> By 2005, according a Department of Energy report (.pdf), the U.S. government owned 87 pounds, of which roughly two-thirds was designated for national security projects, likely to power deep-sea espionage hardware...
how about the U.S. government does less deep-sea espionage-- in the name of deep-space science?
It's much cheaper to explore the ocean than it is to explore space, and many benefits like: OTEC (http://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion http://cleantechnica.com/2013/05/05/lockheed-martin-to-build...), mining ( http://en.wikipedia.org/wiki/Deep_sea_mining), etc.
Others agree:
http://www.forbes.com/sites/quora/2013/01/31/why-dont-we-spe...
http://www.cnn.com/2012/04/09/opinion/etzioni-space-oceans/i...
But, I personally think we should be exploring space and our oceans. We need to make it a top priority of all countries to fund energy and propulsion research to help make exploration cheaper. That means allocating adequate budget and raising taxes for something that the mass media and our government doesn't seem to give much of a shit about, because they don't understand the part of the world we currently are utilizing is running out of resources quickly and that we are constantly a stone's throw from mass extinction.
The plutonium is for RTGs on benthic listening buoys, which are moored deep in the water column, or anchored directly to the sea floor. They have very sensitive hydrophones, and powerful burst ELF transmitters. This allows triangulation of targets.
They're made of steel and are never intended to be recovered - so we can look forward to plutonium salts in the oceans.
That said the argument I heard was that by the time they fall apart, the Pu has all but decayed.
Also, if we found Apollo 13 we could recover some Pu238:
http://science.slashdot.org/story/11/11/28/1637231/will-nasa...
http://unexplainedthings.tumblr.com/post/13563685365/will-na...