This
study was presented in April 2002, at the American Chemical Society National Meeting, by a group of scientists from the New York State Department of Health; School of Public Health, University at Albany, State University of New York, Albany; Fission Energy and Systems Safety Program, Lawrence Livermore National Laboratory, Livermore, Nuclear Science Division, E.O. Lawrence Berkeley National Laboratory; Tritium Engineering Department, Westinghouse Savannah River Company; Physical Biosciences Division, E.O. Lawrence Berkeley National Laboratory.
The first or lead author (Thomas M. Semkow) is from the New York State Department of Health. He traditionally would be the one who started the project and did a lot of the work. The senior author (Philip G. Williams) is from Lawrence Berkeley National Laboratory, and he would be the one who oversaw the whole work.
Now all they really did in this study was to measure tritium levels in a few samples from Ground Zero and around Manhattan, which is pretty trivial. I can do this in my lab. It's not clear why they needed the heavy hitters at Lawrence Livermore for this work, and it is not clear who did what in this study. Certainly the New York State guys would be the ones who got the samples and did the preliminary tests.
One key question is, why did they do this study in the first place? They say "We became interested in the subject of tritium at WTC because of the possibility that tritium RL (radioluminescent) devices could have been present and destroyed at WTC."
This rationale seems kind of dubious to me. In the short months after 9/11, I doubt checking tritium levels released from radioluminescent signs and rifle scopes is a big priority. In general, tritium is not a big health concern, the radiation from tritium is very low beta energy (tritium is a radioactive isotope of hydrogen). So, I have to wonder if the scientists were looking for tritium for another reason. For instance, tritium is used in and is produced as a by-product from nuclear fusion.
Or perhaps, the local guys were curious if radiation was released at Ground Zero because of the intense nature of what happened on 9/11, then they found tritium, made some calls, and the Lawrence Livermore guys hooked up with them to try to manage their findings.
Here is the abstract for the study, which basically says they found tritium around ground zero at levels that were far above the local background:
Traces of tritiated water (HTO) were detected at the World Trade Center (WTC) ground zero after the 9/11/01 terrorist attack. A water sample from the WTC sewer, collected on 9/13/01, contained 0.164±0.074 (2 σ) nCi/L of HTO. A split water sample, collected on 9/21/01 from the basement of WTC Building 6, contained 3.53±0.17 and 2.83±0.15 nCi/L, respectively. These results are well below the levels of concern to human exposure. Several water and vegetation samples were analyzed from sites outside ground zero, located in Manhattan, Brooklyn, Queens, and the Kensico and Croton Reservoirs. No HTO above the background was found in those samples. Tritium radioluminescent (RL) devices were investigated as possible sources of the traces of tritium at ground zero. It was determined that the two Boeing 767 aircraft that hit the Twin Towers contained a combined 34 Ci of tritium at the time of impact in their emergency exit signs. There is also evidence that many weapons from law enforcement were present and destroyed at WTC. Such weaponry contains by design tritium sights. The fate and removal of tritium from ground zero were investigated, taking into consideration tritium chemistry and water flow originating from the fire fighting, rain, as well as leaks from the Hudson River and broken mains. A box model was developed to describe the above scenario. The model is consistent with instantaneous oxidation of the airplane tritium in the jet-fuel explosion, deposition of a small fraction of HTO at ground zero, and water-flow controlled removal of HTO from the debris. The model also suggests that tritium from the weapons would be released and oxidized to HTO at a much slower rate in the lingering fires at ground zero.
What they don't put in their abstract is their actual conclusions that
the tritium found at ground zero can't be accounted for by known sources:
34 Ci of tritium were released from the emergency tritium RL signs onboard the two Boeing 767s, on impact with the Twin Towers at the WTC. The measurements and modeling are consistent with a prompt creation of HTO in the jet-fuel explosion and fire deposition of a small fraction of HTO at ground zero, and water-flow controlled removal from the site. The modeling implies that the contribution from the aircraft alone would yield the HTO deposition fraction of 2.5%. This value is too high by a comparison with other incidents involving fire and tritium. Therefore, the source term from the airplanes alone is too small to explain the measured concentrations, and another missing source is needed. There is evidence that weapons belonging to federal and law-enforcement agencies were present and destroyed at the WTC. Such weapons contain tritium sights by design. The exact activity of tritium from the weapons was not determined. The data and modeling are consistent with the tritium source from the weapon sights (plus possibly tritium watches) in the debris, from which tritium was slowly released in the lingering fires, followed by an oxidation and removal with the water flow. Our modeling suggests that such a scenario would require a minimum of 120 equipped weapons destroyed and a quantitative capturing of tritium, which is too high, since many weapons were found with only minor damage and tritium sights are shielded in a metal. Therefore, such a mechanism alone is not sufficient to account for the measured HTO concentrations. This indicates that the weapons/watches are consistent with the missing source, which would have complemented the airplane source.
Some important points about this study--
1) they analyzed tritiated water (T2O), not tritium gas (T2). Tritium gas is the main component used in RL. T2 is converted to T2O at a very low rate. They did factor this into their study, but we have to assume their calculations are correct about how much T2O to expect.
2) they did NOT check tritium levels in the actual ground zero debris, and certainly not in the main debris pile for WTC1 and 2, where the most tritium would have been deposited either by plane or by mini-hydrogen bomb. They merely checked tritium in ground zero sewer water-- and this is after millions of gallons of water have been sprayed on the debris pile!
3) even if we assume Boeing 767's crashed into the WTC (which I don't think is what happened), the vast majority of RL tritium would end up vaporized out into the atmosphere and a fraction would remain in the building. Much of this remaining material would get aerosolized again as the buildings went down-- and then only a very small fraction of this tritium would get converted into water, and only a very small fraction of this would be detected in the sewer after ground zero was hosed down. Granted, they only found a very very small fraction of what was allegedly in the exit signs in the aircraft, nonehteless, the amount recovered is higher than even THEY predicted, and so they resort to the idea that a great many RL watches were destroyed in the WTC-- a somewhat dubious proposition.
4) the highest levels of tritium they observed were found in water from the basement of WTC6. This is where some debris from WTC1 fell, and could be the source for the tritium. The idea that weapons and watches in WTC1 and WTC6 accounted for the tritium in the basement of WTC6 seems a bit far-fetched to me.
5) if no Boeing 767's crashed into the WTC, they have ABSOLUTELY NO good excuse for the levels of tritium seen at ground zero-- so again, a key question is WHAT HIT THE WTC?
6) tritium is a signature of nuclear fusion (it is commonly used in fusion devices), and thus we have some evidence that small fusion (hydrogen) bombs were used at the WTC. Again, nuclear fusion leaves far fewer radioactive traces compared to fission, and so tritium would be one of the main markers for fusion one could check for.
