The given diagram provides information about the process uranium undergoes so as to be used to produce nuclear power. Overall, it involves 5 fundamental steps, from its collection to the burying of residual matter that cannot be re-used.
To begin with, uranium must be extracted from the earth. Subsequently, in the second passage, its ore is transformed and enriched to obtain U-235 fuel pellets, that are in turn sent to the specific power generators to produce electric energy, in the third stage. However, it is only 4 years later that the product can be utilized and eventually taken away, as a fourth phase.
At this point, there are two possible final outcomes: should the fuel be eligible for this purpose, it is sent back to power generators to provide new energy. Conversely, should this not be the case, the produced energetic material is stored in containers that are ultimately buried.