RTGs for civilian/home use?

[Seret]

RTGs are sealed. Nothing gets out except some gamma rays.

You say that like it isn't a problem.

[Winter Man]

That's why you use bloody large ones buried under many a metre of concrete, and distribute them to every 10,000 people (although obviously not an RTG due to the inefficiency).

[Seret]

That's why you use bloody large ones buried under many a metre of concrete, and distribute them to every 10,000 people (although obviously not an RTG due to the inefficiency).

So a large-scale CHP plant fuelled by radioactive decay instead of fission? If that was any more practical than a fission based plant I think we'd have them already.

The thing with CHP is that electricity is valuable, heat much less so. So the ideal plant will have a high electrical efficiency. In fact currently heat is so low value that it's generally treated as waste after it's used to generate electricity.

[Winter Man]

Nope, a small scale regular plant fueled by decay instead of fission. And maybe a little bit of fission. The point being it needs far less input (all you need to do is drop a steam pipe down into it to thieve its heat) so you can have loads of them, unguarded besides the aforementioned concrete.

[Seret]

Nope, a small scale regular plant fueled by decay instead of fission. And maybe a little bit of fission. The point being it needs far less input (all you need to do is drop a steam pipe down into it to thieve its heat) so you can have loads of them, unguarded besides the aforementioned concrete.

Couple of problems with that. How do you turn the heat into electricity? RTGs use thermocouples, which are very low efficiency. Likewise driving a steam turbine with the heat from radioactive decay would also be extremely low efficiency.

Generally speaking with a heat engine to get decent efficiency you need your input temps to be as high as possible. You're not going to get either a large quantity of heat, or get it at a high enough temperature from radioactive decay to be very effective. Just look at geothermal power, which is indeed powered by radioactive decay. The mass and volume it uses to amass enough heat to do a useful amount of work is rather large! Granted you can compress that somewhat by selecting highly active fuels, but you're still not talking about an energy density that would be competitive with current technology.

[Winter Man]

Except you're missing that a large quantity of warm water can have its energy transplanted into a small quantity of high temperature steam with a Ranque-Hilsch tube (via some kind of gas for transmission, 134a's probably about right), which would drive a turbine efficiently.

[Seret]

I'm not familiar with the Ranque-Hilsch tube, but the wikipedia page seems to say that efficiency is lower than a regular heat pump. You can't magically extract high-grade energy out of a low-grade source with a greater efficiency than just using a higher temp source to start with. If that was possible, all the world's energy problems would be solved.

[Winter Man]

I'm not familiar with the Ranque-Hilsch tube, but the wikipedia page seems to say that efficiency is lower than a regular heat pump. You can't magically extract high-grade energy out of a low-grade source with a greater efficiency than just using a higher temp source to start with. If that was possible, all the world's energy problems would be solved.

Didn't say it was more efficient than using a higher temperature source. That'd be bloody ridiculous, and possibly over-unity. Even if you could get the same efficiency you wouldn't solve the world's energy problems, because they run much deeper than efficiency of extraction at the point of burning it. What it'd do is create a distributed grid system rather than a centralised one, preventing large-scale blackouts or brownouts.

[Kryten]

If you want to look at RTGs for grid power, you really need to be comparing the energy output from the RTGs to the energy output from the nuclear reactor/s you need to produce the RTG fuel in the first place.

[Winter Man]

This is why I don't like forum discussions, no one reads back a page

I'm not on about RTGs, I'm on about a small nuclear reactor little to no moving parts. Granted I couldn't find and link to it at the time, but I've found it now - linkymagig. It doesn't run on strontium/plutonium, but on mildly enriched uranium hydride, which is a self moderating material. Those are what I'm on about distributing.

[nuclearpower13]

You may want to google the Cadillac World Thorium Fuel (WTF) Concept Car.

That looks amazing. Can I have one!

[carde]

Cancer rates would skyrocket as well as spontaneous abortions and lots of really deformed and sick babies would be born.

That's why it will never find its way into the world of commercial application, even if non-fissile isotopes are used..

There is not enough radioactive material available in the world to cause noticeably large increases in background radiation (granted, we are doing our best with mined coal, but...).

Also, mutations are not actually easily generated using radiation. Cancer, to some extent, yes, as an example a deadly dose or radiation has a 1 in 10 chance of causing cancer (of course, you are dead from the direct radiation poisoning in that case, but let's say you get 1% of a full-body ld50 dose, you now have once extra chance in 1000 of getting cancer during your life)

At least if the Linear no-threshold model is true.

[Seret]

What it'd do is create a distributed grid system rather than a centralised one, preventing large-scale blackouts or brownouts.

You can do that with current technology. Microgeneration at household level using solar and microCHP, EVs as household-level storage, with the next layer up being larger CHP, embedded wind and small hydro, district heating, etc. Much of this is already being implemented.

[Winter Man]

And none of it with the same energy density as nuclear (also, not household level, community level).

[Seret]

And none of it with the same energy density as nuclear (also, not household level, community level).

TBH, if you're talking about mini fission reactors it's an idea that has been kicked around a bit, and has merit. Some big companies have mooted containerised reactors that could be plugged in to the grid as far down as the 10kV level. Even if the technology is sound however, I think they'd struggle with regulatory approval and public opinion. How many regular folks would be happy with a nuclear reactor parked at the end of their road, no matter how safe it actually was. It was assumed in the 50s that by now reactors would be powering everything, from aircraft and trains, to our homes. Obviously that hasn't happened. It's telling the companies that are trying to flog tiny SMRs are targeting their product at customers like the military, instead of civilian power companies (or even disaster relief).

[lajoswinkler]

You say that like it isn't a problem.

It's not. Plutonium-238 is a weak gamma ray emitter.

Nope, a small scale regular plant fueled by decay instead of fission. And maybe a little bit of fission. The point being it needs far less input (all you need to do is drop a steam pipe down into it to thieve its heat) so you can have loads of them, unguarded besides the aforementioned concrete.

We don't have that much Pu-238. It's a very expensive isotope.

There is not enough radioactive material available in the world to cause noticeably large increases in background radiation (granted, we are doing our best with mined coal, but...).

Also, mutations are not actually easily generated using radiation. Cancer, to some extent, yes, as an example a deadly dose or radiation has a 1 in 10 chance of causing cancer (of course, you are dead from the direct radiation poisoning in that case, but let's say you get 1% of a full-body ld50 dose, you now have once extra chance in 1000 of getting cancer during your life)

At least if the Linear no-threshold model is true.

Read my post again. I was not talking about the radiation and that was actually the point of my rant.

You're wrong about mutations. They're exactly the stuff that would be abundant. Embryonic development is incredibly delicate and sensitive to this stuff.

[Seret]

It's not. Plutonium-238 is a weak gamma ray emitter.

Fine, but what's the acceptable safe level of gamma ray emission for a domestic setting?

[Tarrow]

Except you're missing that a large quantity of warm water can have its energy transplanted into a small quantity of high temperature steam with a Ranque-Hilsch tube (via some kind of gas for transmission, 134a's probably about right), which would drive a turbine efficiently.

I assume by 134a you mean the R134a that's commonly used in car air conditioning systems. refrigerators etc? You do not want to expose that particular substance to any significant temperature. I've always been both amazed and horrified that it was ever OK'd for use by the public for any purpose at all. It thermally decomposes (at a distressingly low temperature) to a mix of hydrogen fluoride and carbonyl fluoride gases. The former is corrosive enough to be used in etching glass, the latter is functionally a fluorine based version of the trench warfare agent phosgene.

If it came to a choice of being in the same room as heated R134a or swimming to the bottom of a nuclear reactors spent fuel pool - I'd be reaching for my swim goggles. It'd be less immediately lethal.

Edited October 10, 2013 by Tarrow

[frizzank]

Radioactive power has gotten a bad rap for its self. It is a safe and reliable source of power that we should utilize.

http://web.mit.edu/newsoffice/2012/prolonged-radiation-exposure-0515.html

Radioactivity has been a big buzz word ever since the first atomic bomb was detonated. I am guessing since most nuclear big news items have been atomic bombs and exploding power reactors, its given the small stuff a bad name.

In the simplest terms ionizing radiation, in any form, is not good for you. The more you get the worse it is.

But we commonly use materials and compounds that are many times more toxic than low levels of radiation.

Diesel fumes are carcinogenic.

http://scienceblog.cancerresearchuk.org/2012/06/14/diesel-fumes-definitely-cause-cancer-should-we-be-worried/

Does that stop anyone from fueling up at the pump, Nope!

AND!

Coal Ash Is More Radioactive than Nuclear Waste - "the fly ash emitted by a power plant carries into the surrounding environment 100 times more radiation than a nuclear power plant "

http://www.scientificamerican.com/article.cfm?id=coal-ash-is-more-radioactive-than-nuclear-waste

Where is the outrage for this? Well we have been using it for the better part of a century so I guess its OK?

As for dirty bombs more people would be injured in the explosion than the radiation afterwords. It would be much more effective to fill it with mercury or some other toxic, readily available agent. Its a weapon of fear, not effectiveness.

http://www.stratfor.com/weekly/20100421_dirty_bombs_revisited_combating_hype

Edited October 10, 2013 by frizzank

[lajoswinkler]

Radioactive power has gotten a bad rap for its self. It is a safe and reliable source of power that we should utilize.

http://web.mit.edu/newsoffice/2012/prolonged-radiation-exposure-0515.html

Radioactivity has been a big buzz word ever since the first atomic bomb was detonated. I am guessing since most nuclear big news items have been atomic bombs and exploding power reactors, its given the small stuff a bad name.

In the simplest terms Radiation, in any form, is not good for you. The more you get the worse it is.

But we commonly use materials and compounds that are many times more toxic than low levels of radiation.

Diesel fumes are carcinogenic.

http://scienceblog.cancerresearchuk.org/2012/06/14/diesel-fumes-definitely-cause-cancer-should-we-be-worried/

Does that stop anyone from fueling up at the pump, Nope!

AND!

Coal Ash Is More Radioactive than Nuclear Waste - "the fly ash emitted by a power plant carries into the surrounding environment 100 times more radiation than a nuclear power plant "

http://www.scientificamerican.com/article.cfm?id=coal-ash-is-more-radioactive-than-nuclear-waste

Where is the outrage for this? Well we have been using it for the better part of a century so I guess its OK?

As for dirty bombs more people would be injured in the explosion than the radiation afterwords. It would be much more effective to fill it with mercury or some other toxic, readily available agent. Its a weapon of fear, not effectiveness.

http://www.stratfor.com/weekly/20100421_dirty_bombs_revisited_combating_hype

All cool, but instead of radiation, use radioisotopes.

[RuBisCO]

1. Plutonium 238 is EXTREMELY expensive, we don't even have enough reactors producing the fuel to meet limited demand for space probes! There is no way there could be any civilian use with its present price tag.

2. Strontium 90 maybe cheaper, but it last for a shorter time period and needs a lot more shielding, the safety risks are too high.

3. Americium 241 may be common enough in household smoke detectors, to scrounge enough together for an RTG is also going to cost a pretty penny!

[frizzank]

All cool, but instead of radiation, use radioisotopes.

Nope, for clarification by radiation i meant to say ionizing radiation.

[lajoswinkler]

Fine, but what's the acceptable safe level of gamma ray emission for a domestic setting?

If we're talking about the doses an RTG would give you in your room, it would not be a good idea. If it's in your basement behind lead bricks, you're ok.

They'll never ever enter commercial citizen usage. It's extremely expensive per unit of energy given off.

Nope, for clarification by radiation i meant to say ionizing radiation.

You've mentioned "the fly ash emitted by a power plant carries into the surrounding environment 100 times more radiation than a nuclear power plant"

and "As for dirty bombs more people would be injured in the explosion than the radiation afterwords"

[3_bit]

I think they would look cool on the set of a sci-fi movie. I'll give you an internet cookie if you can find me a fictional movie with a fictional spacecraft that has them showing.

[magnemoe]

I think they would look cool on the set of a sci-fi movie. I'll give you an internet cookie if you can find me a fictional movie with a fictional spacecraft that has them showing.

For an spaceship they might make some sense, we use them in probes downside is that a spaceship would use much more energy even then not under power.

Would make it more like an APU who provides backup and start up power so you can start the main reactor and would be able to run basic systems then ship is parked and unmanned.