Safely taking apart a retired radioactive nuclear plant

HostWe spend years and billions of dollars building these massive nuclear plants to be as tough as possible. But eventually, they get old and we have to turn them off. The problem is, you can’t just bring in a wrecking ball and a bulldozer when the very walls and pipes are still glowing with energy.

HostHow do you even start taking apart a building where the stuff inside can hurt you without even touching it?

GuestIt starts with a lot of waiting. You don’t just walk in the day after the lights go out and start swinging hammers. When a plant shuts down, the first thing people do is move the fuel. That fuel is the hottest part. It goes into these deep pools of water right there on the site. Those pools do two things. They keep the fuel from getting too warm and they act like a thick blanket that blocks the invisible energy from reaching the workers. The fuel has to sit there for years, sometimes even a decade, just to cool down enough so it can be moved into big concrete and steel cans. Only after that fuel is tucked away can the real work of taking the building apart begin.

HostThat sounds like a lot of standing around. Why can't we just pour a bunch of concrete over the whole thing, bury it, and leave it alone for a few hundred years?

GuestPeople actually used to do that, but it creates a huge problem for whoever has to deal with it later. If you just bury it, the metal and concrete can still leak into the ground or the water over time. Nowadays, we want to leave the site as clean as a park. To do that, you have to scrub every inch. The toughest part is the big steel tank that held the fuel. For decades, that tank was hit by tiny particles moving at high speeds. Those particles actually changed the metal itself. It isn’t just covered in radioactive dust; the atoms in the steel have changed. The metal is now active all the way through. You can’t wash that off. You have to cut it into pieces, but you can’t have a person standing there with a saw.

HostSo how do you cut up a giant steel tank if no one can get close to it? Do you just use really long tools?

GuestIn a way, yes. We use water. It sounds strange, but water is one of the best tools we have. We fill the whole area around that tank with water and then lower robots into it. Water is great at blocking that invisible energy, so a person can stand at the edge of the pool and look down through the clear water while they drive a robot. These robots have big saws or high-pressure water jets mixed with grit that can slice through thick steel like it's nothing. By doing all the cutting underwater, any dust or tiny bits of metal get trapped in the water instead of floating away in the air where someone could breathe them in. The water stays in a closed loop, getting cleaned by filters, while the robot packs the cut-up pieces of the tank into special boxes at the bottom of the pool.

HostI’m still worried about all that water. If it’s trapping all that hot dust, doesn’t the water itself become a giant puddle of danger? It seems like you’re just making one big problem into a bunch of smaller, wetter problems.

GuestThat's a fair point, but it's much easier to manage a tank of water than a cloud of dust. We run that water through filters that work like the ones in a home fish tank, just way more heavy duty. The filters catch the bad stuff, and then we eventually clean the water so well it could be poured away safely. The real trick is how we sort the solid stuff. Most of a nuclear plant is just normal stuff. Think about all the office chairs, the light bulbs, and the miles of concrete in the outer walls. About ninety percent of the whole plant isn't dangerous at all. We spend a huge amount of time testing every single piece. If a piece of concrete is clean, it gets crushed up and used to fill holes in the ground or make new roads. We only have to worry about that last small bit of material that was right next to the fuel.

HostSo it’s basically the world’s most careful spring cleaning. You’re just sorting the trash from the stuff that needs to go to a special landfill.

GuestThat's exactly what it is. We call it waste streams. You have the stuff that's barely active, like a worker's gloves, which goes in one type of box. Then you have the metal from the heart of the plant, which goes into much thicker, stronger boxes. Every single box is tracked. We know what's in it, how hot it's, and where it's going. The goal is to get to a point where the whole building is gone. We even dig up the dirt underneath to make sure nothing leaked over the years. We keep digging and testing until the sensors show that the ground is just as clean as the woods nearby. In the end, what was once a massive power plant becomes just a flat, green field of grass.

HostThe sensors have to be the final word because we can't see or smell the danger ourselves.

GuestThe most amazing part is that once the last bit of the old tank is packed away, the invisible energy in the room drops so low that you can finally walk across that floor with nothing more than a hard hat.

HostThe wrecking ball finally gets its turn once the invisible glow is gone and the grass can grow back.