Can you speed up radioactive decay of plutonium? We all know the issue of deep geological repositories for fuel rods. Is there a currently feasible way to speed up the rod's decay to render them harmless in less than 10 years?
 A: You can trigger decay of certain nuclei with gamma rays, just like you can stimulate emission of photons from excited atoms with incoming radiation. You can even make a bomb if that is your kind of thing. On the other hand, in case of atoms there is a stimulated emission - with help of photons coherent with the "future" photon. This shows that the "environment" is somewhat important. As soon as the environment is complicated and is hard to control, one can loosely think that the random character of decays is due to random character of the "triggering QM environment".
UPDATE: I forgot to mention that decay probability can be increased, for example via collision with another particle for the right energy, and this is exactly how fission based nuclear bombs work. Here though, again, there is nothing special about the particular atom decaying, and it is simply the particles involved in the collision that have the increased decay probability. (I must admit that I have pared this picture right down to the basics as otherwise it would need to be a far more technical discussion).
A: Yes there is a way to speed up nuclear decay rates.
The ionisation state of the specie has some effect on the decay rate.
http://link.aps.org/doi/10.1103/PhysRevLett.77.5190
Also neutrino flux has some effect.
http://arxiv.org/abs/physics/0412007
These conditions are perhaps insignificant for your fuel rods but 
they certainly worth considering.
A: The simple answer is no, though as usual in Physics things are a bit more complicated than that.
There are several ways in which radionucleotides decay: alpha decay, beta decay, gamma decay, and fission. These are all mediated by the weak and strong nuclear forces, though the electromagnetic force plays some part in alpha decay and nuclear fission. There is no way we know of to tamper with the two nuclear forces. In principle we could change electromagnetic forces by using a sufficiently strong electric field, but the field strength required would be ludicrously high and far outside anything we could conceivably generate.
In principle we can affect the decay of nuclei by firing particles at them. For example uranium can be made to fission by firing neutrons at it (which is exactly what happens in nuclear reactors). In general this is not a practical way to process nuclear waste, though in the specific case of plutonium you can fission plutonium in nuclear reactors (though the products of the fission are still radioactive). Currently the cost of treating radioactive waste in this way would be prohibitive.
A: No.
When it comes to radioactive decay, one unstable nucleus explodes to stable ones this moment. And, an another fully identical nucleus wait for thousands years to explode. This is a great example of principle of uncertainty. We don't know exactly why it happens. We only have observed data of their chances to explode (That's why we talk in probability of decay of large number of nuclei). It happens because of no reason. We don't have full understanding of quantum world yet, so we can't find a way to control it while keeping the solution in "natural way" domain.

A way to process nuclear waste quickly is to do it with non-natural way (the way nuclear bombs etc work), but that would be costly and the process is not environment friendly.
However, research on cheap environment-friendly nuclear waste processing is on its way. If it has been successful, we'll listen about it.
