The finite-element model we propose to analyze the dynamics of accidental drop loads on critical buried structures during steam generator replacement includes representation of drop objects, impacted structures, soil media through which stress waves travel, and buried structures. Analysis accounts for the nonlinear effects of large deformation, steel plasticity and buckling, concrete cracking and crushing , and stress wave damping through soil. Stress and strain in buried structures is used to evaluate the condition of buried structures such as buried prestressed concrete and ductile iron pipelines and reinforced concrete structures housing critical components subjected to accidental drop loads during steam generator replacement near nuclear reactors operations.

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