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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)

#111

Post by tvon »

InclinedPlane wrote: post #83
leni536 wrote: post #32

> To reach the Sun you need to subtract 100 percent of Earth’s orbital velocity; to reach solar escape velocity you need only add 41 percent to it. You could send the waste with near solar escape velocity to travel on a really long ellipsis trajectory, at the furthest point you can get rid of the remaining kinetic energy with minimal fuel and let the waste fall back straight into the Sun. Subtracting Earth's orbital…

To what end? To spend literally decades, perhaps centuries, with nuclear waste floating around the solar system? Why not just leave it in deep space to start with? Why bother sending it into space in the first place? Meanwhile, if you succeed in sending nuclear waste into the Sun what do you think happens to it? It doesn't go away, it just gets vaporized and then scattered into the solar wind.

I think leni536 is just addressing the kind of interesting problem of what it takes to shoot anything into the Sun.

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

#112

Post by pwnna »

acadien wrote: post #84
maxerickson wrote: post #53

Earlier quoted context omitted.

The author always says "an acceleration", which is the same thing as delta-v. I have no idea how particular it is to phrase it that way, but it isn't confused.

The author says multiple times: "an acceleration of [X] km/s is required", maybe they meant to imply that the magnitude of the change of the velocity?

If i go from at rest (0m/s) to walking at 2m/s, I've completed an acceleration of 2m/s.

Delta-v is common in orbital mechanics, which is often referred as "an acceleration".

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

#113

Post by cjslep »

btilly wrote: post #110
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.

There's potential (no pun intended) in pyroprocessing to allow extraction of uranium only, leaving behind plutonium with the rest of the HLW that is hazardous to try to steal or be sneaky with.

For clarification, it's traditionally been PUREX (chemical separation) that is considered a proliferation risk.

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

#114

Post by ChuckMcM »

Back in high school I wrote a program that would let you pilot your ship in orbit around the earth and try to dock with things. I discovered just how annoying the physics of spaceflight can be!

Given the magnetic field of the Sun, one wonders if you could use a terminator tether [1] to get the remaining delta-v.

[1] http://arc.aiaa.org/doi/abs/10.2514/2.3565

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

#116

Post by e12e »

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.

Given that the past years have "proven" that it's "perfectly safe" to set off hydrogen bombs in the desert; I think it'd be reasonable to assume that it's quite possible to launch a container of junk into space. Not sur why one would care if it hits the sun or not...

Iff one can make a container that can survive the blast/lift-off -- one wouldn't need to worry about the launch vehicle exploding in-atmosphere: there'd be no rocket fuel. Added bonus: find a way to use existing war heads, and combine with nuclear disarmament...

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

#117

Post by jheriko »

the article claims that the sun is super inaccessible compared to escape velocity, but they are extremely closely related. as an orbit gets more and more ellipitcal, the delta-v required to get the orbit to cut through the sun drops (for a well timed burn at aphelion), in the limit of escape velocity this delta-v vanishes to zero... the implication is that they are comparable in cost, if you were to use such a method to drop something into the sun.

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

#118

Post by jheriko »

CompelTechnic wrote: post #65
joe_the_user wrote: post #61

Earlier quoted context omitted.

Your "trick" doesn't change any of the conservation of angular momentum considerations in the article. To "get rid of the remaining kinetic energy" would only result in the object getting escape velocity relative to earth. The object would never have "stopped" relative to it's orbit around the sun but even at it's further point would be traveling with fairly close to the same angular velocity as the earth (as describ…

I'm about 80% sure leni536 is right, from playing Kerbal Space Program.

i think you are right based on a similar feeling from that game, but be careful with that intuition. how much delta-v do you spend lifting the orbit so that lowering the periapse is cheap?

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

#119

Post by phkahler »

btilly wrote: post #109
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.

Unless you put the cannon on the moon. It's much easier to rocket to the moon than the sun. Now the railgun or whatever launcher doesn't have an atmosphere to deal with. Use the cannon to take away earth orbital velocity from the waste.

Throw in reusable rockets and... it's still really dumb. We have reactors that can make use of "spent" fuel - they're just not legal.

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

#120

Post by jheriko »

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…

you don't understand the link yourself... there are no bodies mentioned.

its about transferring from one orbit to another with a large elliptical orbit inbetween, its very well established. (and e.g. something i am familiar with before googling it or looking at a wikipedia page)

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