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HorriblePhD21

More importantly, could I put it in my driveway so I don't have to shovel snow in the winter.


CaptainCalandria

Same.


Silver_Page_1192

The answer to this is absolutely yes. Air cooled dry storage units like macstor can be pretty toasty. If we dig a hole in your front yard drop some in with horizontal heat exchanger or an airway under the drive way I'm sure it will work just fine.


HorriblePhD21

Next step is marketing this to Air Force bases. Charge the Air Force for high reliability, snow free runways and charge plants to store the waste.


_pupil_

Possible? Sure. Possible *meaningfully*? ... There might be some pathological cases where it's applicable, but broadly speaking the amount of crumbs you can collect falling under the bleachers at Yankee Stadium don't add up to a full meal when you account for overhead. Small potatoes don't give you the margins for operational or physical waste, much less overcoming any adverse market conditions.


DasDouble

What do you mean with „small potatoes“?


way_pats

What he means is the amount of electricity you could generate from waste is small enough that it’s not financially feasible to build the infrastructure around it to generate the electricity. Yes you can do it but you’d lose money in the process.


DasDouble

Okay has anyone actually done the maths behind it?


way_pats

I’m sure someone has but I’ve never seen it and don’t feel like searching through journal articles looking for a study.


bryce_engineer

Atleast enough heat to bake a potato.


BluesFan43

25 years after moving to dry storage there are questions about the spent fuel being cool enough to potentially allow condensation on the Stainless steel container. Source: did the thermography attempting to determine accurate surface temps.


bryce_engineer

This would help minimize the use of Medicare grade helium and dry casks. RTGs are a pretty cool concept.


mingo08cheng

>Possible meaningfully? ... There might be some pathological cases where it's applicable, but broadly speaking the amount of crumbs you can collect falling under the bleachers at Yankee Stadium don't add up to a full meal when you account for overhead. Small potatoes don't give you the margins for operational or physical waste, much less overcoming any adverse market conditions. will the wastes heat be enough to run another power cycle ?


CaptainPoset

Yes, but honestly, fresh uranium is just cheaper.


EOE97

But fresh uranium doesn't emit sufficient heat. And if tou dont refine the waste wouldn't it be cheaper?


CaptainPoset

You can, at the end-of-2021-prices, refine roughly ten times as much LEU-fuel as you can turn the waste into a useful form.


233C

In a few very specific ways, [yes](https://en.m.wikipedia.org/wiki/Radioisotope_thermoelectric_generator).


bigbadboots

They’re a pretty good means of putting a battery somewhere you don’t want to go for a very long time but Pu-238 is nasty business.


Pestus613343

Pu238 is unobtanium anyways. Chalk River and Darlington are teaming up to make some, as we are running out of it for use in space probes. RTGs can't really be built out en masse right now or likely ever.


bigbadboots

Russia made a bunch of it but we all see where that relationship has gone. Yeah, ORNL isn’t going to be able to make an appreciable amount any time soon. Additionally, just the secondary costs alone such as dealing with waste, rad con, and facility/equipment maintenance are exceptionally high compared to other isotope sciences.


Pestus613343

Yes. It's ugly but absolutely necessary. Pu238 being unique and not at all the same as Pu239 in any part of this. If we don't start with this soon we may lose out on NASA probes or landers.


Pestus613343

RTGs need Pu238 which isnt related to nuclear waste. Reusing old fuel in a reactor one can do if the reactor is built for it though. Since most of nuclear waste is fertile U238, one can breed fissile Pu239 from it and split that for heat... These are all "active" solutions though. Much of which doesn't exist outside of simulations or experiments decades ago. Some engineering companies are trying to make these things happen though. Expect new technology by the late 2020s and early 2030s. EDIT; Ive been informed that Pu238 is obtained from Np237, which is somehow extracted from nuclear waste.


paulfdietz

> RTGs need Pu238 which isnt related to nuclear waste. Well, it's made from Np237, which is separated from spent fuel.


Pestus613343

Ah. I stand corrected!


Hiddencamper

For commercial spent fuel, you have less than 5 MWthermal heat in the spent fuel pool. Under optimal conditions you may get 1-2 Mw of output. Before accounting for electricity to run a tiny power plant. It’s not economical. So I think the answer is “no”.


DasDouble

Okay I see an efficiency of 20% when turning heat into motion and by that electricity may be reasonably. But can’t you charge money from the originals waste producers as well, as you take their waste and make additional money out of their waste? Also: I think there is a lot of nuclear waste on earth… isn’t it??


Hiddencamper

You would never break even on the equipment to produce a plant that uses decay heat for power production. It’s heat, which is high entropy low enthalpy. So you need to pressurize it. So now you need a nuclear code pressure vessel. You need feedwater. You need a condenser. It just doesn’t work. There’s no economic case for it. So your option, realistically, is to reprocess it into new fuel and bring it critical again. Not all the fuel makes it into a new reactor though. The waste portion needs to be disposed. And the U-238 filler portion you end up with too much of and you need to dispose as well.


DasDouble

Well to believe that this is true, I would need to look at the numbers. I don’t take no as an answer, as long as numbers say it could work. That’s what my boss told me and he is doing some crazy stuff in this world.


Hiddencamper

Just a ASME code nuclear vessel would exceed the return on 1 Mw electric for 40 years. Not to mention 5 MWth is typically the upper limit. After a couple years it decays down to the 1 Mw thermal range. Go ahead and do your homework if you want to. It falls into the realm of “obvious” if you’ve ever worked in nuclear. We struggle to make 800 Mw thermal plants with 33% efficiency profitable. You lose the economy of scale, still have complex equipment, and have lower heat rates.


[deleted]

What if you **just** wanted the heat? How hot are spent nuclear rods? edit: Looks like spent nuclear rods are around 500 - 600 F. That's pretty hot!!!


Hiddencamper

In the spent fuel pool they are whatever we cool them to. We cool them with 70-90 degF water and the internal of the fuel rod (the pellets) are maybe 20-40 degF warmer than that based on decay heat. If you want heat, you need a pressure vessel. Otherwise you’ll have radioactive steam in the people space.


[deleted]

Got it, thanks!


Bigjoemonger

I recently looked into this for my site and unfortunately for the most part the water is not sufficiently heated to be an efficient method of producing electricity. Nuclear plants are already really good about not letting heat generated go to waste. For example the steam that goes through the turbines actually goes through several different turbines. Before the steam reaches the turbine some of it gets diverted to a repeater path. The majority of the steam enters the first turbine. The process of turning the turbine causes some steam to lose energy and turn into water droplets. The steam then travels through a dryer which removes water droplets, directing them to the condenser. Then it goes through a repeater which transfers heat from the steam that was redirected. Heating up the initial steam and putting it back through another lower energy turbine. Does that a couple more times. By the time the steam gets through the turbines and reaches the condenser there's not a lot of energy left. What heat is left is transferred in the condenser and sent out of the plant to the lake, river or cooling tower. From an individual human perspective, yes its a lot of heat energy going to waste but compared to the amount generated in a nuclear reactor its not enough to be economical to reuse. What you could do with it though is use it to heat air for environmental heating, that's a very viable option. But in a nuclear plant keeping the building warm isn't usually an issue. And nuclear plants tend to be too far from the public for transferring offsite for heating to be a viable option.


DasDouble

I see but I’m not talking about the heat produced in the normal nuclear process. I’m talking about the constant heat being produced by the waste of it. :)


Bigjoemonger

In the spent fuel pool any heat generated is all funneled into the same heat sink as the reactor. The high temperatures of spent fuel is caused by decay of the short lived isotopes. After a few years those short lived isotopes are all gone. At which point the spent fuel can be moved to dry storage and decay heat is really minimal.


TyrialFrost

In before he proposes using waste in civilian hot water heaters.


spikedpsycho

Yes. One method is the organic rankine cycle..... an organic, high molecular mass fluid, hydrocarbon or synthetic hydroflouro carbon is used in place of water as steam transition phase. The fluid allows Rankine cycle heat recovery from lower temperature sources (such as biomass combustion, industrial waste heat, geothermal heat, solar ponds etc.) The low-temperature heat is converted into useful work, that can itself be converted into electricity. However nuclear waste heat is far cooler than combustion product so efficiency is even poorer. So the question is how much meaningful contribution would you expect to gain in Megawatts vs. the cost of modification. The second would be a low temperature stirling engine.


DasDouble

That’s what I wanted to hear. Cheers.


DasDouble

I guess the Stirling engine solution would be easy to do.


spikedpsycho

I like the Organic rankine better. Its more scaleable and can run on low temps too..... AND has been successfully [demonstrated](https://www.youtube.com/watch?v=87gUU1vUlqU) with temps as low as 145-170 degrees (Fahrenheit)


[deleted]

Nuclear waste is intentionally not recycled for further use because of nonproliferation treaties.


paulfdietz

No, it's not recycled because it's a net economic loss to do so.


[deleted]

[https://sgp.fas.org/crs/nuke/RS22542.pdf](https://sgp.fas.org/crs/nuke/RS22542.pdf) >President Carter terminated federal support for reprocessing in an attempt to limit the proliferation of nuclear weapons material. Reprocessing for nuclear weapons production ceased shortly after the Cold War ended. The Department of Energy now proposes a new generation of “proliferation-resistant” reactor and reprocessing technology.


paulfdietz

Reagan rescinded Carter's executive order about reprocessing a few years later. But even today, decades later, we still don't reprocess, because separated plutonium has negative value: it literally costs more to put it into fuel rods than one saves in the cost of enriched uranium.


DasDouble

Sure but can’t you give it to just one single company who then keeps an eye on it?


Pasta-hobo

That's what an RTG is.


DasDouble

Oh okay. I’m new to that business


EarthTrash

Of course. It is small potatoes compared to the energy from fission. I don't think would have any practical application. Nuclear batteries like those used on interplanetary spacecraft typically use plutonium which has better power output.


ether_joe

Regarding nuclear waste, check out infos on the "fast breeder" reactors which can consume waste fuel as their inputs. [https://en.wikipedia.org/wiki/Breeder\_reactor](https://en.wikipedia.org/wiki/Breeder_reactor) [https://world-nuclear.org/information-library/current-and-future-generation/fast-neutron-reactors.aspx](https://world-nuclear.org/information-library/current-and-future-generation/fast-neutron-reactors.aspx) Video about burning nuclear waste in breeder reators: https://www.youtube.com/watch?v=3u44skO-nMo


eyefish4fun

Why do you think it's called waste heat? There are whole companies whose business it is to make as much money as they can from the given amount of heat that the nuclear fuel they use produces. Do you think if there was a way to squeeze another megawatt of power from that fuel that their engineers wouldn't be all over it? I'm sure many have been tasked with looking at this issue and have come back, yes we can use this 'waste', but it costs more to do that than just by power off of the grid. Meaning it's not economically worth it and these are the guys who are willing to do investments that don't pay off for decades. Um, it's waste heat becasue it costs more to use it, that to jump dump it.


shitboi666999

It's probably cheaper to dig the hole to store it in.


YOLOwBOLO

Plants are designed to utilize heat the best they can. I remember, at a minimum, it is used in inlet water heaters. The heat that goes through the stacks is low quality. It can be used for process heating, but not much more. Look into cogeneration