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farmerben

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Posts posted by farmerben

    Storage of nuclear waste

    in Science & Spaceflight

    Posted

    On 7/30/2024 at 4:54 PM, Nuke said:

    polywells might be better. you dont have grid erosion that contaminates the plasma and requires you to shut it down to change the grid or purge the contaminated deuterium. less consumables less down time. polywells might still be viable for breakeven at some point, its just the proponents opted for computer simulations rather than lab work to nail down the optimal design. best option for a spacecraft power supply if it works. but for now they make excellent neutron sources.

    I heard that polywell disapperead into a venture capitalist blackhole, and hasn't released anything to the public in over 20 years.

     

    Science News Thread (for articles that don't relate to ongoing discussions)

    in Science & Spaceflight

    Posted

    On 7/29/2024 at 11:16 AM, darthgently said:

    Very cool for interplanetary probes.  But given the light signature I imagine ground based astronomers will much prefer it not be a regular thing in Earth orbit.  There are better options within Earth's magnetic field anyway.  Looking forward to the results

    This is a prototype from the New Zealanders.  They might not have the capability to leave Earth's SOI.  Even if they did the mass of communications gear would greatly retard the prototype.

     

    Storage of nuclear waste

    in Science & Spaceflight

    Posted

    I'm still a fan of accelerator driven reactors, which use a proton beam and spallation neutrons to incinerate nuclear waste.  These get rid of all the weapons grade material and longest lived waste.  You still have the cesium and strontium to contain for a few centuries.

    People who are not fans of this approach mostly complain about the expense.  But the expense is worth it, if it eventually leads to cheaper and better proton beams.  Because proton beams have numerous potential applications including ones in spaceflight. 

    One idea I have is that a deuterium beam could be way better than a simple proton beam as a spallation neutron generator.  To the best of my knowledge the research has not been done, and particle accelerators with deuterium have barely been tried.  It would be worth it to create one from a pure research perspective. 

    AI. What could go wrong?

    in Science & Spaceflight

    Posted

    I had a lengthy conversation with Chat GPT about religion and politics.  Much of which I cannot repeat here.  And once hit a temporary violation of Chat GPTs terms of service for a question.  

    Chat GPT says :

    Quote

    Islamic scholars began grappling with contemporary human rights frameworks and individual rights within diverse global contexts from the mid-20th century onwards, influenced by global trends, intellectual movements, and evolving interpretations of Islamic teachings.

    Which is, I suppose, somewhat honest and optimistic.

    For Questions That Don't Merit Their Own Thread

    in Science & Spaceflight

    Posted · Edited by farmerben

    8 hours ago, K^2 said:

    I do wonder how much work it would be to have the maglev pantograph that doesn't experience wear in the same way...

    But realistically, unless there are amazing breakthrough in batteries, I suspect the future for the trains is hydrogen. Diesel turbines can be converted into hydrogen turbines relatively readily. Alternatively, hydrogen fuel cells are an option. In either case, the biggest problem is the size and weight of the fuel tanks, and adding an extra car just for hydrogen isn't going to affect the performance of the train all that much. I'm sure there will be safety concerns, but hydrogen EVs in the recent years have demonstrated that this can be done reasonably safely.

    What do you mean by "maglev pantograph" ?  Does this mean magnets under the track and induction coils on the engines?

    I searched that the typical diesel-electric locomotive carries about 16 tons of fuel.  I'm not sure how many miles/hours that will last.  But it's equivalent to over 600 tons of batteries.  You can put over 100 tons of freight per car ( around 200 tons max total car weight).  So you have to swap batteries often, or recharge them.  It is possible, though probably impractical, to have 6 cars full of batteries just to match the range of diesel.

    For Questions That Don't Merit Their Own Thread

    in Science & Spaceflight

    Posted

    I wonder what the limiting factors are for battery powered train engines.  The most powerful engines existing are powered by overhead pantograph.  We will not see mass electric trains in the US because building the overhead lines would be too disruptive to existing infrastructure.  Unless, we do an interrupted pantograph.  Where the battery can be recharged at stations, or along convenient stretches of rural land.  Charge while moving by overhead pantograph, then go battery only through towns, etc.  It would create demand for the worlds best AC-> DC rectifier.

    Storage of nuclear waste

    in Science & Spaceflight

    Posted

    1 hour ago, Nuke said:

    i think the issue is calling it waste, because most of the isotopes are still useful. part of the process is letting it sit in a pool for a few years to burn off the nasties. once its in dry storage its pretty safe. im always questioning the need for centralized storage. what you do is dedicate a nuclear site to nuclear stuff. when you tear down an old reactor you build a new one in its place. and it might be of a design able to burn up some of the fuel formally known as waste. once we get past that then all you have is medium and low level waste, which is a lot less problematic.

    proliferation issues are moot when we get to the point were we can do nuclear weapons without the isotopes. we aren't far from a point where we can do that.

    Yeah its a resource, not a waste.  After a few centuries most of the radioactive fission products are gone.  You have a few hot rare earth elements including plutonium remaining.

    If we reprocess after cooling in a pool for a few years we have some nasty cesium and strontium that needs to be disposed of or stored safely for centuries, not millennium.  If we reprocess in a few centuries all the radioactive stuff is high value stuff.  The main reasons for not doing it are economic and weapons related.  It's the plutonium that lasts millennium.  

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