Sun as final storage for radwaste?

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Re: Sun as final storage for radwaste?

Postby Tass » Tue Mar 05, 2013 1:08 pm UTC

tomandlu wrote:
Thesh wrote:It's about two to one H to O.


Shoot me now.

(I think I had it in my head that it had to be free O)


You were not wrong. Oxidizing something with water means having to liberate free hydrogen. Oxidizing with elemental oxygen is far easier. Salt water rusts iron because it catalyzes the oxidation, not because it is the oxidizer itself.

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Re: Sun as final storage for radwaste?

Postby Xenomortis » Tue Mar 05, 2013 1:26 pm UTC

Oceanic water, even down in the abyssal regions, has dissolved oxygen. It's a little scarcer really deep down, but there's enough for aerobic life.
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Re: Sun as final storage for radwaste?

Postby p1t1o » Tue Mar 05, 2013 1:32 pm UTC

It seems to me that we have all this waste, thousands of tons, just sitting around - be it vitrified or buried or whatevs - just sitting around giving off heat all day. And they will probably do so for a very long time.

I know its radioactive and shiz, but it does seem like free energy going to waste.

I can't seem to think of a way to exploit it without it being unsafe or just super expensive, though.

What can you use and extremely long lasting but low-intensity energy source for where radioactivity won't be a problem?

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Re: Sun as final storage for radwaste?

Postby HungryHobo » Tue Mar 05, 2013 2:11 pm UTC

p1t1o wrote:It seems to me that we have all this waste, thousands of tons, just sitting around - be it vitrified or buried or whatevs - just sitting around giving off heat all day. And they will probably do so for a very long time.

I know its radioactive and shiz, but it does seem like free energy going to waste.

I can't seem to think of a way to exploit it without it being unsafe or just super expensive, though.

What can you use and extremely long lasting but low-intensity energy source for where radioactivity won't be a problem?


Reprocessing.

you could probably pull some energy from the cooling tanks but it'd be more expensive than it's worth.

they actually do: solid-state thermocouples use plutonium or other long lived elements of nuclear waste to generate power. you get a slow trickle of power for hundreds of years without moving parts .
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Re: Sun as final storage for radwaste?

Postby PM 2Ring » Wed Mar 06, 2013 3:10 am UTC

Xenomortis wrote:Oceanic water, even down in the abyssal regions, has dissolved oxygen. It's a little scarcer really deep down, but there's enough for aerobic life.

Indeed. So metal containers on the seabed would be prone to corrosion. Which is why I prefer the suggestion of the Seabed Working Group to bury the containers under the clay. From the link in my previous post:
As is the case for disposal within Yucca Mountain, the waste canisters themselves would last a few thousand years at most. Under the seabed, however, the muddy clays, which cling tenaciously to plutonium and many other radioactive elements, would prevent these substances from seeping into the waters above. Experiments conducted as part of an international research program concluded that plutonium (and other transuranic elements) buried in the clays would not migrate more than a few meters from a breached canister after even 100,000 years. The rates of migration for uranium and some other radioactive waste elements need yet to be properly determined. Still, their burial several tens to 100 meters or more into the sediments would most likely buy enough time for the radioactivity of all the waste either to decay or to dissipate to levels below those found naturally in seawater.


Also bear in mind that the energy of the radiation emitted by radioisotopes is roughly inversely proportional to their half-life (generally speaking), so most of the highly radioactive material will have decayed by the time the containers start to leak, and only the extremely long-lived (and hence low energy) isotopes would be expected to migrate through the clay and into the seawater, even if they were only buried a few metres below the clay surface. Still I like the idea of burying them much deeper, not just because it slows down post-corrosion migration, but because it'd make it harder for terrorist / rogue states to retrieve the radioactive nasties.


I agree that it seems wasteful to bury radioisotopes. It'd be nice if we could use techniques like neutron bombardment to convert them into useful isotopes, but that process can be tricky, due to the high levels of radioactivity involved, and reactors that can do that sort of thing tend to be discouraged since they can be used to create weapons-grade material. And of course you also have the problem that Idobox mentioned: the reactor housing itself eventually becomes radioactive waste, and this tends to be a worse problem for breeder reactors than it is for standard power reactors.

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Re: Sun as final storage for radwaste?

Postby idobox » Wed Mar 06, 2013 3:48 pm UTC

PM 2Ring wrote:I agree that it seems wasteful to bury radioisotopes. It'd be nice if we could use techniques like neutron bombardment to convert them into useful isotopes, but that process can be tricky, due to the high levels of radioactivity involved, and reactors that can do that sort of thing tend to be discouraged since they can be used to create weapons-grade material. And of course you also have the problem that Idobox mentioned: the reactor housing itself eventually becomes radioactive waste, and this tends to be a worse problem for breeder reactors than it is for standard power reactors.

Technically, all nuclear reactors can create weapon grade material. If you have uranium 238 and neutrons in the same place, you end up with plutonium, which is easy (not that easy, but compared to running a reactor) to extract.
And one of the reason PWR were preferred to thorium cycle reactors is because the latter produces U233 mixed with U232, which is unfit for nuclear weapons. Breeder reactors are unpopular because they are expensive, expensive because they're experimental, experimental because they were not popular in the 50's. And also, because uranium is cheap.

Structural materials of reactors become slightly radioactive, which is a problem because there is a lot it. Fast breeders produce more neutrons, and make materials radioactive faster (more radioactive?). But proponents of liquid fuel reactors claim that there would be a lot less structural materials in the core, and so the issue would be actually improved. They also claim nuclear waste could be used as fuel.
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Re: Sun as final storage for radwaste?

Postby Minerva » Sun Apr 14, 2013 3:06 pm UTC

Why don't we send radioactive waste into space, or into the Sun?

A common answer that people often come up with is that we can't do that because it would be too dangerous. The rocket could blow up and radioactivity would be scattered everywhere!
However, that's not a real problem. We can quite easily put the material in a strong container where it would survive any contingency such as the catastrophic failure of the launch vehicle.

In fact, that's what we do regularly with all the radioisotopic generators that are safely launched on exploratory spacecraft.

With the radioactive material packaged in an appropriate form it can survive anything - even uncontrolled reentry into Earth's atmosphere. (The Pu-238 source cask for the ALSEP RTG stored in the Apollo 13 LM survived exactly this.)

The real answer is that we don't do it because it's just wayyy too expensive and energy intensive to launch stuff into space. And unnecessary. And it possibly violates international treaties such as the Outer Space Treaty.

tomandlu wrote:The linguist Thomas Sebeok was member of the Bechtel working group. Building on earlier suggestions made by Alvin Weinberg and Arsen Darnay he proposed the creation of an atomic priesthood, a panel of experts where members would be replaced through nominations by a council. Similar to the Catholic church - which has preserved and authorized its message for over 2000 years — the atomic priesthood would have to preserve the knowledge about locations and dangers of radioactive waste by creating rituals and myths. The priesthood would indicate off-limits areas and the consequences of disobedience.


You know, sometimes I read some of this stuff and I think, you know, maybe they should get Neal Stephenson to make a submission to the working group with his thoughts on the subject. And they actually did, I believe. :)
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Re: Sun as final storage for radwaste?

Postby Quizatzhaderac » Thu Apr 18, 2013 7:36 pm UTC

Apart from the huge efforts involved in getting it to the sun, doesn't "throwing it into the sun" assume that it will sink into he sun once it gets there?

I'm thinking that once it's gets close, the containers + waste will evaporate, increase in surface area,and be blow back out by solar pressure/wind? I'm sure the radiation would still be trivial compared to what the sun is constantly pumping out, but it seems like such a waste to go to the trouble of hurtling something into the sun, only to have it "blown" back into your face.
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Re: Sun as final storage for radwaste?

Postby thoughtfully » Thu Apr 18, 2013 7:54 pm UTC

Quizatzhaderac wrote:Apart from the huge efforts involved in getting it to the sun, doesn't "throwing it into the sun" assume that it will sink into he sun once it gets there?

I'm thinking that once it's gets close, the containers + waste will evaporate, increase in surface area,and be blow back out by solar pressure/wind? I'm sure the radiation would still be trivial compared to what the sun is constantly pumping out, but it seems like such a waste to go to the trouble of hurtling something into the sun, only to have it "blown" back into your face.

Depends on how fast it's going. Solar escape velocity is about 620 km/s, which is how fast a ballistic waste capsule would be travelling. The pressure from the solar radiation I think would be more important than the solar wind, I expect, and that's straightforward to calculate. But I think engineering solutions would not be all that tricky. A long, slender body that provides a low cross-section combined with ablative shielding and ballast to resist changes in velocity would go a long ways.
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Re: Sun as final storage for radwaste?

Postby gmalivuk » Thu Apr 18, 2013 8:02 pm UTC

But even if it would get thrown back out by the sun, and even if it constituted more than a tiny percent of the deadly radiation the sun already puts out, it shouldn't be hard to send it there in such a way that it wouldn't blow back at earth.
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Re: Sun as final storage for radwaste?

Postby Quizatzhaderac » Thu Apr 18, 2013 9:03 pm UTC

thoughtfully wrote:Depends on how fast it's going. Solar escape velocity is about 620 km/s, which is how fast a ballistic waste capsule would be travelling. The pressure from the solar radiation I think would be more important than the solar wind, I expect, and that's straightforward to calculate. But I think engineering solutions would not be all that tricky. A long, slender body that provides a low cross-section combined with ablative shielding and ballast to resist changes in velocity would go a long ways.
That's a hell of an ablative to work on the sun. Also the slender body would work against it once it got close enough for contact heating.

gmalivuk wrote:But even if it would get thrown back out by the sun, and even if it constituted more than a tiny percent of the deadly radiation the sun already puts out, it shouldn't be hard to send it there in such a way that it wouldn't blow back at earth.
Oh, certainly; but I's still say it defeats the spirit of hurtling something into the sun if it doesn't stay there. If we wanted the waste hurtled randomly about the solar system we'd do that directly.
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Re: Sun as final storage for radwaste?

Postby gmalivuk » Thu Apr 18, 2013 9:28 pm UTC

Yeah, simply putting it in an orbit that doesn't cross Earth's is a lot easier and no less effective at making it no longer our problem.
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Re: Sun as final storage for radwaste?

Postby idobox » Fri Apr 19, 2013 5:54 pm UTC

The outer layer of the sun is made mostly of hydrogen, and it doesn't appear to be blown away very quickly. I imagine that if the pull of gravity wins the tug of war against radiation pressure for hydrogen, it should do the same for heavier stuff, especially if said heavy stuff has original velocity.
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Re: Sun as final storage for radwaste?

Postby PM 2Ring » Sat Apr 20, 2013 1:28 am UTC

idobox wrote:The outer layer of the sun is made mostly of hydrogen, and it doesn't appear to be blown away very quickly.

From http://en.wikipedia.org/wiki/Solar_wind
The solar wind is a stream of charged particles released from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time. These particles can escape the Sun's gravity because of their high kinetic energy and the high temperature of the corona.

[...]

The total number of particles carried away from the Sun by the solar wind is about 1.3×1036 per second.[19] Thus, the total mass loss each year is about (2–3)×10−14 solar masses,[20] or about 4–6 billion tonnes per hour. This is equivalent to losing a mass equal to the Earth every 150 million years.[21] However, only about 0.01% of the Sun's total mass has been lost through the solar wind.[22] Other stars have much stronger stellar winds that result in significantly higher mass loss rates.

Please see the link for further details.

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Re: Sun as final storage for radwaste?

Postby Jorpho » Sat Apr 20, 2013 3:39 am UTC

HungryHobo wrote:people overreact to nuclear waste. it's been turned into such a bogey man that people pretty much turn it into a game. "drop it into the sun" ,"drop it into a black hole", "shoot it into deep space" etc etc when it's not really that exceptional.

lots of regular old industrial waste will kill you, mutate you, poison you etc but nuclear waste gets all the attention. People worry about the many many layers of protection round nuclear waste in uninhabited hell holes failing slightly in millenia but ignore all the heavy metals and carcinogens in regular old fly ash burried under their schools playing pitches contained by plastic sheeting, clay and hope.
Well, the Goiânia accident was pretty terrible.

Minerva wrote:(The Pu-238 source cask for the ALSEP RTG stored in the Apollo 13 LM survived exactly this.)
Wait, you mean they found it somewhere? I can't seem to hit the right Google terms.

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Re: Sun as final storage for radwaste?

Postby Tass » Mon Apr 22, 2013 12:41 pm UTC

PM 2Ring wrote:
idobox wrote:The outer layer of the sun is made mostly of hydrogen, and it doesn't appear to be blown away very quickly.

From http://en.wikipedia.org/wiki/Solar_wind


Not due to radiation pressure, but the high temperature of the corona. The corona is to thin to appreciably heat a properly designed solar diver moving fast. It would vaporize somewhere in the photosphere, but by then it is only 5500K, and as noted the nuclei in the craft would be much heavier than hydrogen.

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Re: Sun as final storage for radwaste?

Postby HungryHobo » Mon Apr 22, 2013 2:26 pm UTC

Jorpho wrote:Well, the Goiânia accident was pretty terrible.


it's not much in comparison to some regular non-nuclear accidents.
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Re: Sun as final storage for radwaste?

Postby yurell » Mon Apr 22, 2013 2:42 pm UTC

When I think of industrial disasters, Bhopal is the first to come to my mind, probably because I read about it in a Star Trek book when I was young and found that it was what set Khan Noonien Singh off on his quest for world domination.
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Re: Sun as final storage for radwaste?

Postby HungryHobo » Mon Apr 22, 2013 4:36 pm UTC

thinking on this more I think people focus too much on industrial stuff too.

Biological threats like diseases are vastly more dangerous and in practice kill more people than any industrial accident and the causes can be incredibly mundane.

One leaking toilet and a sick worker and a few years later you have almost ten thousand people dead:

http://www.theatlantic.com/internationa ... le/273526/

physics and chemistry scare people when really it should be biology sending shivers down their spines.
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Re: Sun as final storage for radwaste?

Postby idobox » Tue Apr 23, 2013 11:31 am UTC

PM 2Ring wrote:
idobox wrote:The outer layer of the sun is made mostly of hydrogen, and it doesn't appear to be blown away very quickly.

The total number of particles carried away from the Sun by the solar wind is about 1.3×1036 per second.[19] Thus, the total mass loss each year is about (2–3)×10−14 solar masses,[20] or about 4–6 billion tonnes per hour. This is equivalent to losing a mass equal to the Earth every 150 million years.[21] However, only about 0.01% of the Sun's total mass has been lost through the solar wind.[22] Other stars have much stronger stellar winds that result in significantly higher mass loss rates.

[/quote]
which results in a whopping 2-10kg/m²s, or about 1µg/m2/hour. As I said, not a lot.

Also, a properly designed craft could use that energy for propulsion. If you have a rod of metal with good heat conduction, and plate at the end covered with some ablative coating on the far side, the heat of the sun will produce thrust toward it.
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Re: Sun as final storage for radwaste?

Postby Jorpho » Tue Apr 23, 2013 1:09 pm UTC

HungryHobo wrote:
Jorpho wrote:Well, the Goiânia accident was pretty terrible.
it's not much in comparison to some regular non-nuclear accidents.
What is alarming is the subtlety. Goiânia happened because a very small number of poorly-informed people happened upon one piece of poorly-disposed-of equipment. Plant explosions and the like are terrible when they happen, but they are rare because there are normally many checks and balances in place and a large number of systematic errors have to improbably accumulate before something goes terribly wrong. Right?

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Re: Sun as final storage for radwaste?

Postby HungryHobo » Tue Apr 23, 2013 1:15 pm UTC

Jorpho wrote:What is alarming is the subtlety. Goiânia happened because a very small number of poorly-informed people happened upon one piece of poorly-disposed-of equipment. Plant explosions and the like are terrible when they happen, but they are rare because there are normally many checks and balances in place and a large number of systematic errors have to improbably accumulate before something goes terribly wrong. Right?

I'll still take that over a leaking toilet in haiti any day for both subtlety and suffering/body count.
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Re: Sun as final storage for radwaste?

Postby scarecrovv » Tue Apr 23, 2013 3:06 pm UTC

Holy shit. I hadn't heard about the cholera outbreak in Haiti. That's atrocious.

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The sun as a nuclear waste incinerator

Postby CutmanCometh » Mon Oct 19, 2015 6:35 pm UTC

Why can't we round up all the spent fuel rods from nuclear power plants, load them on a rocket, and fly them into the sun?

I assume this isn't cost effective or we'd be doing it already. But why isn't it cost effective? Or, are there other practical reasons for not doing this?

It's seems to me that it boils down to the following numbers:

Mn = the mass of all the nuclear waste produced in, let's say, a year
Cr = the cost of building a rocket to carry the waste
Cf = the cost of the rocket fuel to launch the waste and the vehicle into space
Mf = the mass of the fuel itself
Mr = the mass of the carrying vehicle

With the equation for the final cost being, more or less: ((Mn + Mr + Mf) * Cf) + Cr
(I know this is oversimplifying it)

What I don't know is how much nuclear waste we produce, how much the rocket would cost, how much it would weigh, how much fuel it would take to launch it all, or how much the rocket fuel itself costs.

Can anyone help me fill in these details?

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Re: The sun as a nuclear waste incinerator

Postby thoughtfully » Tue Oct 20, 2015 1:21 pm UTC

There's a thread on this already, your answers can be found there.
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Re: The sun as a nuclear waste incinerator

Postby speising » Tue Oct 20, 2015 4:20 pm UTC

What you still miss to balance the equation is the other side: the cost of dumping it all in a hole in the ground. Which is near zero in relation.

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Re: The sun as a nuclear waste incinerator

Postby SDK » Tue Oct 20, 2015 4:30 pm UTC

You don't really need to calculate this. Google can tell you quickly that it takes several thousand dollars to lift a kg of anything into space. That right there should answer your question as to why we don't do it.

NASA's got some lofty goals of bringing the cost down to several hundred dollars per pound in the next 25 years and tens of dollars in the next 40. That'll rely on a space elevator, of course, which is still pretty far out of reach. Even then, chucking a barrel down a hole is just way too cheap to pass up.

There's also the danger of having the rocket explode on the way up, contaminating an entire continent. We should probably just keep it in the ground...
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Re: The sun as a nuclear waste incinerator

Postby Izawwlgood » Tue Oct 20, 2015 7:13 pm UTC

thoughtfully wrote:There's a thread on this already, your answers can be found there.

Reading that thread I'm more convinced than ever that KSP is a fantastic educational tool.
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Re: The sun as a nuclear waste incinerator

Postby BlackSails » Wed Oct 21, 2015 2:17 am UTC

SDK wrote:You don't really need to calculate this. Google can tell you quickly that it takes several thousand dollars to lift a kg of anything into space .


Takes significantly more than that to get it into the sun

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Re: Sun as final storage for radwaste?

Postby gmalivuk » Wed Oct 21, 2015 6:20 pm UTC

Merged with the identical topic from previously.
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Re: Sun as final storage for radwaste?

Postby Wolfkeeper » Thu Oct 22, 2015 9:11 pm UTC

It actually takes a lot less rocket to send the waste into interstellar space; the delta-v is much, MUCH less.

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Re: Sun as final storage for radwaste?

Postby Tyndmyr » Fri Oct 23, 2015 6:21 pm UTC

Well, if we embraced the Orion project, surely we could overcome the delta-v, with only the side effect of creating a bunch of radwaste...

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Re: Sun as final storage for radwaste?

Postby gmalivuk » Fri Oct 23, 2015 7:25 pm UTC

Wolfkeeper wrote:It actually takes a lot less rocket to send the waste into interstellar space; the delta-v is much, MUCH less.
If you ignore the option to slingshot around Jupiter (which can get you to the Sun or interstellar space for the same amount of propellant), the delta-v to escape entirely is 41% as much as the delta-v to stop dead in Earth orbit.

Significantly less, and with a mass ratio of just 1/11 of what you'd need to drop into the Sun, but I'm not sure "much, MUCH less" is an apt descriptor.
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Re: Sun as final storage for radwaste?

Postby Wolfkeeper » Fri Oct 23, 2015 9:37 pm UTC

Oh a rocket less than a tenth the size, that's not much, much less at all!

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Re: Sun as final storage for radwaste?

Postby gmalivuk » Sat Oct 24, 2015 12:41 am UTC

A single order of magnitude may justify "much", but not "much, MUCH".

And in any case, the claim was about delta-v, not mass ratio.
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Re: Sun as final storage for radwaste?

Postby Wolfkeeper » Sat Oct 24, 2015 4:20 pm UTC

So equally you'd be saying that 10 on the Richter scale isn't much, much larger than 4 on the Richter scale.

After all, we're comparing exponentials, not the damage done to the cities, so they're basically the same sized earthquake.

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Re: Sun as final storage for radwaste?

Postby gmalivuk » Sat Oct 24, 2015 6:08 pm UTC

A difference of 6 Richter points is a difference of 6 orders of magnitude in shaking amplitude, or 9 in energy released.

I'm talking about a difference between a 4 and a 5. One order of magnitude in propellant. A difference of 60% in delta-v. (Delta-v is a real quantity that measures a real thing in its own right, which just happens to translate to an exponential increase in another quantity. It's no more intrinsically an exponent than distance is intrinsically squared just because you square it to find out the force of gravity between two things. The Richter scale is *just* the exponent, and doesn't measure anything directly.)

In any case, it's not even necessarily a 10-fold propellant increase, because I did the math wrong. The mass ratio changes by a factor of K^(2-sqrt(2)), where K is the mass ratio to drop into the sun. That works out to 10 or more for chemical rockets, sure, but a more intelligent choice for a mission that doesn't need to be finished in any particular amount of time would probably involve much higher specific impulse.

Edit: And again, you didn't say it would require much much less propellant, you said it was much much less delta-v. I contend that 12km/s is not "much much less" than 30km/s, even if it is much much more attainable using a conventional chemical rocket.
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Re: Sun as final storage for radwaste?

Postby Wolfkeeper » Sat Oct 24, 2015 11:12 pm UTC

I contend that 12km/s is not "much much less" than 30km/s


:roll:

oh yeah, big time it is.

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Re: Sun as final storage for radwaste?

Postby gmalivuk » Sun Oct 25, 2015 1:07 am UTC

In the same way that 12mph is much much less than 30mph, because of how much easier it is for a human to run 12mph than 30mph.

Oh you're driving a car? Well too bad, the only reasonable way to compare velocities is by looking at how easy it is to run that fast.

(Which is to say, not only are chemical rockets far from the only way to do rocketry, rocketry is not the only way to get delta-v.)
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Re: Sun as final storage for radwaste?

Postby Wolfkeeper » Sun Oct 25, 2015 3:13 pm UTC

Yeah, but 30km/s is much, much more than 12km/s in the same way that 200 mph is much, much less than 2000 mph.

As in, there is no car that can go 2000 mph, and there is no space vehicle that can do 30 km/s delta-v.


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