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The characteristic growth phenomena require an asymmetric material response and a way to retain irreversible change. Low crystal symmetry and directional defect or deformation behaviour make uranium and zirconium important examples, whereas an ideal cubic material has isotropic linear thermal expansion and no symmetry-selected traceless single-crystal growth tensor in an otherwise isotropic environment.

alpha uranium is orthorhombic and has strongly anisotropic thermal response. In a textured polycrystalline material, incompatible crystal grain strains can be accommodated asymmetrically over a thermal cycle and leave macroscopic distortion. The same metal can also show irradiation growth through anisotropic irradiation-defect evolution. zirconium and its hexagonal close-packed alloys are major examples of irradiation growth; their basal and c-axis directions need not acquire the same strain.

Cubic austenitic steel does not exhibit the same intrinsic orientation-driven response merely because it is irradiated. It can nevertheless undergo void swelling, irradiation creep, thermal-stress plasticity or distortion under gradients. Thus absence of this growth mechanism does not imply dimensional stability under all reactor conditions. Conversely, a noncubic crystal is not guaranteed to grow during every thermal cycle: constraints, inelastic accommodation and the microstructure still matter.