The U.S. Department of Energy employs approximately 238 nuclear weapons couriers. Their job is to transport either weapons, the critical mass containers, triggers or other major components of nuclear weapons between manufacturing and storage sites.
The sites that are possibly served by these couriers are:
The couriers are actually a convoy of a special tractor-trailer set called a Safe Secure Trailer (SSTs). Each is heavily armored 18 wheelers with special mountings inside for transporting weapons or components. So far, according to the DoE, there has never been a terrorist attack on a nuclear weapons shipment, however the DoE Transportation Safeguards Division trains for that eventuality...with the rather negative but realistic attitude that "it is just a matter of time" before an attempt is made.
With a $100 million budget, the division takes great care that they are both trained and prepared for that first time. The convoys can consist of a couple of dozen members including drivers, back up drivers, and guards. The guards are heavily armed federal law enforcement officers with a classified set of rules for engagement that is centered on keeping the material they transfer in the hands of U.S. federal agents.
Agents have driven nearly 3.5 million miles as of 1996, and have only had a few major roadway accidents despite almost daily use of some 50 tractor-trailer combos.
The tractor is called a Marmon, and includes a spare sleeper and a communications/computer terminal used to keep in contact with their headquarters in Alburqurque, New Mexico. The Safeguard trailer (called an SST for Safe Secure Trailer) is also armored and specially designed to keep the nuclear material and their carrying containers 100% safe even in the worst highway accident.
The agents go through a rigorous 12 week training course at Kirtland Air Force Base. Most agents have a military or law enforcement background and are trained as a tactical security response team, able to repel attackers and protect their cargo.
The convoys have had a small number of vehicular accidents as might be expected over their 25 years of existence. A Department of Transportation study showed that the SST units have a driving record of .066 tow-away accidents per million miles travelled, which is 25 percent lower than any comparable commercial trucking firm in the U.S
Recent information released to the press indicates that there are approximately one to two fender bender type accidents a month, usually occurring when others back into the trailer rig. Only several major accidents have occurred, the author of the article citing some 5 examples of serious accidents (trailer flipped over, went off the road, etc.), with one of these being a drunk walking out in front of a moving rig. In all the cases cited there is only one that may have had severe impact on the cargo, a classified event that occurred in North Dakota on July 25, 1991. All others did not have nuclear material in danger or exposed. Again the DoE says no terrorist attacks have been made on the convoys.
The material hauled can be a nuclear bomb casing which is laden with high explosive (HE) which is dangerous in of itself. Nuclear weapons are never fully assembled until wartime conditions, so there is no chance what-so-ever of a nuclear explosion. Materials such as enriched uranium or plutonium are of themselves highly radioactive substances and are quite dangerous. However, the carrying cases used are quite crushproof and virtually indestructible. These are placed in special "cradles" for stowing in the armored trailer, which has its own crumple zones, etc. to further protect the material. The biggest risk to the public would be the explosion of a bomb casing, while possible, very highly unlikely. The only other risk would be the accidental release of toxic nuclear material such as enriched uranium or plutoniam. This is a very low level risk, however, since the design of containers and transports make it virtually impossible.
According to the Bee article, citing a court case where some information was disclosed, the trailers contain "multiple mechanical, electrical, chemical, and electronics systems to deter penetration, (improper) movement and theft" of material. These same systems are presumed to aid dramatically in the prevention of damage due to collision as well.
According to the Bee article, the following is a sample of some of the accidents that have occurred with the SSTs:
Escort Vans have had their share of accidents as well:
All in all, the traffic record of the Division appears to be quite below what one might expect on the U.S. highways, and clearly the SST's design has proven capable of dealing with their use on public roads.
It might be interesting to hear what occurred in the North Dakota accident, and certainly a brief statement as to what occurred without detail must be possible.