6 ms·

Here are the energy densities in MJ/kg: Deuterium-Tritium fusion - 337,000,000 MJ/kg Nuclear fission (of U-235) - 88,250,000 MJ/kg Natural uranium (99.3% U238,

Here are the energy densities in MJ/kg: Deuterium-Tritium fusion - 337,000,000 MJ/kg Nuclear fission (of U-235) - 88,250,000 MJ/kg Natural uranium (99.3% U238, 0.7% U235) in fast breeder reactor - 24,000,000 MJ/kg Enriched uranium (3.5% U235) in light water reactor - 3,456,000 MJ/kg Natural uranium (0.7% U235) in light water reactor - 443,000 MJ/kg The higher output is a function of the higher energy density. Your numbers may be correct about how much uranium there is in the earth's crust but you are missing two very important points. Only a tiny fraction of the uranium is in concentrated enough deposits to allow for economic recovery of the mineral. This and the fact that U-235, the fissile isotope of natural uranium, occurs in only 0.711% of uranium containing minerals leaves only enough uranium with reprocessing for the next 1000 years. http://www.world-nuclear-news.org/ENF_Exploration_drives_uranium_resources_up_17_0206082.html http://www.world-nuclear-news.org/ENF_Exploration_drives_ura... Thorium required a breeder reactor in order to produce the U-233 necessary for fission, and as stated in another comment, these reactors are still in experimental stages and have a much lower level of operational safety record.

DabAsteroid 18y ago
The higher output is a function of the higher energy density. That might have cleared everything up for me, except that I do not know what you mean by "higher output". Are you referring to power output? You are saying that, generally, in a given case of equal-sized reactors, a fusion reactor would be able to produce higher power than a fission reactor?
DabAsteroid 18y ago
Only a tiny fraction of the uranium is in concentrated enough deposits to allow for economic recovery of the mineral. Given that that very point was addressed at the link I provided, one might suspect that you did not visit it before answering. It is not merely 40 trillion tons of uranium that are in the crust. It is 40 trillion of uranium that is also economically-recoverable. Why is nearly all of the uranium in the crust is economically-recoverable? It is because the energy density of uranium is so high. The same goes for thorium.
- jmackinn 18y ago
  On the contrary the article you provided did not once mention the words 'economically recoverable'. What you are looking for is the reserves of Uranium in the world. Reserves, in mining means the amount of ore that can be economically removed from the earth. For those numbers please refer to the link that I listed previously. If the percent of uranium oxide in an ore is less than 0.1% (by weight) then it is not economical to mine.
  - DabAsteroid 18y ago
    Reserves, in mining means the amount of ore that can be economically removed from the earth. No, it doesn't. http://www.google.com/search?q=site%3Ajuliansimon.com%2Fwritings%2FUltimate_Resource+reserves http://www.google.com/search?q=site%3Ajuliansimon.com%2Fwrit...
    - jmackinn 18y ago
      Julian Simon was a professor business administration, not a mining engineer. Those articles refer to scare tactics presented in terms of resource scarcity by environmental fanatics. He says nothing about the definition of a mineral reserve. But I can help us with that. Reserve definition Reserve definition is undertaken to convert a mineral resource into an ore reserve, which is an economic asset. The process is similar to resource evaluation, except more intensive and technical, aimed at statistically quantifying the grade continuity and mass of ore. Reserve definition also takes into account the milling and extractability characteristics of the ore, and generates bulk samples for metallurgical testwork, involving crushability, floatability and other ore recovery parameters. Reserve definition includes geotechnical assessment and engineering studies of the rocks within and surrounding the deposit to determine the potential instabilities of proposed open pit or underground mining methods. This process may involve drilling diamond core samples to derive structural information on weaknesses within the rock mass such as faults, foliations, joints and shearing. At the end of this process, a feasibility study is published, and the ore deposit may be either deemed uneconomic or economic. from http://en.wikipedia.org/wiki/Mineral_exploration http://en.wikipedia.org/wiki/Mineral_exploration
DabAsteroid 18y ago
U-235, the fissile isotope of natural uranium, occurs in only 0.711% of uranium If I had disregarded that, how do you figure I got a 60x energy boost by applying fuel-breeding?
- jmackinn 18y ago
  I'm really not sure, I have no idea where you are getting a 60x energy boost from.
DabAsteroid 18y ago
http://www.world-nuclear-news.org/ENF_Exploration_drives_uranium_resources_up_17_0206082.html http://www.world-nuclear-news.org/ENF_Exploration_drives_ura... Those are "identified resources", which means that they are irrelevant. There are 2 trillion tons (5 billion years' worth) of economically-recoverable uranium in granite, alone. http://nuclearinfo.net/Nuclearpower/UraniuamDistribution http://nuclearinfo.net/Nuclearpower/UraniuamDistribution
- jmackinn 18y ago
  You're using a link that claims the resource limit to be 1000 years (the first one). And did you really state that taking uranium out of granite is economical? The granite you want to mine is worth more than the uranium in it, not to mention that it would take more energy to mine it than you would get from it. There are only 3-10 part per million of uranium in granite.
  - DabAsteroid 18y ago
    You're using a link that claims the resource limit to be 1000 years (the first one). It's your link. I was quoting you and commenting on it.
  - DabAsteroid 18y ago
    it would take more energy to mine [granite] than you would get from it. There are only 3-10 part per million of uranium in granite. Have you read this?: http://nuclearinfo.net/Nuclearpower/UraniuamDistribution http://nuclearinfo.net/Nuclearpower/UraniuamDistribution The Rossing mine in Nambia mines Uranium at an Ore concentration of 300 ppm at an energy cost 500 times less than the energy it delivers with current thermal-spectrum reactors. If the energy cost increases in inverse proportion to the Ore concentration, shales and phosphates, with a Uranium abundance of 10 - 20 ppm, could be mined with an energy gain of 16 - 32. Extrapolating from that, the energy gain is 1.6 for every ppm of uranium. As you say, granite contains 3-10 ppm of uranium. Therefore, mining granite for its uranium would provide an energy gain of 4.8 to 16. That would be without improving current reactor thermal-efficiency at all, and without improving current reactor breeding efficiency at all (all fission-reactors fueled with a mixture of U235 and U238 breed to some extent). Running a uranium economy off of such a low-grade ore would, of course, in the real world provide incentive to improve fuel-efficiency (thermal; breeding-ratio; etc.) of reactors (even thermal-spectrum reactors can have their breeding-efficiencies improved). Thus, in the real world, the energy gain from mining granite for uranium would likely be higher than 4.8 to 16.
DabAsteroid 18y ago
Thorium required a breeder reactor in order to produce the U-233 necessary for fission, and as stated in another comment, these reactors are still in experimental stages and have a much lower level of operational safety record. A thorium breeder is not the same thing as a uranium breeder. http://thoriumenergy.blogspot.com http://thoriumenergy.blogspot.com

DabAsteroid 18y ago

The higher output is a function of the higher energy density. That might have cleared everything up for me, except that I do not know what you mean by "higher output". Are you referring to power output? You are saying that, generally, in a given case of equal-sized reactors, a fusion reactor would be able to produce higher power than a fission reactor?

DabAsteroid 18y ago

Only a tiny fraction of the uranium is in concentrated enough deposits to allow for economic recovery of the mineral. Given that that very point was addressed at the link I provided, one might suspect that you did not visit it before answering. It is not merely 40 trillion tons of uranium that are in the crust. It is 40 trillion of uranium that is also economically-recoverable. Why is nearly all of the uranium in the crust is economically-recoverable? It is because the energy density of uranium is so high. The same goes for thorium.

jmackinn 18y ago
On the contrary the article you provided did not once mention the words 'economically recoverable'. What you are looking for is the reserves of Uranium in the world. Reserves, in mining means the amount of ore that can be economically removed from the earth. For those numbers please refer to the link that I listed previously. If the percent of uranium oxide in an ore is less than 0.1% (by weight) then it is not economical to mine.
- DabAsteroid 18y ago
  Reserves, in mining means the amount of ore that can be economically removed from the earth. No, it doesn't. http://www.google.com/search?q=site%3Ajuliansimon.com%2Fwritings%2FUltimate_Resource+reserves http://www.google.com/search?q=site%3Ajuliansimon.com%2Fwrit...
  - jmackinn 18y ago
    Julian Simon was a professor business administration, not a mining engineer. Those articles refer to scare tactics presented in terms of resource scarcity by environmental fanatics. He says nothing about the definition of a mineral reserve. But I can help us with that. Reserve definition Reserve definition is undertaken to convert a mineral resource into an ore reserve, which is an economic asset. The process is similar to resource evaluation, except more intensive and technical, aimed at statistically quantifying the grade continuity and mass of ore. Reserve definition also takes into account the milling and extractability characteristics of the ore, and generates bulk samples for metallurgical testwork, involving crushability, floatability and other ore recovery parameters. Reserve definition includes geotechnical assessment and engineering studies of the rocks within and surrounding the deposit to determine the potential instabilities of proposed open pit or underground mining methods. This process may involve drilling diamond core samples to derive structural information on weaknesses within the rock mass such as faults, foliations, joints and shearing. At the end of this process, a feasibility study is published, and the ore deposit may be either deemed uneconomic or economic. from http://en.wikipedia.org/wiki/Mineral_exploration http://en.wikipedia.org/wiki/Mineral_exploration

DabAsteroid 18y ago

U-235, the fissile isotope of natural uranium, occurs in only 0.711% of uranium If I had disregarded that, how do you figure I got a 60x energy boost by applying fuel-breeding?

jmackinn 18y ago
I'm really not sure, I have no idea where you are getting a 60x energy boost from.

DabAsteroid 18y ago

http://www.world-nuclear-news.org/ENF_Exploration_drives_uranium_resources_up_17_0206082.html http://www.world-nuclear-news.org/ENF_Exploration_drives_ura... Those are "identified resources", which means that they are irrelevant. There are 2 trillion tons (5 billion years' worth) of economically-recoverable uranium in granite, alone. http://nuclearinfo.net/Nuclearpower/UraniuamDistribution http://nuclearinfo.net/Nuclearpower/UraniuamDistribution

jmackinn 18y ago
You're using a link that claims the resource limit to be 1000 years (the first one). And did you really state that taking uranium out of granite is economical? The granite you want to mine is worth more than the uranium in it, not to mention that it would take more energy to mine it than you would get from it. There are only 3-10 part per million of uranium in granite.
- DabAsteroid 18y ago
  You're using a link that claims the resource limit to be 1000 years (the first one). It's your link. I was quoting you and commenting on it.
- DabAsteroid 18y ago
  it would take more energy to mine [granite] than you would get from it. There are only 3-10 part per million of uranium in granite. Have you read this?: http://nuclearinfo.net/Nuclearpower/UraniuamDistribution http://nuclearinfo.net/Nuclearpower/UraniuamDistribution The Rossing mine in Nambia mines Uranium at an Ore concentration of 300 ppm at an energy cost 500 times less than the energy it delivers with current thermal-spectrum reactors. If the energy cost increases in inverse proportion to the Ore concentration, shales and phosphates, with a Uranium abundance of 10 - 20 ppm, could be mined with an energy gain of 16 - 32. Extrapolating from that, the energy gain is 1.6 for every ppm of uranium. As you say, granite contains 3-10 ppm of uranium. Therefore, mining granite for its uranium would provide an energy gain of 4.8 to 16. That would be without improving current reactor thermal-efficiency at all, and without improving current reactor breeding efficiency at all (all fission-reactors fueled with a mixture of U235 and U238 breed to some extent). Running a uranium economy off of such a low-grade ore would, of course, in the real world provide incentive to improve fuel-efficiency (thermal; breeding-ratio; etc.) of reactors (even thermal-spectrum reactors can have their breeding-efficiencies improved). Thus, in the real world, the energy gain from mining granite for uranium would likely be higher than 4.8 to 16.

DabAsteroid 18y ago

Thorium required a breeder reactor in order to produce the U-233 necessary for fission, and as stated in another comment, these reactors are still in experimental stages and have a much lower level of operational safety record. A thorium breeder is not the same thing as a uranium breeder. http://thoriumenergy.blogspot.com http://thoriumenergy.blogspot.com