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Arivne
topic
08:41:12 PM Apr 8th 2013
edited by Arivne
Removed the following Natter from The Iron Giant example in the Films - Animation folder.

  • If the Iron Giant had been a bit more familiar with Earthling technology, he might have realized that it would be possible to cripple the missile from a safe distance with a long-range weapon like a laser — instead of ramming into the missile head-first in a self-sacrificing kamikaze attack. But, obviously, that would've been emotionally anticlimactic.
    • It's not explicit, but it is strongly implied he doesn't have conscious control of his weapon systems (like his laser), so the above solution wouldn't be viable.
Fallingwater
topic
06:46:08 AM Dec 16th 2012
I'd just like to point out that "the rods promptly blew the fuck up. It was not actually a nuclear blast, it just threw radioactive shit everywhere." is way informal even for this wiki, but as it's the most succintly efficient way of explaining Chernobyl that I've ever read, I feel compelled to leave it in place.
David7204
topic
10:47:25 PM Sep 16th 2012
I was looking at Wikipedia's entry on Nuclear Meltdowns. The first line on the page is this:

"Nuclear meltdown is an informal term for a severe nuclear reactor accident that results in core damage from overheating. The term is not officially defined by the International Atomic Energy Agency by the U.S. Nuclear Regulatory Commission. However, it has been defined to mean the accidental melting of the core of a nuclear reactor, and is in common usage a reference to the core's either complete or partial collapse."

Evidently, a pretty loose term. To that end, I have a question about nuclear meltdowns occurring in fission vs. fusion reactors. Right now, the article says that meltdowns are exclusive to fission reactors, presumably because fission reactors possess a danger of "runaway" reactions and fusion reactors require precisely controlled conditions to operate at all.

So meltdowns wouldn't happen to a fusion reactor by accident. But what if someone was deliberately attempting to cause a meltdown to damage or disable the reactor as in the Mass Effect 2 example? If that someone had access to the computer and equipment controlling the reactor, it seems plausible to me that they could damage it by overheating, which seems to qualify as a meltdown according to Wikipedia. I know very little about the design of modern fusion reactors (much less whatever designs they use in science fiction) but the Fusion Power article mentions lithium being used as a coolant, so I assume excess heat is a real concern.
David7204
03:52:06 PM Sep 22nd 2012
No whiz-bang nuclear physicists eager to dazzle me with their knowledge and experience?
SeptimusHeap
01:37:20 PM Sep 24th 2012
^While "runaway reaction" isn't a concern for fusion plants, whether a failure of the magnetic containment would be harmless is another issue. Basically, if there is enough hot gas in the plant, it will simply explode.
ActualScientist
11:50:15 AM Sep 26th 2012
edited by ActualScientist
A fusion reactor cannot melt down because there's simply nothing to melt.

What melts in a meltdown is the fuel (the fuel assemblies are what make up the core of a fission reactor). And whereas a fission reactor contains fuel enough to last it for years, a fusion reactor contains only the fuel it needs right now - like in a gasoline combustion engine, it's injected as needed. To add to that, the fuel in a fusion reactor is gaseous at room temperature...

So in conclusion: while you can think of many spectacular ways that a fusion reactor can fail, a meltdown isn't one of them.
David7204
10:14:25 PM Sep 26th 2012
edited by David7204
...That really sounds sketchy to me. You're making it sound like the fuel melts but nothing else is damaged. If there's enough heat the melt the fuel, surely there's enough to damage the physical structure of the fuel rods and whatever other assemblies are inside the core. A quick Google search reveals uranium dioxide doesn't melt until almost 3,000 degrees C. I'm skeptical of you saying there's "nothing to melt" when there's solid matter and lots of heat in both fission and fusion reactors. Even if the fuel itself doesn't melt, damage to other elements of the core by excess heat sure seems to quality as a meltdown by Wikipedia's definition.

Also, as I said, this wouldn't be due to a random accident. It would be due to someone having full and deliberate control of the reactor, including the fuel injection systems.

ActualScientist
10:28:03 AM Oct 9th 2012
edited by ActualScientist
I don't know how on Earth you got to "nothing else is damaged" from what said, but I'll try to explain again.

The whole idea of meltdown being A Thing is because a fission reactor has tonnes of (solid) fuel inside that produces massive amounts of heat - and continues to do so after the excrement has hit the ventilator, for quite a while even after/if you stop the actual fission. This mass, if allowed to melt, will start melting through pretty much whatever is in its way until you manage to cool it back under control.

Fusion OTOH works with gram amounts of (gaseous) fuel, anything that goes wrong will stop fusion from occurring, and as soon as the reaction stops, so does the heat production. That you can melt components of a fusion reactor doesn't mean it's a meltdown. You can melt the pistons of a combustion engine - that doesn't make it a meltdown.
StarSword
09:23:39 PM Oct 10th 2012
edited by StarSword
Original poster of the example here. Basically, I put it there because it's a terminology mistake. As ActualScientist pointed out, "meltdown" specifically refers to the fuel rods melting down. Fusion reactors don't have fuel rods, so this falls under "fusion = fission BUT MORE!"

Besides which (and yes, I'm going off on a tangent), any intelligently designed fusion reactor (which admittedly is rare in sci-fi) would have hardware failsafes (using the bare minimum fuel flow to keep the reactor running, the deadman switch principle, etc.) to prevent the kind of tampering of which EDI speaks. Even the Star Trek Technical Manual basically says that core ejection failures so often seen in TNG equate to the writers not reading their own reference material: they're electromagnets holding the core in place and require power to not work. Realistically, the best EDI could do is trip the failsafes and cause the reactor to shut down (which still leaves the ship without power, so the Normandy comes out on top anyway).
OldManHoOh
topic
12:19:52 AM Jan 15th 2012
  • Resident Evil 2. The Umbrella Corporation uses a 5 kiloton tactical nuclear warhead on Raccoon City to destroy the zombie infestation, as well as all evidence that they were responsible for it. They plan to claim that the explosion was a meltdown at a nuclear power plant, ignoring the fact that nuclear plants can't explode like a nuclear bomb (#1).
    • Actually, despite what the end of RE 2/RE 3 makes it look like, the later Outbreak series established that there were multiple bombs/missiles used to destroy Raccoon City, and that they were definitely not nuclear.
    • Umbrella did no such thing. The U.S. government bombed Raccoon City as a measure of last resort, and the president resigned out of shame for having ordered it. And how much sense would it make for Umbrella to be sending in UBCS and USS to kill witnesses and assassinate rogue employees if they themselves planned to bomb the city to dust anyway?

Yeaaaahh. I've played some Resident Evil (albeit not 2 or 3), and even I'm baffled.
OldManHoOh
topic
11:49:27 PM Jan 14th 2012
  • Space: 1999. Nuclear waste stored on the Moon undergoes a chain reaction and detonates. The explosion is strong enough to throw the whole Moon out of the solar system, at a sizeable fraction of light speed. Real spacecraft take decades to get to the edge of the solar system, but in this show, the Moon supposedly got there in weeks.
    • Actually, despite the ridiculousness of nuclear waste sending the moon out at a significant percent of c, real spacecraft don't travel anywhere near any significant portion of c. Voyager 1, the fastest spacecraft (which received a large speed boost from Saturn), will still take 14,000 years to travel one light year. Having never seen the work in question, this troper guesses that 'sizeable fraction of light speed' would be well over 1% of c (taking a mere century to travel one LY), which is significantly faster than Voyager 1.

I'm somewhat confused by the "1 light year" references. Is the edge of the solar system really that far?
ActualScientist
11:26:25 AM Jan 15th 2012
Depends on how you define "edge of the solar system". The outermost planet, Neptune, is around 30.5 AU (1 AU = the mean distance between the Earth and the Sun), or 0.0005 light years, away from the Sun at its farthest point. The heliosphere, a volume of space filled with a medium emitted from our sun, extends out to around 100 AU (0.002 light years) at its closest end. If you include the Oort cloud or simply define it as the radius in which our sun dominates the gravitic influence, however, it's around 1 or 2 light years...

It doesn't really matter though. The second troper was merely using light years as an example to show how absurd the premise is.
OldManHoOh
topic
11:40:36 PM Jan 14th 2012
  • H. G. Wells's novel The World Set Free (1914) features what may be the first ever appearance of atomic explosives anywhere, but considering that it was written at the tail-end of the Victorian Era, the physics are quite dodgy. Extrapolating from the idea of radioactive decay as something with a tremendous amount of energy releasing it over a long period of time, Wells' nukes work by somehow speeding up this process. Instead of releasing all of its nuclear energy in an instantaneous, massive explosion, the bomb speeds up radioactive decay to the point where you have a huge fireball that hangs around for several days before dying down.
    • Wells based his story on a paper by Dr. Frederick Soddy (1877-1956), who was an early pioneer in nuclear physics and collaborated with Dr. Ernest Rutherford in first defining the nature of nuclear reactions. Interestingly enough, Wells (who unlike Dr. Soddy, was not a physicist by trade) was describing a variant of the Bethe solar phoenix reaction, which won Dr. Hans Bethe (1906-2005) a Nobel Prize in physics when he defined it and its role in stellar reactions and the formation of stars- in the late 1950s. Bombs working on a similar principle, but even more powerful, known as "Hellburners", appeared in several of H. Beam Piper's Terro-Human Future History stories, notably Space Viking (1964).

I can't tell if the second half is contradicting it or expanding.
ActualScientist
10:58:26 AM Jan 15th 2012
edited by ActualScientist
Neither. It's basically trivia... that mixes facts (Wells was inspired by science at the time and Bethe did pioneering work on stellar nucleosynthesis) with science fiction ("Bethe solar phoenix" is, AFAIK, a term invented by H. Beam Piper, and the nuclear processes in the sun bear no resemblance to what Wells describes). The original entry should be re-added.
OldManHoOh
topic
11:13:59 PM Jan 14th 2012
  • The 2009 Astro Boy movie includes a line which states that the blue energy sphere is "more powerful" than nuclear energy. Sorry, professor, Artistic License - Physics. No energy is more or less powerful than any other energy. This is like saying a pound of steel weighs more than a pound of feathers. A watt is a watt is a watt. If he had specified the energy source having more watts or greater voltage than a comparable source, it might have actually meant something.

Uhh, what?
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