I'm no physicist, but I think the appearance of radionuclides at Ground Zero is proof positive of the use of nukes on 9/11.

There was probably some combination of explosives and thermite , along with an underground nuke used to take down the towers.  Hopefully Chuck can shed some light on the radionuclide evidence during his debate with Morgan  Feb 6

on the Real Deal with Dr Fetzer moderating  .... woohoo!   ps. The first USGS link has a graph showing high strontium.

The second USGS link now belongs in the bottom group.  hmm 

....  http://www.epa.gov/rpdweb00/radionuclides/index.html  ....  http://pubs.usgs.gov/fs/fs-0050-02/fs-050-02_508.pdf  ....  http://wtcdemolition.blogspot.com/2007/06/on-issue-of-nuclear-demolition-of-wtc.html   .... http://www.nucleardemolition.com/GZero_Sample.pdf  ....  http://wtcdemolition.blogspot.com/    .... http://eddieleaks.org/barrett-khalezov-duff/  ......  and a few from the dark side trying to lead you astray:    http://www.journalof911studies.com/letters/a/Hard-Evidence-Rebudiates-the-Hypothesis-that-Mini-Nukes-were-used-on-the-wtc-towers-by-steven-jones.pdf  .... 

http://www.takeourworldback.com/wtcnukeddisinfo.htm  ....  http://911research.wtc7.net/wtc/analysis/theories/nuclear.html  ....  http://911research.wtc7.net/wtc/evidence/dust.html  ....  https://e-reports-ext.llnl.gov/pdf/241096.pdf

....  http://www.usgs.gov/blogs/features/2011/09/10/september-11-2001-studying-the-dust-from-the-world-trade-center-collapse/