I do think the borehole plan (3km deep, rather than 400m deep) is better, although it is more speculative and this proposal has the overwhelming advantage that it’s being enacted.
Finland's plan to bury spent nuclear fuel for 100k years
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Re: Finland's plan to bury spent nuclear fuel for 100k years
#12Personally I'm rooting for the future where a fleet of falcon 9's launch escape velocity stage 2's that head straight for the sun. Underground is nice until you get radioactive groundwater. The time cost of 100k years of maintaining safety seems more than the financial cost of maintaining a F9 fleet and disposing of second stages.
My engineering students explored this idea for a project. It turns out that sending something into the sun is really difficult. You have to overcome the velocity of planet earth orbiting the sun, which means you need a delta-V of 8.8 km/s to get the waste into a high orbit above the sun, followed by another burn to reduce its velocity to zero at that orbit.
That’s the same delta-V as going to Jupiter. You would need a lot of rockets.
Re: Finland's plan to bury spent nuclear fuel for 100k years
#13There is nice arty documentary film ”Into eternity” about Onkalo (made already 2010) https://www.youtube.com/watch?app=desktop&v=ayLxB9fV2y4
Re: Finland's plan to bury spent nuclear fuel for 100k years
#14Personally I'm rooting for the future where a fleet of falcon 9's launch escape velocity stage 2's that head straight for the sun. Underground is nice until you get radioactive groundwater. The time cost of 100k years of maintaining safety seems more than the financial cost of maintaining a F9 fleet and disposing of second stages.
How many falcon 9's would that require?
Re: Finland's plan to bury spent nuclear fuel for 100k years
#15What I don't get is the following: If your nuclear waste is that "hot" (highly radioactive), then you're not draining as much energy out of the material. Ideally, the closer to lead you are, the more energy is drained out. And that's what I'd hope to see from the mining required for uranium. Instead, we seem to run it once and then go "whoop have to stop".
Not sure I'm following. Fission reactors split uranium into smaller atoms like barium and krypton. The remaining energy that comes out as afterglow heat in the repository is a small fraction of what already came out during fission. less than 1% remains an hour after fissioning.
You have the numbers reversed.
In spent nuclear fuel 96% of the mass is the remaining uranium is still usable. Spend nuclear fuel (=LEU) used in these reactors have almost all potential energy left.
You can use them if you close the nuclear fuel cycle with fast neutron reactors. The downside of it is that they FNR's are also good for making fuel for nuclear weapons.
Re: Finland's plan to bury spent nuclear fuel for 100k years
#16Personally I'm rooting for the future where a fleet of falcon 9's launch escape velocity stage 2's that head straight for the sun. Underground is nice until you get radioactive groundwater. The time cost of 100k years of maintaining safety seems more than the financial cost of maintaining a F9 fleet and disposing of second stages.
"...it's surprisingly hard to actually go to the Sun: It takes 55 times more energy to go to the Sun than it does to go to Mars.
Why is it so difficult? The answer lies in the same fact that keeps Earth from plunging into the Sun: Our planet is traveling very fast — about 67,000 miles per hour — almost entirely sideways relative to the Sun. The only way to get to the Sun is to cancel that sideways motion."
https://www.nasa.gov/feature/goddard/2018/its-surprisingly-h...
Re: Finland's plan to bury spent nuclear fuel for 100k years
#17Personally I'm rooting for the future where a fleet of falcon 9's launch escape velocity stage 2's that head straight for the sun. Underground is nice until you get radioactive groundwater. The time cost of 100k years of maintaining safety seems more than the financial cost of maintaining a F9 fleet and disposing of second stages.
How would this ever be acceptable, given that rockets have a failure rate that’s not zero?
Re: Finland's plan to bury spent nuclear fuel for 100k years
#18I'm excited that Onkalo will be coming onine soon, so we don't have to hear the myth that there's no solution for spent nuclear fuel anymore. The solution that enjoys a solid scientific consensus is the deep geologic repository. Another thing that is weird to me is that everyone says nuclear waste is hazardous for a uniquely long time, but it become less hazardous over time. Many non-radioactive materials, like arsen…
Burying things in the ground is not a solution. It's more an Ostrich policy.
Re: Finland's plan to bury spent nuclear fuel for 100k years
#19Earlier quoted context omitted.
Not sure I'm following. Fission reactors split uranium into smaller atoms like barium and krypton. The remaining energy that comes out as afterglow heat in the repository is a small fraction of what already came out during fission. less than 1% remains an hour after fissioning.
You have the numbers reversed. In spent nuclear fuel 96% of the mass is the remaining uranium is still usable. Spend nuclear fuel (=LEU) used in these reactors have almost all potential energy left. You can use them if you close the nuclear fuel cycle with fast neutron reactors. The downside of it is that they FNR's are also good for making fuel for nuclear weapons.
I don't have the numbers reversed. I'm talking about when a single atom actually undergoes fission, it releases 93% of its energy promptly as fission product kinetic energy, gamma rays, and neutron kinetic energy. An hour later, another 6% of the energy goes out as delayed betas and gammas. After that, only 1% remains to emerge as heat in the repository.
What you're referring to is the fact that some reactors (aka breeder reactors, fast or thermal) can fission a much higher percentage of the total atoms loaded into the reactor, including most of the majority isotope (U-238) in addition to the minority (U-235).
I wrote a bit about breeding and recycling here: https://whatisnuclear.com/recycling.html
Re: Finland's plan to bury spent nuclear fuel for 100k years
#20I'm excited that Onkalo will be coming onine soon, so we don't have to hear the myth that there's no solution for spent nuclear fuel anymore. The solution that enjoys a solid scientific consensus is the deep geologic repository. Another thing that is weird to me is that everyone says nuclear waste is hazardous for a uniquely long time, but it become less hazardous over time. Many non-radioactive materials, like arsen…
Burying things in the ground is not a solution. It's more an Ostrich policy.
Better in the ground that the air.