Explanation:

Potential energy of a system is the stored energy
associated with the configuration of the system.
Electrical energy of a system is also stored energy in the form of electrostatic potential energy. Similarly, chemical energy is stored in the form of chemical potential. Potential energy associated with the chemical bonds.
But nuclear energy is obtained by breaking a heavy nucleus into light nucleus of comparable masses. It can also be obtained by the formation of a heavy nucleus due to fusion of two light nuclei. Therefore, it is not a form of stored energy.