POTRBLOG ALERTS us to this NRC detection. http://pissinontheroses.blogspot.com/2012/08/maximum-alert-cesium-137-detected-in.html
Watch their video at the link.
Potrblog suspects that the cesium fallout detected on the truck is from precipitation that came from the jet stream. The NRC claims the truck was not contaminated from the source.
Potrblog has reported high readings recently and their analysis suggests that the jet stream is the source (with radiation ultimately originating from Fukushima) (http://majiasblog.blogspot.com/2012/08/fukushima-emissions-august-2012.html
There is no way of proving without testing where the contamination originated from, but I do recommend watching the video:
Here is a summary of Potrblog's video analyzing the NRC detection:http://pissinontheroses.blogspot.com/2012/08/maximum-alert-cesium-137-detected-in.html
[exerpted] 30,000 DPM of Cesium-137 were detected on a 100 square centimeter surface of a dry casket tractor trailer rig in Pennsylvania; NRC Event Number: 48178. This detection was of REMOVABLE Cs-137, meaning that weathering would have removed the contamination after some time period.
We suspect that the rig was contaminated by the Jet Stream borne rain storm which blew through the Pa area around approximately August 5th. Our own readings have detected significantly elevated levels of airborne and surface radioactive contamination in the past free weeks. See the video above for full details on the Cs-137 detection.
NRC LINK OF THE DETECTION
NRC Event Text: DRY FUEL STORAGE TRANSFER TRAILER DETECTED WITH REMOVABLE CONTAMINATION
[Excerpted] "On Aug 7, 2012 at 1734 EDT, PPL Susquehanna personnel were in the process of releasing the Dry Fuel Storage Transfer Trailer from the Unit 1 Reactor Building 101 rail bay and detected removable contamination on the trailer.
"PPL Susquehanna Health Physics personnel identified removable surface contamination up to 30,000 dpm/100 sq cm on the transfer trailer. Gamma spectroscopy performed on smears identified the presence of Cs-137. No other radionuclides were identified on any of the analyzed smears. Cs-137, by itself, is not a nuclide characteristic to Susquehanna due to Susquehanna's high fuel integrity performance. In addition, no loose surface alpha contamination was identified.
"The area around the trailer, located in the 101 bay, has been posted and controlled as a contaminated area. Decontamination of the transfer trailer is in progress. Onsite surveys of areas that were occupied by the transfer trailer, indicate no removable surface contamination. In addition, no Susquehanna personnel contamination events have been attributed to the contamination found on the transfer trailer.
"Although the receipt of this transfer trailer was not identified as an incoming radioactive shipment to Susquehanna from its' supplier, this event is immediately reportable to the NRC Operations Center in accordance with 10 CFR 20.1906(d), since the Department of Transportation acceptance limits identified in 49 CFR 173.433 for this type of container are 22,000 DPM/100 sq. cm and PPL Health Physics personnel identified removable radioactive surface contamination in excess of the limits of 10 CFR 71.87(i) which refer to the DOT limits of 49 CFR 173.433.
"The final delivery carrier and NRC Senior Resident Inspector have been notified." The licensee will be notifying the Commonwealth of Pennsylvania.