The basic Reactor Vessel is constructed as follows:
Take a piece of 24” Stainless Steel tubing with a 4” diameter and place two Bored Conflat Flanges, CF 6”, Bored 4”, tapped holes. Weld them in place.
Standard practice is to polish all the welds and then pickle such fabrications in (most recently) strong and hot citric acid, rinse them off with deionized water and check for leaks at the designed operating temperature.
Source of 24" x 4" stainless steel pipe:
Why 304 stainless instead of 316? Does it matter? What did Mizuno use?