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FlavivsAetivs12 karma

I've seen many pointing out, notably Dr. Suzy Baker, that nuclear has been really bad with social/environmental justice approach in the past and that needs to change. Sen. Cory Booker used this approach in New Jersey and got the ZEC's through there, appealing to minority communities in how fossil fuels disproportionately impacts them (IIRC the exact number is that air pollution impacts 71% of minority communities vs. 56% of low-income white communities).

Fundamentally a solar panel on every poor person's roof has a great public image while a monolithic concrete plant surrounded by a razorwire fence with military grade security is almost Orwellian in its imagery.

FlavivsAetivs7 karma

After the shutdowns of Three Mile Island and Duane Arnold this year, I believe we're down to 95 reactors. IIRC Oyster Creek brought us down to 97 last year.

FlavivsAetivs6 karma

Tidal/Wave has a long way to go before becoming viable. Geothermal is geographically limited.

All technologies produce waste, including wind and solar. Nuclear waste has the particular advantage in that it becomes radiologically relatively safe roughly about 300 years. Most of the talk about "thousands of years" actually has to do with the old hot particle theory of Plutonium (which has been proven false since 1975) and chemical toxicity of transuranics. After all the fission products decay in a few hundred years, it not really radiologically active enough to be a major concern.

Chemical toxicity never goes away, it lasts until protons decay (if that happens). Radiotoxicity does.

FlavivsAetivs6 karma

I've never heard that it's radiologically safe after 300 year. What new method makes it safe after 300 years? Rods are only good for 3 years in a reactor until they aren't a viable source of energy. So if it is even 300 years it's radiologically active for a 100 times longer then we even had use for it? That a lot of metal co trainers that do break down in our atmosphere.

The "300 years" number is the point where the fission products, the actual waste in the spent nuclear fuel, is mostly gone. Those are the most radiologically active particles, and thus have the shorter lifespan. Remember radioactivity and lifespan have an inverse relationship; the shorter the lifespan, the more radioactive it is.

It's not radiologically inert after that, but you could be exposed to the used fuel rod for a far greater period of time without receiving a potentially impactful dose. Most of what's leftover, other than Uranium (94 to 96% of nuclear waste is actually usable Uranium fuel) are transuranics, some of which are pretty radioactive, some of which aren't. Uranium itself is the only part which really lasts a long time, but Uranium is pretty much barely radioactive in comparison, and all Uranium emits is alpha particles, which bounce off the skin unless you ingest it. And even then you'd have to eat enough uranium to kill you by kidney failure before you'd come anywhere near getting a dangerous dose of radiation from it.

As for lifespan vs. storage, Reinforced Concrete dry casks are designed to last 100 years. Geological repositories take 10,000 years to fail assuming everything goes wrong. So the scientists who design this stuff know how to handle the material.

Uranium has 76,000,000 Mj/kg of energy vs. ~40 for high-quality Coal or Natural Gas. So it's a lot less material too, and therefore a lot less waste. You can get a lot more life out of fuel rods through various means as well - better cladding materials and burnable fission poisons allow some of the military's naval reactors to operate for 40 years on a single fuel load. With liquid fuel and a fast neutron spectrum, you can get even longer in some of the Generation IV designs. In both cases, more of the material is used up.

Just to be clear, my area is energy storage for renewables, not nuclear reactors. So if one of the nuclear physicists in this AMA thread corrects me, please defer to them.

What renewables have any radiotoxicities?

Well mining waste is usually a little bit radioactive but not enough to shake a stick at. But renewables usually have chemical waste impacts, mainly from mining but also from end-of-life disposal and even recycling will generate chemical byproducts.

Just because it hasn't been researched doesn't mean we shouldn't research it. The planet is covered in coastlines it would be stupid to not use a resource we are surrounded by.

I agree we should research it, I just said it has a long way to go.

FlavivsAetivs5 karma

Physics question for you: I have some background in physics at the nuclear scale (Physical Chemistry), and understand some of the basics of how nuclear interactions work (de Broglie, neutron cross-sections, etc.), but most of that is surface knowledge or stuff for chemistry, not nuclear physics.

So my question is, could you explain the difference between fast spectrum and thermal spectrum reactors?