Why the sun is a poor dumping ground for nuclear waste (2010) • Hacker News Board

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

#171

Post by mrfusion » Tue, Apr 14, 2015, 2:42 PM UTC

DrStalker wrote: post #128

mrfusion wrote: post #121

Offshoot topic but noting how things we launch from earth already have all the energy they need to orbit the sun, why isn't it really easy to get to earth sun Lagrange points? It seems like we could kind of just float over there since we don't need any additional speed to orbit the sun.

You can't just "float over" to another point along your orbit; to move the forward Legrange point you would have to slow down, causing you to drop into a lower orbit which moves around the sun quicker, then speed up to a larger orbit that intersects with the desired Lagrange point and then finally speed up again when you reach that point to stabilize the orbit. To try this in Kerbal space Program: place two craft int…

Ok, that kind of makes sense. But as an extreme example let's say you moved out to earth sun L4 leaving from earth and moving at 1MPH*.

Once you got there, you're there besides station keeping. So in theory there's no deltaV required? That's what confused me.

Of course moving at 1MPH you'd be expending energy fighting earth's gravity until you got there. But I think that's a separate issue.

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

#172

Post by phkahler » Tue, Apr 14, 2015, 2:59 PM UTC

lmm wrote: post #158

phkahler wrote: post #119

Earlier quoted context omitted.

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.

It takes more energy to send something to the moon than to send it escaping the earth. Space elevator with a railgun at the top of it maybe makes sense.

>> It takes more energy to send something to the moon than to send it escaping the earth.

Sure, but far less than de-orbiting into the sun. Use the rocket to get to the moon-based rail gun where there is no atmosphere.

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

#173

Post by sbov » Tue, Apr 14, 2015, 6:52 PM UTC

lmm wrote: post #157

sbov wrote: post #93

Earlier quoted context omitted.

Do we know enough about our oceans to know that there would be no harm from this?

Define "know". Do we have it carved in tablets of stone from on high? No. Are we reasonably confident? Yes. There are already hotter things in the ocean (e.g. black smokers). What kind of effects are you worried about?

Is it a big deal if they break/leak? Are there any theoretical problems that I, as not-an-oceanic non-nuclear-waste expert, am not aware of? Not just over 5 or 10 years, but over hundreds of years? Are we able to monitor them for these problems? How difficult or expensive is it to fix any problems?

I ask because I genuinely don't know. I'd be OK with it if scientific consensus and consultation between the ocean and nuke people said we know enough about them to say there aren't issues. I don't want to just say "lets just dump them in a place I don't personally care about that's really far from me".

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

#174

Post by DrStalker » Tue, Apr 14, 2015, 10:40 PM UTC

mrfusion wrote: post #171

DrStalker wrote: post #128

Earlier quoted context omitted.

You can't just "float over" to another point along your orbit; to move the forward Legrange point you would have to slow down, causing you to drop into a lower orbit which moves around the sun quicker, then speed up to a larger orbit that intersects with the desired Lagrange point and then finally speed up again when you reach that point to stabilize the orbit. To try this in Kerbal space Program: place two craft int…

Ok, that kind of makes sense. But as an extreme example let's say you moved out to earth sun L4 leaving from earth and moving at 1MPH*. Once you got there, you're there besides station keeping. So in theory there's no deltaV required? That's what confused me. Of course moving at 1MPH you'd be expending energy fighting earth's gravity until you got there. But I think that's a separate issue.

If you accelerate by 1MPH you're not in the same orbit anymore. It's not like driving on earth, where you can go faster along the same path by pushing the accelerator down; the speed you're moving at is a component of your orbit.

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

#175

Post by DonHopkins » Wed, Apr 15, 2015, 12:15 AM UTC

elcct wrote: post #156

Cerium wrote: post #137

Earlier quoted context omitted.

Solar energy is simply a nuclear power system with a sensible waste disposal strategy.

But it also has not been approved by any authority. It is just like sending waste to some shady dude few blocks away "to take care of it"

The sun isn't the shadiest dude in the solar system.

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

#176

Post by opo » Wed, Apr 15, 2015, 4:35 AM UTC

mahranch wrote: post #154

opo wrote: post #135

Earlier quoted context omitted.

None of the countries that have developed nuclear weapons have gotten their plutonium from nuclear waste because there are much easier ways to get weapons grade plutonium. Form the wikipedia page: "Ordinarily (in spent nuclear fuel), plutonium is reactor-grade plutonium. In addition to plutonium-239, which is highly suitable for building nuclear weapons, it contains large amounts of undesirable contaminants: plutoniu…

> None of the countries that have developed nuclear weapons have gotten their plutonium from nuclear waste Just because someone hasn't done it before doesn't mean someone won't in the future. You're also ignoring the larger threat to that plutonium; the issue that someone may not want to separate the contaminants. If they're making a dirty bomb, they don't care if it has contaminants or not.

>Just because someone hasn't done it before doesn't mean someone won't in the future.

It isn't random chance that no one has developed nuclear weapons using nuclear waste from a commercial reactor. It is because it would be far more expensive, a far bigger engineering challenge and far more difficult to hide than any of the other ways to create a nuclear bomb.

>You're also ignoring the larger threat to that plutonium; the issue that someone may not want to separate the contaminants. If they're making a dirty bomb, they don't care if it has contaminants or not.

I didn't talk about dirty bomb because the original statement I was replying too was saying that reprocessing akes plutonium easy to separate out and was a nuclear proliferation risk. It is impolite to criticize me for not bringing up a different issue. In the case of a dirty bomb, it would be many times less dangerous than a nuclear weapon would be and there are many, many potential sources of material for a dirty bomb that would be much easier to obtain and work with than the waste from a commercial nuclear reactor.

As I said before, a very good approach to deal with nuclear waste would be recycle it.