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Why the sun is a poor dumping ground for nuclear waste (2010)

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Re: Why the sun is a poor dumping ground for nuclear waste (2010)

#101

Post by BlackAura »

joe_the_user wrote: post #86
benjoffe wrote: post #67

Earlier quoted context omitted.

That "trick" would indeed work and is a well known orbital manoeuvre: http://en.wikipedia.org/wiki/Bi-elliptic_transfer (without the final circularising burn). This manoeuvre would be preferable to the article's alternative (a Hohmann transfer reducing periapsis to the sun's radius without the final circularising burn) in all cases where the initial semi-major axis (relative to the sun) is roughly greater than 11.94…

Sorry, your link doesn't mean what you think it means. What you're missing is that both waste and the earth are already in orbit around the sun whereas the maneuver your link describes involves switching between orbits around different smaller bodies. Edit: Which is to say as the other have mentioned, this doesn't send the waste into the sun (as the parent post implied) but merely on some orbit similar to the earth a…

No, he's right

A bi-elliptic transfer is used for transferring between two orbits around the same body. In some situations, this is more efficient than a straightforward Hohmann transfer, at the cost of taking much, much longer.

For a Hohmann transfer, you reduce the ship's orbital velocity relative to the sun, reducing the orbit's perihelion to somewhere inside the sun. That requires cancelling out almost all of the Earth's orbital velocity.

For a bi-elliptic transfer, you first increase the ship's orbital velocity relative to the sun, increasing the orbit's aphelion to somewhere in the outer solar system. That's your first Hohmann transfer, going apparently the wrong direction, but requires less than 40% as much energy as dropping it into the sun did. Then, at aphelion, when the ship's orbital velocity is lowest, you reduce the ship's orbital velocity to drop it's perihelion inside the sun. From that far out, and at such an eccentric orbit, that requires only a fraction of the energy it did from Earth's orbit.

The entire manuever, potentially, could be far more efficient than a direct transfer. It just takes far longer, and if the ship fails to make the second maneuver, it'll be left in an orbit that crosses Earth's orbit.

Re: Why the sun is a poor dumping ground for nuclear waste (2010)

#102

Post by hydrogen18 »

tsotha wrote: post #68
iwwr wrote: post #55

It could be much lower than that if you take roundabout trajectories with gravity assists from Earth, Venus and Mercury. Not having to establish orbit is definitely a plus. Besides, nuclear waste is still mostly unburned fuel which could be reprocessed and burned for power in special reactors.

>Besides, nuclear waste is still mostly unburned fuel which could be reprocessed and burned for power in special reactors. That was my reaction. Future generations will want to use that stuff for fuel. There's no reason to launch it into space.

Well yes, it could be fuel in the future.

But at current in the US it is stored in holding pools all over the country. None of those are getting any larger, although they are frequently reworked to allow better use of the volume available.

Very little of it is 'weapons grade' and not many people have access to the equipment to weaponize it into a nuclear weapon. But turning any of it into a dirty bomb is trivial if you can steal it.

There is also the problem of accidents, why by definition are unavoidable.

So, you really do want to get rid of the fuel. Launching it into space is impractical. But it should be stored in a difficult to access facility where the chance of it escaping is minimal. The US federal government collected billions for the construction of such a facility, but it was never completed. So as a result, we have fuel scattered all over the US.

Re: Why the sun is a poor dumping ground for nuclear waste (2010)

#103

Post by darkmighty »

joe_the_user wrote: post #86
benjoffe wrote: post #67

Earlier quoted context omitted.

That "trick" would indeed work and is a well known orbital manoeuvre: http://en.wikipedia.org/wiki/Bi-elliptic_transfer (without the final circularising burn). This manoeuvre would be preferable to the article's alternative (a Hohmann transfer reducing periapsis to the sun's radius without the final circularising burn) in all cases where the initial semi-major axis (relative to the sun) is roughly greater than 11.94…

Sorry, your link doesn't mean what you think it means. What you're missing is that both waste and the earth are already in orbit around the sun whereas the maneuver your link describes involves switching between orbits around different smaller bodies. Edit: Which is to say as the other have mentioned, this doesn't send the waste into the sun (as the parent post implied) but merely on some orbit similar to the earth a…

I believe they're referring to a Solar radius orbit as the destination given by the article. Doesn't sound wrong to me.

Re: Why the sun is a poor dumping ground for nuclear waste (2010)

#105

Post by whoopdedo »

cryptoz wrote: post #63
MichaelCrawford wrote: post #52

Sometimes rockets fail. I mean like they blow up on launch. When the Shuttle was first commissioned, my concern at the time was that America's most reliable rocket was the delta, which failed every thirty launches. When it's nuclear waste, it's not good enough just to have launch insurance.

> When the Shuttle was first commissioned, my concern at the time was that America's most reliable rocket was the delta, which failed every thirty launches. You were right to be concerned. The shuttle had "a 40% vehicular failure rate and a flight failure rate of 1.5%", killing more people than any other space vehicle. [1] [1] http://www.forbes.com/sites/carolpinchefsky/2012/04/18/5-hor...

And the space shuttles carried many more people than other space vehicles except for the current generation of Soyuz.

You don't measure failure rate by number built divided by number crashed. You measure by how much it's used. The more often something is used the more likely it it that it will fail one of those times.

Re: Why the sun is a poor dumping ground for nuclear waste (2010)

#106

Post by tbrownaw »

Every time the question of nuclear waste disposal comes up, someone is sure to say, “Why not shoot it into the Sun?” It seems so obvious.

Or we could get over our stupid fear of recycling. The stuff's only hazardous because we haven't taken all the energy out of it yet.

Nuclear fuel reprocessing is performed routinely in Europe, Russia and Japan. http://en.wikipedia.org/wiki/Nuclear_reprocessing

Re: Why the sun is a poor dumping ground for nuclear waste (2010)

#107

Post by pdonis »

benjoffe wrote: post #88
kllrnohj wrote: post #78

Earlier quoted context omitted.

A straight Hohmann transfer requires ~0.5-1% more dV than a bi-elliptic transfer. Calling this "by far" not optimal is by far not correct. So instead of 32 km/s you need 31.68 km/s. This changes nothing.

Where did you get the "0.5-1%" figure from? That may be true in some cases, but not in this extreme case, here it's closer to half the delta-v (which, due to the rocket equation is enormously less difficult to achieve). Solar escape velocity is about 16.5km/s* , and since ~99% of this manoeuvre's delta-v budget is used at launch the entire delta-v cost is asymptotically this value. * http://en.wikipedia.org/wiki/New_…

> Solar escape velocity is about 16.5km/s

No, it's about 42 km/s, i.e., sqrt(2) times the Earth's orbital velocity around the Sun, which is 30 km/s. New Horizons was launched to take as much advantage of the Earth's orbital velocity as it could, so that the rocket didn't need to provide all of the 42 km/s of delta-v needed for solar escape.

(You could use the same trick for your scheme, of course. The main issue I see with your scheme is that it greatly lengthens the time that the waste is out in space.)

Re: Why the sun is a poor dumping ground for nuclear waste (2010)

#108

Post by maxerickson »

tbrownaw wrote: post #106

Every time the question of nuclear waste disposal comes up, someone is sure to say, “Why not shoot it into the Sun?” It seems so obvious. Or we could get over our stupid fear of recycling. The stuff's only hazardous because we haven't taken all the energy out of it yet. Nuclear fuel reprocessing is performed routinely in Europe, Russia and Japan. http://en.wikipedia.org/wiki/Nuclear_reprocessing

Japan doesn't seem to have a plant online at the moment (http://www.world-nuclear-news.org/WR-Rokkasho-start-up-delay... ).

La Hague apparently has 1/2 of the global light water reprocessing capacity:

http://en.wikipedia.org/wiki/COGEMA_La_Hague_site

That Wikipedia table is interesting, but it is hard to understand who is currently doing what from it. I think Japan is mostly sending their spent fuel to France.

Re: Why the sun is a poor dumping ground for nuclear waste (2010)

#109

Post by btilly »

kavalec wrote: post #41

Use the Jules Verne solution: a cannon. A solar powered mass-driver could sling a steady stream of pellets from Earth orbit into Solar non-orbit using existing technology. That being said, burying it deep near the the start of a plate subduction zone makes at least as much sense.

The biggest problem with the cannon idea is that things traveling at that speed in the atmosphere tend to burn up before getting anywhere. And you get to start in the hardest part of the atmosphere to move in.

Re: Why the sun is a poor dumping ground for nuclear waste (2010)

#110

Post by btilly »

tbrownaw wrote: post #106

Every time the question of nuclear waste disposal comes up, someone is sure to say, “Why not shoot it into the Sun?” It seems so obvious. Or we could get over our stupid fear of recycling. The stuff's only hazardous because we haven't taken all the energy out of it yet. Nuclear fuel reprocessing is performed routinely in Europe, Russia and Japan. http://en.wikipedia.org/wiki/Nuclear_reprocessing

One of the downsides of reprocessing is that it makes plutonium easy to separate out in a form that is good for making nuclear bombs. Therefore it represents a nuclear proliferation risk.
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