Previous studies on the waste glass crystallization and its effect on the virtrigfication of high-level nuclear wastes stored at Hanford site, USA are reviewed. Crystalline phases that can precipitate at TV>105$0^{circ}C$ and thus can cause processing problems in the 115$0^{circ}C$melter were identifiesd as spinel types [Ni, F $e^{2+}$)(F $e^{3+}$, Cr)$_{2}$ $O_{4}$] and zirconinum containing phases (ZrSi$P_4$, sodium-zirconium silicate, etc). The liquidus temperature of ohter crystalline phases observed, such as clinopytoxenes, orthopyroxenes, olivine, nepheline, etc. were lower than 105$0^{circ}C$. Crystallization during cooling of glass in canister can decrease the chemical durability and make the glass unacceptable for final disposal in a geologic repository. Strong decrease of chemical durability was observed in glasses that precipitated nepheline, lithium-aluminum silicate, and crystalline Si $O_2$after heat treatment following the simulated canister centerline cooling.g.