'86 
And you?
Class 8501.
Protype at S1C 
8604, D1G
I am curious how many other readers are familiar with what we are talking about.
Navy Nuc Power School?
Tris
Hey, take a look:
Natural U-235 reactor in ancient streambed
http://www.alamut.com/proj/98/nuclearGarden/bookTexts/Lovelock_Oklo.html
Comparison of Oklo natural reactor to modern versions
http://www.physics.isu.edu/radinf/oklo.htm
Oklo fossil reactor FAQ
http://www.curtin.edu.au/curtin/centre/waisrc/OKLO/index.shtml
D1G Ball! 
Naval Nuclear Propulsion School. Orlando, Florida (then).
Prototype Reactors are for hands-on training, to turn the theory into knowledge (and weed out the people who were book-smart, practice-dumb).
S1C == Submarine Reactor, 1st Combustion Engineering design.
D1G == Destroyer (Cruiser) Reactor, 1st General Electric design
Is that windsor plant still there? I went in 75.
Here’s an online nuclear reactor simulator; can YOU prevent the meltdown?
8002, S1C
8807 S5G (at least… I THINK it was 8807… been so long)
and an ELT at that…
ELT as well
9202, S1C
I was in the next-to-last class to go through Windsor (or 2nd-to-last class - can’t remember for sure, but I know it was shut down in '93). I heard from one of the instructors that came to my ship after shutdown that when they did radiographic testing on the pipes, about the only thing holding Main Steam 1 together was the lagging 
critter42
Oh, forgot to add - wire-biter here
critter42
Apologies for resurrecting an old thread, but I just wanted to say that I had no idea there were so many ex-Navy nukes around here.
–robby (9107, D1G)
The Canadian-designed reactor (CANDU) is able to run on unenriched uranium. Is this a big advantage? If these are such a good idea, why isn’t this design more common?
Also, the gas-cooled reactors (they use helium or carbon dioxide as the coolant)-are these better than PW reactors?
Finally-can a reactor be built that is totally foolproof? I mean-it would shut itself down automatically, without human intervention, in the event of a coolant leak, etc.?
How odd! I get to talk about decay heat in two different threads on the same day…
Of course, there can never be a foolproof anything.
That said, in most cases, reactors will shut themselves down when anything untoward happens (e.g. loss of coolent flow).
The main problem, as I see it, is that even though the rods are at the bottom of the core, you aren’t out of the woods yet. Most of the random fission products created by fission are unstable and begin to decay as soon as they are formed. This decay process generates copious amounts of heat that must be removed from the core, for obvious reasons. The decay heat is generally a substantial fraction of the power level prior to shutting down.
Consequently, whenever you shut down a reactor, normally or unexpectedly, you must still provide coolant flow to remove this decay heat.
There are, of course, systems and backups of systems for providing this cooling in emergency situations, but the fact remains: some means of cooling must be present for a certain amount of time after shutdown. If all backup systems are hosed, the reactor will get really hot.
>> It is the job of the moderator to slow down neutrons
That might explain why the moderators are required to wear those tinfoil hats
CANDU reactors do in fact run on un-enriched uranium, but require heavy water (D[sub]2[/sub]O, with the deuterium isotype of hydrogen). IIRC, it’s a toss-up as to which is more expensive to produce, enriched uranium or heavy water, although I have to go with D[sub]2[/sub]O as the less dangerous of the two.
Atomic Energy of Canada, Limited (AECL) lists ten operational CANDU 6 units (plus one under construction). In all, they list eleven locations around the world with CANDU reactors.
LOL! That does explain a lot!
Actually, I’m posting to add in a small detail that seems to have escaped being mentioned in the above discussion: To achieve chain-reaction fission, whether in a reactor or a bomb, you require to have a concentration of a fissionable isotope. (While any isotope other than protium (H-1) can be fissioned, “fissionable isotope” here is a term of art, describing an isotope that naturally undergoes fission at an appreciable rate in the presence of neutrons.)
Only one isotope exists in nature in any reasonable quantity which meets this description: Uranium-235. And in nature, it’s diluted in U-238 to approximately a 1:114 ratio. However, at least two other isotopes can be easily created from relatively common nuclides of elements: U-233, from Th-232, and Pu-239, from U-238 – the latter of which you have on hand in quantity from concentrating the U-235 to a pile-worthy degree. (I think U-234 is also fissionable, but it’s an order of magnitude rarer than U-235, which is itself less than 1% of natural uranium.) There are also numerous fissionable transuranic nuclides, but the only one I know of with any practical use is Americium, I believe isotope 241 – which could be used to make very small nuclear weapons and “portable” piles.