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TBPN · 3 min · Jul 23, 2026

Spent nuclear fuel retains most of its potential energy

Seth Cohen says spent reactor fuel retains about 97% of its potential energy, and the U.S. has 100,000 tons of it. He frames reprocessing as an energy resource, not just waste management.

Seth Cohen

Co-founder, Mavria

Co-founded Mavria, which designed the Nuclear Lifecycle Campus; previously DOE chief counsel for nuclear policy.

  • John Coogan, Host · Co-host, TBPN

    Co-founded Soylent and Lucy; OpenAI bought his show TBPN in April 2026.

  • Jordi Hays, Host · Co-host, TBPN

    Founded Branded Native; co-founded fintech Capital, which Rho bought.

About this segment

Seth Cohen says spent reactor fuel retains about 97% of its potential energy, and the U.S. has 100,000 tons of it. He frames reprocessing as an energy resource, not just waste management.

From “AMD CEO Lisa Su Live on TBPN”, Jul 23, 2026. Watch the full episode

“About 97% of the potential energy remains in a fuel rod after it's done and has to be taken out of a reactor.”
Seth Cohenat 56:10 · TBPN56:10

Takeaways

  1. Commercial spent fuel retains roughly 97% of its potential energy.
  2. About 100,000 tons of spent fuel fit on one football field.
  3. Its remaining energy exceeds Saudi Arabia's proven oil reserves fourfold.

In this episode

Full episode
  1. 39:05Most AI compute is lost to poor scheduling and low utilization3:54
  2. 1:37:06Claude is helping AMD accelerate hardware development3:59
  3. 1:40:58Different workloads need different kinds of compute4:23
  4. 48:48Reinforcement learning scales when experiments give clear feedback3:06

  5. 54:20Spent nuclear fuel retains most of its potential energy3:18

  6. 9:00World models should learn broadly before task-specific tuning3:54Up next
  7. 29:58Design customers need on-prem models to protect product IP2:55
  8. 1:32:43AMD must speed up roadmaps built years in advance2:25

Transcript

From the transcript TBPN publishes with the episode.

  1. 54:25

    It's good to be among friends. Yeah. But when so what we did with nuclear waste was actually we shifted the narrative and went from Yucca Mountain being the only place where you could put aisles of waste completely off limits Mhmm. To where we are now. 27 governors applied for this program that Adam and I started called the Nuclear Lifecycle Campus. And there are I I can't tell you the exact number, but it fits on two hands. The number of governors currently fighting to host the full back end fuel cycle.

  2. 54:56

    So would that be There could be one additional nuclear waste storage plan. Three. Three.

  3. 55:01

    Okay. One of three. And these are gonna be cities Yeah. Yeah. By the way, that that if everything goes according to plan, will be competitive with our major metropolitan areas because we're gonna reindustrialize

  4. 55:12

    Wait. Yeah. Yeah. Cities. I feel like you're just talking about a hole in the ground. I need, like, two guys to protect it. What what else is going on around a nuclear waste protection site?

  5. 55:19

    Well, so it's not know, to take a step back Yeah. Is it too late to offer up my backyard? The ultimate EMB. No. I I I think what so first off, when we talk about nuclear waste, that's real we we have this strange idea, and it's probably the Simpsons' fault. Oh, yeah. Glowing. Yeah. I have seen the blue glow of a spent fuel rod, which is actually very, very cool. Mhmm. But there's no green goo. Yeah.

  6. 55:48

    Right? So almost all com all waste in the in The United States is medical stuff. It's like gloves because some person went behind a wall and put pressed an x-ray button. Oh, interesting. I didn't realize that. By volume that's That

  7. 56:00

    falls in there. You think of it as like the pellets, but it it's really anything that touches that. So there needs to be a whole processing facility for that. That makes sense.

  8. 56:07

    Yeah. That's most. But the second is commercial spent fuel. Yeah. And just so we're clear, it's it is fuel, but it's not spent Mhmm. By any means. About 97% of the potential energy remains in a fuel rod after it's done and has to be taken out of a reactor. Mhmm.

  9. 56:22

    So why why take it out if there's if 90% of the the rod's potential is still still there? Mhmm.

  10. 56:30

    So there are two main isotopes, one of which is getting split and and used up. So And as that potential goes down, the ability to sustain a fission reaction also goes down. And then you accumulate byproduct material. So it's everything from plutonium to some really, really interesting stuff. So, but like before we get there, right, it's that let's talk about like that remainder. Mhmm. Right? So natural uranium is around point 9% of this really good isotope. Most commercial fuel is three and a half to five. When you're done with a rod, it's around point seven. We have a 100,000 tons of this stuff.

  11. 57:08

    And this is from the lifetime of the commercial fleet. Which, by the way, that fits in one football field. Yeah. Like, six But years of also should be repurposed in some way. Yeah. Yeah. That there is four times more energy sitting on those pads outside of our reactors than Saudi Arabia has in its proven oil reserves. That's that's actually crazy. But that's not where the money is.

  12. 57:30

    Yeah. So where is the money? Where are you spending your time? How much time is in DC, lobbying? Like, the old stuff.