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Blue Fuel Cells

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sefrick:
Good Stuff!!

I'm glad to see so many people jumped on this thread. When I decommed Sand Lance our spent fuel cells went straight from the grappling mechanism into a train car that was basically just a drum filled with water with fins to dissapate heat. I'm sure that there was plenty of lead shielding in that car as well. I have no idea where they were shipped to. This was at the Puget Sound shipyard.

Does anyone have any idea what a realistic contact rad level (or how far away the 1mR/hr line would be from an exposed rod) would be on a typicall S5W spent fuel rod. I'm pretty sure that our fuel rods are wayyyy more enriched than the cells in commercial plants. Just curious.

Already Gone:
It's hard to say.  Navy fuel is enriched at least 30 times as much as commercial fuel, but it contains far, far less fuel in total.  The majority of material in Navy fuel is the cladding and other non-fuel components, while commercial fuel is mostly uranium inside cladding tubes.  Even though most of that Uranium isn't 235, it is still active.
Commercial fuel also "burns" a lot more than Navy fuel.  Consider that it is at full power almost constantly.  The fission product buildup is huge.  Full power is a lot more in a commercial reactor than in a Navy reactor.  A 500MWe commercial plant (about the smallest there is) is the equivalent of around 1750 MW thermal.
Commercial fuel is also much, much bigger.  A bundle is ablout 12 feet long, with an active fuel area of 8 to 10 feet.  It is also subjected to a much greater neutron flux.

Depending on the size, power history, and time since removal of a particular bundle, commercial fuel ranges from 500,000 to a couple of million Rem per hour on contact.  The highest actual meter reading I have ever gotten on a bundle in the transfer tube is 200 Rem/hr, but that was a very thin beam shining through a gap in the shielding from several feet away.
The highest contact reading I ever got on a Navy reactor was maybe 50 Mr/hr on contact with the Rx head at about 10,000 EFPH.
Anybody else have any good numbers?

Phurst:
Good place for nuke info http://www.nucleartourist.com/

RDTroja:
I stuck an RO-7 underwater probe into the Cherenkov glow from a freshly removed bundle and got a reading of just over 400,000 R/hr (I cannot vouch for the calibration of the probe, but it was still very impressive) around 6 inches from contact with the bundle -- under water, of course. Beer Court had the numbers about right -- it varies from half a million R/hr to about 4 Million R/hr estimated dose.

It is estimated that if you put a fresh bundle (right out of the core after its effective lifespan) on the 50 yard line of a football field and you came out from behind a 'perfect' shield at the goal line and ran toward the bundle as fast as you could, you would be dead by the time you hit the 30 yard line. If you drove past the bundle on a motorcycle at 60 mph you would not reach the opposite goal line alive. No volunteers for the test run as yet.

As for the fuel storage issue, several plants have built dry storage facilities (Calvert Cliffs has one that is fairly large) and some plants have toyed with storing other plants' fuel, but I think so far no one is doing it. Imagine how entertaining it would be in the room with the corporate lawyers when that subject comes up...

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