homebuilt neutron source?

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Spencer DePue
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Re: homebuilt neutron source?

Post by Spencer DePue » Wed Sep 07, 2011 7:14 pm

I agree, your absolutely right. I should take time to slow down and move in a consistent direction as opposed to making up all sorts of newfangled ideas and never sticking with one. This forum has actually helped me a lot with practicality and which ideas are worth endeavoring. I will try to do better with this.

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Chris Bradley
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Re: homebuilt neutron source?

Post by Chris Bradley » Wed Sep 07, 2011 7:23 pm

Spencer,

Not wishing to be all-stick and no-carrot, may I suggest this as an 'exercise':

Take a look at;

http://www.rexresearch.com/nucell/nucell.htm

..spend a week or two researching what it is claiming, then if you have arrived at some well-formed conclusions, come back on the forum and (in an appropriate forum - this one isn't it) discuss with us here what your further reading has drawn up as to the strengths and/or weaknesses of the claims in it. In other words, do you think this should work, or not work, and why?

Rob Osterman
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Re: homebuilt neutron source?

Post by Rob Osterman » Wed Sep 07, 2011 7:43 pm

Spencer,

It's fun to have a lot of ideas that would seem to work, the difficult part is to back it up with the advanced science (something I am still struggling with as well!). I found that searching questions through Google only provided half-answers, and often times poor advice from different forums (fusor.net being the exception).

What helped me a bit is by going through MIT's Open Course Ware on Nuclear Engineering. A lot of the lectures and slides are available for free from the undergraduate level all the way to the graduate. It gives a good primer for a more guided self-education. Check out the link, you can spend hours looking through the information. http://ocw.mit.edu/courses/nuclear-engineering/

George Dowell
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Re: homebuilt neutron source?

Post by George Dowell » Wed Sep 07, 2011 8:17 pm

"Check out the link, you can spend hours looking through the information. http://ocw.mit.edu/courses/nuclear-engineering/

Days/weeks in my case. I read slow. I understand slower.

Geo

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Carl Willis
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Re: homebuilt neutron source?

Post by Carl Willis » Wed Sep 07, 2011 8:48 pm

The quantity of uranophane that would fit into a typical test tube has a few microcuries of alpha activity in it. Under the best of circumstances, assuming a Po-210 alpha spectrum, one can obtain 80 neutrons / 1E+06 alpha particles from the (a,n) reaction on beryllium. So at best, you'd be looking at neutron yield in the single digits per second with this activity available. Detecting that is practically impossible.

But it gets worse. Unfortunately, the situation you describe is far from ideal as only the uranium atoms within a few microns of the beryllium surface can contribute to the reaction--the vast majority of alpha particles from the volume will be stopped before they reach the beryllium. Furthermore, the (a,n) yield is highly dependent on incident energy, and your alpha particles predominantly from U-238 at a max of ~4.2 MeV have nowhere near the yield as those from radium, Po-210, and Am-241. I would be surprised to see even 1/1000 of that 80/1E+06 figure, making other sources of neutrons--like (a,n) on silicon and oxygen in the uranophane and spontaneous fission of U-238--competitive. The numbers of total neutrons will be distinguishable from background only by the most rigorous technique using the most sensitive equipment.

The battery part of the idea can be dismissed wholesale from some cursory considerations of energetics.

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Spencer DePue
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Re: homebuilt neutron source?

Post by Spencer DePue » Wed Sep 07, 2011 9:13 pm

I had the idea the yield would be terrible. As for Paul Browns battery, its a definite hoax and bad science. But now I am disappointed. I thought I was going to make a "nuclear magnetron". And now that it is labeled as bad science, I cant develop it without getting crappy efficiencies.. Here is what I found.

Claim 1: No waste or nuclear reaction
False: Really? a nuclear battery with no byproducts or nuclear reaction.. hmmm. Thats the indicator
that this is completely bad science.

Claim 2: Nucell yields 7500 watts/gram of Sr90
False: I did some math. Based on some common sources, Sr90 has an activity of 5.094x10^12 Becquerels. Multiply that by 8.747888222x10^-14 joules(energy of the beta particles) ( 546,000 electronvolts converted to joules) and the answer is .445 watts per gram of Sr90. Nice try.

Claim 3: magnetic energy of the emitted particles is greater than the kinetic energy.
False: In order for the particles to have magnetic energy, they have to have kinetic energy first, which will degrade as heat ultimately reducing this magnetically attractive claim to be false.

The list goes on...

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Chris Bradley
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Re: homebuilt neutron source?

Post by Chris Bradley » Wed Sep 07, 2011 9:26 pm

Spencer DePue wrote:
> Claim 1: No waste or nuclear reaction False: Really? a nuclear battery with no byproducts or nuclear reaction.. hmmm. Thats the indicator that this is completely bad science.
I think that part is referring to 'just beta emissions', resulting in 'electrons' and just stable isotopes remaining (just like when activated materials decay back to something stable).


> Claim 2: Nucell yields 7500 watts/gram of Sr90 False: I did some math. Based on some common sources, Sr90 has an activity of 5.094x10^12 Becquerels. Multiply that by 8.747888222x10^-14 joules(energy of the beta particles) ( 546,000 electronvolts converted to joules) and the answer is .445 watts per gram of Sr90. Nice try.
But what does the Sr90 decay into, and how much energy could you get out of whatever it decays into?

Spencer DePue
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Re: homebuilt neutron source?

Post by Spencer DePue » Wed Sep 07, 2011 9:41 pm

Woah, missed a piece of data, according to the combined decay energy of strontium 90 and yttrium 90, it would be around 7500 watts.

Yttrium 90: 2279800 Mev to joules: 3.652643877e-13 joules x 20000 Tbq/gram= 7305 joules
plus other decay energies from Sr 90 and occasional gamma ray.


Interesting.. I thought of a magnetron in reverse configuration utilizing nuclear decay yesterday, and then I came across this. I doubt its as efficient as they claim. Lots of energy still wasted as heat.

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Re: homebuilt neutron source?

Post by jcs78227 » Thu Sep 08, 2011 4:53 am

Spencer DePue wrote:

> Yttrium 90: 2279800 Mev to joules: 3.652643877e-13 joules x 20000 Tbq/gram= 7305 joules
> plus other decay energies from Sr 90 and occasional gamma ray.

Careful on your math and units. The way you have it written, Yttrium-90 has a value of over two TRILLION electron volts. You probably intended a decimal point after the first digit...? Your sigfigs are all over the place in this thread, so even mentioning the uncertainty would be pointless.

I know you've been thoroughly dressed-down, so I'll trust you do it more carefully on paper.

J-

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Richard Hull
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Re: homebuilt neutron source?

Post by Richard Hull » Thu Sep 08, 2011 1:57 pm

Overall, this post and its responses have been instructional. What was learned....

Orders of magnitude are important when considering nuclear processes that seem great at first glance. The physics of nuclear processes is such that easy sources of real energy are just not to be had at the amateur or even the common manufacturing level.

No matter what nuclear process is used in a useful nuclear battery, the waste heat is always there. Oddly, this is actually the only nuclear battery technology, (trapping and using that heat), that works to give significant electrical outputs.

Any nuclear battery that might be produced is forced into controlled, government use and constant oversight due to the amount of isotopic material demanded.

In space, nuclear batteries, (thermionic generators), are a real valuable asset for long period, deep space missions where solar cells are no longer viable and common battery technology that they might charge is lifespan limited. Such generators/batteries are often "one-offs", designed for a specific mission and not picked up from any manufacturer's inventory

You can't make a useful, easily verifiable neutron source from any radioactive ore. (NORM).

Dreams and ideas are often quickly shattered by any number of real world issues blocking implementation.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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