Growing up in Miamisburg, Ohio, the word atomic was just part of the local soundtrack. Mound Labs — the old Monsanto nuclear research facility — sat right in town, and plenty of my classmates had parents who worked there. We knew they handled radioactive materials, but the message was always the same: it’s safe, it’s controlled, and the people working there know exactly what they’re doing.

So nuclear energy was never something I feared. I just didn’t spend much time thinking about the science behind it — mostly because my degree is in political science, not the kind of science that involves neutrons, isotopes, and decay chains.

Then I rolled into Thermopolis, Wyoming.

Three old guys (their chosen title, not mine) wandered over to help me set up the RV. When they heard I was headed to Arco, Idaho, they practically ordered me to visit EBR‑I — the Experimental Breeder Reactor. So I did. And I’m glad I listened.

EBR‑I looks unassuming from the outside, but inside, it feels like stepping into the moment the world changed. Construction began in 1949, and on December 20, 1951, this little reactor in the Idaho desert became the first place on Earth to generate usable electricity from atomic energy, lighting four 200‑watt bulbs in its control room.

The next day, it powered the entire building.

But the real magic of EBR‑I wasn’t the electricity — it was the experiment behind it.

Most nuclear reactors run on uranium‑235, which makes up less than 1% of natural uranium. It’s the “good stuff,” but it’s rare and expensive to enrich. Once the U‑235 is used up, the fuel is considered “spent,” even though over 90% of the energy potential is still locked inside the leftover uranium‑238. Breeder reactors were designed to solve that problem.

Before any of the breeding magic happens, everything starts with uranium‑235. That’s the isotope that actually splits — fissions — when it absorbs a neutron. When a U‑235 atom breaks apart, it releases a burst of energy and several high‑speed neutrons. Those neutrons are what keep the chain reaction going, but they also do something else: some of them go flying out into the surrounding uranium‑238, which makes up the vast majority of the fuel.

When U‑238 absorbs one of those stray neutrons, it doesn’t split — instead, it begins a transformation that eventually turns it into plutonium‑239, which can be used as fuel. So the U‑235 is the spark plug that starts the engine, and the U‑238 is the big fuel tank waiting to be converted into something useful.

Here’s the simple version:

• U‑238 absorbs a neutron → becomes U‑239
• U‑239 decays into Np‑239
• Np‑239 decays into Pu‑239
• Pu‑239 can be used as fuel in another reactor

It’s like a sourdough starter that feeds itself.

Why Pu‑239 Matters:

This was my big question, and our guide — a young woman who clearly loved her job — explained it beautifully.

Pu‑239 is valuable because:

• It’s fissile, meaning it can sustain a chain reaction.
• It releases more neutrons per fission than U‑235.
• It lets reactors extract far more energy from the same amount of mined uranium.
• It reduces long‑term waste because more of the original material gets used.

In other words: Pu‑239 stretches the uranium supply dramatically. That’s why countries like France, Japan, Russia, India, and China continued breeder reactor research long after we stopped.

U‑235 is the spark that starts the reaction, but it’s scarce. To get enough for a reactor, you have to enrich uranium — a complicated, expensive process. And as mentioned previously, once the U‑235 is gone, the fuel is considered spent even though most of the energy is still trapped in the U‑238.

Breeder reactors flip that equation. They don’t rely on U‑235 as the main act — they use it as the ignition that unlocks the energy in the U‑238.

Our guide walked us through the control room, the heat‑exchange systems, the sodium‑potassium coolant loop, and the turbine that turned all that heat into electricity. She explained it in a way that made sense even to someone whose scientific training stopped at “rocks for jocks.” (???)

She also showed us the shielding:

• four feet of concrete,
• four feet of water,
• or three feet of lead.

And then she pointed to the 36 layers of leaded glass separating us from a storage area that once held radioactive materials. Seeing that glass in person makes the concept of radiation protection very real.

So…Are We Still Using Breeder Reactors?

One thing I wondered after leaving EBR‑I was whether the U.S. still uses breeder reactors today. After all, the science behind them makes a lot of sense.

The answer surprised me. We don’t have a single breeder reactor operating in the United States today. 

Not one. We built several experimental ones — including EBR‑II right next door — but every U.S. breeder project has been shut down.

Meanwhile, we still have 93 commercial nuclear reactors running at 54 power plants across the country, quietly generating almost 20% of America’s electricity. So nuclear power is very much alive — just not the breeder kind.

Why We Walked Away From Breeder Reactors

This is where my political science background kicked in, because the reasons aren’t purely scientific.

Back in the 1950s, everyone thought we’d run out of uranium‑235. Breeder reactors were supposed to solve that by turning the abundant U‑238 into Pu‑239. But then a few things happened:

• We discovered huge uranium deposits in the U.S., Canada, and Australia. Suddenly, uranium didn’t look scarce at all.
• Pu‑239 raised proliferation concerns.
  It’s excellent reactor fuel — but it’s also the material used in nuclear weapons.
• Breeder reactors are more complex and more expensive to build and maintain.
• After Three Mile Island and Chornobyl, anything “experimental nuclear” became politically radioactive.

So the U.S. quietly stepped away from breeder technology, while other countries kept going.

Just down the road, Arco proudly advertises itself as the first city in the world powered entirely by nuclear energy. In 1955, the BORAX‑III reactor lit up the whole town — briefly, but enough to make history. The locals still wear that badge with pride.

I walked into EBR‑I knowing almost nothing about nuclear physics. I walked out understanding:

• • Why breeder reactors matter
  • Why Pu‑239 is valuable
  • Why U‑235 scarcity is a real challenge
• and why countries like France and Japan leaned into this 

Most of all, I walked out with a sense of awe. This little building in the Idaho desert wasn’t just a lab — it was the birthplace of an idea that could have reshaped the world’s energy future. 

And for someone with a political science degree, that’s saying something.