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Feral Integral posted:I thought most of the water use from a (nuclear) plant was from the steam-turbine energy generation, not the pool that surrounds the reactor? So wouldn't the generator water not be irradiated? Most of the water "use" of a nuclear power station is exactly the same as the water "use" for a coal power station: removing waste heat. Power plants that boil water to turn turbines fall into a category of machines called "Carnot heat engines". They transfer heat from a hot area to a cold area making it do useful work along the way. The hotter the hot side or the colder the cold side, the more work can be extracted in the middle. The reactor is the hot side, the turbines are the "along the way" and the waste heat removal system is the cold side. Tall, concrete cooling towers are iconic of nuclear power but they're used at coal plants as well for exactly the same reason. Inside the towers are jets that spray the (still very hot) water that's just been through the turbines straight up. The water breaks into droplets and the hotest of the water molecules evaporate and are removed by an updraft (the sweeping shape of the tower helps this). This effectively makes the cold side of the heat engine colder, improving efficiency. A second method of getting rid of waste heat is by pumping cold lake, river or ocean water into one side of heat exchangers and the post-turbine steam into the other. Sometimes long, serpentine canals are used to get rid of waste heat too. What all this means is that any coal or nuclear power station will "use" many thousands of liters of water every day to get rid of waste heat. Use is in quotation marks because it means "temporarily come into contact with", rather than "consume"; the water is invariably returned to the environment almost exactly where it was removed and only slightly hotter. Other uses of water in a nuclear power plant are miniscule compared to waste heat removal.
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Sep 19, 2012 05:14
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silence_kit posted:The Japanese have had to abandon entire cities due to radiation released from the plant in the Fukushima disaster. Even if we grant that no one was or will be harmed by the nuclear radiation, which I honestly do not know if that is true, having to relocate a city's worth of people is a pretty high price that the Japanese government is paying right now for the disaster. If you're upset about an energy source making land uninhabitable then boy howdy are you going to be pissed when you learn about the effects of hydroelectric dam construction.
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Apr 3, 2013 23:56
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computer parts posted:Yes, just don't use Uranium. The answer is: Plutonium fuel with more than 7% Pu-240 burnt in a fast neutron reactor. Pu-240 causes nuclear bombs to "pre-detonate" and produce very low yields if there's more than 7% in the Plutonium mix. It's also extremely difficult to separate from Pu-239 because it has only one extra neutron (or 0.4% mass difference). Fast neutron reactors will burn anything that's even thinking about fissioning. The Russians have used a bunch of lead-cooled fast reactors for submarine propulsion. There's also a proposed Gen IV lead/bismuth cooled reactor.
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Aug 7, 2013 00:06
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Phayray posted:they seem to be against anything that's not a perfect, already-proven improvement of current light water reactor technology. Where they say that CANDU reactors "have certain safety issues that make them less desirable" one of which is "higher volume of waste". Well, that is true, but the reason is because CANDU fuel bundles are designed to be sub-critical in light water, so they're slightly larger or more voluminous per gram of fuel than light water reactor fuel bundles. What this means is in the event of a problem the cooling loops and core can be flooded with light water and it will automatically make every fuel bundle sub-critical, even in the absence of the control rods, or the gadolinium nitrate injectors (a neutron poison). It also makes wet-storage inherently less complicated. GOOD GOD! That "higher volume" sounds like a safety feature mis-interperited as a flaw.
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Mar 10, 2014 02:54
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Baronjutter posted:[Small nuclear reactor question] http://en.wikipedia.org/wiki/Small_modular_reactor Small reactors can output 10-250MWe and are generally small enough to transport on a rail car.
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Jul 15, 2014 00:01
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Lurking Haro posted:I guess Germany will have to buy its electricity exclusively from the east soon. They will burn more coal; more efficiently, mind you, but more nonetheless.
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Aug 1, 2015 21:15
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Sethex posted:To speak to the point about imagined nature or expectations of an unmolested version of nature, I generally think this comes from the desire for authenticity. A philosophical problem with environmentalism today is the half-assimilation of "deep ecology", where humanity is supposed to bed imagined as being part of nature, rather than separate from it. The takeaway lesson however tends to warp into some kind of "in harmony with nature" philosophy where humanity must somehow attempt to never, ever have any kind of effect on the natural environment. This attempts to reinsert humanity into the natural environment and be part of it. Problem: this is, in fact, not deep ecology because it still views humanity as somehow separate. To speak of a natural environment is to not only implicitly contrast it with a "human environment", but treat all non-human environments as if they were equal and in harmony with each other. It has long been pointed out that animals and plants alter their environment to better suit themselves and they violently compete with each other for the scarce resources available. It is impossible to speak of a "natural environment" then because it is not one thing. In thier capacity to do so, beavers create a beaver environment, ants and ant environment, pine trees poison the ground with thier needles creating a pine tree environment (one of the reasons why pine forests have shallow soil). It is perfectly harmonious with deep ecology that humanity creates for itself a human environment defined by our mastery of technology, while leaving anything that need not be disturbed unmolested. We can even deliberately avoiding challenging other living things to their environments when our technology allows us to avoid it (because they'll always lose, hands down). I quote your post here because many notions of authenticity are wrapped up in notions of nature and purity, concepts that are very much present in the environmental conciousness. "Natural" things are good, "pure" things are good. Nature being defined as "not human" and "pure" defined as "untainted by synthesized chemicals", which itself disregards that synthesized chemicals are generally much purer than naturally derived ones. So, the desire for authenticity in energy generation tends toward "not human", which is impossible, so that gets mutated to "least human", and "untainted" gets mutated to "simplest to understand". You can see where the environmentalist penchant for wind and solar power comes from, and why nuclear is so vehemently opposed; they are complete opposites using these two criteria. Let us remember now that the view of humanity as separate from nature is categorically opposed to deep ecology. So in terms of philosophies that view humanity as part of nature, those energy generation methods that disturb non-human environments the least should be considered most environmental and those that disturb it the most, least environmental. Notice that on this criteria, nuclear power becomes most environmental, while wind and solar become ranked somewhere alongside hydroelectric due to the absolutely massive footprint and materials needed.
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Aug 2, 2015 16:59
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Trabisnikof posted:
It's actually a risk for only a very small number of designs, and not at all for reactors intended for electrical production. To produce plutonium-239 (the nuclear bomb type) you need to neutron irradiate uranium-238 for short periods of time. The goal is to make each uranium atom capture one neutron and transmutate into plutonium-239. The difficulty is that plutonium-239 is capable of capturing a second neutron and changing to plutonium-240, which is a poison for nuclear bombs; it fissions too fast and causes what's called "pre-detonation" or a nuclear "fizzle". It's suspected that this occurred to one of North Korea's nuclear tests where the seismic signal of the explosion was much larger than what a conventional explosion could cause, but much smaller than you would expect of even a small nuclear bomb. In a light water reactor, the pressure vessel is typically loaded with fuel and then bolted closed, remaining closed for a number of years before the next scheduled service and fuelling outage. In this length of time quite a lot of plutonium is created from the u-238, but a far too high percent of it is pu-240 to be useful in nuclear bombs. Given there's only one neutron difference between them, separation of pu-240 from pu-239 is a technical feat that's so difficult not even the United States bothers to do it. They're researching it right now, but they've not really found an effective way to do it on a viable scale. The best and only real way to create pu-239 for bombs is to have a purpose built reactor and irradiate u-238 for precisely controlled lengths of time, which is exactly how every nuclear nation who has made their own pu-239 has gotten it. It's all been made in research reactors. Theoretically, it could be done with a reactor that does on-power refuelling, but this would be immediately obvious to any observer who would just have to stand there and notice them constantly cycling fuel in and out of one particular fuel channel. It is also possible to make nuclear bombs out of u-235, but this requires high enrichment (which is the concern with Iran's nuclear enrichment program), but this fear can be mitigated by selling fuel to whoever we don't trust to make it themselves and pre-poisoning it with pu-240, so it will work just fine in reactors, but if they try to use it for bombs they'll run into the same problem the US has yet to solve. Note, I'm not advocating selling fuel to assholes, just that if we need to, it can be done in a way to mitigate the proliferation risk. edit: chemical symbol for plutonium is pu, not p. 
ductonius fucked around with this message at 16:07 on Aug 3, 2015 |
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Aug 3, 2015 15:50
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ElCondemn posted:Also do modern reactors need cooling stacks like those? Technically no reactor needs cooling stacks like those, they're just one very common and economical way to cool water. Lots of coal plants use them too. Many nuclear plants use direct heat exchange with a lake or ocean to cool. I think there's a plant in Arizona that cools with sewage outflow.
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Oct 24, 2015 17:38
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GreyjoyBastard posted:That's hilarious. "So, pumped hydro works, right? What if we... pumped something denser?" Pumped mercury storage. I want a silvery lake of mercury, shining in the sun and I will build a cabin on its shores. I will sit and stare at what we have done and as it sparkles, weighty on the earth, every day enjoy my growing madness. ductonius fucked around with this message at 04:56 on Nov 17, 2015 |
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Nov 17, 2015 04:49
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Bolow posted:You can't turn solar panels into weapons You can't turn spent fuel into weapons either, and power reactor research has precious little to do with nuclear weapons development. Nuclear weapons tech and nuclear power tech are connected by virtue of using the same chemical elements but after that nearly everything about them is different.
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Dec 1, 2015 14:45
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Phayray posted:I didn't say it was easy, just that it's possible, refuting ductonius' claim that "You can't turn spent fuel into weapons either". What refuting? You've done none of that. The points brought up that separating usable nuclear bomb material from spent fuel is prohibitively difficult is exactly what I was getting at. Power reactor fuel is a mixture of u-235 and u-238 and as such is garbage for producing bomb-grade materials. Garbage in, garbage out. Of all the nuclear nations none of them got their bomb plutonium from spent power reactor fuel. None of them. They all used research reactors to irradiate U-238 just enough to get a usable ratio of Pu-239 to Pu-240. Do power reactors make pu-239? Absolutely, it's just so mixed up with other crap that spent power reactor fuel is not useful for making bombs. It's so prohibitively difficult not even the United Stated ever did it. Anyone who could try would find it much easier to build a research reactor instead. ductonius fucked around with this message at 21:53 on Dec 1, 2015 |
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Dec 1, 2015 21:51
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Reactor's happy! It's got a chain reaction. Sustained and controlled to boot! Reactor's happy! Coolant's flowing merrily in the primary coolant loop! Steam turbine is spinning up to make more electricity! Reactor's happy! To power lights and industry that's what fission means to me.
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May 23, 2016 20:16
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Phanatic posted:The green revolution was made possible by the extensive use of natural gas as a source of hydrogen to produce ammonium nitrate, and petrochemical-derived pesticides. Proven natural gas reserves are somewhere around 190 trillion m^3. Recoverable shale gas is around 200 trillion m^3. World consumption is around 3.5 trillion m^3 per year. If graphed, an accounting of total world natural gas reserves forms an inclined plane. We are literally finding natural gas faster than we are consuming it at this point. Where to get hydrogen for fertilizer isn't even close to being a problem.
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Feb 5, 2017 21:02
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BattleMoose posted:I thought the first civilian reactors were based very heavily off of the naval ones, because they had already done the R&D and consequently cheaper? Depends on what you mean by "civilian reactor". Both early and modern research reactors use HEU in ceramic plates as fuel, which is the same kind of design as early naval reactors. Early "civilian" power reactors had an output that could light a 60 watt bulb, or are we talking about early commercial power reactors?
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Aug 7, 2017 16:53
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