It is buried while it runs. At end-of-life, you dig it up and properly dispose of it (whatever that process may be).
And what "end of life"? Fuel will be exhausted in 3-5 years max. And I very much don't want disposable nuclear reactors. Modern PWRs are designed to last for 50 years and can probably last for 100.
TerraPower wanted to build "nuclear candle" reactors that can last for 50 years without refueling, but they had an inconvenient problem of requiring unobtanium for the reactor vessel walls (a material that can sustain 400-500 dpa, while the best steels can maybe push 150). "DPA" is "displacements per atom".