Nuclear Propulsion - The best way for space travel

Auqakah · 2002-12-22 14:14:36

What? Nuclear power isn't zero-emission. What are those cooling towers for, hm? Releasing water-vapour into the atmosphere? Thats an emission. And many of the reactors that are chugging along today are too old, and in need of replacement. I don't see nuclear power (of any sort) as a viable source of energy down here on Earth.

However... it is currently the only viable and cheap source of power for space exploration. And therefore... I say onwards, with nuclear reactors powering our way.

soph · 2002-12-22 14:40:43

we have to get our power from somewhere. fossil fuels wont last forever. hydrothermal power and geothermal power are pretty limited. wind and solar power are unreliable...what other alternative do we have?

Auqakah · 2002-12-22 14:51:45

Australians, cycling little bikes in power plants to turn the coil/magnet inside the magnet/coil.

No, joking aside (and apologies to any Aussies reading... you were just the first people to come to mind, so take that as a compliment ) there are alternatives. Wind farns aren't exactly unreliable, when used with solar farms. If it isn't sunny, then its probably windy. So you use a combination; solar power in the summer, wind farms in the winter. Geothermal power and tidal power pick up the slack, perhaps with very very few nuclear power stations as back-up's in case of emergencies.

My main concern, though, about nuclear power is thermal pollution - which seems to be something nobody ever thinks of, or talks about. One reactor creates a massive amount of heat; NuclearSpace, if I may ask, do you know how much that is? I'm curious, but I haven't been able to dig up any info on it.

mauk2 · 2002-12-27 14:01:38

Auqakah:

One reactor creates a massive amount of heat; NuclearSpace, if I may ask, do you know how much that is? I'm curious, but I haven't been able to dig up any info on it.

Well, I'm not NuclearSpace, but I'll take a stab at answering this.

As a rough rule of thumb, take the electrical output rating of a nuclear plant and triple it for the thermal output. So, a 1 gigawatt nuclear powerplant has a thermal output of about 3 gigawatts, and the other 2 gigawatts is radiated as waste heat.

While that may sound like a lot, humans today have no hope of effecting the energy budget of the Earth. Solar energy impacts the Earth 24 hours a day at a rate of roughly 1.368 kilowatts per square meter.

The Earth is 6,378 kilometers in radius, so doing a little math:

A = Pi R^2

Pi = 3.14
R = 6,378,000 meters.

A = 3.14 * 40,678,884,000,000
A = 127,731,695,760,000 square meters * 1.368 Kilowatts =
174,736,959,799,680 kilowatts

The earth receives roughly 175 trillion kilowatts of solar energy every second of every day, and has for millions of years. Our measly little 1000 kilowatt nuclear power plants won't affect that energy budget at all. But our coal plants sure can.

This example shows why the threat of CO2 is so potent. To get a few gigawatts of useful electricity we are tinkering with the thousands of terawatts of insolation.

And before you triumphantly state that Solar power is the answer to our needs, I will calmly point out that until we have tremendous breakthroughs in either transmission or storage, no it isn't. If you are a utility, the first calm night will black out your entire customer base. This ain't a happy thing.

Nuclear Power is Good.

Preston · 2002-12-27 15:15:23

A nuclear plant will generate more like 2 gigawatts of thermal power. The issue of thermal pollution as actually one of a much more local concern than global warming. The idea is a nuclear plant is placed right next to a river or lake so that it can easily get rid of excess heat, and the temperature increase above the normal level changes the ecology negatively. I don't know any details.

Bill White · 2002-12-27 16:49:17

Okay - suppose there are Rickover style reactors on Mars all happily making electric power and additional reactors are installed on board nuclear ion powered vessels which travel rapidly between the Earth and Mars and elsewhere in our solar system.

How long until the fuel cores need to be replaced and recycled?

What equipment is needed to properly service a nuclear reactor once its initial fuel supply is consumed?

How much infrastructure will be needed on Mars and in various on-orbit facilities to repair, maintain and refuel nuclear powered vessels?

soph · 2002-12-27 17:06:28

Now, im ignorant in this field, but couldnt you create an artificial water barrier around the reactor to absorb heat, that isnt part of an ecosystem? could you also then use this heated water to produce hydroelectric or steam power (forgive me if i dont know how water power works)?

Auqakah · 2002-12-27 17:26:25

Nuclear power is, in a (very loose) way, hydroelectric power. So is coal power. After all, the thermal energy from the reactor is used to heat water which becomes steam, which then turns turbines.... and so on.

soph · 2002-12-27 17:27:44

so if you surrounded the reactor with a water barrier, wouldnt you negate the waste heat?

Auqakah · 2002-12-27 17:46:13

Not really, because the heat still needs to be gotten rid of - after all, energy cannot be destroyed, only transferred.

And surrounding a nuclear reactor (argh, edited here) entirely with water would surely cause safety problems, wouldn't it?

soph · 2002-12-27 18:02:49

isnt there any way to harness the waste heat? no way at all?

Auqakah · 2002-12-27 18:21:43

Well, there probably is, but a way hasn't been found yet to my knowledge. Its rather like the lightbulb - our use of energy is unfortunatley horrendously inefficient on this planet.

Austin Stanley · 2002-12-28 21:26:12

Soph - um actualy what you're talking about is EXACTLY what is done. In modern pressurised water reactors (PWR), the fuel rods (where the nuclear reactorion actualy takes place) are moderated with water, which also takes in the heat produced. This heat is then used to turn a turbine just the same as in a fossil fuel plant. Not all this heat can be used in this manner, and it must be disposed of in some other means, usualy by a cooling tower, a nearby river, or even a cooling lake. Many fossil fuel plants require cooling facilities for the same reasons.

Here's a diagram of PWR to make it all clearer.
http://www.tva.gov/power/wbndiag.htm]click here

soph · 2002-12-29 07:53:22

thanks for the link austin. so how efficient is this process? what percentage of heat is wasted, just a ballpark estimate?

Preston · 2002-12-29 14:18:25

Typically the efficiency is ~34%. Canadian CANDUs are 40%. So a 2.5 thermal gigawatt plant has a lot of waste heat.

mauk2 · 2002-12-31 13:30:05

Just a quick comment or three:

The current crop of nuclear power reactors are dinosaurs. They were designed using slide rules and chalk boards, for pete's sake. We can build MUCH MUCH better plants today, if we'd just get over our irrational fears.

For example, Westinghouse has a fully licensed and ready to build modular PWR using extensive passive safety systems called the http://www.ap600.westinghouse.com/] AP-600 ready to go right now.

They have a larger and more efficient version of the same design called the AP-1000 which should be ready any time now.

These are designs which start their design life 100 times safer than the current crop of plants which have had 40 years of impovements added to them.

And these PWR designs are STILL fairly primitive compared to far more advanced designs which are on the horizon.

I like the lead-bismuth cooled "Energy Amplifier" Accelerator Driven system fueled with Thorium. Able to safely generate vast amounts of power with huge burnup figures while simultaneously disposing of high level wastes. Hard to argue with it, actually.

Thorium is three times as common as Uranium, and Thorium out of the ground has 100 times the available energy of Uranium out of the ground, when it is burned in an EA.

Plus, an EA can be easily run as high temperatures due to the lead/bismuth coolant. Those high temperatures allow the EA to provide the heat needed to run a sulfur/iodine hydrogen cracking cycle. For all you folks advocating hydrogen fuel cells, this is a non-hydrocarbon source for vast quantities of the stuff. Plus, the hydrogen making process runs at a hot enough temperature that the "waste heat" from making the hydrogen is actually about the right temperature to run a conventional steam turbine to make electricity.

For a really complete utilization cycle, you can then use the waste heat from the steam stubines to boil sea water. This makes fresh water. You use a portion of the fresh water for feedstock to make hydrogen out of, and you use the rest for irrication or as drinking water.

So, by using new nuclear technology, we can:

A) Switch to a much larger supply of fissile fuel, in Thorium.

B) Have a much safer power source in the Energy Amplifier.

C) Provide high temperatures to create hydrogen, so we stop burning gasoline in our SUV's.

D) Make huge amounts of electricity, which the world is already hungry for.

E) Make huge amounts of freash water for crops and drinking.

F) Do all this while getting rid of 99 percent of our current nuclear waste.

Sounds too good to be true, doesn't it?

Well, it's all based on solid science and all of these projects are being worked on my teams of scientists right now. If you don't believe me, I will be happy to post links.

Nuclear is Good!

soph · 2002-12-31 13:40:21

links links links!

in any case, could there be breeder reactors for thorium? could thorium be used to make nuclear weapons?

Just have to eliminate all the irrational fears...

Echus_Chasma · 2002-12-31 14:38:21

So, by using new nuclear technology, we can:
A) Switch to a much larger supply of fissile fuel, in Thorium.
B) Have a much safer power source in the Energy Amplifier.
C) Provide high temperatures to create hydrogen, so we stop burning gasoline in our SUV's.
D) Make huge amounts of electricity, which the world is already hungry for.
E) Make huge amounts of freash water for crops and drinking.
F) Do all this while getting rid of 99 percent of our current nuclear waste.
Sounds too good to be true, doesn't it?
Well, it's all based on solid science and all of these projects are being worked on my teams of scientists right now. If you don't believe me, I will be happy to post links.
Nuclear is Good!

I gotta tell this to my enviromentalist friends.

The idea is a nuclear plant is placed right next to a river or lake so that it can easily get rid of excess heat, and the temperature increase above the normal level changes the ecology negatively. I don't know any details.

It kills off the fish and stuff when the heat in the water rises. There is like a limit thing where they have to shut the power-plant down if the water gets too hot. At least thats what they do in New Zealand anyway.

soph · 2002-12-31 14:51:50

what could be used as a coolant to keep the exiting water cool? any ideas? using thorium, would the heat be wasted as well?

mauk2 · 2003-01-01 04:32:34

soph: Thorium by itself is non-fissile, and cannot assemble a critical mass. An Energy Amplifier is technically speaking an Accelerator Driven breeder, in which Th232 is converted using neutron bombardment into U233.

Now, U233 is EXCELLENT bomb material. To reduce the proliferation risk, two things can be done.

First, in an EA about 7 percent of the Th232 gets converted into U234 if you run the reaction to equilibrium. U234 is TERRIBLE bomb-making material, because it emits lots of neutrons spontaneously, but for an EA it is just as good at U233 as fuel.

Second, when you load your EA with Th232, make sure to include a decent amount of the Th230 isotope. Th230 absorbs neutrons and becomes U232. U232 is an even more effective bomb poison than U234, because it emits even more neutrons and it's decay products also emit lots and lots of nasty gamma rays.

Spiking your EA in this way can pretty much guarantee it'll never be used to make bombs.

Now for links:

http://www.nea.fr/html/ndd/reports/2002 … 09-ads.pdf

http://web.gat.com/hydrogen/agenda.html … genda.html

http://itumagill.fzk.de/ADS/publication … ations.htm

Those three should have enough info to keep ya reading until 2004.

Nuclear is Good. Don't let the propaganda fool you. The current crop of nuclear power reactors are primitive dinosaurs. The only redeeming feature they have is that they are working.

Oh, and here's a pet peeve of mine: North Korea is getting a lot of press right now for re-starting a couple of nuclear reactors. Well, according to some pictures that got flashed up on the tube, those are a 5 megawatt and a 50 megawatt reactor. In those sizes, those are test machines, or weapon makers, NOT power reactors. Yet nobody in the media mentions this, painting nuclear power yet again with propagandistic lies. <grrrrrrrrrr>

soph · 2003-01-01 07:00:26

when i read in the New York Times that it was a 5 mW test reactor, i said to myself, thats not going to power many people, and if they are using it for power, why kick us out?

i had a long discussion with my family about nuclear. my father is pro-nuclear anyway...my mother wants me to prove to her using "credible sources" the safety of nuclear. so im going to research the topic. im going to gather whatever i can, from both sides, and make an objective analysis. i might even mail greenpeace and see what theyre response is.

Josh Cryer · 2003-01-03 00:51:54

You nuclear propulsion advocates need to head over to the http://www.newmars.com/cgi-bin/wiki.cgi]NewMars wiki. I made a page for http://www.newmars.com/cgi-bin/wiki.cgi … on]nuclear propulsion.

Josh Cryer · 2003-01-03 01:02:32

The current crop of nuclear power reactors are primitive dinosaurs. The only redeeming feature they have is that they are working.

So when environmentalists go about saying that nuclear reactors are dangerous (ie, primitive dinosaurs), are they lying? If they're not, what's the big deal? I honestly haven't seen protestors protest a clean nuclear plant. That would be as stupid as anti-abortionists or tree huggers protesting against invetro or fertilizer companies respectively. If they do, someone needs to educate some people badly...

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