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Ansuman
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Nuclear power plant which use of fission process have been made but why not fusion power plants, what affect its feasibility ??
Simon Bridge said:This is an active area of research.
So far, nobody has been able to produce a controlled fusion reaction that outputs the same (or more) energy than it uses. A quick google will show you lots of things that have been and are being tried.
The fusion process has yet to be perfected.Ansuman said:Nuclear power plant which use of fission process have been made but why not fusion power plants, what affect its feasibility ??
Muon catalyzed fusion does not require such high temperatures - it's use for power generation keeps coming up but afaik nobody has made much headway. The trouble there is that muons don't last and they cost a lot to make.It is thought to require millions of degrees for several seconds.
but these r only 4 experimental purpose and can't be used for energy production ( googled some stuff )...anyway thanks for the help.Astronuc said:The fusion process has yet to be perfected.
There are various efforts ongoing, particular the international program, ITER, near Cadarache.
www.iter.org - ITER is under construction in southern France adjacent to the CEA Cadarache Research Centre, located in the commune of Saint-Paul-lez-Durance.
http://www.ccfe.ac.uk/ - Abingdon, Oxfordshire, UK
http://www.pppl.gov/ - Princeton, NJ, US
https://fusion.gat.com/global/Home - General Atomic, CA, US
and others
Most experimental systems have been exploring ways to heat and stabilize the plasma. Along the way, they have also discovered the challenges of confining plasmas long enough to sustain a fusion reaction.
Other attempts have been made with inertial confinement, which currently looks pretty dismal. https://lasers.llnl.gov/
Yes - they are ongoing research programs. The objective has been, and still is, to develop fusion to the point where it is commercially viable. That objective has proved elusive over the last 6 decades. If it was so simple, we'd have commercial fusion plants.Ansuman said:but these r only 4 experimental purpose and can't be used for energy production ( googled some stuff )...anyway thanks for the help.
Simon Bridge said:This is an active area of research.
So far, nobody has been able to produce a controlled fusion reaction that outputs the same (or more) energy than it uses. A quick google will show you lots of things that have been and are being tried.
Astronuc said:Yes - they are ongoing research programs. The objective has been, and still is, to develop fusion to the point where it is commercially viable. That objective has proved elusive over the last 6 decades. If it was so simple, we'd have commercial fusion plants.
Sustained confinement of fusion plasmas has not yet been achieved such that fusion is ready for commercial application. The research has however been moving in that direction, albeit rather slowly. The objective of ITER is to approach the minimum conditions for sustainable fusion, however, it could very well fall short of commercial viability.
If ITER is successful, then perhaps there is a chance - depending on how successful the experiment is.Ansuman said:so after these all experiments have been done, is there any chance to use the same technology to make commercially viable plants in near future
The question asked was "why not fusion plants" and these examples show you why not.Ansuman said:but these r only 4 experimental purpose and can't be used for energy production ( googled some stuff )...anyway thanks for the help.
I'm making a (somewhat glib) reference to thermonuclear weapons. This approach to getting a fusion reaction works but is not feasible for power generation for, hopefully, obvious reasons.Ansuman said:i understood that it requires about 10 million K to initiate a fusion reaction but since the energy output is not high as the input it would not initiate further reactions...so what is meant uncontrollable reaction
... muons cost a lot of energy to make, relative to the energy resulting from the fusion process.Simon Bridge said:Muon catalyzed fusion does not require such high temperatures - it's use for power generation keeps coming up but afaik nobody has made much headway. The trouble there is that muons don't last and they cost a lot to make.
Joint European TorusAstronuc said:Along the way, they have also discovered the challenges of confining plasmas long enough to sustain a fusion reaction.
30 s does not a commercially viable reactor make. Try 30 days, then 30 months, and even 30 years with a capacity of greater than 0.90, and preferably greater than 0.95.Joseph Chikva said:Joint European Torus
http://en.wikipedia.org/wiki/Joint_European_Torus
"Lifetime of the plasma: 5–30 s"
This is more than enough. For ITER this parameter should be even longer.
The problem more in the achievable temperature. As density is also enough but reactivity of plasma is still low due to low temperature achieved.
ITER has projected Plasma Internal Energy about 520 MJ and total Heating Power about 70 MW. Neglecting energy losses they need 520 / 70 = 7.4 sec for increasing internal energy till required value.
More power will turn TOKAMAK out from stability area. That is a real problem.
Also neutral beam injection NBI is technically inconvenient for practical reactors way as assumes the direct connection of gas filled "neutralizer" with vacuum camera (reactor vessel).
http://www-users.york.ac.uk/~bd512//teaching/media/mcf_lecture_08.pdf See Figure on page 19
TOKAMAKs always (from the beginning till now) was thought as pulse machines. Recall that current required there for creation of poloidal field is an induced current and therefore is a pulse current.Astronuc said:30 s does not a commercially viable reactor make. Try 30 days, then 30 months, and even 30 years with a capacity of greater than 0.90, and preferably greater than 0.95.
Just in case someone thought I meant the dollar cost? Fair enough.mheslep said:... muons cost a lot of energy to make, relative to the energy resulting from the fusion process.Simon Bridge said:Muon catalyzed fusion does not require such high temperatures - it's use for power generation keeps coming up but afaik nobody has made much headway. The trouble there is that muons don't last and they cost a lot to make.
Simon Bridge said:I'm making a (somewhat glib) reference to thermonuclear weapons. This approach to getting a fusion reaction works but is not feasible for power generation for, hopefully, obvious reasons.
Power generation is much significant challenge than task of improvement (and not creation) of weapons that never be used and huge inventory of which is already in existence.d3mm said:Not all fusion research is for power. More than a few fusion dollars go into weapons research. For example it is the main mission of NIF fusion lab in America. I wonder what percentage of the total fusion budget is split this way.
I doubt on "a lot".Simon Bridge said:There are lots of reasons to study fusion besides energy production and weapons development - but I bet those are the big payers.
By pulse do you mean a repetitive pulse operation with some reasonable duty cycle? If so, no major tokamak has been run like that, nor will ITER. Normal operation is one shot for some seconds, then days or months until the next.Joseph Chikva said:TOKAMAKs always (from the beginning till now) was thought as pulse machines. ...
ITER is indented for longer pulse then 30 sec - approximately 1000 sec. But in either way machine is indented to run "pulse by pulse" or "shot by shot".
...
ITER is not commercial reactor. Yes, commercial reactor should repetitive pulse operation: 1000 sec pulse and very soon the following shot and so on.mheslep said:By pulse do you mean a repetitive pulse operation with some reasonable duty cycle? If so, no major tokamak has been run like that, nor will ITER. Normal operation is one shot for some seconds, then days or months until the next.
I should have said typical experimental performance to date, not 'normal'.Joseph Chikva said:... Why they need days months? I doubt about "months", but "days" - may be.
Viability implies a demonstrated long operation time, something greater than few seconds, or a high duty cycle for shorter pulses. So far, no tokamak has even remotely approached those conditions.TOKAMAKs are viable right now. As they provide enough plasma density long enough time.
I said study not "use", but, since you asked for just one... muon catalyzed fusion is used to build large nuclei for study.Joseph Chikva said:I doubt that "a lot".
Can you mention one more reason of usage fusion except power generation or weapon?
Space traveling? Actual?
Brothers Right too demonstrated flight only on some hundred meters, then offered their flying toy to USA army from which they naturally refused. Some people have seen that the concept worth for further development. As result today the main strike force of any advanced army is aviation and civilian aviation.mheslep said:I should have said typical experimental performance to date, not 'normal'.
Viability implies a demonstrated long operation time, something greater than few seconds, or a high duty cycle for shorter pulses. So far, no tokamak has even remotely approached those conditions.
Really? The birth of one muon IIRC 210 MeV even neglecting low efficiency of process followed from low selectivity.Simon Bridge said:I said study not "use", but, since you asked for just one... muon catalyzed fusion is used to build large nuclei for study.
Joseph Chikva said:I doubt on "a lot".
Can you mention one more reason of usage fusion except power generation or weapon?
Space traveling? Actual? We live in the end of oil era, when risk of big nuclear conflicts are neglectable with increasing risks of asymmetric conflicts in which technology advanced countries fight with outdated combatants and therefore only power generation is significant for us today. Because of it DOE and similar other organizations are the best payers. And not for example NASA and DOD.
I've seen Lockheed's presentation. There are many words about challenges humanity has. But nothing about what kind fusion (concept) they are going to do in such short time period. If that is a presentation - very strange presentation.d3mm said:Space travel is both. Either you use the reactor for power, or you blow up a bomb behind you and surf the blast.
Defence company Lockheed Martin last week at Google's Solve for X announced they will have fusion power prototype in 4 years(!). He predicted they can generate 100 MW by 2017. I do not think his claim is realistic.
Google's solve for X: https://www.solveforx.com/
You can find the Lockheed fusion presentation in the moonshots section but a copy is here: He shows the Lockheed Martin prototype fusion reactor.
DoD is funding a lot more fusion reserch tha you probably think. They want to stop buying oil from people they do not like, and they need electrical power for lasers. NIF is a defense lab not because their laser is weak but because "scientific curation" of nuclear weapons was theiroriginal mission .
Yes, NIF lasers are very powerful but I said “efficiency of laser is weak – about 1% or little more or little less”.d3mm said:I also don't know why you say their laser is weak; it is the world's largest.
Both or the same? And 3 or 4 people worked, only several millions were spent and only for the first phase. One NAVY's missile worth more. As result several table-top machines with no scaling at all. The last machine showed fractions of milliwatt fusion power with kWs input.d3mm said:DoD has 2 publically announced fusion projects, being EMC2 and Whiffleball, both attempts to build a shipboard fusion reactor.
Agreed. People put in the word "weapon" some mystic sense. While weapon is also an engineered product like many others and while NIF is a typical inertial confinement approach similar to canceled now "Light Ions Fusion" and not yet heavily started "Heavy Ions Fusion". May be in the program scale some weapons simulations was done. I really can not imagine what but funding from DoD is the fact. As well as fact is that at today's level of technology laser fusion has not any posibility to produce net power.the_wolfman said:I don't deny that NIF has weapon applications, but to date most of the research on NIF has gone to support peaceful purposes not weapons.
The US$3.5-billion NIF uses lasers to crush a 2-millimetre pellet of hydrogen fuel to the point of fusion. Rather than irradiating the fuel directly, the lasers shine into a cylindrical capsule. The capsule walls then emit X-rays that squeeze the fuel pellet until it explodes (see diagram).
This indirect approach mimics the ignition system in a thermonuclear weapon, which uses radiation from a fission 'primary' stage to squeeze hydrogen isotopes in the fusion 'secondary' — creating a powerful explosion.
The NIF's main mission is to gather laboratory data on the process to help weapons scientists to care for the ageing US nuclear stockpile
Simon Bridge said:...
...
I didn't want to write too much in case nobody was interested. ...
...I was more interested in pointing to an example of low-temp fusion that wasn't junk science.
Fusion does not have to involve very high temperatures but:
1. the high temperature projects look like they have more promise these days
2. there is a lot of junk and pseudo-science around low-temp fusion ideas to trap the unwary investor.
E.g., Heroin (diacetylmorphine*hydrochloride) was developed as medicine drug but now is marketed only by clandestine dealers. As its properties does not allow usage for medical application. History of science knows many such examples when failure in one branch gives some results used in another.d3mm said:It really did surprise me how slowly fusion power was progressing despite all the money being spent on it, but then I realized that a lot of the money being spent on fusion isn't going towards power.