Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Fusion reactors: Not what they’re cracked up to be

thebulletin.org

Post reply on HN
Print view View original

11–20 of 222 posts

Re: Fusion reactors: Not what they’re cracked up to be

#11

Post by leephillips »

madaxe_again wrote: post #3

"In experiments to date the energy input required to produce the temperatures and pressures that enable significant fusion reactions in hydrogen isotopes has far exceeded the fusion energy generated." Wrong. NIF and others have achieved Q>1, albeit in single events. http://www.bbc.co.uk/news/science-environment-24429621

No, they haven't, not even in single events, although their press releases claim that they have. Their actual papers make it clear that the claim of >1 energy gain is a result of somewhat arbitrary definitions. There has not been a single shot on the NIF where more energy was supplied by the fusion reaction than was used to fire the lasers - it's not even close.

Re: Fusion reactors: Not what they’re cracked up to be

#12

Post by Recurecur »

I'm interested in the approach being investigated at LPPFusion, on a shoestring budget no less.

http://lppfusion.com/

LPPFusion is attempting to harness hydrogen-boron fusion, which doesn't produce neutrons, only gamma radiation and helium nuclei (alpha particles). Both the gamma radiation and the alpha particles can be directly converted into electricity. There are many potential benefits of this approach, but a primary one is that with no neutrons, there is no nuclear waste (or potentially plutonium) produced.

I hope LPPFusion can secure substantially more funding, it's doing more worthwhile research than the majority currently being done.

Re: Fusion reactors: Not what they’re cracked up to be

#13

Post by dsr_ »

When a reporter calls their credibility into question in the second sentence, there's a problem.

"they would produce vast amounts of energy with little radioactive waste, forming little or no plutonium byproducts that could be used for nuclear weapons."

Fusion products are helium, neutrons, and neutrinos. Stars eventually fuse products up to iron.

To generate plutonium requires a supernova...

Re: Fusion reactors: Not what they’re cracked up to be

#14

Post by [deleted] »

dsr_ wrote: post #13

When a reporter calls their credibility into question in the second sentence, there's a problem. "they would produce vast amounts of energy with little radioactive waste, forming little or no plutonium byproducts that could be used for nuclear weapons." Fusion products are helium, neutrons, and neutrinos. Stars eventually fuse products up to iron. To generate plutonium requires a supernova...

[deleted]

Re: Fusion reactors: Not what they’re cracked up to be

#15

Post by throwaway55523 »

dsr_ wrote: post #13

When a reporter calls their credibility into question in the second sentence, there's a problem. "they would produce vast amounts of energy with little radioactive waste, forming little or no plutonium byproducts that could be used for nuclear weapons." Fusion products are helium, neutrons, and neutrinos. Stars eventually fuse products up to iron. To generate plutonium requires a supernova...

He describes plutonium production as achievable by placing uranium into the reactor.

Re: Fusion reactors: Not what they’re cracked up to be

#17

Post by SomeStupidPoint »

leephillips wrote: post #11
madaxe_again wrote: post #3

"In experiments to date the energy input required to produce the temperatures and pressures that enable significant fusion reactions in hydrogen isotopes has far exceeded the fusion energy generated." Wrong. NIF and others have achieved Q>1, albeit in single events. http://www.bbc.co.uk/news/science-environment-24429621

No, they haven't, not even in single events, although their press releases claim that they have. Their actual papers make it clear that the claim of >1 energy gain is a result of somewhat arbitrary definitions. There has not been a single shot on the NIF where more energy was supplied by the fusion reaction than was used to fire the lasers - it's not even close.

Are you guys talking about different things?

One seems to be talking about energy released by while the other is talking about energy captured from.

I think GP was criticizing the news for making it sound like the first hasn't happened when only the second hasn't happened. (At least, in my understanding.)

Re: Fusion reactors: Not what they’re cracked up to be

#18

Post by leephillips »

adrianN wrote: post #16

Releasing Tritium is no problem, even if it's in kilogram amounts, because, as the author himself notes, the half life is less than two weeks. Edit: My reading comprehension is clearly lacking...

Where does the author note that?

"Tritium has a half life of 12.3 years which means it will be dangerous for at least 120 years, since the hazardous life for a radionuclide is ten to twenty times longer than its half-life"¹

If you come in contact with it during that time you will get cancer.

[1]https://www.nirs.org/wp-content/uploads/factsheets/tritiumba...

Re: Fusion reactors: Not what they’re cracked up to be

#19

Post by leephillips »

SomeStupidPoint wrote: post #17
leephillips wrote: post #11

Earlier quoted context omitted.

No, they haven't, not even in single events, although their press releases claim that they have. Their actual papers make it clear that the claim of >1 energy gain is a result of somewhat arbitrary definitions. There has not been a single shot on the NIF where more energy was supplied by the fusion reaction than was used to fire the lasers - it's not even close.

Are you guys talking about different things? One seems to be talking about energy released by while the other is talking about energy captured from. I think GP was criticizing the news for making it sound like the first hasn't happened when only the second hasn't happened. (At least, in my understanding.)

Neither one has happened.

Re: Fusion reactors: Not what they’re cracked up to be

#20

Post by justinpombrio »

leephillips wrote: post #18
adrianN wrote: post #16

Releasing Tritium is no problem, even if it's in kilogram amounts, because, as the author himself notes, the half life is less than two weeks. Edit: My reading comprehension is clearly lacking...

Where does the author note that? "Tritium has a half life of 12.3 years which means it will be dangerous for at least 120 years, since the hazardous life for a radionuclide is ten to twenty times longer than its half-life"¹ If you come in contact with it during that time you will get cancer. [1] https://www.nirs.org/wp-content/uploads/factsheets/tritiumba...

Can confirm: I have a keychain thing that glows from Tritium, and has for years.
Post reply on HN