• Welcome to the new COTI server. We've moved the Citizens to a new server. Please let us know in the COTI Website issue forum if you find any problems.
  • We, the systems administration staff, apologize for this unexpected outage of the boards. We have resolved the root cause of the problem and there should be no further disruptions.

Fusion Power Plants

About the replacemrnt of the shielding at teh NIF.. I get that figure from going to school in SF, and doing volunteer work at Lawrence-Livermoore and Lawrence-Berkely Labs (and it is likely that I will be doing an internship there in 2009/2010, if I keep my grades at their current level)... where... I helped to replace titanium and concrete, which is how this whole thread got started (By me wondering what could be done in Traveller if they had shielding that didn't require replacing)

and...

DOH! What you are describing is the shielding for a fission plant, which water will work for, since fission reactions produce roughly .000000000001 the amount of the neutrons of a fusion reaction (They do however produce an inverse square amount of gamma, beta and alpha radiation)...

So, not really applicable.

As to their "bouncing"... They will bounce off of large atoms that are not in a crystalline lattice (that is why I posted the bit on the wigner effect, where it explains all of that).

Problem is, with the neutrons coming from a fission reactor, they produce so little impact upon the surroundings that you can just let them slide on by. It is likely that the damade they do to anyone will only be to a few cells.

Whereas with a Fusion reaction, you get 6x10^23 neutrons per 2 grams of reactant in a deuterium reaction, or 2.5 grams of Deuterium-Tritium reaction.

That is:

600,000,000,000,000,000,000,000 neutrons per 100GJ produced (Roughly, based upon the numbers provided in the wiki on Nuclear Fusion).

Compare that with the approximately 1 billion neutrons released per GJ of fission reaction.. Not a lot of neutrons...

When I get the emails back from ITER and my old prof at School (and an employee of the NIT) I will post them, and get permission for anyone to contact them to verify said numbers.

AND REALLY PEOPLE... Quit concentrating upon the reactions... It is the application that I am more concerned with.

ANY solution to this problem indicates a substantial technology that could be used in MANY applications OTHER than fusion...

This is not a problem that requires handwavium, unobtanium or any other such non-sense. There are real-world applications to solve these issues (one of which I just revealed in my last post: Wigner Effect Annealing).

These applications need to be examined for T5, and not just thrown out the window because they do not conform to past canon.

Even the Catholic church has a system for changing established canon (for instance, they "killed" the devil in 1972 with the abandonment of the office of Exorcist by Pope Paul VI).

Shouldn't Traveller have the ability to alter canon and be improved in the process?

Do people really want it to become a static product that becomes akin to Victorian Sci-Fi by future generations of gamers?
 
Do people really want it to become a static product that becomes akin to Victorian Sci-Fi by future generations of gamers?
Click to expand...
well, I certainly wouldn't want to be accused of holding back traveller, so, hey, have at it.
 
Judas Iscariot said:
DOH! What you are describing is the shielding for a fission plant, which water will work for, since fission reactions produce roughly .000000000001 the amount of the neutrons of a fusion reaction
Click to expand...
More like 25%, though it depends on the fuel mix you're using in both cases. Fission produces fewer neutrons per unit energy than fusion (about 2.5 neutrons in a reaction that's some 10x as energetic) but it still produces quite a lot.
Judas Iscariot said:
As to their "bouncing"... They will bounce off of large atoms that are not in a crystalline lattice (that is why I posted the bit on the wigner effect, where it explains all of that).
Click to expand...
They will bounce off of large atoms regardless of whether the atoms are in a crystalline lattice. Neutrons don't give a damn about what chemical bonds the atom might be involved in. If you want to absorb (rather than slow) neutrons, lithium-6 and boron-11 are good choices.

None of which is really related to the problem of neutrons in fusion reactors, which has more to do with neutron activation and embrittlement of structural materials.
Judas Iscariot said:
AND REALLY PEOPLE... Quit concentrating upon the reactions... It is the application that I am more concerned with.

ANY solution to this problem indicates a substantial technology that could be used in MANY applications OTHER than fusion...
Click to expand...
Whereas none of the other implausible technologies I posted has any unusual applications?

Here's the dirty little secret: Traveller is not Hard SF.
 
Anthony said:
They will bounce off of large atoms regardless of whether the atoms are in a crystalline lattice. Neutrons don't give a damn about what chemical bonds the atom might be involved in. If you want to absorb (rather than slow) neutrons, lithium-6 and boron-11 are good choices.
Click to expand...

See:

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

"Neutrons that collide with the atoms in a crystal structure must have enough energy to displace them from the lattice. "

and

"The atoms that do not find a vacancy come to rest in non-ideal locations; that is, not along the symmetrical lines of the lattice. These atoms are referred to as interstitial atoms, or simply interstitials. "

By "boucing off" I mean the neutrons collide with and then leave the matrix...

as to whoever provided the comments about water being a good shield for a fusion reactor.

please post a source.
 
OH.. and if you are suggesting using Lithium and Boron... GREAT!

Those reactions can produce a mostly aneutronic reaction.

That just means that the Canon involving fuel for Fusion plant is wrong...

Can't get boron from the ocean in significant quantities needed for fusion, same with lithium...

So, we just need to convince Mark that he needs to change this.
 
Judas Iscariot said:
"Neutrons that collide with the atoms in a crystal structure must have enough energy to displace them from the lattice. "
Click to expand...
The Wigner Effect is what I was calling Neutron Embrittlement. It has nothing to do with effectiveness of a material as neutron shielding, it has to do with how much damage the material takes from being used as neutron shielding.
 
flykiller said:
http://en.wikipedia.org/wiki/Radiation_shielding
Click to expand...

All of this info applies to Ionizing radiation, which Neutron radiation is not precisely. It produces Ionizing reactions as a secondary feature, but free neutrons on their own are not ionizing.

Ions are charged particles. Neutrons have no charge.

It even goes as far as to say this:

"Neutron radiation is not as readily absorbed as charged particle radiation. Neutrons are absorbed by nuclei of atoms in a nuclear reaction (which often leads to emission of gamma photons, causing additional shielding concerns), but fast neutrons have first to be slowed down (moderated) to slower speeds, by inelastic collisions with heavy nuclei or by elastic collisions with light ones. A large mass of hydrogen-rich material, eg. water (or concrete, which contains a lot of chemically-bound water), polyethylene, or paraffin wax is commonly used. It can be further combined with boron for more efficient absorption of the thermal neutrons."

This quote talks NOT about shielding Neutrons, but slowing them down so that they do not emit Gamma radiation when they do impact upon a shield (I already brought this up in one of my earlier posts).

You REALLY seem to be having (maybe it is others as well) with making a distinction between fission and fusion reactions...

EVERY bit of data on that link deals with fission reaction gamma shielding.

These are not really applicable to the primarly fusion reaction, but could be appropriate for the tertiary radiation produced from neucleon conversion and positron destruction, which isn't an issue if you have appropriate neutron shelding.

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

This does mention that hydrogen based compounds are good at slowing neutrons so that they are slow enough to be able to sustain a chain fisssion reaction, but they mention that this produces large amounts of gamma radiation. It also will create a degredation of the material as well; even simple hydrogen, but it just becomes deuterium or tritium.

Saying what I said above: You will still need to contain the Neutrons, not just slow them down.

Saying what I have said before, again... If Hydrogen, water, and such were such excellent Neutron shielding... More Fusion reactors would be using such materials.

Plus, from established Canon designs of starships... There is no such shielding around a power plant in the floor plans I have seen.
 
Anthony said:
The Wigner Effect is what I was calling Neutron Embrittlement. It has nothing to do with effectiveness of a material as neutron shielding, it has to do with how much damage the material takes from being used as neutron shielding.
Click to expand...

I never said it did. This was to point out that such materials used as shielding would have to be replaced at regular intervals, and would probably be expensive (they are at the reactors I have recently contacted (and where I helped) as most of the shielding needs to be replaced using remote handling (Remote controlled robots, and so on... Hence my interest in it: My degree is in Mechatronics engineering, or "Robotics")
 
Hi !

Well, first in actual practical radiation protection business neutron "radiation" is considered as ionizing radiation just as alpha, beta or gamma radiation, because of the property to cause ionization effects in target materials (regardless if direct or indirect).

The real life the shielding in experimental fusion reactors (e.g. ITER) is usually called "blanket", an is in fact a more complex contruction, which moderates/slows down the fast neutrons (suggested moderators are Be and Li-ceramics), removes heat via a helium gas flow and catches slowed down neutrons with a Li+n > T or H1->H2 reaction.
The neutron catching reaction indeed causes gamma radiation, which has to be shielded again. In some actual prototypes the blanket is about 1 m thick.
But indeed the blanket contruction is something, which would have to be replaced from time to time, because of the commulated amount of stressed and activated (radioactive) parts. A more or less funny aspect of real life fusion plants is, that they produce around the same amount of radioactive waste as fission reactors. Well, the good side is, that the decay rates are much higher here, and you could get rid of the stuff in a few decades....

For those really interested I could provide a pretty good paper for real life fusion technology (its in German but contains a large amount of very good figures and pictures).
Edit: Ok. Found the origin: http://www.ipp.mpg.de/ippcms/de/pr/publikationen/pdf/berichte.pdf
E.g. on page 21 you will find a blanket prototype picture.

Anyway we know, that Traveller and also it fusion reactor are science fictional.
We know, that those fictional reactors run with hydrogen, so some kind of D+D or D+T reaction is likely, maybe H+H reactions at higher TLs too.
And we know, that they are pretty safe and clean and terrible inefficient :)
One perhaps neglected aspect could be, that Traveller fusion reactors make use of gravitic technology, too, which would make particle flow control and shielding (especially of neutrons) a hell lot easier and considerable smaller.
As both anti-grav and fusion plant come up with TL 9, this would be a clue.

Apparently the ITER project developes a bit.
Perhaps I will try to learn french and get a ITER research/engineering job in beautyful southern France :)

Regards,

TE
 
Last edited:
GEEZ.. FINALLY!

This is what I have been trying to get across...

Thanks for the paper... would you like that translated into english?

I am going to take it back to school with me in the fall, and look for one of my German friends/fellow students to help me wade through it.

I had hesitated to post links to papers I personally have not read, and the ones that I have read I cannot find online.

I did go through the Plank Insistutes site, but couldn't find any technical specifications in english (German, French, Italian...yes... But no English... Frustrating)

I am just a sophomore Physics student at the moment, but I hang out with a lot of the Interdisciplinary studies students who are much more advanced than I...

This whole issue arose from helping replace the concrete around the NIT reaction vessel a few years ago so that I could make a study of the remote handling technologies that were used. When I noticed that one of the Interns had a T-Shirt with a Traveller Imperial Sunburst located on it, I began to talk to him about technological development in Traveller.

The issue of Fusion power came up since we were in a fusion ignition facility.

OUR comments mostly centered around the unintended consequences of fusion power availability.

ie, gravitic control that confines teh reaction and helps to control neutron emisssion, and at higher TLs possibly initiates protium reactions (although we both felt that these were too poor to use effectively as power generators, and at higher TLs they would be using more exotic isotopes of Hydrogen and Helium).

It was also raised that the materials used in a fusion reaction chamber would likely have applications outside of the fusion vessel itself. Notably, that theh ability to confine and prevent neutron emission would indicate a possibe source of shiedling against Energy weapon basic attacks, which are themselves just ionizing radiation in the form of an energetic plasma (assuming I am interpreting both the wiki and the textbook that I will be using next fall)

Thanks for the link.
 
You know, I recall an old web page out there that thought CNO fusion was what Traveller "must" be using. I don't recall why it would be better than any other kind.

Ah, here it is. Good old Missouri Archive!

http://traveller.mu.org/house/fusion.html

I note that he doesn't mention radiation much.
 
Hi !

Hm, I guess it should be possible to find a similar paper in english language.
At least I will have a look for that.
The Projects described in the paper are pretty international and there should be something in Your native language :)

Anyway I will try to make a few extracts of some core facts.

BTW:
Some more links:
http://www.fusion.org.uk/techdocs/isfnt7_pampin.pdf
http://www-ferp.ucsd.edu/ARIES/MEETINGS/0601-USJ-Workshop/Maisonnier.pdf
http://ej.iop.org/links/rEXI3Vljf/cgZPa3kl3BGlUiaaav5vpA/nf7_7_S01.pdf
http://www-ferp.ucsd.edu/LIB/MEETINGS/0407-Erice/Maisonnier.pdf
Perhaps You will like the last one :)

RObject, thanks for the links. I don't know why the author is in favour of the CNO cycle. Perhaps he likes it just hot...

Regards,

TE
 
The more I read, the more I like catalyzed cold fusion. A little more handwavium and far less "BUT...".

Does this discussion qualify for Continuing Education credits?
 
I just found a blurb in FFS that describes fusion reactions as being D-T or Protium (Unrefined fuel)...

I am writing up a proposed tech solution for this, and unintended technology applications that can be produced as a result.

One of the things that I think REALLY needs to be done is to have a power output table that shows the output of a fusion plant (they are obviously designed to operate on more than one type of fuel). A recent paper I wrote that I sent to Marc on Materials tech had a proposed material that would allow a reactor to operate on more than one type of fuel by having a dynamic/reactive alloy (Similar to Terminiator 2' Memetic-Poly alloys, but not as fast in their ability to adapt. They are a develpment of Electroactive Polymers and Alloys) that would allow the reaction chamber to be reconfigured for a new fuel while it still contained a high-energy plasma active inside (so that the reactor did not need to be cold-started. something that would be impossible if using "unrefined fuel" ie Protium).

As far as "continuing education credits".. I am going to submit the paper I write as a result of this discussion to one of my teachers who will appreciate it..

Now that I finally have an answer as to what canon really says.. I can work out a solution that preserves most of the canon (I REALLY think that TL 9 - 11 Fusion plants should not be able to run on Protium/Unrefined fuel. fortunately, you can make D-T fuel out of plain hydrogen with a simple neutron source to dope the hydrogen with... any old it of fissile and an appropriate small pre-reaction vessel will do. Or, in a pinch, ALL water and hydrogen gas contains small amounts of Deuterium. You could force a low-yeild D-D reaction (and have additional "emergency" shielding that can be put in place for just such an ocassion) for a short period of time.. Maybe enough to get .5 of a jump out of the available Deuterium in the "fuel"...
 
DUH! Thanks for the link to the papers... I have several of them in hard-copy in an IEEE publication, but I have not got around to reading them yet (I am still going through the stuff about nano-scaled deposition of transparent displays and computational substrates in sturctural materials construction.. A LITTE bit over my head at this point, but with wiki and Wolfram Mathworld... I can make out most of the stuff)...

I will go take a look at that last one.
 
You must log in or register to reply here.

Similar threads

C
Power plant question
2 3
Replies
43
Views
2K
kilemall
kilemall
W
T4 merchant design challenge
Replies
9
Views
1K
warwizard
W
M
Higher Technology Items on Low Tech Worlds and Improvements
2 3
Replies
44
Views
3K
chipla
C
HanleyTucks
The VoidQ
Replies
3
Views
389
Diveguy
D
W
2100 AD
2
Replies
33
Views
4K
whartung
W
Back
Top