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Some important distinctions of the statements made in this article have been published by the Safecast team, who have been independently measuring radiation lev

Some important distinctions of the statements made in this article have been published by the Safecast team, who have been independently measuring radiation levels in this area for years: http://blog.safecast.org/2017/02/no-radiation-levels-at-fukushima-daiichi-are-not-rising/ http://blog.safecast.org/2017/02/no-radiation-levels-at-fuku...

jessriedel 10y ago
> It must be stressed that radiation in this area has not been measured before, and it was expected to be extremely high. While 530 Sv/hr is the highest measured so far at Fukushima Daiichi, it does not mean that levels there are rising, but that a previously unmeasurable high-radiation area has finally been measured. This completely invalidates the Japan Times article.
deleted 10y ago
[deleted]
ChuckMcM 10y ago
The Safecast article is much clearer (and certainly less frightening). As an engineer it's fascinating to me to see what sort of problems a failed reactor bring to table. One of the reasons all of this is new R&D is because its only the second major event in history. Given the relatively small volume of the fuel mass I have always wondered if there might be a way to build a coring drill that could be used to separate from the main mass a useful amount of material, which could then be put into a fairly conventional cask for transport to a secure storage / disposal facility. For example there has been a lot of study of the 'elephant's foot' which is the column of fuel that froze once it became subcritical underneath the reactor at Chernobyl. Could you repeatedly core it with a system to remove a few 10's of kilos with each core? What about a system that cut basically puck side nodules that you then put into the cask? There doesn't seem to be a lot of papers on how you might achieve this sort of disassembly sadly.
- TheOtherHobbes 10y ago
  My understanding was that the radiation was too intense to allow machinery to operate. Beyond a certain intensity no non-sci-fi technology works reliably. Not only are electronics fried, but metals and ceramics literally fall apart. And humans die in seconds, never mind minutes. So unfortunately there are one or two problems to be worked out before corium engineering can become a thing.
  - Gravityloss 10y ago
    Plain solenoids, pneumatics or hydraulics would work fine.
  - ChuckMcM 10y ago
    Radiation doesn't prevent machinery from operating it can prevent electronics from operating. A lot of the existing tools for moving around highly radioactive things are hydraulically activated mechanisms. The other issue is with the heat generated, which if it is too high will weaken structures and potentially trigger exothermic reactions (fires) which would not have started otherwise. There are a number of good articles on the machinery used in fuel reprocessing which can deal with this level of radiation.
    - azernik 10y ago
      Radiation can indeed cause machinery to stop operating - high-energy particles hitting metals, for example, will cause atomic displacement and change the properties (usually hardness and brittleness). Materials used in reactors usually have to be carefully chosen to function in the face of this continuous damage.
      - ChuckMcM 10y ago
        True, but by that same logic we can state that water can make machinery to stop operating by oxidizing the iron in it into rust :-) That is very much unlike semiconductors which are particularly susceptible to high radiation as it damages the silicon crystal structure and can change the doping concentrations pretty much instantly if you aren't careful. I certainly would not disagree with the statement that one needs to also pick your materials carefully though.
- simcop2387 10y ago
  One problem i see with trying to cut or drill into it is that that'll shoot radioactive dust into the air which can be a much worse problem than just "nobody can ever go in there". You can use cutting fluid of some kind but then you've got radioactive fluid you have to clean up. maybe that's easier to deal with? I don't know.
  - ChuckMcM 10y ago
    Both good questions. In the case of Chernobyl there is the whole building around it (the sarcophagus) which does dust containment. That said, it might a workable idea to grind it into dust and vacuum out the dust into containment vessels. (easier to transport from the dismantling point to containment.) Depending on how warm it is I wonder if you could spray it with epoxy to coat/encapsulate dust.

jessriedel 10y ago

> It must be stressed that radiation in this area has not been measured before, and it was expected to be extremely high. While 530 Sv/hr is the highest measured so far at Fukushima Daiichi, it does not mean that levels there are rising, but that a previously unmeasurable high-radiation area has finally been measured. This completely invalidates the Japan Times article.

deleted 10y ago

[deleted]

ChuckMcM 10y ago

The Safecast article is much clearer (and certainly less frightening). As an engineer it's fascinating to me to see what sort of problems a failed reactor bring to table. One of the reasons all of this is new R&D is because its only the second major event in history. Given the relatively small volume of the fuel mass I have always wondered if there might be a way to build a coring drill that could be used to separate from the main mass a useful amount of material, which could then be put into a fairly conventional cask for transport to a secure storage / disposal facility. For example there has been a lot of study of the 'elephant's foot' which is the column of fuel that froze once it became subcritical underneath the reactor at Chernobyl. Could you repeatedly core it with a system to remove a few 10's of kilos with each core? What about a system that cut basically puck side nodules that you then put into the cask? There doesn't seem to be a lot of papers on how you might achieve this sort of disassembly sadly.

TheOtherHobbes 10y ago
My understanding was that the radiation was too intense to allow machinery to operate. Beyond a certain intensity no non-sci-fi technology works reliably. Not only are electronics fried, but metals and ceramics literally fall apart. And humans die in seconds, never mind minutes. So unfortunately there are one or two problems to be worked out before corium engineering can become a thing.
- Gravityloss 10y ago
  Plain solenoids, pneumatics or hydraulics would work fine.
- ChuckMcM 10y ago
  Radiation doesn't prevent machinery from operating it can prevent electronics from operating. A lot of the existing tools for moving around highly radioactive things are hydraulically activated mechanisms. The other issue is with the heat generated, which if it is too high will weaken structures and potentially trigger exothermic reactions (fires) which would not have started otherwise. There are a number of good articles on the machinery used in fuel reprocessing which can deal with this level of radiation.
  - azernik 10y ago
    Radiation can indeed cause machinery to stop operating - high-energy particles hitting metals, for example, will cause atomic displacement and change the properties (usually hardness and brittleness). Materials used in reactors usually have to be carefully chosen to function in the face of this continuous damage.
    - ChuckMcM 10y ago
      True, but by that same logic we can state that water can make machinery to stop operating by oxidizing the iron in it into rust :-) That is very much unlike semiconductors which are particularly susceptible to high radiation as it damages the silicon crystal structure and can change the doping concentrations pretty much instantly if you aren't careful. I certainly would not disagree with the statement that one needs to also pick your materials carefully though.
simcop2387 10y ago
One problem i see with trying to cut or drill into it is that that'll shoot radioactive dust into the air which can be a much worse problem than just "nobody can ever go in there". You can use cutting fluid of some kind but then you've got radioactive fluid you have to clean up. maybe that's easier to deal with? I don't know.
- ChuckMcM 10y ago
  Both good questions. In the case of Chernobyl there is the whole building around it (the sarcophagus) which does dust containment. That said, it might a workable idea to grind it into dust and vacuum out the dust into containment vessels. (easier to transport from the dismantling point to containment.) Depending on how warm it is I wonder if you could spray it with epoxy to coat/encapsulate dust.