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Wikipedia: Size of BWRs
A modern BWR fuel assembly comprises 74 to 100 fuel rods, and there are up to approximately 800 assemblies in a reactor core, holding up to approximately 140 tons[vague] of uranium. The number of fuel assemblies in a specific reactor is based on considerations of desired reactor power output, reactor core size and reactor power density.
That's 50 thousand to 80 thousand fuel rods, which means each rod is 2 to 3 tons of uranium. The density of uranium dioxide is about 11 tons per cubic metre.

So, in what may be my last act of "advising", I'll advise you to cut the jargon. -- My old PhD advisor, to me, 26/2/11
by Carrie (migeru at eurotrib dot com) on Thu Mar 17th, 2011 at 03:44:09 PM EST
[ Parent ]
That is confusing, especially in conjunction with the diagrams we have seen. I think we need to implement Migeru's new sig line on this issue. A diagram showing, in turn, a fuel rod, an assembly and a complete core would be helpful.

"It is not necessary to have hope in order to persevere."
by ARGeezer (ARGeezer a in a circle eurotrib daught com) on Thu Mar 17th, 2011 at 04:55:08 PM EST
[ Parent ]
As fas as I can tell:

This is a diagram of a single fuel assembly consisting of 96 rods in 4 bundles of 24 with the corner rod of a 5x5 array missing. The cut in the middle is not really there, it's to show certain internal structures of the arrangement.

The fuel rods are 4m+ long and very thin.

There are hundreds or these hundred-rod assemblies in each reactor core. As you can see the assembly has a hole at the top through which a crane's hook could grab the assembly in order to lift it out of place or lower it down into place.

So, in what may be my last act of "advising", I'll advise you to cut the jargon. -- My old PhD advisor, to me, 26/2/11

by Carrie (migeru at eurotrib dot com) on Thu Mar 17th, 2011 at 05:15:27 PM EST
[ Parent ]
Apparently here they call "rod" what I have been calling an "assembly". In that case the "rod" would actually contain of a hundred cylindrical canisters.

So, in what may be my last act of "advising", I'll advise you to cut the jargon. -- My old PhD advisor, to me, 26/2/11
by Carrie (migeru at eurotrib dot com) on Thu Mar 17th, 2011 at 05:25:35 PM EST
[ Parent ]
Try here. They talk of "pins", "assemblies" and "core".

So, in what may be my last act of "advising", I'll advise you to cut the jargon. -- My old PhD advisor, to me, 26/2/11
by Carrie (migeru at eurotrib dot com) on Thu Mar 17th, 2011 at 05:28:30 PM EST
[ Parent ]
You can see the square assemblages here

Nuclear Wasteland - IEEE Spectrum

BLUE GLOW OF SUCCESS: Fuel assemblies cool in a water pond at the French nuclear complex at La Hague. The blue light is generated by Cherenkov radiation, which arises from a particle's traveling through a medium faster than the speed of light in that medium


Any idiot can face a crisis - it's day to day living that wears you out.
by ceebs (ceebs (at) eurotrib (dot) com) on Thu Mar 17th, 2011 at 05:43:09 PM EST
[ Parent ]
Thanks. I clearly had mistaken an assembly of rods for the core.

"It is not necessary to have hope in order to persevere."
by ARGeezer (ARGeezer a in a circle eurotrib daught com) on Thu Mar 17th, 2011 at 05:48:53 PM EST
[ Parent ]

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