At one time it was thought that the deep-ocean trenches at subduction zones would be a good place for disposal of high-level radioactive waste. Why is this not a good idea? Explain what can happen at a subduction zone and what might occur if the waste were buried there. (Hint: see oceanic-continental convergence)
Disposing radioactive waste at deep-ocean trenches should not be done. The subduction is very slow. The fastest subduction zone is only 25 centimeters a year. Even if future generations left the waste alone, the seawater and seafloor will corrode and be breached. Further, the logistics and the costs of transporting and disposing of thousands of barrels each year ...
This posting gives you a step-by-step explanation of the problems of disposing radioactive waste in deep sea trenches. The response also contains the sources used.