OK – I read the 1966 report from Hanford on U-233. Basically this is what Sorensen is saying. Yes, one can make a workable nuke out of U-233 but it is inferior to plutonium. Remember, Hanford built the plutonium Nagasaki bomb while Oak Ridge built the Hiroshima bomb. The key takeaway is that it is possible to make a bomb out of U-233 but there is little point in doing so because it is far, far easier to make a bomb out of U-235 and Plutonium.