Ward is quoting Heinz Pommer, whose slide show is copied here:
https://edwardmd.files.wordpress.com/2019/10/pompdfpics1.pdf
Pommer's theory is unveiled at slide #65 of 111. He argues that each bomb was a relatively primitive uranium-thorium ball that emulated a Chernobyl effect, sinking into bedrock and creating a focused explosion directed upwards into the core of the building.
Ward thinks that the event was highly radioactive and dirty. Nuclear weapons are normally designed with a casing made of depleted uranium, that absorbs high energy neutrons while providing additional explosive power. Pommer's bomb doesn't have any such casing, which is why the designation of "neutron bomb" is correct.
In my analysis of the WTC event, I was assuming the opposite, that the explosion left little or no radioactive trace. Pommer blames Steve Jones for the misinformation, if indeed that's what it is / was.
