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 Post subject: Question on NIF
PostPosted: Feb 09, 2014 4:54 pm 
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The Wiki entry on NIF,

http://en.wikipedia.org/wiki/National_Ignition_Facility

Mentions a recent run with 1800 kj laser input, 14 kj energy out.

This is the source.

http://news.sciencemag.org/physics/2013 ... -%E2%80%A6

Can it really be this bad? Billions of dollars have gone into this device. They are talking about "scientific breakeven". and about this being an important step. Completely dishonest! This performance is atrocious, the device is a complete failure as an energy generator, and the researchers should come out with that. We are not even considering the laser inefficiency, which even with more advanced lasers is expected to be under 20%. Plus the losses from heat to electricity.


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 Post subject: Re: Question on NIF
PostPosted: Feb 09, 2014 5:09 pm 
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Cyril R wrote:
The Wiki entry on NIF,

http://en.wikipedia.org/wiki/National_Ignition_Facility

Mentions a recent run with 1800 kj laser input, 14 kj energy out.

This is the source.

http://news.sciencemag.org/physics/2013 ... -%E2%80%A6

Can it really be this bad? Billions of dollars have gone into this device. They are talking about "scientific breakeven". and about this being an important step. Completely dishonest! This performance is atrocious, the device is a complete failure as an energy generator, and the researchers should come out with that. We are not even considering the laser inefficiency, which even with more advanced lasers is expected to be under 20%. Plus the losses from heat to electricity.


It is a crime against humanity, a sin against all things holy to spend billions of dollars to research worthless ideas like this when, a simple LFTR liquid fluoride thorium reactor that was/is working safe clean cheap and durable since the 1970's was mothballed.

It seems the main power players of usa believe that the world will forever be under the control of usa backed fossil fuel industry. The world cannot and will not forever be under the control of fossil fuels. The world will take the LFTR we developed in usa, and build LFTR in every city of the world.

When the world starts using LFTR, ( and the world will use lftr sooner than anyone expects) USA superpower status WILL BE GONE FOREVER.


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 Post subject: Re: Question on NIF
PostPosted: Feb 09, 2014 6:16 pm 
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I believe that the NIF was intended to be used as a dual-use machine: for nuclear weapons simulations and for ICF research. I don't know whether it has been useful for nuclear weapons simulations, but it sure has cost the American taxpayers a lot of money. The French are building a similar machine, the Laser Megajoule (LMJ), near Bordeaux. The reason for building that machine was that nuclear weapons testing in French Polynesia could be abandoned.

I am afraid that the ITER project (magnetic confinement fusion) is going to be another money sinkhole. The projected costs of this machine are running at 15 billion Euros.

If only a fraction of these amounts was spent on MSR R&D ...


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 Post subject: Re: Question on NIF
PostPosted: Feb 09, 2014 6:20 pm 
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NIF is a Thermonuclear bomb development facility.

The lasers have to be tuned to produce a far more precise laser pulse than would otherwise be necessary.
It has to mimick the behavior of a primary device in a thermonuclear weapon.

Additionally the lasers for NIF were locked in years ago.
Lasers have progressed independently since then.

EDIT:

Also that appears to have been an overall gain of 14kJ.
Not a total output energy of 14kJ.


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 Post subject: Re: Question on NIF
PostPosted: Feb 10, 2014 11:27 am 
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As if the usa needs to develop more advanced nuclear weapons.

These billions of dollars could have built LFTRs that will ensure cheap clean safe LFTR energy for america for the next 1000 years.


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 Post subject: Re: Question on NIF
PostPosted: Feb 10, 2014 11:35 am 
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NicholasJanssen wrote:
As if the usa needs to develop more advanced nuclear weapons.

These billions of dollars could have built LFTRs that will ensure cheap clean safe LFTR energy for america for the next 1000 years.


You always need more advanced weapons.

Those who beat their swords into ploughshares will, at the end of the day, plough for those who didn't.


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 Post subject: Re: Question on NIF
PostPosted: Feb 10, 2014 12:19 pm 
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E Ireland wrote:
NIF is a Thermonuclear bomb development facility.

The lasers have to be tuned to produce a far more precise laser pulse than would otherwise be necessary.
It has to mimick the behavior of a primary device in a thermonuclear weapon.

Additionally the lasers for NIF were locked in years ago.
Lasers have progressed independently since then.

EDIT:

Also that appears to have been an overall gain of 14kJ.
Not a total output energy of 14kJ.


Ok, makes sense. So they put in 1800 kj of laser beam. Then get 1814 kj of thermal energy. But its still terrible. The best figures I've found for projected future solid state lasers is 25%. So you need to put in 7200 kj of electricity. To make 1814 kj of heat. That will then make 900 kj of electricity (at most).

So the electricity in is still 8x bigger than the electricity out even with the best future solid state lasers.

I also find the total output atrocious. 900 kj/s is 900 kWe. Less than a MWe for a billion dollars. Even at 10 capsules per second it is a billion dollars for 9 MWe. Completely economically non viable. (i didn't consider the 1 additional billion in research).


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 Post subject: Re: Question on NIF
PostPosted: Feb 10, 2014 2:17 pm 
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Location: Taunusstein, Germany
E Ireland wrote:
Also that appears to have been an overall gain of 14kJ.
Not a total output energy of 14kJ.


By breakeven they mean that more that 14kJ was generated, while the fuel absorbed 14kJ of xray energy:

https://en.wikipedia.org/wiki/National_ ... _Milestone

Quote:
That gain (output divided by input) should be greater than 1. NIF's laser input was 1.8 MJ. The output of the reaction—14 kJ; was a gain of 0.0077.


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 Post subject: Re: Question on NIF
PostPosted: Feb 10, 2014 3:30 pm 
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Now I'm confused. Is the problem that very little of the laser beam actually gets absorbed by the target at all?

If so then it is far worse than what Ed Ireland says. All they're doing is heating up a chamber pointlessly.


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 Post subject: Re: Question on NIF
PostPosted: Feb 10, 2014 4:32 pm 
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Location: Taunusstein, Germany
This is what the science article says:

Quote:
The ultraviolet beams are fired into the hohlraum through holes at each end but not directly at the fuel capsule. Instead they hit the inner walls of the hohlraum, heating it so much that it emits a pulse of x-rays. The x-rays cause the plastic capsule to explode, driving the fuel inward toward its center.


By indirect generation of xrays a lot of energy is lost. Then only a fraction of these xrays hit the target.


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 Post subject: Re: Question on NIF
PostPosted: Feb 10, 2014 5:21 pm 
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Ok now I understand.

It is even more stupid than even I thought. If you start with 1800 kj of laser power and only 14 kj gets absorbed, then even with a factor of 10 fusion output you only get 140 kj. But you put in 1800 kj! So you have 1800+140 kj = 1940 kj of heat. This contraption does not make sense even with very high fusion to input energy yield.

Rube Goldberg would no doubt be very proud of NIF however.

Image


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 Post subject: Re: Question on NIF
PostPosted: Feb 10, 2014 10:18 pm 
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Location: Montreal
The energy input ends up as shown in this graphic (note that this ignores laser beam generation inefficiencies):


Attachments:
NIF_laser_energy_spread.png
NIF_laser_energy_spread.png [ 93.6 KiB | Viewed 2176 times ]
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 Post subject: Re: Question on NIF
PostPosted: Feb 10, 2014 10:49 pm 
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Joined: Aug 29, 2008 4:55 pm
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Location: Idaho Falls, Idaho
could you use a gamma source to do the same thing?


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 Post subject: Re: Question on NIF
PostPosted: Feb 11, 2014 2:57 am 
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Joined: Jun 05, 2011 6:59 pm
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Location: NoOPWA
NicholasJanssen wrote:
As if the usa needs to develop more advanced nuclear weapons.
Its not about building new advanced weapons but about knowing we can rely on existing weapons after years of decay without being able to test the weapons.

_________________
DRJ : Engineer - NAVSEA : (Retired)


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 Post subject: Re: Question on NIF
PostPosted: Feb 11, 2014 3:19 am 
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jaro wrote:
The energy input ends up as shown in this graphic (note that this ignores laser beam generation inefficiencies):


Where did you get this figure from?

For NIF, it not 10-20%, but <1%. 14 kj is more than the absorbed energy onto the capsule, out of 1800 kj laser beam. Thus the absorbed energy is less than 14 kj and the laser input is 1800 kj. So 0.7%.

For a 25% efficient laser system we are left with 0.2% efficiency. For a 50% conversion of heat to electricity we are left with 0.1% total system efficiency.


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