JF Ptak Science Books Quick Post Part of the series on Atomic and Nuclear Weapons
Here's an interesting formerly Top Secret document from the Lee Groves collection of the George C. Marshall Foundation:
The document is dated two days after the Trinity test of 16 July--I presently do not know why this is so.
"The sketch is of a test cylinder procured and installed at a time when we were uncertain as to the explosive power of the bomb. If, at the time of the test, we anticipated that the force might be relatively small or even that there might be no nuclear explosion, we were going to place the bomb in the cylinder so that it would be possible to recover the plutonium."--Marshall Foundation, below.
The cylinder/container for the bomb was called "Jumbo", and was 25'x10' and 214 tons--a big thing. It was decided at some near point that "Jumbo" would not be necessary as it became evident to many that the bomb would indeed "work". "Jumbo" and the tower were constructed and ready but abandoned for their intended purpose--it was left to stand, about 800 yards from the point of explosion; afterwards, "Jumbo" remained intact but its steel tower was completely destroyed.
Source: the George C. Marshall Foundation: http://marshallfoundation.org/library/documents/steel-test-cylinder-tower-july-18-1945/#sthash.ccG8PSRb.dpuf
Thanks to Gene Dannen at www.dannen.com for the lead on this.