Brittle fracture evaluation is important for type B(U) packagings carrying fissile materials in conformity with IAEA Regulations. Packaging materials susceptible to brittle fracture can be evaluated by Linear Elastic Fracture Mechanics (LEFM) or other credible methods as shown in IAEA TECDOC 717. Major similarities and differences between the packagings and reactor pressure vessels are here compared in terms of the brittle fracture evaluation. Examples of brittle fracture evaluations of 100 ton class ductile cast iron (DCI) packaging (casks) under hypothetical accident conditions are discussed. (author).