This article is part of a series covering Idaho National Laboratory (INL). Scroll visited different projects from INL, and this publication covers their Advanced Test Reactor that is located west of Idaho Falls.

Deep in the desert of Idaho, far from any civilization, lives a lone nuclear reactor with a blue glow.

“(Right now) you’re seeing the Cherenkov glow, the blue glow,” said Joseph Campbell, a communications specialist at the Advanced Test Reactor. “You’ve seen in the Simpsons … (the) green glow. I don’t know where they got the green from, it doesn’t look like that.”

The ATR uses the neutrons generated to test the durability of its products. It is stored in water due to its low melting point.

The ATR uses the neutrons generated to test the durability of its products. It is stored in water due to its low melting point. Photo credit: Isabelle Justice

The Advanced Test Reactor (ATR) is unlike a standard nuclear reactor. All nuclear reactors generate heat and neutrons, and while standard nuclear reactors use the heat generated to create electricity, the ATR uses the neutrons generated to test the durability of its products.

“The core (of the reactor) is arranged in these 45-degree arcs,” said Campbell. “Forty of these make up the core, and they’re … arranged in (this) cloverleaf shape. Each one of (the) 19 plates has the fuel element (uranium) inside of it. And then it’s coated with pure aluminum on the outside.”

Since aluminum has a low melting point, the ATR is kept at a low temperature of 180 degrees Fahrenheit and is cooled using water.

The Advanced Test Reactor is located at the Idaho National Laboratory Site west of Idaho Falls.

The Advanced Test Reactor is located at the Idaho National Laboratory Site west of Idaho Falls. Photo credit: Isabelle Justice

Water is also used in canals throughout the reactor to shield the radiation from those working in the laboratory.

“This is gamma radiation, and it’s not dangerous for us to be here because there’s the water,” said Campbell.

The blue glow explained

According to Campbell, when the reactor is shut off for regular cleaning, all the pent-up neutron energy reacts with the water’s electrons and causes the water to move faster than the speed of light. This reaction creates a blue glow.

“It’s kind of the equivalent in light of a shock wave you get when a plane breaks the sound,” Campbell said. “The plane exceeds the speed of sound, and the sound waves … form a cone. When that cone hits the ground, we hear it as a shock … or sonic boom of light is the best way to describe it. No other test reactor can do … that.”

According to Campbell, one main function of the ATR is to test the durability of products that are sent to them by NASA, the Navy and other large entities.

All products see a certain amount of damage over time and the ATR speeds up that process by hitting the product with the neutrons it generates to see how well the product holds up.

The products are placed in the canal and the experiment runs for one cycle, about 60 days, 24/7. After the experiment is done, the products are removed and inspected for damage. Then the reactor is cleaned out and prepared for another cycle.

Isotope production

Another main function of the ATR is that it creates isotopes.

One of the isotopes that it produces is plutonium-238, which NASA uses to make Radioisotope Power System space batteries.

“The plutonium-238 we’re making right now will end up in the Dragonfly mission … which is pretty cool,” said Campbell.

The Dragonfly mission is part of NASA’s New Frontiers program, and will launch in 2026 to explore Titan, Saturn’s icy moon. This moon contains organic compounds and water similar to Earth and could provide insights into how life developed on our planet.

However, plutonium-238 is different from the more common plutonium-239.

“Usually, when you hear about plutonium, we’re talking about plutonium-239 … It can be used as a reactor fuel. It’s also called for use in weapons, so it’s very tightly controlled. We don’t make (plutonium-239),” said Campbell.

Joseph Campbell, a communications specialist at ATR, speaks with Scroll reporter, Kenzie Fox.

Joseph Campbell, a communications specialist at ATR, speaks with Scroll reporter, Kenzie Fox. Photo credit: Isabelle Justice

Another isotope that is produced in the ATR is cobalt-60, which is mainly used in cancer treatments as “finely focused rays of gamma radiation,” according to Campbell.

The future of ATR

The ATR Scroll visited was the third generation, which began operation in 1967. The first generation, the Materials Test Reactor, started operating in 1952. The second generation, the Engineering Test Reactor, started operating in 1957.

After operating for over 50 years, there is talk about building a fourth-generation reactor. The only setback is cost.

“These are very expensive machines to build and maintain because they’re all (built) one at a time, there’s no mass production,” Campbell said. “The longer you maintain it, the more expensive it is to keep running. Just like … houses … get to the point where it doesn’t make sense unless there’s some historical value to it. Sooner or later, it’s smarter … to build that new one.”

Campbell describing the Advanced Test Reactor model.

Campbell describing the Advanced Test Reactor model. Photo credit: Isabelle Justice

Campbell said that if the reactor was able to convert to a digital control system, then it may have better precision, and save money in the long run.

“If I was betting, I’d be betting on (getting a) generation four (ATR),” Campbell said.