If you had a half life of 5 minutes you'd only need to store the waste for a couple hours before burying it somewhere and there's a certain (smallish) amount of

If you had a half life of 5 minutes you'd only need to store the waste for a couple hours before burying it somewhere and there's a certain (smallish) amount of high-grade waste at any given moment, no matter how long you run the reactor. 10 years isn't 5 minutes, but it means you just need to keep it secure for a few decades before burying and forgetting it rather than many human lifetimes. Any leaks will be (to some extent) self-cleaning, insofar as they'll decay substantially within a human lifetime, so if you stop the leak you can wait a couple decades and it will have cleaned itself up. That's much better than the long-life stuff fission produces.