6 ms·
> This option leaves you with a few ugly buildings in the middle of nowhere, but the cost unbeatable (even way less than decommissioning thousands of wind turbi
by eqvinox 7y ago
> This option leaves you with a few ugly buildings in the middle of nowhere, but the cost unbeatable (even way less than decommissioning thousands of wind turbines).
Aren't you forgetting something? Buildings slowly deteriorate, even if not used. So now you have to maintain the disused reactor, for ... how long exactly?
(Amendment: wind, rain, sunlight, rodents, ... idiots with power tools ... https://en.wikipedia.org/wiki/Goi%C3%A2nia_accident https://en.wikipedia.org/wiki/Goi%C3%A2nia_accident )
- littlestymaar 7y ago> Buildings slowly deteriorate, even if not used. So now you have to maintain the disused reactor, for ... how long exactly? And here comes radioactive decays to the rescue! Half-life of Co60 is a little bit more than 5 years, for instance. The important thing to consider is that dangerous radioactive materials are also the ones with the shortest half-life (because the same number of atoms emits more radiation per second), so as long as you took out the fuel[1] you don't have anything really dangerous for too long. It could still be a problem when decommissioning (because you spill everything out in a short time and you have workers just nearby) but if you let the building just decay slowly, you don't have issues. [1]: the fuel is a bit special, because it has long half-life but it's still dangerous for two reasons. 1) it's alpha emitters, the worst kind of radioactive substance. 2) the concentration is enormous.
- eqvinox 7y agoCo-60 isn't the only side product though. A quick Google search yields me https://mitnse.files.wordpress.com/2011/03/radiation_npp_07.pdf https://mitnse.files.wordpress.com/2011/03/radiation_npp_07.... which lists: Krypton-85 Beta/Gamma 10 years Strontium-90 Beta 28 years Iodine-131 Beta/Gamma 8 days Cesium-137 Beta/Gamma 30 years Carbon-14 Beta 5770 years Zinc-65 Beta/Gamma 245 days Cobalt-60 Beta/Gamma 5 years Iron-59 Beta/Gamma 45 days Tritium Beta 12 years I'm also not sure where you got the idea that alpha emitters are the worst kind of radioactive substance; alpha radiation is easily shielded. On the other hand, sure, just leaving the reactor there for 50 years may be part of a cost effective solution. https://www.dndkm.org/DOEKMDocuments/BestPractices/26-EFCOG%20Best%20Practice%20-%20SRS%20P%20and%20R%20Reactor%20Basins%20ISD%20Final.pdf https://www.dndkm.org/DOEKMDocuments/BestPractices/26-EFCOG%... (linked from https://en.wikipedia.org/wiki/Nuclear_decommissioning https://en.wikipedia.org/wiki/Nuclear_decommissioning) claims a 71% reduction in decomissioning costs. However, this includes neither fuel waste disposal costs nor future costs for full dismantling at some point.
- belorn 7y agoThe parent talk about how the building material like rebars absorbs the isotopes, and then how long it can afterward be harmful. Do those isotopes also get absorbed, and if so, at what rate? Since I don't know the physic I don't know if all isotopes can get absorbed at the same rate, but my intuition is that the answer is no. I would also guess that nuclear plants get exposed to different amount of each type of isotope, so the above table would need to include both in order to compare the radiation risk after X years.
- MrEldritch 7y agoAlpha radiation is easily shielded from external exposure, but for that exact reason it's also the most damaging; gamma radiation, for instance, will mostly pass right through you, while alphas will deposit all of their energy right into your cells. They're shielded by your dead skin, but if you ingest or inhale them, then there's no dead skin to protect you, and all that radiation goes straight into your cells. In fact, according to the weighting system that converts joules of energy absorbed (Grays) to severity of radiation dose (Seiverts), a joule of alpha radiation is 20 times worse than a joule of X-rays, beta radiation, or gamma rays. And it's ingestion or inhalation that we're worried about from environmental contamination; not that the environment itself would become so radioactive, Fallout-style, that you'd take rads just from standing around - but that radioactive dust from demolition might get into the air, or that contaminants might leak into the groundwater.
- eqvinox 7y agoYeah, but - context. We're talking about leaving a disused reactor around in some type of safe manner. Ideally it won't be leaking... but some radioactive material is still in it. Aren't the beta & gamma radiators more dangerous, even as far as irradiating other parts of the structure itself is considered?
- MrEldritch 7y agoNeither beta nor gamma radiation will "activate" other parts of the structure to make them radioactive themselves; only neutron radiation (which can convert stable isotopes into unstable isotopes with more neutrons in them) can do that. Nor will they weaken the structure. So as long as people don't enter the reactor without proper precautions, there's really no reason to worry about radiation inside it. And this problem can be solved pretty well with a fence and warning signs.
- hinkley 7y agoHalf life is almost as confusing as statistics. A halflife of 5 years means 10% of the radioactivity is still there 16 years later. You'll still get 1% of the rems 33 years later, and that's if the materials don't migrate. Alpha decays are still problematic for any material that can by aspirated or ingested. Demolition means flying dust. A leaky building means groundwater contamination. A lot of these substances are also heavy metals, so even without the alpha decay problem they are highly toxic. Can you keep a building full of alpha sources water tight for five or six half lives?
- littlestymaar 7y agoThere would be no alpha sources left in the plant, as they are confined in the fuel rods, that would be taken away from the plant. (And be managed like spent fuel, which is a totally different problem than decommissioning).
- lazyguy2 7y ago> A halflife of 5 years means 10% of the radioactivity is still there 16 years later. But it's very likely that 10% is irrelevant. Radioactivity is not a all or nothing thing. It exists all around you right now. Camping out at a old abandoned nuclear power plant 20 years after it's decommissioned probably gives you less radiation exposure then you would get from a flight from California to Hong Kong.