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Background Attack Aftermath Evidence Misinformation Analysis Memorial

Nuclear Devices

Theories that Nuclear Weapons Destroyed the Twin Towers

Some have theorized that the demolitions of the Twin Towers were achieved through the use of nuclear or thermonuclear devices. Theories that known variants of such devices were used can be rejected out of hand because the destruction of the Towers was not consistent with the inherent features of known nuclear devices: whereas the Towers were gradually blasted over intervals of about 15 seconds, nuclear detonations are focused in a single point in time. Hence nuclear theorists have suggested that several 'mini-nukes' were used to destroy the Towers in a series of detonations. Such theories are also untenable for reasons described below.

A Litany of Flimsy Claims

Some of the claims that have been used to support the nuclear weapons theory include:

  • Extreme heat in spots deep in the rubble piles
  • Massive subterranean explosions preceding the falls of the Towers
  • Reports that the cell phones of people near the WTC went dead at the commencement of the South Tower collapse, suggesting an electromagnetic pulse (EMP) of the type associated with the detonation of a thermonuclear device
  • Afterglows captured on electronic cameras at the end of each of the Towers' collapses (see videos of the collapses.)

Aside from the first claim, which is ambiguous, none appear to be supported by credible evidence:

  • There are no reports of temperature measurements deep in the rubble pile when Ground Zero was hottest, and high temperatures are consistent with residual heat in the rubble piles from residues or ongoing reactions of energetic materials used to demolish the buildings.
  • The idea that massive subterranean explosions preceded the collapses is based primarily on misinterpretations of seismic data, and is contradicted by the accounts of people on the ground.
  • The cell phone outages story may be an urban myth, perhaps based on reports of communications disruptions from the loss of the North Tower's rooftop antennas.
  • Videos do not consistently show the alleged afterglows, which could simply be an artifact of camera aperture adjustments.

Claims About Radioactive Fallout

Any use of nuclear devices would have produced vast amounts radioactive fallout detectable even at great distances from Lower Manhattan. No such contamination has been found. Nonetheless, advocates of the nuclear weapons theory claim that scientific reports examining the chemical composition of World Trade Center remains and dust support their theory. Two such claims concern the detection of tritium and uranium.

Tritium

Tritium is a radioactive isotope of hydrogen in which the nucleus contains one proton and two neutrons. Nuclear fusion produces large amounts of tritium.

Although tritium is formed naturally through the interaction of cosmic rays with the atmosphere, it does not accumulate because of its short half-life of 12.3 years. Because its decay products cause phosphors to glow, tritium is used in self-illuminating devices found in watches, exit signs, and gun sights.

Proponents of the WTC nuclear weapons theory have cited the following passage, which reports the detection of tritiated water around the WTC, as evidence for their theory.

The quantities reported are extremely small, and, as the same report states, their likely source was tritium radioluminescent devices in the World Trade Center.

Uranium

Uranium is a naturally-occurring element (atomic number 92) used to fuel nuclear reactors and manufacture plutonium (atomic number 94) for nuclear weapons. Uranium has several different isotopes, which are radioactive to different extents.

Proponents of the WTC nuclear weapons theory have cited the following passage from a scientific study of dust and smoke emanating from Ground Zero as evidence for their theory.

Radionuclides. We analyzed the gamma spectrum of the samples using an EG&G/Ortec high-purity Ge detector (50% relative efficiency) gamma counter (EG&G/Ortec Instruments, Inc., Oak Ridge, TN). We analyzed approximately 50 peaks based on statistical significance (counting/lack of interferences). These included thorium, uranium, actinium series, and primordial radionuclides. Liquid scintillation analyses were conducted for emissions on the total dust and smoke samples using a Packard Tri-Carb Model 2770 TR/SL (Packard Instrument, Meriden, CT). The MDA [mimimum detectable activity] for alpha radioactivity was 0.30 DPM (0.14 pCi) based on a NIST-traceable 226Ra standard (National Institute of Standards and Technology, Gaithersburg, MD). When placed in the liquid scintillation fluid, the WTC samples are somewhat darker than the backgrounds and calibration standard, which may cause slight underreporting of the beta activity due to quenching and standard-to-sample efficiency bias. 2
[NOTE: MDA means minimum detectable activity, and DPM means decays per minute.]

The passage indicates that the radioactivity of the WTC samples was only slightly above background levels, which is not surprising, given that small quantities of radionuclides are used in applications likely present in the Towers.

Steven Jones tested a solidified metal sample for radioactivity and found no radioactivity above background levels.


References

1. Study of Traces of Tritium at the World Trade Center, llnl.gov, 10/1/02
2. Characterization of the Dust/Smoke Aerosol that Settled East of the World Trade Center (WTC) in Lower Manhattan after the Collapse of the WTC 11 September 2001, ehponline.org,

page last modified: 2009-09-11