Lasers could cut lifespan of nuclear waste, a Nobel winner suggests | Hacker News Reader

Lasers could cut lifespan of nuclear waste, a Nobel winner suggests

bigthink.com

141 pointstokstesla77 comments

For all we know this is possible but not at all practical. The NIF [1] already does experiments with lasers that start nuclear processes in the ICF [2] capsule. An exeptionally good shot produces 2e16 neutrons [3], from (about) 2e16 nuclear reaction. But that single shot required more than 400 MJ of energy from the electrical grid to charge the capacitor banks that drove the flash lamps that pump the lasers that input 500 TW of laser light for a tiny fraction of a second into a hohlraum to heat it so high that the thermal x-ray compresses the implosion capulse in the middle to a sufficient temperature and density that nuclear processes start. Per neutron that was 2*10^-8 Joules. A typical large 1000 MW nuclear reactor produces 25–30 tons of spent fuel per year [4]. Assuming that nuclear waste has an average Z of about 50 and weights 100 daltons, 100 grams of material are one mole, so we have 3e5 mole to reprocess with 2e29 nucleii that need to be treated. Assume that on average only one neutron needs to be added or removed that will requires 3e21 MJ. But the 1000 MW reactor running for 365 days, 24 hours a day, 3600 seconds per hour only produced 3e10 MJ to begin with. In other words it would require 100 billion times as much electrical energy to convert nuclear waste that way than you get out of the reactor creating that waste. Can we make things more efficient by a factor 2 here and a factor 100 there? Probably. But that wont make a dent.

Transmuting elements with lasers is really cool for basic science, but completely useless as a solution for nuclear waste.

1: https://en.wikipedia.org/wiki/National_Ignition_Facility

2: https://en.wikipedia.org/wiki/Inertial_confinement_fusion

3: https://www.llnl.gov/news/nif-achieves-record-double-fusion-...

4: https://en.wikipedia.org/wiki/High-level_waste

To be fair, it looks like what he's proposing is fundamentally different from inertial confinement fusion. Inertial confinement with lasers is so hard because it's so tricky to apply perfectly even, symmetric force on every side of the hohlraum. What's being proposed here seems to be more on the line of <attosecond laser pulses directly exciting the nucleus, so wouldn't be useful for fusion but would have very different yields and wouldn't have the same trouble with maintaining confinement.

Maybe. It is hard to find any scientifically accurate information on his proposal. But if you say he wants laser intensities that are directly sufficient to get 1 MeV (typical nuclear energies) across the 10fm of a nucleus he would need intensities that are about a factor 100 above the Schwinger limit [1] where the laser simply produces electrons and positrons out of the vacuum. Cool if you want to study the plasma environments of pulsars, but probably a HUGE loss mechanism in getting energy into the nucleus.

In the end it all boils down to the fact that visible light an laser operate on the energy scale of electronic transitions whereas nuclear transmutations occur at the vastly different energy scale of the strong force. This huge separation between electromagnetic interactions and strong nuclear interactions is btw also the reason why radioactive material is not typically green glowing goo.

1: https://en.wikipedia.org/wiki/Schwinger_limit

Totally. As Mourou puts it in the talk, "we are boiling the vacuum!" Going of the figures in the talk, it looks like he would be counting on ultrashort pulses that are well into the realm of relativistic optics, and possibly approaching the QCD regime.

I feel you are looking on the wrong numbers. Yes, individual photons are hugely more energetic, and the process is lossy, but it does not mean the process will consume a lot of energy - very few might be needed.

You previous calculations are for creating light pressure sufficient for fusion, that's a uniquely energy consuming process, You can't reuse those numbers here because they are not trying to crush Uranium atoms together.

But likewise I could not find concrete details for the proposal.

Swinger?

Sorry, that was a horrible typo for "Schwinger limit" that is now fixed. An explanation can be found at [1].

The limit comes from the following process: Thanks to quantum mechanics there is an uncertainty principle between position and momentum. Less known it the uncertainty between time and energy. (If you have studied classical mechanic you will recognize that the variable pairs are the same that you know from Noethers theorem [3].)This implies that nature can (and will) violate conservation of energy by an amount deltaE for a time deltat up to hbar/deltaE. One such process is the creation of a electron-positron pair out of vacuum. That violates energy conservation by about 1 MeV and you have to return the (virtual) particles within hbar/1MeV or approximately 6e-22 seconds. If however the electric field is sufficiently large that the particles get accelerated to an energy of 1 MeV within that time they get to stay. An electric field that can do that has a field strength of 1.3e18 V/m.

At that intensity the laser light does not simply propagate through vaccuum as predicted by Maxwells equations, but is producing a pair plasma and gets damped. The process is fairly well described by QED. We are currently trying to get laser up to that intensity and to make accurate measurements of this QED effect as it does not only work for electron-positron pairs, but arbitrary particle-antiparticle pairs. Experimental deviations from the QED predictions would therefore imply the existence of additional light particles (and antiparticle) that we have not found through other methods.

1: https://en.wikipedia.org/wiki/Schwinger_limit

2: https://en.wikipedia.org/wiki/Uncertainty_principle

3: https://en.wikipedia.org/wiki/Noether%27s_theorem

>>In other words it would require 100 billion times as much electrical energy to convert nuclear waste that way than you get out of the reactor creating that waste.

I'd bet that something lost in the translation or someone else would have pointed this out before.

I know about such suggestion for about, I guess, 20 years. It was suggested as a way to clear radioactive waste in Chrenobyl contamination area.

And if you can read Russian, here a paper for your amusement for semisuccessful attempt to implement that: http://www1.jinr.ru/Pepan_letters/panl_2017_6/13_Andreeva.pd...

It contains a short English abstract which I copy here: The influence of laser irradiation on the gamma-activity of aqueous solutions of both 137Cs and 134Cs is experimentally studied in presence of Au nanoparticles at laser intensity of order of 10^(12)W/cm2. It is found that laser irradiation reduces the gamma-activity of both nuclides. This decrease is not accompanied by excessful gamma radiation in the spectral range of gamma-activity of their spontaneous decay. Possible mechanisms are discussed of the influence of laser radiation on the activity of isotopes on the basis of laser field enhancement on the plasmon resonance of nanoparticles.

... Or just burn it in a fast reactor, and get some use out of all that leftover energy, instead of calling it waste?

Whats a fast reactor. I have never heard of it?

Neutrons come out of a fission event at high speed, about 20% the speed of light. These are called fast neutrons. In almost all nuclear reactors we've built, we deliberately slow these neutrons down with a moderator material (which must have light atoms in it: things like graphite, water, beryllium). It's much easier to get a pile of nuclear fuel to chain react when you slow neutrons down, largely because Uranium-235's liklihood of absorbing a slow neutron is much higher than its liklihood of absorbing a fast neutron.

(Aside: slow neutrons are often called "thermal" neutrons because they're in thermal equilibrium with the atoms around them. At room temperature they're going 2200 m/s, which corresponds to an energy of about 0.0253 electron-volts, slowed down from 2 million electron-volts when they emerged from fission)

A fast-neutron reactor ("fast reactor") is a reactor where the neutrons that emerge from a fission event are kept moving fast, simply by not putting a moderator into the design. These reactors use heavy nuclei or very low density material as coolants (sodium metal, lead-bismuth eutectic, helium, etc), so as to not slow down any neutrons. It takes much more fissile fuel to get a pile of nuclear fuel chain reacting in this configuration, but once you get it going, you get some very nice benefits.

Once started, fast neutron chain reactions have a vast surplus of neutrons going around. This is for two main reasons: (1) The number of neutrons emitted per fission increases dramatically as the neutron speed increases above a threshold around 1 MeV, and (2) parasitic absorption of fast neutrons is low for all nuclides. With so many extra neutrons around, you can afford to put extra "stuff" in your reactor, such as spent nuclear fuel (nuclear waste) or extra fertile material (uranium-238 or thorium-232).

You can make these reactors into breeder reactors (which convert U-238 or Th-232 into fissile fuel in such a way that could power the entire of humanity 10x over for a few million years, at least, using known resources), or you can make these reactors into burner reactors, whose job it is to transmute used fuel from other reactors into shorter-lived material (similar to what OP's article is about, but much more practical).

A definitive guide to understanding transmutation of spent fuel in fast-neutron reactors is put out by the UN's International Atomic Energy Commission [TRS-435]:

"Implications of Partitioning and Transmutation in Radioactive Waste Management" https://www-pub.iaea.org/MTCD/Publications/PDF/TRS435_web.pd...

A handful of fast-neutron reactors have been built, starting with tiny single critical mass assemblies in the 1940s, to the first true demo of breeding more fuel than you consume in EBR-1 in 1951 to the EBR-2's safety demo weeks before Chernobyl showing that the reactor could passively shut down and cool itself without any human intervention or external power or control rods inserting, to India's PFBR fast reactor that's been under construction for the past 18 years.

Only the Russians have successfully operated fast reactors commercially, via the BN-350 and BN-600. In general, fast neutron reactors are considered more complex and expensive to build and operate than traditional water-cooled thermal neutron reactors.

We once thought uranium was very scarce, and so we put a lot of money into fast breeder reactors. Then it turned out that there's lots of uranium and fast reactors are largely on hold internationally. France just announced the cancellation of its national fast reactor program (ASTRID). Russia delayed their next BN fast reactor, saying their VVER (slow neutron) reactors are bout 4x cheaper. China and India are pushing forward. The US shut down its last fast reactors (EBR-II and FFTF) in the early 1990s. Many nuclear startup companies are now exploring options to get back into fast reactors.

The US DOE is putting forth a major project to build a new fast reactor very similar to the FFTF, but in Idaho instead of Washington and with metal fuel rods instead of oxide ceramic ones. The project is called the Versatile Test Reactor (VTR) and is actively discussed in current nuclear news.

Extremely informative comment, thanks for taking the time to write it out and contextualize the info against current events.

You're welcome. My pleasure. I spend all day dealing with this info so it's easy to just pound out a answer like this quickly.

Lemme guess, they haven't become popular yet because there wasn't a way to weaponise the results?

No. Weaponization of nuclear fission technology was completed in 1944. Plutonium production plants of similar design to those used in the Manhattan Project were used throughout the Cold War (at Hanford and Savannah River). There are myths about various nuclear technologies being cancelled because they "couldn't be weaponized" (usually talking about molten salt reactors), but these myths are quite wrong.

Fast reactor tech hasn't been popular because it's more expensive than regular old water-cooled fission reactor tech. To keep neutrons going fast you have to use exotic coolants like sodium metal. Since you don't want to mix a chemical hazard with a radiological one, you insert an additional intermediate heat transfer loop into the system. Hot radioactive sodium transfers heat to hot non-radioactive sodium which transfers heat to water which boils and turns a turbine to crank a generator to push electrons around to provide low-carbon service to human quality of life.

Can you please not call sodium "exotic"? Doing so adds to an irrational fear of relatively benign technology.

Molten sodium is easy to pump, non-corrosive to many metals including steel, and a good heat transfer medium. The chemical industry uses it routinely. In a nuclear reactor, it would also chemically sequester a particularly annoying fission product (I-131) in case of a fuel element leaking. Unpressurized, it is good up to 800C before it boils.

By contrast, water at 300C will corrode most steels. At higher temperature, it will corrode zircalloy, forming hydrogen. And it really wants to be a gas, hence the giant containment buildings around LWR.

What did you say? "But sodium explodes in contact with water?" That's easy to solve, just keep the water out. A sodium cooled reactor should be coupled to a supercritical CO2 turbine instead of a steam turbine. That removes the problem of leaking and exploding heat exchangers.

(Footnote: I like molten salts better than sodium. But sodium is still better that water.)

Sodium coolant is exotic from an operational point of view. Exotic doesn't mean dangerous. Sodium systems from a probabilistic risk statement are usually 100x safer than pressurized systems because of passive decay heat removal capabilities. Exotic means "different from normal." So far, all operating sodium-cooled plants have suffered from operational and economic challenges due to sodium's characteristics. This is solvable with experience, but it's not easy.

Have you ever studied a detailed procedure for heating up a large sodium valve from the solid sodium phase to the liquid? If not I highly recommend doing so. It's truly remarkable. Molten salt systems are the same level of complexity, but much more radioactive in the primary system. Remote maintenance of this stuff is totally doable, but it sure as hell is exotic. Rickover's characterization of sodium systems stands to this day.

Traditional sodium systems with void-swelling resistant structural materials may not go to high enough temperatures to strongly justify the tech development needed for a sCO2 balance of plant in the short term. Sodium-water steam generators with leak detection have worked well-enough to build a few more of them while sCO2 turbomachinery gets figured out at the 100s of MW scale.

To the contrary. You can use these things to breed very dangerous material for bombs. Hence most industrial countries (say Germany) are nudged by the superpowers to not implement such devices. If Iran would build one, for instance, it would immediately be bombed by Israel or become a nuclear superpower in a few weeks of operation.

You can breed weaponizable fissile material in fast reactors. But by far the easiest way to make bomb material in a reactor is what they did in the Manhattan Project, using graphite moderated thermal neutron production reactors (not fast reactors). And it's even easier still to just build gas centrifuges and enrich uranium without needing a reactor at all.

Becoming a nuclear superpower weeks after operation of a fast-neutron reactor is a bit of an overstatement.

A reactor with a fast, as opposed to thermal, neutron spectrum. Among other things, implies that it must be cooled by something else than plain water, which is is a neutron moderator (that is, slows down the neutrons to thermal velocities). Often the coolant of choice is a metal like sodium or lead.

Fast reactors enables breeding, that is producing more fissile material from the fuel than is consumed. They are also better at burning up various isotopes that thermal reactors have trouble with.

https://en.wikipedia.org/wiki/Fast-neutron_reactor

Yeah, no. We should not exchange large quantities of relatively slowly decaying radioactive materials (hence the long half-life) hidden somewhere deep underground with a very dangerous device somewhere close to population.

The long half-life [actually the mixture of lengths of half-lives] is really the problem. You've got stuff that's super-hot [fast decay] and so very dangerous mixed with much slower-decaying [so not as dangerous] stuff that needs to be isolated for a super long time. If you run it through a fast reactor/reprocessor, you can use most of the energy and be left with mostly just medium-duration stuff, that will burn out in a reasonable timescale for underground storage, say 1000 years.

We have many dangerous devices extremely close to the population already. Cars kill more people in a year than all nuclear reactors have killed in the whole time of their existence. Should we bury the cars underground instead?

A very dangerous device. I suppose you have heard about that irresponsible experiment conducted in 1986 where they simply turned off all cooling to a reactor? Remember what happened?

No, not Chernobyl. I'm talking about EBR-II, a fast reactor. Nothing happened. That's how dangerous the device is!

You mean a reactor that is cooled with Sodium, a material that, according to Wikipedia, spontaneously explodes when it comes into contact with a rare substance called water?

Not spontaneously, only when contacting water. But you see, there is no water in such a reactor. And it can't get in, because if water can get in, other stuff can get out, and stuff getting out of a reactor is a disaster anyway, so the thing is a closed system. Even though, since sodium cooled reactors are not pressurized, stuff wouldn't necessarily come out of a small leak.

On the other hand, water at 300C and 200bar will explode spontaneously without coming into contact with anything. A steam explosion is no fun, according to Wikipedia.

Can someone with more knowledge explain to me why it's so hard to reuse waste? Like if it is emitting enough energy to contaminate entire swaths of land, why can't you just build something to absorb all the radiation? I can't imagine it is that much less efficient than a solar cell if you just stick it in a box.

It's not, and many other countries do. However, there are still big concerns about the overall economic payback of reprocessing, and also concerns about nuclear proliferation:

https://www.forbes.com/sites/realspin/2014/10/01/why-doesnt-...

https://en.m.wikipedia.org/wiki/Nuclear_reprocessing

Makes sense all the other power source industries would try to lobby nuclear into the ground - if it was used to its potential without political shenanigans and scaremongering in the way we'd have all the cheap green energy we needed with all the other sources out of business.

You mean, something like a RTG (https://en.m.wikipedia.org/wiki/Radioisotope_thermoelectric_...)? I vaguely recall some suggestion to use fission products from reprocessing as RTG fuel, or just as a low grade heat source. I'd guess the hazards of FP's would make it very expensive indeed.

The solid nuclear fuel business is structured like the multi-color printer cartridge business: once a specific uranium isotope is depleted, you have to throw the whole thing away. FWIW, there are several projects, including one funded by the Bill & Melinda Gates Foundation, trying to solve the issue, but are running into significant political pushback.

https://en.wikipedia.org/wiki/TerraPower

Am I reading this right?

"erraPower notes that the US hosts 700,000 metric tons of depleted uranium and that 8 metric tons could power 2.5 million homes for a year.[9] Some reports claim that the high fuel efficiency of TWRs, combined with the ability to use uranium recovered from river or sea water, means enough fuel is available to generate electricity for 10 billion people at US per capita consumption levels for million-year time-scales."

That sounds completely crazy haha

It might sound crazy, but it's true. The amount of energy that can be extracted from nuclear fuel is mind boggling.

This is also why the "let's throw it into the sun" style proposals are bonkers.

Do you know how rare, useful and valuable those heavy atoms are?

I have always thought it will be super valuable in the future and we will end up reprocessing it and using it for some other form of reactors.

So might it even be smart to buy up nuclear waste and store it deep underground somewhere until it is?

Besides whatever regulatory hurdles I imagine you would run into, you can basically leave it in a dry stable underground place for much longer than any of us will live. Old salt mines.

It seems unlikely to me that this could be an efficient way to burn radioactive waste. However, there is another approach that combines a linear electron accelerator with infrared laser pulses to generate absurdly high power (compared to traditional accelerator sources) gamma rays: https://www.sciencedaily.com/releases/2011/04/110426160211.h...

The tunability of this gamma rays source makes it possible to target and induce nuclear reactions in unstable atoms.

If I remember correctly, when I saw the seminar talk by the originator of the concept, a few years ago, he said that an existing super-conductor-based linear accelerator in Japan could feasibily by modified to generate enough gamma rays to burn thousands of tons of radioactive waste per year. (Don't quote me on the exact amounts, though, it's been a while).

Even if it somehow works, photofission will never be energy efficient. You will be spending gigawatt hours per gram of fissioning matter

Why do you say that? The approach I linked can be an absurdly efficient way to generate gamma rays with super-conductor magnets and electron recycling, like the Japanese electron accelerator has. And keep in mind, these atoms are already unstable. The photon just excites the nucleas out of the meta-stable ground state.

> Take the nucleus of an atom. It is made up of protons and neutrons. If we add or take away a neutron, it changes absolutely everything. It is no longer the same atom, and its properties will completely change.

Are they talking about transmutation with lasers? Would it work for Lead -> Gold too?

Yes, but not economically. For an encore, the oceans contain plenty of gold too, a coupe of parts-per-trillion. It's yours for the taking.

(shhh don't tell him about biological fouling) Did I say that out loud?

I suspect it's vastly easier to add or remove a single neutron rather than to remove several protons like you'd have to do to transmute between elements.

Is that figure correct, 22,000 m3?

That's just a cube 28m on a side, maybe the same size as a small apartment block.

Just dump it into a subduction zone

Nice idea, but refuted already: https://www.nwmo.ca/~/media/Site/Reports/2015/11/11/06/32/12...

Am I skimming this too quickly, or does it actually say sub-seabed/subduction sequestration is one of the few options that actually works - it's just not currently possible because of international "dumping at sea" treaties?

With such a small volume I think 'do nothing' is fine at the moment until we can find an economical use for it (fast breeder, traveling-wave etc, etc), or agree the best way to dispose of it - 20,000-year managed repositories don't seem viable to me.

I don’t understand how high-intensity CPA photons with wavelengths in order of a micron are supposed to have any effect on the nucleus, but there definitely are a lot of electrons ready to absorb them. Regardless, there are many much more efficient ways to generate thermal neutrons if that’s what he’s after, which agree with, and you can get controlled energy out of it! Years ago I proposed a small nuclear waste fueled engine design based on this principle.

My understanding was that you’d need gamma radiation for the nucleus to even notice it. Lots of low energy photons isn’t the same as fewer high energy photons.

That is true until you have to so many photons that you hit the QED regime where photons interact with each other and electrodynamics becomes non-linear. However at that point no just the nucleii notice, but you start to get all kinds of other effects.

Awful reporting about a bad idea.

The actual proposal isn't to irradiate nuclear waste with lasers. The idea is to use the laser to accelerate protons, irradiate heavy nuclei with those protons to get them to either fission or at least emit neutrons, irradiate long-lived waste with those neutrons to transmute it. It's possible in theory.

In practice, it's nonsense. These accelerators have low efficiency and produce few neutrons. This makes the process slow and inefficient. So inefficient in fact, that all practical (for small values of "practical") proposals are actually for sub-critical reactors that use nuclear fission to amplify the neutron output.

But then the idiocy becomes clear: instead of a sub-critical reactor and an unbelievably expensive accelerator, you might as well build a critical reactor, recycle the actinides directly and maybe transmute the fission products.

In other words, this is a guy who just likes particle accelerators. He has a solution, now he's looking for a suitable problem.

If nuclear material is irradiated by tunable lasers, are there particular wavelengths that increase or decrease alpha/beta/gamma emission?

Short of neutron guns, are there environmental conditions that affect nuclear half-life?

This must actually be about stimulated emission on the nuclear scale, with much getting lost in translation on the way to something politically marketable...

There is much to be learned in this space still.

I failed physics but, in theory if you could keep pouring neutrons into fissile material, couldn't you lower the amount of nuclear fuel required to achieve critical mass (which is bound by the rate of neutron loss)?

Wouldn't this basically boost mpg and/or increase safety of reactors?

I believe there are some newer theoretical reactor designs based around this concept! In essence, they are designed such that the fuel is not in itself capable of sustaining a chain reaction. It is only with the active addition of neutrons that you can get the fission reaction underway. So if you halt that supply of neutrons from the neutron generator, the reaction dies off, greatly enhancing passive safety.

The mpg of reactors (or rather the burnup) is measured by the energy extracted from the primary fuel. In practice that is not limited by neutron flux, but by accumulation of gaseous fission products inside the fuel or the cladding. They do not get any better when you supply external neutron flux. Other, secondary concerns such as the fact that you need to leave the fuel in the ractor for a long time inside the reactor, which leaves a lot of time for corrosion to take place might be reduced. But in the end it is rather costly to produce neutrons with non-nuclear means on the outside.

I've been waiting for Atomic Vapor Isotope Separation (AVLIS or MLIS or SILEX) to let a small group or small state produce their first nuclear weapon basically outside the current nonproliferation controls.

Is storing nuclear waste even a significant concern? The entirety of US nuclear power generation's waste can fit in a rectangle that is 20 feet high and the width and length of a football field. This is trivial in terms of volume of waste disposal. There's really not much difficulty in disposing this. Bury it in a site without groundwater.

Yes I've often maintained that we could just drill a hole in the middle of Australia and dump the worlds nuclear waste in it. Its the perfect spot, no ground water (if you make sure its west of the great artesian basin), geologically and politically stable, no one lives there for miles, and there's already a shit ton of radiation there anyway - thats where the Uranium comes from.

One problem would be transporting it, but again, solvable problems, we tanker oil around the world, so it can be done. The trouble is though political. No one wants all that nuclear waste in their back yard, even if no one ever uses the backyard.

Fukishima added to the problem - if the Japanese, whose engineering skill is the best in the world, have problems then what about the rest of the world? I see this as a very valid objection.

One of the problems I see in the popular mind is the idea that radiation is somehow unique and only occurs in nuclear reactors, and any of it appears somewhere then we're all dead. The coal industry makes sure no one finds out that the amount of radiation expelled by coal powered stations exceeds that produced by nuclear reactors https://www.scientificamerican.com/article/coal-ash-is-more-...

As you say the amount to be stored is pretty small, and could probably be dumped down a hole in an afternoon and home in time for tea

An anecdote - I went to a radiology clinic a while ago for a tour (writing some software) and we stopped by the room where they store the radioactive material, pretty low level stuff and all stored away. The manager taking me around said "This is where we store the radiocative stuff" looking at me and waiting for a reaction - a bit of fun I imagine he has - expecting me to run away and panic, but I have a physics degree so no drama - he was disappointed, and we laughed. But this is the public mind - radiation is scary stuff that causes mutations and kills you, so there's a real marketing problem. No doubt this has been pumped up by the oil and coal industry over the years.

Nuclear waste storage is a huge issue politically though.

My point remains: is there any actual safety concern with putting nuclear waste underground other than potential groundwater pollution if the containment casks get perforated (which can be avoided by not burying waste where there's groundwater)?

The only scenarios that people have presented in which nuclear waste could result in contamination are borderline absurd, like if humanity hypothetically loses all records of where waste is buried along with knowledge of what radiation is and some future civilization might dig up the waste canisters and crack them open.

There’s plenty of research on this topic. Perhaps you can find the Wikipedia entry a useful jumping off point. https://en.wikipedia.org/wiki/High-level_radioactive_waste_m...

Nothing in your link covers the safety or dangers of waste disposal beyond the vague statement that, "There is general agreement that placing spent nuclear fuel in repositories hundreds of meters below the surface would be safer than indefinite storage of spent fuel on the surface." That article is a couple paragraphs on waste containers, and a list of different countries' waste management schemes. It doesn't dig into any long term risk assessment.

It's not that trivial. It's hard to find places that are geologically stable over very long timeframes.

However, anti-nuclear activists deliberately focus too much on the problem of storing it indefinitely in the near term.

If we plan storage for tens of thousands of years, waiting out a few hundred years for economic and technological development is in order. The waste of tomorrow might be the fuel of the future.

The waste needs to be stable over the span of ~10,000 years. This is very short in terms of geological time frames. Yucca mountain isn't going to be pulled apart by continental drift any time in the next several million years.

> The waste needs to be stable over the span of ~10,000 years.

How did you arrive at that number? The waste is harmful for hundreds of thousands or even millions of years.

Like I said, I think the "indefinite storage" question is a red herring posed by anti-nuclear activism.

Perhaps a better question would be: How much we should be concerned about the inhabitants of this planet in 10,000 years when supposedly there's a mass extinction coming up in the next 100 years due to the energy needs of today and yesterday.

The waste itself is harmful, for eternity, simply by virtue of the fact that it is uranium. It's a toxic heavy metal, like lead, regardless of any radioactivity. The duration of the serious concern due to radiation is gone in roughly 10,000 years but if course the original enrichment and subsequent use of the fuel can have large impacts on this figure.

The reality is, nuclear waste should mostly be treated similarly to the toxic waste that is generates by other sectors of heavy industry.

Maybe another idea is when rockets are cheap enough < cost of storing. Send them into the sun.

Launching things from the Earth to the Sun is very difficult. We're talking a Saturn-V-sized rocket to move less than a lunar-lander-mass of waste. The fundamental problem is that the Earth moves fast in its orbit, and in order to drop your spaceship's orbit towards the Sun you have to slow down.

https://space.stackexchange.com/questions/13396/do-any-curre...

And if something goes wrong and nuclear waste is scattered through the atmosphere? I think we'll get to a point where we can do it safely, but there's always a chance. Maybe if costs are low, generating energy in space and shipping it back (either as batteries or a literal wire) would be better.

It’s not a good idea, but it could be done very safely. Personally, I think nuclear power is simply to expensive to be particularly useful going forward, but IMO waste is a smaller issue than generally perceived.

Sure, you would encase them in something that could survive reentry or detonation of the rocket. Choosing a launch location and trajectory for easy recovery is also possible.

However, paying 1,000+$/lb to get rid of Nuclear waste is extremely expensive. Simply storing it in a pond for ~120 years and the stuff gets vastly less radioactive as short half-life material decays. Strontium-90 and cesium-137 have half-lives of about 30 years so you get 6% as much of them and essentially everything with a shorter half life is gone. Plutonium-238 has a longer half life of 87 years, but you also get rid of ~2/3 of that.

You still have almost off the Plutonium-239 with a half-life of 24,000 years, but that stuff is not nearly as nasty and can be reprocessed for fuel. Further, reprocessing becomes cheaper after waiting for it to cool down.

PS: Plutonium-238, Strontium-90 and cesium-137 can also be used for space probes via: https://en.m.wikipedia.org/wiki/Radioisotope_thermoelectric_...

On the other hand, the risk of it blowing up in the sky shoots down the plan.

why does it need to be sent to the sun? Just launch it at the moon

We see all these pie in the sky solutions all the time but please don't start counting on them becoming reality. It's great to dream and work towards the dream but don't count on it as a solution.

For now, the solution is to use nuclear fuel in the most efficient manner so as to minimize waste.

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