Radiation Warning Sign

 "Reason obeys itself; and ignorance submits to whatever is dictated to it." - Thomas Paine

 Decades ago - in the mid 1980's, I was stationed aboard a nuclear fast attack submarine named USS Barb.  One day I fished a very battered, but cool sign out of a trash can.  It was a radiation warning sign that had been posted in the torpedo room - the one I salvaged from the trash had been replaced by a new sign that was not damaged.

You might be asking yourself why the torpedo room had a radiation sign, when the nuclear propulsion system was way in the back of the ship... After all, this wasn't a Ballistic Missile Submarine.  The reason for radiation warning signage in the torpedo room (which also served as a berthing area) was the SUBROC weapon.   

The UUM-44 SUBROC was a submarine-launched rocket-propelled nuclear depth charge.  It carried a W55 fusion warhead with a yield of 250 kilotons TNT equivalent - which is a bit excessive to my mind.  This was a tritium boosted thermonuclear weapon utilizing a Plutonium 239 pit, with Lithium Hydride fuel to support the fusion reaction.  The Plutonium pit would have had traces of the contaminant Plutonium 240.  Plutonium 240 decays by spontaneous fission, so the warhead would emit a fair bit of neutron and gamma radiation.  Thus the need for a radiation warning sign.

Here's the thing about that weapon:  There is only so much rocket propellant you can stuff into a 21 inch torpedo tube, so it's not possible to launch the weapon very far.  The destructive radius of the nuke weapon was wide enough that it was very dangerous even to the ship firing it.  So the firing sequence was to shoot the SUBROC from a shallow depth to reduce compression stress on the hull, then turn 180 and go flank speed to get some extra distance before it arrived at the target and detonated.

Below:  The SUBROC launch sequence.  The weapon is ejected from the torpedo tube with several Gs of acceleration, which clears it from the ship and also triggers a switch to ignite the rocket motor.  The rocket breaks the surface of the water, flies toward the target, and the warhead detaches.  Warhead follows a ballistic trajectory to the target, and can either be detonated in an airburst mode, or via hydrostatic pressure switch as a depth charge.

Below: Casing of the SUBROC weapon at left, and rocket, right.

I'm always reminded of Professor Fate's rocket sled from the movie "The Great Race" - maybe one idea begat the other...

Before my time, the Navy submarine service had also fielded the MK 45 ASTOR nuclear torpedo.  The yield on the MK 45 warhead was only 11 kilotons, so this was not such a hazard to the ship sending it away.  Those torpedoes were no longer in use by the time I was aboard the ship.  Below: MK 45 ASTOR

Legal Boilerplate:  I can neither confirm nor deny the presence of nuclear weapons on board the ship - just that it was capable of carrying them and firing them.   

Back to my radiation sign though.  I've not been able to locate the box that the sign was packed away in, so many years ago.  There was some irreplaceable stuff in there too (grade school and navy class photos), so I'd like to find it again.  The sign however, I was able to replicate - minus the dings and scrapes.

I had intended to hang the old sign to a wall in the shop somewhere, but this new one will work for now!