Another poster already mentioned that transuranics and other such byproducts tend to be very dense, so a swimming pool can in fact hold tens of thousands of tons of spent fuel. Also, ‘nuclear waste’ is a generic catch-all term that includes less radioactive material, compared to ‘spent fuel’ which is just the really ‘high-grade’ material.

The part about not needing enrichment is worth discussing, but we do have solutions to that already. There are entire classes of reactors dedicated to not producing weapons byproducts or needing enrichment using the same processes capable of generating weapons-grade material. The reason we see reactors that can make these materials so often is because many of the early reactor designs (many still in use today) were explicitly selected for use by the US government during the early days for their dual-use ability to make plutonium for nuclear weapons. Examples of proliferation-safe designs include molten salts and integral fast reactors, but there’s an engineering experience chicken-and-egg problem - they don’t get built very often because we don’t have experience building them. A new design like this will face the same challenges.

TL;DR: Combining a particle accelerator and a nuclear reactor to turn Uranium-238 into Plutonium-239, which then fissions. The reactor itself is subcritical, so if the proton accelerator turns off then the reaction stops.

The main advantages of the system claim to be ‘increased efficiency of fuel use’ since the uranium doesn’t need to be enriched, the ability to burn long-lived nuclear waste, as well as the system being passively safe.

The first point strikes me as an odd thing to focus on, since all nuclear reactors are already very fuel efficient, and if you want maximum efficiency then breeder reactors exist already, which produce more fissile material than they consume - you can’t get much more efficient than that. Fast breeder reactors are also great for burning up nuclear waste too, but they never really took off because, well, there isn’t actually much nuclear waste to use, precisely because typical reactors are already very efficient: A reactor might consume one ton of fuel per year. You could fit all the spent nuclear fuel humanity has ever used into a single swimming pool. I mustn’t be too critical though - any attempt to close the fuel cycle is good, I just don’t think it’s a really pressing issue. Lastly, being passively safe is cool and all, but almost all new reactor designs are, and attaching a particle accelerator to a nuclear reactor sounds like an expensive way of doing it.

All of that being said, I’m always interested to hear about new reactor designs, so I guess we’ll see how it goes.

The MSP430 is just the chip I happen to use at work, if you’re not convinced you could try looking for an actual ultra low power chip, I found the STM32U0 at 70uA/MHz and the STM32U5 at 16uA/MHz in the first result.

Even ignoring selecting a more efficient micro, a smattering of tiny ceramic caps will buy you a few hundred microjoules for bursts. If you’re already operating at 2V you can get a 6V rated 100uF cap in a 1210 package - and that’s after considering the capacitance drop with DC biasing. Each one of those would buy you 200 microjoules, even just one ought to be plenty to wake up for a few tens of milliseconds every second to get a reading from some onboard peripheral (as an example) then go to sleep again.

For sure, you’re not going to be doing any heavy lifting and external peripherals could be tricky, but there are certainly embedded sensor use cases where this could be sufficient.

It’s more than you think. I work with the MSP430 microcontroller, which is capable of a sleep current of 40nA @ 2V, full active mode at 140uA/MHz with all onboard peripherals turned on. With this you could achieve almost a 20% on-off ratio with a 1MHz clock, or keep it in active mode all the time at ~150kHz, which is sufficient for many embedded sensor applications.