There are eight major property changes that may occur in irradiated materials due to a variety of micro­structural changes. Listed in order of increasing temper­ature where the effects are typically dominant, these
phenomena are radiation-induced amorphization, radi­ation hardening (often accompanied by loss of tensile elongation and reduction in fracture toughness), decrease in thermal and electrical conductivity, mechanical property or corrosion degradation due to radiation-induced segregation and precipitation, dimensional instabilities due to three distinct phenom­ena (anisotropic irradiation growth, irradiation creep, void swelling), and high temperature embrittlement of grain boundaries due to helium accumulation. The microstructural origins associated with these eight deg­radation processes are summarized in the following sections, and more detailed descriptions ofthe property degradations in metals and nonmetals are given in accompanying chapters in this Comprehensive. The radiation doses at which these phenomena emerge to become of practical engineering significance are gener­ally dependent on irradiation temperature, PKA energy, and material.