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Thanks, I had no idea lead-bismuth reactors existed. It seems the large number of unstable lead isotopes and their long decay chain would assure a long cooldown requirement before any maintenance could be done in the reactor compartment/primary coolant system. Not only that, but this stuff would present a huge disposal problem. https://en.wikipedia.org/wiki/Isotopes_of_lead

It seems the Alfa class was decommissioned for scrapping, though one was refitted with a pressurized water reactor for a while. https://en.wikipedia.org/wiki/Alfa-class_submarine#Decommiss...

An interesting issue with this design is that if the Pb-Bi coolant ever solidified, the reactor control rods became frozen in place.


It may just be easier to design a zero G litter box. A screen bottom with a coarse granular material and sufficient airflow through the bed could work. No idea how a cat would dig in zero G though.


Sturdy screening to give claws a grip would probably serve as the equivalent of human handholds just generally. I don't know how comfortable or feasible walking on it would be, but I bet a cat could learn pretty quick to catch on to it and then push off along a desired vector, and they're already better at gyroscopic pointing than we are.


I have a couple of EM tables,one from 1956,the other from 1966. Schematics used to be freely available untill somebody scooped up the copyrights and issued takedown notices so they could change a premium.

Maybe this tool will help me get them back up..



I've often wondered if a double envelope would be worthwhile. Use a thin outer envelope containing He, and an inner lifting envelope with H. The outer envelope would contain any H that leaked through the inner membrane.


As noted, the lower explosive limit for hydrogen in air is 4%. Significantly lower with pure oxygen. https://www.safeopedia.com/definition/2205/explosive-flammab...

The problem is that hydrogen is a very small molecule and readily escapes containment. It can even travel along grain boundaries through solid metal.


Exactly, the lower limit, when hydrogen has escaped into the air, not when air has leaked into the contained hydrogen. The article makes clear that above 75% H2, ignition is impossible (but only if you read it).

"Traveling along grain boundaries" can only leak trace amounts. With, as I said, positive airflow, trace leaks can be constantly diluted below the concentration where ignition is possible.


A British film documenting theory and operation of the V2 rocket.


More interesting than copper as used in the example would be nickel or rhodium.


Can you explain more about this? Do these have certain properties that you find beautiful, or useful?


Strength to weight ratio and high temperature properties.


Probably corrosion resistance, if I had to guess.


An easy path to metal matrix composites.


As someone who has spent some time and effort attempting to develop this exact process, it's limited by poor fiber adhesion to the metal matrix.


Unfortunate but not entirely surprising. Though perhaps the fiber pull out strength could be increased by modifying the compositions of the metals/fibers to increase the binding strength. Or perhaps fiber geometry. Interesting process though nevertheless.


Every single component in every single aircraft certificated in the USA is tracked all the way to the mine. A quick web search reveals around 11.3 million people work in the aviation industry directly. A significant portion of this would have to be duplicated if the FAA were to verify everything.


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