Atomic battery - beta or alpha radioactivity based

I wonder if there would be a safe way to use all of the spent fuel from Nuclear Power plants?

Nuclear industry will always generate different kind of radioactive waste as other industries do but at very low level if planned properly. Radioactivity is easily detacted using sensitive instruments. Dispersion in air for short lived isotopes is very common. One can also monitor on ground the level is finally reaching. Stacks are very high to 300m and people monitor the dispersion all the time. Some amount may also go into water. The remaining amount is condensed and encapsulated for medical use if that is worth using that way and the rest is put to rest in special containers. Almost every bit is useful. Only strong neutrons sources are not given out for public as they may activate other elements and will make them also radioactive. Other sources are harmful only when handled improperly. Accounting of radioactive sources is is a very difficult task and is done in India by BARC. I was one of them long ago.

Out of millions of sources out in the use we find only once a white some problem and we act on that very fast. It is easy to locate hidden source by aerial survey helicopter and ground survey subsequently. This is like a police job.