While the desert dump/evolution in action approach may seem
appealing to some, recent experience in the Bay Area suggests
that any metal of any possible value - the fence, signs, and any
reclaimable parts of the waste - drums or other containers, any
iron, steel, copper, brass, etc. - would quickly be collected and
recycled.
Recall an incident from the 1980s where widespread
contamination was revealed only by happenstance -
a wrong turn during a delivery of rebar at Los Alamos:
If you did want to dispose of waste by attaching it to subducting plate you would probably need to drill down through any sediments as these tend to get scraped off by the non-subducting plate to form an accretionary prism:
I remember when I first read this that I was struck not by the silliness, but by the way in which a variety of issues with "cash" were affected by the properties of the cash itself. (I particularly liked the bank robber coming into the bank in a lead suit) but noted the bank couldn't keep all that money in one place anyway.
For a second I thought this proposal was brilliant:
Drop the radioactive wastes, in canisters, in to the seabed folds where the continental plates are sliding under each other. The radioactives would disappear back into the magma from which they came.
Until I realized, this radioactive stuff would get vaporized and eventually escape in to atmosphere and ocean. Wouldn't that be much worse than getting spilled on land?
* You underestimate the size of the Earth or overestimate the amount of the waste or the effects of radiation. Most of the nuclear waste could be just ground to dust and spread into oceans and the atmosphere, were it not a political suicide. The high-activity waste that's a real problem, on the other hand, decays into virtual inertness in a few decades.
* The lithospheric magma is not hot enough to vaporize or even liquify solid capsules of nuclear waste. Even the magma itself isn't liquid, just ductile solid.
* We're talking about subduction zones where the underlying magma conveyor belt is going down. It isn't going to return any time soon, giving plenty of time for the actually dangerous high-activity stuff to decay.
Actually, that could provide really valuable scientific data.
Refine the nuclear waste to separate out the different radioactive elements and isotopes. Drop a distinct cocktail (of short-lived and long-lived isotopes, not reusing any isotopes between cocktails) into each crevice. Measure subsequent outflow from around the world, looking for traces of the cocktails.
This could provide a lot of interesting data on the speed at which materials are recycled, how liquid the upper layers of the crust are (are any of the materials returned, or do they just sink towards the center?), what directions the under-plate currents flow in, how much mixing is going on, et cetera et cetera et cetera.
Hell, we need to begin injecting nuclear waste into the sea bed.
Recall an incident from the 1980s where widespread contamination was revealed only by happenstance - a wrong turn during a delivery of rebar at Los Alamos:
https://en.wikipedia.org/wiki/List_of_civilian_radiation_acc...
http://www.orau.org/ptp/collection/accidents/juarez.htm