U-234 mention in the paper

The best efficiency for a single centrifuge is VERY much smaller
than 30%, thats why they build trains of dozens of the damm things


Thats because of seperation factor which is around 1,05.

They would , they'd say he never designed a single one since all
US enrichment plants until 1981 were the gaseous diffusion type


Thats correct and proves my point ,before arrival of Zippe at Virginia,US was a
backward country as far as gas centrifuge technology concerned and to correct
this situation US scientists launched a campaign to bring Zippe to US as
development helper.Only after Zippe's arrival,US recognized the importance of
centrifuge technology for the production of nuclear weapons,as a consequense of
this late recognization US pressurized (West) German goverment to classify ALL
centrifuge research made in (West) Germany.West German government bowed to US
pressure and classifed ALL German centrifuge research on August 1,1960,needless
to say many of classified research was conducted by Zippe.
(I always wondered why US classifies so many scientific documents,to protect
advanced US technology or to protect much more advanced foreign technology?)