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

Nuclear fusion milestone passed at US lab

bbc.co.uk

Post reply on HN
Print view View original

111–120 of 222 posts

Re: Nuclear fusion milestone passed at US lab

#111

Post by ballard »

beloch wrote: post #68
dekhn wrote: post #48

A good place to start if you want to understand the purported rationale for the NIF (stockpile stewardship), I suggest reading and understanding this light introduction to modern nuclear weapons. http://en.wikipedia.org/wiki/Thermonuclear_weapon (the rhodes books, Making of the Atomic Bomb is required background reading, as is Dark Sun, if you want to get into the backstore). In particular: The NIH experiment recapit…

The NIF is probably more useful for coming up with new fusion bomb designs than for stockpile stewardship, as you say, but what makes you say hot fusion can never be economically viable? The sun is proof that nature can do this on a grand scale! It may be a long ways off, but "a long ways" becomes "never" without experimental work like the NIF. Yes, the U.S. is probably doing this primarily to create new weapons just…

Would fusion only weapons be covered under any existing non-proliferation or test ban treaties?

Re: Nuclear fusion milestone passed at US lab

#112

Post by tanzam75 »

cyanoacry wrote: post #92
sam wrote: post #47

It is an important milestone. But to have a commercially viable fusion reactor, you'll need a factor of 50-100 more energy out than in to make up for inefficiencies in electricity generation using this kind of scheme. The real story here is that this facility allows the US to do nuclear weapons research without violating the nuclear test ban treaty. If the goal was to develop a commercially viable fusion reactor, the…

This is definitely true, and the BBC totally omitted these facts. The official NIF announcement[1] tried a little bit to cover their tracks. They posted some flashy numbers about the total energy output from neutrons, but nestled in the bottom of the page is the total energy dumped into the entire system: 1.7 megajoules. In comparison, the fusion power produced was a paltry 8 kilojoules, which they compare to the "en…

> total energy dumped into the entire system: 1.7 megajoules. In comparison, the fusion power produced was a paltry 8 kilojoules

In other words, the National Ignition Facility hasn't achieved ignition yet.

If you can actually achieve ignition, then nobody will care about the megajoules needed to get it ignited. Because once you've got ignition, you can get an arbitrary amount of energy out.

But if you can't get ignition, well, then, that pesky 0.3% heating efficiency will still leave you a couple of orders of magnitude away from engineering breakeven.

Re: Nuclear fusion milestone passed at US lab

#113

Post by bcoates »

nikatwork wrote: post #106
dekhn wrote: post #48

A good place to start if you want to understand the purported rationale for the NIF (stockpile stewardship), I suggest reading and understanding this light introduction to modern nuclear weapons. http://en.wikipedia.org/wiki/Thermonuclear_weapon (the rhodes books, Making of the Atomic Bomb is required background reading, as is Dark Sun, if you want to get into the backstore). In particular: The NIH experiment recapit…

> It's just that the western nations decided to go stupid about fission I have many highly intelligent friends who subscribe to your view. Unfortunately they forget that fission is only as safe as the weakest link, and the consequences of failure are severe, especially when near a water source. I'm not talking about crumbling old soviet-era reactors or even older Japanese ones. Witness Australia's only nuclear facili…

That appears to be an accident handling the output of an isotope manufacturing reactor, not anything involving a power reactor.

> I would argue that there needs to be a significant improvement before fission is publicly acceptable.

I would argue that fission is already held to a standard well above that of almost any human endeavor, even those with roughly similar risk profiles (compare almost any form of mining, or the shipping of hazardous cargo by rail)

Re: Nuclear fusion milestone passed at US lab

#114

Post by tanzam75 »

ballard wrote: post #111
beloch wrote: post #68

Earlier quoted context omitted.

The NIF is probably more useful for coming up with new fusion bomb designs than for stockpile stewardship, as you say, but what makes you say hot fusion can never be economically viable? The sun is proof that nature can do this on a grand scale! It may be a long ways off, but "a long ways" becomes "never" without experimental work like the NIF. Yes, the U.S. is probably doing this primarily to create new weapons just…

Would fusion only weapons be covered under any existing non-proliferation or test ban treaties?

The Comprehensive Test Ban Treaty bans testing of any "nuclear" explosions. Doesn't matter if it's fission or fusion or both. (The United States has not ratified the CTBT, but generally abides by it.)

The Non-Proliferation Treaty bans the proliferation of any "nuclear" weapons. Again, doesn't matter if it's fission or fusion or both.

Re: Nuclear fusion milestone passed at US lab

#115

Post by NamTaf »

hyperbovine wrote: post #107
nikatwork wrote: post #106

Earlier quoted context omitted.

> It's just that the western nations decided to go stupid about fission I have many highly intelligent friends who subscribe to your view. Unfortunately they forget that fission is only as safe as the weakest link, and the consequences of failure are severe, especially when near a water source. I'm not talking about crumbling old soviet-era reactors or even older Japanese ones. Witness Australia's only nuclear facili…

If the Japanese can't do it safely, it can't be done safely.

Why? What makes you think their corporations cut fewer corners than Western ones? What makes you think their employees/scientists/etc. are inherently more infallible than Western ones?

Re: Nuclear fusion milestone passed at US lab

#116

Post by rlucas »

hyperbovine wrote: post #107
nikatwork wrote: post #106

Earlier quoted context omitted.

> It's just that the western nations decided to go stupid about fission I have many highly intelligent friends who subscribe to your view. Unfortunately they forget that fission is only as safe as the weakest link, and the consequences of failure are severe, especially when near a water source. I'm not talking about crumbling old soviet-era reactors or even older Japanese ones. Witness Australia's only nuclear facili…

If the Japanese can't do it safely, it can't be done safely.

It wasn't "the Japanese" that didn't do it safely at Fukushima. It was GE, which is about as American as you get, along with Toshiba and Hitachi. Also it was the 1960s, which is the age of the technology deployed in these relative archaisms. See http://blog.rlucas.net/tech_and_market_reflections/fukushima...

Re: Nuclear fusion milestone passed at US lab

#117

Post by ars »

TylerE wrote: post #93
sam wrote: post #47

It is an important milestone. But to have a commercially viable fusion reactor, you'll need a factor of 50-100 more energy out than in to make up for inefficiencies in electricity generation using this kind of scheme. The real story here is that this facility allows the US to do nuclear weapons research without violating the nuclear test ban treaty. If the goal was to develop a commercially viable fusion reactor, the…

If we could get a fusion design that works a bit over unity, couldn't you, well, chain them? E.g. 1MW basic plant that drives a 1.5MW plant that drives a 2.25MW -> 4 -> 6 -> 9 etc, however many stages you need.

Yes, but you have to pay for the power plant, and being just a bit over unity won't cover the expense of the next stage in the chain.

You have to be enough over unity to pay for another plant plus surplus to actually use. In which case you can just build a bunch of plants - you don't need to chain them. There are plenty of other power sources you can use to bootstart the power plants.

Even regular power plants need power to start them see https://en.wikipedia.org/wiki/Black_start

Re: Nuclear fusion milestone passed at US lab

#118

Post by ars »

tanzam75 wrote: post #112
cyanoacry wrote: post #92

Earlier quoted context omitted.

This is definitely true, and the BBC totally omitted these facts. The official NIF announcement[1] tried a little bit to cover their tracks. They posted some flashy numbers about the total energy output from neutrons, but nestled in the bottom of the page is the total energy dumped into the entire system: 1.7 megajoules. In comparison, the fusion power produced was a paltry 8 kilojoules, which they compare to the "en…

> total energy dumped into the entire system: 1.7 megajoules. In comparison, the fusion power produced was a paltry 8 kilojoules In other words, the National Ignition Facility hasn't achieved ignition yet. If you can actually achieve ignition, then nobody will care about the megajoules needed to get it ignited. Because once you've got ignition, you can get an arbitrary amount of energy out. But if you can't get ignit…

> get an arbitrary amount of energy out.

Not really. You have to build larger, or more, power plants. So you have to make enough extra energy to sell to pay for plants.

Re: Nuclear fusion milestone passed at US lab

#119

Post by NamTaf »

2muchcoffeeman wrote: post #87

What ever happened to the polywell reactor design?

The University of Sydney have continued research of polywell reactors. I'm not terribly across their progress but I try to read papers whenever they're released though I haven't read any of their 2013 papers. It seems the last few years (2010-2012 at least) have focused around minimising point- and line-cusp losses.

More reading here: https://en.wikipedia.org/wiki/Polywell#University_of_Sydney

Re: Nuclear fusion milestone passed at US lab

#120

Post by ars »

crystaln wrote: post #91
beloch wrote: post #68

Earlier quoted context omitted.

The NIF is probably more useful for coming up with new fusion bomb designs than for stockpile stewardship, as you say, but what makes you say hot fusion can never be economically viable? The sun is proof that nature can do this on a grand scale! It may be a long ways off, but "a long ways" becomes "never" without experimental work like the NIF. Yes, the U.S. is probably doing this primarily to create new weapons just…

Coal power is more deadly than fission power? When has coal power ever created the sort of crisis that occurred in Fukushima? Because of fission reactors, the safety of entire regions of the world is dependent on a consistent power supply and lack of human error, something that clearly we can not rely on. In the event of a cosmic emp or major meteor strike, these power plants are at risk.

Coal causes about 100 times as much radiation as nuclear power:

http://www.scientificamerican.com/article.cfm?id=coal-ash-is...

https://en.wikipedia.org/wiki/Radioactive_waste#Coal

Post reply on HN