Nuclear power plants are absolutely massive, and don't have big wins when it comes to the amount of material needed versus, say, solar. Here's a presentation touting the AP1000, which needs ~5x less concrete than Sizewell B's design (slide 11):

https://web.archive.org/web/20110722031413/http://www.nuclea...

At 2500kg/m^3 of concrete, and excluding the rebar, that's roughly 4.5W/kg of material. For Sizewell B, than's 0.9W/kg.

Meanwhile, a 300W solar panel weighs ~40 pounds, and even if it has massive mounting structures that weigh twice as much as the panel itself, that's 5-10W/kg.

A nuclear powerplant has a lifetime of 40-60 years. Solar panels have warranties of 25 years, but often operate a decade or more longer. Nuclear does not have an "exceptionally long lifetime" in comparison.

Nuclear power plants built in the past were massive.

That doesn't mean we have to still build them. Technology marches on - we have improved designs. Micro-reactors solve a lot of issues - including transmission loss/electrical grid fragility/diversification of generation.

I was hopeful about this, but sadly, it's just not true. NuScale is a great example. They're failing because they can't hit the cost numbers on their pilot project, and note that this project is cited on DoE land that did not require any form of political negotiation with voters or anti nuclear activists.

I'd be ecstatic if someone figures out how to change the ROI on nuclear, but I'm no longer optimistic about it. Just saying the words "small modular reactors" isn't a solution.

> Meanwhile, a 300W solar panel weighs ~40 pounds, and even if it has massive mounting structures that weigh twice as much as the panel itself, that's 5-10W/kg.

Someone's forgetting capacity factor-- 10 to 30%.

I also don't think looking at mass-- and primarily concrete-- is the best way to measure resource usage.

> A nuclear powerplant has a lifetime of 40-60 years. Solar panels have warranties of 25 years, but often operate a decade or more longer. Nuclear does not have an "exceptionally long lifetime" in comparison.

A nuclear powerplant might have a design lifetime of 40 years, but we're finding that there is little issue with operating them to 80 years and beyond with maintenance and retrofit programs.

> Someone's forgetting capacity factor-- 10 to 30%.

Which puts solar and nuclear on completely the same scale...

If you don't think mass is a good way to compare, and you're concerned about resources, please suggest the metric that will somehow make nuclear look good. Because that concrete is not very recyclable. So the 95% recyclability of solar panels is making them look a looooot better than nuclear once we move beyond mass to something more nuanced.

how does it put them on the same scale? nukes are online 80%+ of the time.

I think the capacity factor of nuclear is much closer to 95% or higher these days, but call it 100% for simplicity

PV capacity factor is typically 16%-28% [1], which adjusting the W/kg, gives us:

Solar PV: 0.8W/kg - 2.8W/kg, capacity factor adjusted (with supporting infrastructure weighing 2x the panels, a total spitball)

Nuclear: 0.8W/kg - 4.5W/kg, capacity factor adjusted, two different modern reactor designs, concrete only.

With this ratio, higher numbers mean better power densities, and the ranges completely overlap between nuclear and solar PV. Nuclear isn't achieving orders of magnitude better power density over solar.

[1] https://www.eia.gov/todayinenergy/detail.php?id=39832

You're still not adjusting for actual life (solar ain't making nameplate power 15 years in, for instance).

No one claimed an order of magnitude better. Nuclear looks somewhat more sustainable than renewable, and it can do some things renewables can't.

We should be doing both.

It's just so funny to read comments on here.

How can one even imagine a space-faring civilization powered by wind mills?

I suggest this is a problem with your imagination, not a problem with wind turbines.

Nuclear is a perfectly cromulant technology for space vehicles. It is not a good technology to power cities on earth in the 21st century however.