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uranium 235 and plutonium 239, have a half life of 24,000 years - U235 has a half life of 700,000,000 years. If he gets pulses 10,000 times faster, he says he

uranium 235 and plutonium 239, have a half life of 24,000 years - U235 has a half life of 700,000,000 years. If he gets pulses 10,000 times faster, he says he can modify waste on an atomic level. The article says nothing about how he hopes to gain 4 orders of magnitude. Is there some kind of Moore's law in the "speed" of these pulses? I wasted my time reading this article, it explains nothing.

belter 5y ago
It's not a novel idea: "Laser induced nuclear waste transmutation" https://arxiv.org/abs/1603.08737 https://arxiv.org/abs/1603.08737 "Transmutation prospect of long-lived nuclear waste induced by high-charge electron beam from laser plasma accelerator" https://arxiv.org/abs/1705.05770 https://arxiv.org/abs/1705.05770 "Fusion Driven Transmutation of Transuranics in a Molten Salt" https://arxiv.org/abs/2109.08741 https://arxiv.org/abs/2109.08741 "Generic method to assess transmutation feasibility for nuclear waste treatment and application to irradiated graphite" https://arxiv.org/abs/2201.02623 https://arxiv.org/abs/2201.02623
- adrian_b 5y ago
  The first 2 papers indicated by you refer indeed to the same thing as the article that started this thread, but they explain the possible method. The principle is very similar with the sources of deep ultraviolet light used for photolithography. The laser pulses are used to produce hot plasma and to accelerate the electrons from plasma, which hit then a target, like in the traditional X-ray tubes. The interaction of the accelerated electrons with the target produces gamma rays. Finally, the gamma rays can be used to transmute the nuclear waste. There are 2 problems with this approach. As everybody knows, improving the deep UV sources to have an intensity great enough to be usable in the production of integrated circuits took several decades and many billions of dollars. The gamma ray sources that would be needed for waste treatment are significantly more complex and the output intensity must be much higher, so it is impossible to guess how much time and money would be needed, but certainly much more than for photolithography. The second much more serious problem is that already mentioned in another post. If these gamma-ray sources would have a global efficiency of 1%, starting from the electrical input power, passing through pump diodes for lasers, then solid-state lasers for pulse generation, then heating plasma, accelerating electrons, radiation from the electron target and finally absorption in the nuclear waste, that would be an amazing achievement. Actually a global efficiency of less than 1 per ten thousand would be more likely today. The energy required to transmute all the waste from a nuclear reactor might be of 10% or more of the output energy of the reactor. Multiplied with a factor between 100 and 10000, the result is that a nuclear reactor would not be a net producer of energy, but a huge consumer of energy, making it useless. A little more realistic would be to not treat all the nuclear waste, but only 1 or a few especially dangerous isotopes, e.g. only the radioactive iodine. While this would reduce a lot the energy required for transmutation, a lot of additional energy would be needed for the separation of the desired isotopes from the radioactive waste. Maybe transmuting only the iodine could be done in a distant future with a little less energy than the nuclear reactor produces. However that would not solve the problem with the storage of the nuclear waste. Consuming a huge amount of energy with the elimination of the iodine would only lessen the danger of what would happen if the storage of the waste would be compromised and the waste would be dispersed into the environment (because the vertebrates extract the iodine from the environment and concentrate it into the thyroid, so radioactive iodine is dangerous even at smaller concentrations than the rest of the waste).
- contravariant 5y ago
  It never really occurred to me that transmutation is a reputable field of scientific study nowadays.
  - belter 5y ago
    A sub-skill of Alchemy :-) https://en.wikipedia.org/wiki/List_of_alchemists https://en.wikipedia.org/wiki/List_of_alchemists
    - westurner 5y ago
      Gold of the soul! Could superconducting diamonds or atomic batteries or graphene sheets for filtration be made from any remaining carbon and peanut butter under pressure? What can be made from brine with e.g. lasers?
  - stjohnswarts 5y ago
    Of course it is, at the scale of eliminating significant amounts of nuclear waste, ehhhhhhhh
adrian_b 5y ago
I have looked at the French article quoted in this but neither that one is more explicit. In the initial article, an allusion is made to what happens if you irradiate nuclear waste with gamma rays, which extract neutrons, or some times protons, from nuclei, transforming the radioactive nuclei into other isotopes with much shorter lifetime. However, that method does not work for waste treatment, because there is no gamma-ray source of sufficient intensity to treat a macroscopic quantity of waste. Then the article talks about lasers with record high impulse power, but there is no connection between these 2, no matter how high the intensity of the laser pulse, the frequency of the light is too low to transmute nuclei. It is true that multi-photon reactions are possible with very high-intensity pulses, but for transforming nuclei about a million photons would have to take part in each reaction. The probability of such a reaction is astronomically low. Another way to cause reactions that need high-energy photons, by using laser pulses, is like in the deep UV lithography for up-to-date CMOS processes, by producing hot plasma with the laser pulses. However even this method can produce only soft X rays, not the hard gamma rays needed for transmuting nuclear waste. But there is a much stronger reason why this method cannot be useful, even if it could work. The nuclear waste nuclei with a long lifetime have such a long lifetime because they have only a small energy excess over stable nuclei. When you transmute them into nuclei with a short lifetime, those have a much higher energy excess, so you must provide energy for the transmutation. If this method of treating nuclear waste would be possible and it would be employed, then the global fission reaction from U235 to fission products will be changed, replacing the low-energy products with high-energy products, so the total energy produced by a nuclear reactor, which is the difference between the energy stored in the input fuel and the energy stored in the output products, would be diminished with the value needed for waste treatment, which would be similar in magnitude with the energy produced by the nuclear reactor. Depending on the exact reactions used for waste treatment, a complex computation of the energy would be needed, but after taking into consideration the very low efficiency of the intermediate devices used, like lasers, it would not be surprising if the energy output of a nuclear reactor would be diminished 10 times or more, making nuclear energy completely noncompetitive. So, no, this does not have any chance. What would be a real breakthrough would be if it would be possible to extract energy from a nuclear reaction where the products are non-radioactive, because this would solve the waste problem, while simultaneously providing a maximum energy output. Unfortunately this is hopeless for fission reactions, because those cannot have unique output products, and among the many possible output nuclei it is certain that some will be radioactive. This is also hopeless for deuterium or tritium fusion reactions, because those are guaranteed to generate huge amounts of neutrons. Other more difficult fusion reactions without radioactive output nuclei are theoretically possible, but no practical method to perform them is known yet.
tgv 5y ago
At the end of the article, it says they want to "shrink the distance a light beam has to travel to transmute atoms by a further 10,000 times". So, which is it: faster or nearer-by?
- deleted 5y ago
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deleted 5y ago
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fsckboy 5y ago
> I wasted my time reading this article, it explains nothing. had you previously heard of the idea to process radioactive material this way? That was the point of the article, and they relayed that a physicist with credentials in the relevant area thinks it's a good idea. I think the article succeeded in its goal, I don't think it aspired to be a physics paper.

belter 5y ago

It's not a novel idea: "Laser induced nuclear waste transmutation" https://arxiv.org/abs/1603.08737 https://arxiv.org/abs/1603.08737 "Transmutation prospect of long-lived nuclear waste induced by high-charge electron beam from laser plasma accelerator" https://arxiv.org/abs/1705.05770 https://arxiv.org/abs/1705.05770 "Fusion Driven Transmutation of Transuranics in a Molten Salt" https://arxiv.org/abs/2109.08741 https://arxiv.org/abs/2109.08741 "Generic method to assess transmutation feasibility for nuclear waste treatment and application to irradiated graphite" https://arxiv.org/abs/2201.02623 https://arxiv.org/abs/2201.02623

adrian_b 5y ago
The first 2 papers indicated by you refer indeed to the same thing as the article that started this thread, but they explain the possible method. The principle is very similar with the sources of deep ultraviolet light used for photolithography. The laser pulses are used to produce hot plasma and to accelerate the electrons from plasma, which hit then a target, like in the traditional X-ray tubes. The interaction of the accelerated electrons with the target produces gamma rays. Finally, the gamma rays can be used to transmute the nuclear waste. There are 2 problems with this approach. As everybody knows, improving the deep UV sources to have an intensity great enough to be usable in the production of integrated circuits took several decades and many billions of dollars. The gamma ray sources that would be needed for waste treatment are significantly more complex and the output intensity must be much higher, so it is impossible to guess how much time and money would be needed, but certainly much more than for photolithography. The second much more serious problem is that already mentioned in another post. If these gamma-ray sources would have a global efficiency of 1%, starting from the electrical input power, passing through pump diodes for lasers, then solid-state lasers for pulse generation, then heating plasma, accelerating electrons, radiation from the electron target and finally absorption in the nuclear waste, that would be an amazing achievement. Actually a global efficiency of less than 1 per ten thousand would be more likely today. The energy required to transmute all the waste from a nuclear reactor might be of 10% or more of the output energy of the reactor. Multiplied with a factor between 100 and 10000, the result is that a nuclear reactor would not be a net producer of energy, but a huge consumer of energy, making it useless. A little more realistic would be to not treat all the nuclear waste, but only 1 or a few especially dangerous isotopes, e.g. only the radioactive iodine. While this would reduce a lot the energy required for transmutation, a lot of additional energy would be needed for the separation of the desired isotopes from the radioactive waste. Maybe transmuting only the iodine could be done in a distant future with a little less energy than the nuclear reactor produces. However that would not solve the problem with the storage of the nuclear waste. Consuming a huge amount of energy with the elimination of the iodine would only lessen the danger of what would happen if the storage of the waste would be compromised and the waste would be dispersed into the environment (because the vertebrates extract the iodine from the environment and concentrate it into the thyroid, so radioactive iodine is dangerous even at smaller concentrations than the rest of the waste).
contravariant 5y ago
It never really occurred to me that transmutation is a reputable field of scientific study nowadays.
- belter 5y ago
  A sub-skill of Alchemy :-) https://en.wikipedia.org/wiki/List_of_alchemists https://en.wikipedia.org/wiki/List_of_alchemists
  - westurner 5y ago
    Gold of the soul! Could superconducting diamonds or atomic batteries or graphene sheets for filtration be made from any remaining carbon and peanut butter under pressure? What can be made from brine with e.g. lasers?
- stjohnswarts 5y ago
  Of course it is, at the scale of eliminating significant amounts of nuclear waste, ehhhhhhhh

adrian_b 5y ago

I have looked at the French article quoted in this but neither that one is more explicit. In the initial article, an allusion is made to what happens if you irradiate nuclear waste with gamma rays, which extract neutrons, or some times protons, from nuclei, transforming the radioactive nuclei into other isotopes with much shorter lifetime. However, that method does not work for waste treatment, because there is no gamma-ray source of sufficient intensity to treat a macroscopic quantity of waste. Then the article talks about lasers with record high impulse power, but there is no connection between these 2, no matter how high the intensity of the laser pulse, the frequency of the light is too low to transmute nuclei. It is true that multi-photon reactions are possible with very high-intensity pulses, but for transforming nuclei about a million photons would have to take part in each reaction. The probability of such a reaction is astronomically low. Another way to cause reactions that need high-energy photons, by using laser pulses, is like in the deep UV lithography for up-to-date CMOS processes, by producing hot plasma with the laser pulses. However even this method can produce only soft X rays, not the hard gamma rays needed for transmuting nuclear waste. But there is a much stronger reason why this method cannot be useful, even if it could work. The nuclear waste nuclei with a long lifetime have such a long lifetime because they have only a small energy excess over stable nuclei. When you transmute them into nuclei with a short lifetime, those have a much higher energy excess, so you must provide energy for the transmutation. If this method of treating nuclear waste would be possible and it would be employed, then the global fission reaction from U235 to fission products will be changed, replacing the low-energy products with high-energy products, so the total energy produced by a nuclear reactor, which is the difference between the energy stored in the input fuel and the energy stored in the output products, would be diminished with the value needed for waste treatment, which would be similar in magnitude with the energy produced by the nuclear reactor. Depending on the exact reactions used for waste treatment, a complex computation of the energy would be needed, but after taking into consideration the very low efficiency of the intermediate devices used, like lasers, it would not be surprising if the energy output of a nuclear reactor would be diminished 10 times or more, making nuclear energy completely noncompetitive. So, no, this does not have any chance. What would be a real breakthrough would be if it would be possible to extract energy from a nuclear reaction where the products are non-radioactive, because this would solve the waste problem, while simultaneously providing a maximum energy output. Unfortunately this is hopeless for fission reactions, because those cannot have unique output products, and among the many possible output nuclei it is certain that some will be radioactive. This is also hopeless for deuterium or tritium fusion reactions, because those are guaranteed to generate huge amounts of neutrons. Other more difficult fusion reactions without radioactive output nuclei are theoretically possible, but no practical method to perform them is known yet.

tgv 5y ago

At the end of the article, it says they want to "shrink the distance a light beam has to travel to transmute atoms by a further 10,000 times". So, which is it: faster or nearer-by?

deleted 5y ago
[deleted]

deleted 5y ago

[deleted]

fsckboy 5y ago

> I wasted my time reading this article, it explains nothing. had you previously heard of the idea to process radioactive material this way? That was the point of the article, and they relayed that a physicist with credentials in the relevant area thinks it's a good idea. I think the article succeeded in its goal, I don't think it aspired to be a physics paper.