New neutron moderation oven build
Posted: Thu Jul 17, 2014 6:42 pm
Well, with all the new shielding, and the difficulty of handling heat, and leaks near where we have to kind of have them to let some out to measure, I thought I'd do a new take on the old neutron oven. This one will be easier to shield around, and will help with the heat issues as well - at least for the top half of the fusor, I'll still need a fan blowing across the bottom half - and that will have to be converted from a "hole" to an "elbow" so as to stop the leak through the original (small but straight) hole. At any rate, Carl Willis once computed for us the thickness of the initial layer, assuming it was HDPE, to get a neutron energy spectrum centered around the big resonances in silver, indium, and gold. It was ~~ 1.5". This version will use water plus ethylene glycol (pure, not antifreeze since I have no idea what the neutron capture characteristics are of those secret ingredients it contains), and will allow for boiling and re-condensation to help keep at least the top half of the fusor not much above 100c. It will be made of copper, and silver soldered, with an exhaust tube near the top going to a vertical condenser about 5' high made of 3/4" Cu pipe - the idea being to let that condense anything the boils and let it drip back in there. Since water+glycol isn't going to be quite as good a moderator as HDPE (oxygen is heavier than carbon) - I made the thinnest part 2" for this one. The top will be plain old HDPE, which I now won't have to worry about melting and so forth - and encased in some of our thickest lead (capture gammas, power supply X rays, and so on). There will still be some getting out, but it's far from the operator position at least.
Here's where it starts:
More when I have more. I'm alternating between writing software (data aq, scope control and so on) and machine projects depending on how I feel that day.
As usual, there are about 10 things "in progress" so I always have something to do that matches my current motivation. Or almost always...
Here's where it starts:
More when I have more. I'm alternating between writing software (data aq, scope control and so on) and machine projects depending on how I feel that day.
As usual, there are about 10 things "in progress" so I always have something to do that matches my current motivation. Or almost always...