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.
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.
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.
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.
>>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.
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