Shine - a real use for fusion, now!

Reflections on fusion history, current events, and predictions for the 'fusion powered future.

Re: Shine - a real use for fusion, now!

Postby Richard Hull » Mon Dec 12, 2016 9:05 pm

As noted in his talk to the ANS, Canada will be shutting down, forever its major, production of Mo99 next year! This is why Shine is forging ahead into construction now. It is important to remember that once you have refined M099 in hand, its half life is on the order of 6 hours and that the technicium decay product also has a very short half life. So, if you make Mo99 in Timbuktu you need to air express it to Bejing before its medical value rots away. The US uses more Mo99 than any nation on Earth. Canada was a good rapid, inexpensive source. That is going to disappear.

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Re: Shine - a real use for fusion, now!

Postby Paul W Fontana » Fri Feb 17, 2017 12:44 am

Has anyone here tried to generate Mo99 by neutron bombardment of Mo98? Would it be feasible (just to observe the transmutation to Tc99, not for commercial purposes) with a Po-Be neutron source, if not a fusor? I saw a thread (http://www.fusor.net/board/viewtopic.php?f=13&t=6266) where @RobertTubbs did it with photon bombardment, but couldn't find any references to neutron activation experiments.

If one were to try it, say with a Po-Be, what would be the ideal configuration? Better off with a thick or thin piece of moly? Moderator between the source and the metal? How much?
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Re: Shine - a real use for fusion, now!

Postby Richard Hull » Fri Feb 17, 2017 10:44 pm

If you own a good gamma spectrometer and setup everything properly with a very robust neutron source you might...just might detect Mo99. This would not be a walk in the park for the casual amateur effort.

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Re: Shine - a real use for fusion, now!

Postby David Kunkle » Sat Feb 18, 2017 2:04 am

Had a Po-Be neutron source for a while. ( A nuclespot- until the State of IA made me give my toy back). It made a very small, but measurable, amount of neutrons with my bubble detector and He3 tube. IMO, bombarding Mo with that small neutron source would produce so little Mo99 as to be undetectable by any of our methods.
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Re: Shine - a real use for fusion, now!

Postby Jon Rosenstiel » Sat Feb 18, 2017 9:47 pm

I had a go at this back in 2007. (Note that images are now in reverse order)

viewtopic.php?f=13&t=5817

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Re: Shine - a real use for fusion, now!

Postby Richard Hull » Sun Feb 19, 2017 3:08 am

Thanks Jon! This tells the story here. Yes you can make Mo99! Great huh? However, you can't prove it! Sure you can.....All you need is a multi-thousand dollar EDAX detection system hooked to your Gamma Spectrometer and to blast the Mo target for 45 minutes continuously with 3 million neutrons per second just like Jon did.

Jon is our premier activation guy with all the best gear that money can buy. He can prove he got Mo99 using his plus-ultra, kick-ass fusor and his lucky find EDAX detection system plugged into his lucky find gamma spectrometer, using his best, time honed, technique and some locally supplied liquid nitrogen.

Wanna' give it a go at your end?

The long struggle to answer your question.....No, you cannot make detectable Mo99 with a nucleospot in average amateur hands. You need lots of neutrons poured over a long time into the Mo target and a lot of very specialized and expensive detection gear to be able to say you did it.

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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Re: Shine - a real use for fusion, now!

Postby Paul W Fontana » Mon Feb 20, 2017 5:09 pm

Thanks, Jon! Nice work.

Gamma spec we got. Nuclespot Po-Be source we got. Time for long activation runs we got. Moly we don't have yet - I'm guessing a run-of-the-mill coin will do the trick? Is there an ideal thickness?

I'm looking for some interesting and challenging things for the students in the Advanced Lab to do with the neutron source - since Jon has demonstrated proof-of principle on this one, sounds like it might be worth a shot! Students learn a lot from trying hard experiments, even if they don't end up getting the results they're after (possibly the best lesson in real-world science of all). I might have them try In-115 + n --> In-116* first, though, since we already have some indium activation foils and from what I've read that may have a higher chance of success.

-- pwf
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Re: Shine - a real use for fusion, now!

Postby Richard Hull » Mon Feb 20, 2017 9:07 pm

Indium, Silver and Rhodium activation are all very easy to do and have been very common activation efforts for fusioneers here for many years. Harder efforts are manganese and gold.

The first three, noted above, activate very fast, needing only minutes of exposure in a neutron oven to reach saturation activation. Plus, they need no gamma spec, just a GM counter to indicate activation has taken place. This assumes you have a decent source of neutrons. Tons of info and reports on these "easy three" abound here on fusor.net.

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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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Re: Shine - a real use for fusion, now!

Postby Paul W Fontana » Thu Mar 09, 2017 10:17 pm

Update: The students got the neutron detector tuned up (a small 3He tube device), but were only able to detect about 1 cpm (over a background of about 0.2 cpm) from the Po-Be source after counting with and without moderator for 45 min each. We estimate that source is generating about 6000 n/s isotropic, and it was located fairly close to the tube. That makes the efficiency of the geometry, moderator, and detector combined about 1:400,000. They tried activating indium foils for an extended time by sandwiching moderator between them and the source and surrounding everything with moderator, then took gamma spec for 4 hours, replacing the foil with a "hot" one every hour to compensate for its decay, but could see no sign of 116In or any other indium lines above background.

I guess the bottom line is that a NucleSpot Po-Be source is no match for a well-operated fusor for neutron production rate, and hence for transmutation. It just can't keep up with the decay of an isotope with a half-life on the order of an hour. Needless to say, we won't be trying with moly, at least until we have a relatively efficient fusor going.

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Re: Shine - a real use for fusion, now!

Postby Richard Hull » Fri Mar 10, 2017 2:17 pm

A well operated fusor is a great source for neutrons. I have run tests just recently and found that I prefer silver activation best of all. If you are willing to take great care and can transfer your silver within 10 seconds from the moderator to a "digital readout" geiger counter, 100,000 neutrons per second, isotropic will give an easy proof that you have activated silver. The exposure time for the fast silver would take and exposure of only 2 minutes, but the longer you go, the second longer lived isotope, builds up over many minutes. 300,000 or more n/s, isotropic will activate most any of the easy activated elements based on their half lives and times of exposure.

It is to be remembered that ever larger numbers of neutrons per second will not activate any element faster, but instead to higher levels of radiation emission, (specific activity), per unit time of exposure. Likewise exposure times at a given neutron rate of more than 5 times the half life of the expected activation product will gain nothing as the isotope would be in equilibrium. (decaying as fast as it is produced.)

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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