools circulate water around the spent nuclear fuel (SNF), drawing off heat and enabling it to slowly decay to safer radiation levels. Another option is dry storage. After cooling in pools, the SNF is loaded into casks—massive containers of multilayered concrete, steel, and lead. Filled with inert gas, they’re designed to resist tornadoes, floods, projectiles, and other scenarios, while keeping SNF safely in check. The casks are stored on-site or transported to interim storage sites to await their final resting place: permanent underground repositories. Unfortunately, none currently exist—in the US or internationally.

That last sentence reveals one of the primary problems plaguing nuclear energy since the 1950s, when the first commercial reactor became operational: What to do with the SNF? Hot and highly radioactive, it will stay this way for eons, decaying first into radium, then radon, polonium, and finally lead. In 1992 Congress mandated the US Department of Energy to develop a repository at Yucca Mountain in New Mexico. Though dry and desolate, this spot became a political hot potato between those for and against nuclear energy.


The Nuclear Regulatory Commission, an independent nuclear safety regulator, recently released a multiyear study on SNF storage. The commission determined that storing SNF in on-site pools and at regional interim storage sites has “small” impacts on people, land use, air quality, and the environment and will continue to be safe for hundreds of years.

As of mid-2022, the US had 83,000 metric tons of SNF in wet and dry storage in 34 states.


Is nuclear energy green?

Typing this question into a search browser reveals this topic’s many complexities. Nuclear energy can certainly be considered the antithesis of all things green because of the energy needed to mine and process uranium, the tons of concrete and steel used to construct reactors, and the never-ending SNF conundrum.


Even so, modern-day regulations, many of which came into force in the 1970s, have cleaned up this industry, making it safer and less taxing to the environment. Before these regulations, the leftover effluent (raffinate) from processing uranium ore was released back to nature untreated. Similarly, the tailings ended up in towering piles near mines. Uncovered, these wind-swept and rain-soaked piles scattered radon far and deep.

But there are other parts to nuclear energy that have few, if any, emissions. Reactors bombard uranium with high-energy particles called neutrons. When these particles collide with uranium atoms, they cleave them in two, releasing energy in the form of radiation and heat. This heat boils water, and the resulting steam spins turbines to produce electricity. And none of this—the fission, the steam, the electricity—would be possible without the humble uranium pellet.


The size of a thimble and weighing no more than a tablespoon of butter, an enriched uranium pellet is equivalent to 1 ton of coal. Just 1 gram can supply electricity to 727 households for 24 hours. Another way to examine its heating potential is with British thermal units (BTUs), which measure the heat needed to raise a pound of water by 1°F. As a point of reference, 1 BTU is equivalent to the heat from a wooden match. Here’s a comparison of BTUs in 1 pound of various types of heating fuels:

  • Wood pellets – 8,250

  • Dried wood – 8,600

  • Anthracite coal – 12,500

  • Number 2 fuel oil – 19,500

  • Natural gas – 20,000

  • Uranium – 1.25 billion

Uranium packs an enormous punch. It also produces fewer carbon dioxide emissions than coal, natural gas, and petroleum combined:

No easy answer

Nuclear energy accounts for a fifth of electricity generation in the US, yet it’s responsible for less than 1 percent of carbon dioxide emissions. This is an important fact to remember, especially after this summer, with its thousands of broken daily high temps. Or the megadrought that continues to beleaguer the western and southwestern US. Or the four once-a-1,000-year flooding events that struck places like Death Valley. Other parts of the world experienced similar weather events.

This is just a glimpse of what will only get worse.


There’s no denying that nuclear energy comes with some serious baggage. But so do fossil fuel–fired power plants. Put simply, we can’t have our cake and eat it too. Between now and 2100, the world population, now at 7.9 billion, is estimated to increase by 3.1 billion. This growth will exacerbate demands on world food and energy producers, increasing carbon dioxide and other greenhouse gas emissions.


Nuclear energy isn’t THE solution to climate change, but it’s certainly part of it.


Here’s a final thought. For the past five decades, nuclear energy has prevented about 70 gigatons of carbon dioxide from being emitted into the atmosphere. Imagine what this summer would have been like had it not been for nuclear power.


Further reading

Backgrounder on Dry Cask Storage of Spent Nuclear Fuel.” US Nuclear Regulatory Commission, March 2021.

Energy and the Environment Explained: Where Greenhouse Gases Come from.” US Energy Information Administration, June 24, 2022.

Galindo, Andrea. “What Is Nuclear Energy? The Science of Nuclear Power.” International Atomic Energy Agency, August 31, 2022.

Monthly Energy Review, May 2022.” US Energy Information Administration, May 25, 2022.

Storage and Disposal of Radioactive Waste.” World Nuclear Association, 2022.

Uranium Quick Facts.” Depleted UF6 Management Program Information Network, no date.


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