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Comment by sargun | Hacker News Reader

So, I believe this has been under research since ~2015 at Microsoft. Bill Gates had invested in nuclear power and introduced the idea.

It seems like a good idea. One problem that pops out is that even with a large, geographically distributed data center, you’re talking about ~250MW. In order to get the same level of resiliency the grid has you need to have some redundancy. That gets really complicated. If the unit fails, and you need to start a 125MW power draw from the grid. Which…isn’t practical.

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When I was studying nuclear in 2010 Gates was employing my professor as technical advisor for standing wave reactors, so he’s been interested in nukes for a while. Modular reactors were cool theoretical ideas at the time similar to 3D printers, crazy to see how far they’ve come.

That's surprising considering that most modular reactors are just smaller versions of the ones we have now.

Of course, all the ratios are wrong is you scale everything and you might not get to criticality. So it is a completely different design with different manufacturing techniques for many parts. It is like a model of an airplane also wouldn't fly without adjustments to many parts which of course changes various ratios.

I'm aware of that, but to get to normal sized reactors they first built smaller prototypes that had outputs that were much closer to the modular reactors that are now being investigated. So they're not really theoretical.

I would have thought that SMR design would be more inspired by nuclear submarines and such which are already small, not necessarily large power stations, but admittedly I don't know anything in this area.

Nuclear subs are a lot more exotic, you need to go from 0-60 in a few seconds, so they make fuel plates instead of rods so it really bumps up the neutron population quickly.

There’s no need to adjust criticality that rapidly at a generating station.

Also, they tend to use much higher enrichment ratios on the fuel from what I have read. I guess that is all for the fast power output regulation as you write. Stunning technology and a security nightmare, just imagine a nuclear sub bumping into a click in territorial waters of a not-so-friendly nation and making the area uninhabitable.

How are they different from the reactors in US Navy submarines?

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