This paper present basic nuclear reactor physics that may help to understand next challenges that nuclear industry have to face in the future. The ones considered in this work are waste production and natural resources consumption. This paper shows that waste and resources are linked by the plutonium status that could be considered as the principal waste or a valuable material that should be saved for a future transition to breeder reactors that could be for instance Sodium-cooled Fast Reactors (SFRs). This kind of reactors does not rely on natural resource supply, as it produces its own fissile material, plutonium-239, after a neutron capture on uranium-238. However, the operation of SFRs needs a huge amount of plutonium that should be produced in current Pressurized Water Reactors (PWRs). Natural uranium available on earth is expected to allow the operation of the global current fleet until approximately 2100 without major issues. The transition from PWRs to SFRs is then needed if and only if the nuclear industry will face an increase at a global scale during this century. If not, plutonium, the most radiotoxic element produced in PWRs, should be considered as a waste. Consequently, the plutonium status depends on the future evolution of nuclear energy. This paper shows that a status-quo means that plutonium should be considered as the most problematic element that should be handled on a long-term basis. On the other hand, a strong increase in nuclear energy on a global scale would imply that plutonium is a valuable material that would make a transition to SFRs possible.