Seismic considerations in the evaluation of temporary loads

Temporary loads in nuclear power facilities can result from a number of activities including special one time operating conditions, repair and upgrade conditions, and ALARA requirements for operation, inspection and maintenance. Many times evaluation of these loadings includes their consideration in conjunction with other design basis loadings such as normal loads and extreme event loads including earthquake loadings. At times this combination with design basis extreme loads, such as earthquake, results in predicted structural demands which exceed the design basis capacity. Many times a major contributor to this demand prediction is the earthquake loadings. Discussed in this paper are analytical methods, probabilistic considerations, and earthquake experienced based evaluations which can be applied to reduce the earthquake demand for short term temporary loadings