In response to the severe reactor accident at the Fukushima Dai-ichi site, many plants in the US have decided to perform Seismic Probabilistic Risk Assessment (SPRA) or update the existing models. As part of SPRA, it is required to compute the in-structure response in order to analyze the vulnerability of equipment at different locations in the plant. Most plants in the US constructed Lumped Mass Stick Models (LMSM) for their design-basis dynamic analysis, but these models are ineffective in capturing local response. On the other hand, Finite Element Models (FEM) can provide more accurate estimation of the local response, but assembling FEM's are resource intensive. Besides that, the data required to develop these models are hard to assimilate for the older nuclear power plant structures. This paper summarizes a set of techniques and procedures that were developed by the authors to use the existing LMSM in making FEM, that captures the behavior of the as-built structure by taking advantage of available resources and previous LMSM's.
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