The burst dam in Ukraine is causing problems for the Zaporizhzhia Nuclear Power Plant : NPR

Geoff Brumfiel

A major dam in Ukraine has collapsed. The failure is a grave blow to the region's water supply and is putting further stress on the Zaporizhzhia Nuclear Power Plant.

ARI SHAPIRO, HOST:

In Ukraine, a catastrophe is unfolding. A dam burst holding back a reservoir the size of Utah's Great Salt Lake. A huge torrent of water is now careening downstream, flooding villages and towns. This is also creating big problems upstream, including at the Zaporizhzhia nuclear power plant.

NPR science correspondent Geoff Brumfiel is here to talk more about what the loss of this dam means. Geoff, begin with just explaining what happened at the site of the dam.

GEOFF BRUMFIEL, BYLINE: This dam sits right on the front lines, with Ukrainian forces on one side and Russian troops on the other. And for months, it's been battered by artillery fire and explosions. Then, in May, the reservoir controls flooded with spring rainwater. It seems like no one was on the Russian side to open the dam's gates up and let some of that water out. So the water level got so high it was spilling over the top of the dam. And then, this morning, it appears that the dam was almost completely washed away. Russia blames Ukraine for attacking it. Ukraine blames Russia for blowing it up. But given all the stress it was under, it's also possible it just collapsed.

SHAPIRO: So the dam was holding back this huge reservoir, and the Zaporizhzhia nuclear power plant is right on the shores of that reservoir. What are the implications for the plant?

BRUMFIEL: Yeah. Well, nuclear plants create a lot of heat, and that heat needs to be dissipated to avoid a meltdown. And this is why nearly all nuclear reactors are located near lakes or the ocean. Zaporizhzhia used this reservoir, and now the reservoir is draining. The good news is the plant's reactors have been shut down for months. They are still hot, but they're a lot less hot than they were in operation. I spoke to Jacopo Buongiorno, a nuclear engineer at MIT. He says, right now, they only need about a fire hose worth of water to keep all the reactors cool.

JACOPO BUONGIORNO: The bottom line is that they're not going to run out of that amount of water anytime soon.

BRUMFIEL: The plant has its own cooling pond, and that should stabilize things for a while. But, you know, Ari, this dam is gone. The water's not coming back. And so I think this creates a real challenge in the medium to long term.

SHAPIRO: So there's not an immediate threat, but could this eventually lead to a nuclear meltdown?

BRUMFIEL: In theory, yes, it could, though it would not be the sort of thing that happened at Chernobyl. That, of course, was the world's worst nuclear accident, which also happened in Ukraine. These reactors are much more modern and much safer. But just like the dam, this plant has been battered by war. It's endured shellings, blackouts, fires, a brutal, brutal Russian occupation and now this. It's hard to know kind of which straw could break the camel's back. But, I mean, this is one of the bigger straws, I would argue, that could happen to the reactors.

SHAPIRO: And the reservoir was, of course, being used for more than just the nuclear plant. What other problems could this cause for southern Ukraine?

BRUMFIEL: Yeah. Towns on both sides of the reservoir used it for drinking water. I spoke to David Helms, a retired meteorologist with the U.S. government who's been tracking what's going on at the dam very closely. He guesses roughly around a million people are going to need to find water from somewhere else.

DAVID HELMS: It'll have to be trucked in, which - you know, for a million people, that's a huge challenge.

BRUMFIEL: Beyond that, this reservoir fed around a thousand miles of irrigation canals. This was one of the largest networks in Europe. Those canals watered fields of vegetables and cash crops like rapeseed. So going into a hot summer and beyond, losing this reservoir is going to have a huge economic and humanitarian impact for Ukrainians on both sides of the front lines.

SHAPIRO: NPR's Geoff Brumfiel, thank you.

BRUMFIEL: Thank you.

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