

How do you dismantle a nuclear submarine? - otoolep
http://www.bbc.com/future/story/20150330-where-nuclear-subs-go-to-die

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brandmeyer
The defueling process is pretty slick. On a 688-class submarine, they remove a
semi-cylindrical section of the hull around the reactor compartment (RC)
before landing a temporary building on the RC.

One tricky bit is the fact that the spent fuel is so radioactive that it still
makes a significant amount of heat. The thermal power is low enough that
sinking it away from the fuel isn't difficult, but if such measures were not
in place, the fuel would heat up until (redacted) Something Bad Happens. So
every step along the way has either timing and/or heat sinking requirements
involved.

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burger_moon
When I was in the Navy I was stationed at Puget Sound and got to watch the
yard workers dismantle a submarine. Every day I would walk past the dry dock
on my way to my ship and check out the progress. It's pretty cool seeing a sub
in dry dock getting cut apart section by section.

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MichaelCrawford
My father was a civil service EE at mare island naval shipyard in vallejo, on
north-east san francisco bay. He told me that when they drain the reactor
cooling water, there is a flange where they cut the hole in the hull, with a
pipe running to there to a cement mixer. They make concrete out of the
radioactive water, then haul the concrete and the mixer to hanford, to bury
it.

But one time they neglected to bolt the flange together. When they pumped out
the water, it poured down on a shipyard worker who was standing on the floor
of the drydock.

While he was not injured, he exceeded his lifetime maximum dose of radiation.
At the time Dad told me this story, the guy still worked at Mare Island but
was no longer permitted in the nuclear yard.

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brandmeyer
Normal reactor coolant isn't nearly that radioactive. However, there is a
continuous filtration system that gets flushed from time to time, and it is
extremely nasty stuff. Its possible that the yard worker was actually doused
with filter media.

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mpyne
I actually don't think it's possible. If I remember my OPWACHEM course
correctly, if the media you're thinking of did wash onto the yard worker he'd
have been severely injured by radiation exposure, and not just quickly bumped
up to his maximum lifetime allowable exposure. It is indeed extremely nasty
stuff.

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brandmeyer
Spent fuel will be dangerous on time scales much greater than recorded
history. However, the old reactor compartments primary source of radioactivity
is Cobalt-60, with a half-life of about 5 years. So on time scales on the
order of our national history, we should be able to recycle them.

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caf
In case anyone is wondering, the Cobalt-60 is produced from Iron by multiple
neutron capture and beta decay, in particular Iron-58.

~~~
brandmeyer
Also Cobalt-59, which is a commonly used hardening agent in ferrous alloys. In
the old days, valve seat wear products were a strong source of radioactive
cobalt.

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Evolved
Would a solar furnace be hot enough to incinerate the nuclear waste so that it
is much safer to dispose of?

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WalterBright
Should store it at the south pole. It's inaccessible to anyone that is not
very well-financed, the cold will slow down decomposition of the containers,
anything liquid will freeze and stay put.

Any leaks will also be thousands of miles from anything important.

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fiatmoney
One big problem is that the longer the transit, the greater the window of
vulnerability. That and mutated super-penguins.

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WalterBright
I thought the penguins only hung out on the coast. Antarctica is, after all, a
continent, and a big one.

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Roboprog
Well, they did, but during the winter months they like to warm their flippers
around the rosy glow of this new place :-)

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WalterBright
I'd be impressed if they were willing to leave their food supply and waddle a
thousand miles to get there.

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CamperBob2
They can call the screenplay _2101: A Penguin Odyssey._ Humans have nuked
themselves into oblivion, making room at the top of the intellectual food
chain. Then, the first few penguins stumble upon the abandoned waste site...

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TazeTSchnitzel
If only it were cheaper to send things into space. It'd be nice if we could
blast spent nuclear fuel into the sun.

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sampo
Earth's orbital velocity is 29.78 km/s, and the escape velocity from the Solar
System, at Earth's distance, is 42.1 km/s.

Of you want to get rid of something, it would be energy-wise cheaper to shoot
it out of the solar system, than to slow it down completely so that it would
drop into the Sun.

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ghshephard
If you shoot it out of the solar system though, then you are littering the
region outside our solar system with nuclear waste that future generations
might stumble across as they start exploring the galaxy.

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nitrogen
Space is a pretty big place.

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ghshephard
It's pretty big _inside_ the solar system - I can't even begin to imagine how
large a space nuclear fuel capsule shot on a solar-system escape velocity
would have to itself.

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MichaelCrawford
Carefully.

