A look inside a nuclear reactor

Dave Mosher is a science reporter who’s written for Scientific American, Popular Mechanics, National Geographic News and discovery.com. Throughout his career he’s watched humans and robots launch into space, flown over the North Pole to catch a total solar eclipse and toured a cutting edge nuclear reactor. He joins Hari Sreenivasan to discuss firsthand experience inside a nuclear reactor.


Dave Mosher is a science reporter who has written for newsanddiscovery.com.

Throughout his career, he's watched humans and robots launch into space, flown over the North Pole to catch a total solar eclipse, and toured a cutting-edge nuclear reactor.

He joins me now to discuss firsthand experience inside a nuclear reactor.

Most people don't know that we were decommissioning one or we had one to decommission.

Yeah, so, this is actually -- it's sort of a side tour to what I was actually going out to, NASA Glenn, which is in Cleveland, Ohio.

But NASA had a nuclear reactor -- its first, last, and only nuclear reactor.

It was called the Plum Brook facility.

And that's where they were investigating nuclear-powered rocket propulsion.

And it's funny because nuclear is so tied into the space race.

You know, you think about nuclear weapons, I mean, the reason we got to the moon is because we wanted to also have the ability to annihilate our opponents with nuclear weapons.

So there's a very strong parallel between those things.

So NASA built this facility to test nuclear-powered flight, or the principles of it, and, as part of that story, that lab also works with nuclear batteries -- you know, radioisotope power supplies, as they call them, or RPSs.

So, how far did we get in this pursuit of nuclear-powered rocket propulsion?

So, this is the earlier thread of NASA's sort of tie-in with nuclear.

And we got very far.

We made a nuclear-powered rocket engine.

It worked. It worked great.

It was twice as efficient as chemical rockets and is still twice as efficient.

And it would be a fantastic technology to travel through space with.

The problem is people are very spooked about nuclear technology.

They don't quite understand it.

It's very complex.

You know, I've been spent many days trying to understand it myself.

So we kind of petered out in, I think, the '60s, maybe early '70s, and that program was shut down.

What NASA has done now is they've transitioned to these radioisotope power supplies, which are nuclear batteries.

They don't like that term, but it's plutonium-238 from the Cold War.

This is a byproduct.

They put it in this heat-to-electric sort of device.

They put it on the spacecraft, and then you can have something last for 40 years in deep space.

That's how we have Voyager.

That's how we have Pioneer.

That's how we Cassini, which is still around Saturn.

And what is the facility like that they were decommissioning?

So, the facility they were decommissioning and the program that they were tying into was called NERVA.

I can't remember the exact acronym for that.

But it was very hollowed out by the time I got there.

They had ripped out all the display panels, all the reactor equipment itself because it was radioactive from years of use.

And it takes a very long time to scan every square inch of a facility like this, determine whether or not it can be put in a landfill or it needs to be casked and put into a mountain or a salt mine or something.

So it was very empty and very eerie-looking.

They were just about ready to tear it down, but I had the opportunity to tour this facility and see how they moved material from one part to the other and how they were exploring this idea of making a nuclear-powered rocket.

And people used to work there once.


There's really great archival photos, and that's part of the work I did for was showing, 'Okay, here's what it looks like now, and here's what it used to look like at its heyday when they were researching this technology.'

And there are some out there who still believe that we should pursue this.


You just run hydrogen through a nuclear core, it gets really hot, and it blows out of a rocket engine.

And it makes a really efficient power source.

But, of course, the risk is you're putting uranium or plutonium or whatever you want to use for that nuclear core on a rocket, and rockets can blow up.

Rockets can re-enter the Earth's atmosphere, and so that's a risk.

And not to mention the humans that might be sitting on top of the rocket, trying to get somewhere, if that explosion happened, along with all the humans for several miles around them, right?

That's right.

So, is there a sense in the people who guided you from this tour -- I mean, are they kind of sad that it's over?

Or this is just part of doing business?

This is the -- I mean, I think they must have had some sort of a 'hall pass' from the nuclear agencies to be able to have this place running, right?

Yeah, so, I think that there's definitely a lot of pride about the facility.

It worked, you know?

They broke a lot of ground.

They provided the basic science that allowed them to actually build and engineer a rocket-engine system that worked.

So there was a lot of pride from the people who were touring me around.

There's also a sort of disconnect, too, because it was back in the '50s and '60s and just its heyday had come and gone.

And so... But there was a sense that, 'Yeah, you know, we should --' This is still a really good technology, and it still works, and it's still one of the most efficient ways we can get into space.

Obviously, there are companies like SpaceX and Blue Origin, who are trying to figure out reusable rockets.

But in terms of deep-space travel, nuclear is a pretty good way to get to Mars and back without spending years and years stuck inside of, you know, a living-room-sized spacecraft.

[ Chuckles ] Dave Mosher.

Thanks so much for joining us.