Re: remembering SP nuclear shipments-They only let me handle bombs and missiles...
Belch, OK here you go: one day after the Chernobyl disaster, I was called off the W.O. extrabord for a cab hop to go to Flosden on the line to Vallejo, which was the interchange point between the Navy's Mare Island freight line and the SP (still is, although the line to Vallejo has been out of service for at least 10 years).
There were, just as others have mentioned, several cars: some which I don't recall the puproses (probably an idlers because the flask on its flat car is a shifable load), the flask on its car, and a caboose. The flask contained the spent fuel elements; the caboose carried armed guards (guessing here, but I suspect they were Marines, because I've seen them performing similar duties before, at the Concord Weapons Station.
I had to be accompanied by the RFE (whether this was Company policy or a AEC requirement, I don't know). The RFE granted me special permission to take the engine (an 8400 -- SD40) down the branch to Flosden because it was "overweight". We picked up the cars at Flosden (the Navy engine didn't appear until we got there), and took them to Davis, where a Sac crew (with Sac RFE) took the train north.
We never saw hide nor hair of the guards, which should NOT be taken to mean they weren't there. The US has never shipped this sort of stuff without an armed escort (except perhaps in the early years of the Manhattan Project).
As for the integrity of the flask on the flatcar, see: [www.youtube.com
] . True, this is British, but the US has similar types of flasks.