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Okay, but is the fuel a major cost for fission plants? And it's not clear to me how nuclear waste can both be extremely long-lived and also very dangerous that

Okay, but is the fuel a major cost for fission plants? And it's not clear to me how nuclear waste can both be extremely long-lived and also very dangerous that entire time.

317070 5y ago
Fuel is not a major cost right now, but it inevitably will be at some point. Current estimates are that we have 80-250 years of uranium left [0], so we could use a different energy source for the long run. The difference in radioactive danger, is because not all nuclear reactions are treated equally. Tritium decays once, emitting a 0.019MeV beta particle [1]. Uranium creates an avalanche of particles [2] for a total of 51.7 MeV. So it has the leeway to be both more radioactive and to be it for longer. But both the type and energy of the radiation have intricate effects on how they interact with biology and so how dangerous they really are. That said, exactly how radioactive fusion waste will be is a bit a philosophical problem, as nobody knows what the minimal requirements are for a functional plant. [0] https://bettermeetsreality.com/how-much-uranium-is-left-in-the-world-on-land-in-oceans-when-will-we-run-out/ https://bettermeetsreality.com/how-much-uranium-is-left-in-t... [1] en.m.wikipedia.org/wiki/Tritium [2] https://en.m.wikipedia.org/wiki/Decay_chain https://en.m.wikipedia.org/wiki/Decay_chain
- flaviut 5y ago
  FYI the bettermeetsreality site you link to is SEO spam. But anyway, those numbers sound about right, here's what wikipedia (and their source, https://doi.org/10.1787/uranium-2018-en https://doi.org/10.1787/uranium-2018-en) says: > As of 2017, identified uranium reserves recoverable at US$130/kg were 6.14 million tons (compared to 5.72 million tons in 2015). At the rate of consumption in 2017, these reserves are sufficient for slightly over 130 years of supply. The identified reserves as of 2017 recoverable at US$260/kg are 7.99 million tons (compared to 7.64 million tons in 2015). I wouldn't be too worried right now though, because Table 1.1 in uranium-2018 shows that the known recoverable uranium sources @ $40/kgU grew 50% between 2015 and 2017, and known recoverable uranium sources @ $80/kgU grew 4.6% over the same time period. No one's going to go around prospecting unless they think they can make a profit doing it.
- duvenaud 5y ago
  Finally some numbers! Thank you. So again, this sounds like more evidence against an economic advantage of fusion over fission, is that correct in your opinion?
lazide 5y ago
Fuel is not a major cost of fission plants. Nuclear waste is not actually that dangerous that long. Everyone (including the planners) like to hype it up for their own reasons. Fusion has many fusion pathways, some of which are pretty light on the dangerous radiation, others that are pretty heavy on it. Most advocates don’t know which one they’re advocating for. The radiation ‘activates’ and damages the interior of the fusion reactor, making it radioactive. This is not a solved problem yet. It may never be.
- ascar 5y ago
  > Nuclear waste is not actually that dangerous that long. Everyone (including the planners) like to hype it up for their own reasons. Can you elaborate? E.g. Plutonium-239 has a half life of 24000 years. That hardly sounds like "not that long"? Leftover uranium-238 even stays radioactive for billions of years (half life of 4.5 billion years).
  - ncmncm 5y ago
    Plutonium, anyway, is not waste, but fuel. And weapons material. But there are other long-lived isotopes, as well. Safe disposal is not a difficult technical problem, but is a political football causing limitless distraction.
  - lazide 5y ago
    The more radioactive it is, by it’s very nature, the shorter it’s half life. That is literally what is going on. Decay means release of radiation. Decay means less of the original radioactive material. Some of these elements have pretty high overall energy levels released in their decay chains (so it’s not just one decay) some less - but sources that are more radioactive are decaying and releasing energy faster, have shorter half lives, and are very dangerous for shorter periods of time. You can literally buy Uranium 238 ore through the mail and handle it with no more special precautions than washing your hands afterwards and not eating it. It’s seriously fine. Except in a few spots where it was heavily concentrated, most of the legitimately dangerous stuff has decayed to ‘meh, not that bad’ levels already even at Chernobyl. It’s still not a good idea to lick it, or spend all your time in the main reactor hall, but give it another 50 years and you’ll probably be able pet the elephants foot on a tour. Hiroshima and Nagasaki has been fine for awhile. People do tours at ground zero of the Trinity test site. Some of these elements are chemically active in weird ways, and even without the radioactivity, eating plutonium, cesium, or uranium will be a bad time. Same with mercury, lead, cadmium, etc. so I’m not advocating for being careless with them. But the idea of a big chunk of radioactive waste being a glowing orb in 10k years is fantasy.
flaviut 5y ago
> And it's not clear to me how nuclear waste can both be extremely long-lived and also very dangerous that entire time. This is a really good question, and as someone who knows nothing about this, here's what I've found: There's 4 kinds of nuclear waste: - Very low-level waste - Low-level waste - Intermediate-level waste - High-level waste You just dump very low-level waste into a landfill[1]. This stuff is basically random concrete, etc. that comes from demolishing a nuclear power plant. Low-level waste is still pretty boring stuff like clothing and rags that got irradiated somehow, and is 90% of the volume and 1% the radioactivity of radioactive waste[1]. The radioactivity in this mostly comes from atoms with a half-life of less than 5 years, although it seems like trace amounts of slightly long-lasting radioactive isotopes are allowed[2]. Intermediate-level waste looks like it's pretty varied things: sludges, fuel cladding, reactor parts from decomissioning. It's 7% of the volume and has 4% of the radioactivity[1]. Looks like this stuff is generally pretty long-lived: takes about 1000 years to become 10x as radioactive as low-level waste, and 100k years to become as radioactive as low-level waste. High-level waste is basically spent fuel. It's special in that it requires some kind of cooling, at least for a few decades. It's 3% of the volume and 95% of radioactivity[1]. It can often be re-processed into more fuel. After about 200 years, it becomes about as radioactive as intermediate-level waste, and 100k years to become as radioactive as low-level waste. [1]: https://world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-wastes/radioactive-waste-management.aspx https://world-nuclear.org/information-library/nuclear-fuel-c... [2]: https://en.wikipedia.org/wiki/Low-level_waste https://en.wikipedia.org/wiki/Low-level_waste [3]: https://www.radioactivity.eu.com/site/pages/ML_LLW.htm https://www.radioactivity.eu.com/site/pages/ML_LLW.htm [4]: https://www.radioactivity.eu.com/site/pages/HLW_Waste.htm https://www.radioactivity.eu.com/site/pages/HLW_Waste.htm

Okay, but is the fuel a major cost for fission plants? And it's not clear to me how nuclear waste can both be extremely long-lived and also very dangerous that entire time.

317070 5y ago

Fuel is not a major cost right now, but it inevitably will be at some point. Current estimates are that we have 80-250 years of uranium left [0], so we could use a different energy source for the long run. The difference in radioactive danger, is because not all nuclear reactions are treated equally. Tritium decays once, emitting a 0.019MeV beta particle [1]. Uranium creates an avalanche of particles [2] for a total of 51.7 MeV. So it has the leeway to be both more radioactive and to be it for longer. But both the type and energy of the radiation have intricate effects on how they interact with biology and so how dangerous they really are. That said, exactly how radioactive fusion waste will be is a bit a philosophical problem, as nobody knows what the minimal requirements are for a functional plant. [0] https://bettermeetsreality.com/how-much-uranium-is-left-in-the-world-on-land-in-oceans-when-will-we-run-out/ https://bettermeetsreality.com/how-much-uranium-is-left-in-t... [1] en.m.wikipedia.org/wiki/Tritium [2] https://en.m.wikipedia.org/wiki/Decay_chain https://en.m.wikipedia.org/wiki/Decay_chain

flaviut 5y ago
FYI the bettermeetsreality site you link to is SEO spam. But anyway, those numbers sound about right, here's what wikipedia (and their source, https://doi.org/10.1787/uranium-2018-en https://doi.org/10.1787/uranium-2018-en) says: > As of 2017, identified uranium reserves recoverable at US$130/kg were 6.14 million tons (compared to 5.72 million tons in 2015). At the rate of consumption in 2017, these reserves are sufficient for slightly over 130 years of supply. The identified reserves as of 2017 recoverable at US$260/kg are 7.99 million tons (compared to 7.64 million tons in 2015). I wouldn't be too worried right now though, because Table 1.1 in uranium-2018 shows that the known recoverable uranium sources @ $40/kgU grew 50% between 2015 and 2017, and known recoverable uranium sources @ $80/kgU grew 4.6% over the same time period. No one's going to go around prospecting unless they think they can make a profit doing it.
duvenaud 5y ago
Finally some numbers! Thank you. So again, this sounds like more evidence against an economic advantage of fusion over fission, is that correct in your opinion?

lazide 5y ago

Fuel is not a major cost of fission plants. Nuclear waste is not actually that dangerous that long. Everyone (including the planners) like to hype it up for their own reasons. Fusion has many fusion pathways, some of which are pretty light on the dangerous radiation, others that are pretty heavy on it. Most advocates don’t know which one they’re advocating for. The radiation ‘activates’ and damages the interior of the fusion reactor, making it radioactive. This is not a solved problem yet. It may never be.

ascar 5y ago
> Nuclear waste is not actually that dangerous that long. Everyone (including the planners) like to hype it up for their own reasons. Can you elaborate? E.g. Plutonium-239 has a half life of 24000 years. That hardly sounds like "not that long"? Leftover uranium-238 even stays radioactive for billions of years (half life of 4.5 billion years).
- ncmncm 5y ago
  Plutonium, anyway, is not waste, but fuel. And weapons material. But there are other long-lived isotopes, as well. Safe disposal is not a difficult technical problem, but is a political football causing limitless distraction.
- lazide 5y ago
  The more radioactive it is, by it’s very nature, the shorter it’s half life. That is literally what is going on. Decay means release of radiation. Decay means less of the original radioactive material. Some of these elements have pretty high overall energy levels released in their decay chains (so it’s not just one decay) some less - but sources that are more radioactive are decaying and releasing energy faster, have shorter half lives, and are very dangerous for shorter periods of time. You can literally buy Uranium 238 ore through the mail and handle it with no more special precautions than washing your hands afterwards and not eating it. It’s seriously fine. Except in a few spots where it was heavily concentrated, most of the legitimately dangerous stuff has decayed to ‘meh, not that bad’ levels already even at Chernobyl. It’s still not a good idea to lick it, or spend all your time in the main reactor hall, but give it another 50 years and you’ll probably be able pet the elephants foot on a tour. Hiroshima and Nagasaki has been fine for awhile. People do tours at ground zero of the Trinity test site. Some of these elements are chemically active in weird ways, and even without the radioactivity, eating plutonium, cesium, or uranium will be a bad time. Same with mercury, lead, cadmium, etc. so I’m not advocating for being careless with them. But the idea of a big chunk of radioactive waste being a glowing orb in 10k years is fantasy.

flaviut 5y ago

> And it's not clear to me how nuclear waste can both be extremely long-lived and also very dangerous that entire time. This is a really good question, and as someone who knows nothing about this, here's what I've found: There's 4 kinds of nuclear waste: - Very low-level waste - Low-level waste - Intermediate-level waste - High-level waste You just dump very low-level waste into a landfill[1]. This stuff is basically random concrete, etc. that comes from demolishing a nuclear power plant. Low-level waste is still pretty boring stuff like clothing and rags that got irradiated somehow, and is 90% of the volume and 1% the radioactivity of radioactive waste[1]. The radioactivity in this mostly comes from atoms with a half-life of less than 5 years, although it seems like trace amounts of slightly long-lasting radioactive isotopes are allowed[2]. Intermediate-level waste looks like it's pretty varied things: sludges, fuel cladding, reactor parts from decomissioning. It's 7% of the volume and has 4% of the radioactivity[1]. Looks like this stuff is generally pretty long-lived: takes about 1000 years to become 10x as radioactive as low-level waste, and 100k years to become as radioactive as low-level waste. High-level waste is basically spent fuel. It's special in that it requires some kind of cooling, at least for a few decades. It's 3% of the volume and 95% of radioactivity[1]. It can often be re-processed into more fuel. After about 200 years, it becomes about as radioactive as intermediate-level waste, and 100k years to become as radioactive as low-level waste. [1]: https://world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-wastes/radioactive-waste-management.aspx https://world-nuclear.org/information-library/nuclear-fuel-c... [2]: https://en.wikipedia.org/wiki/Low-level_waste https://en.wikipedia.org/wiki/Low-level_waste [3]: https://www.radioactivity.eu.com/site/pages/ML_LLW.htm https://www.radioactivity.eu.com/site/pages/ML_LLW.htm [4]: https://www.radioactivity.eu.com/site/pages/HLW_Waste.htm https://www.radioactivity.eu.com/site/pages/HLW_Waste.htm