Abstract: During the half side operation of PWR CPR1000 units, the condenser cooling pipes have broken for many times, resulting in serious safety impact and economic loss. Elastic steam flow induced vibration caused by large spacing during half side operation is one of the main possible reasons. The corresponding calculation method is not given in relevant design specifications such as Heat Exchange Institute (HEI). Combined with the basic theory of cooling pipe vibration, the mathematical model used in condenser support plate spacing calculation is deduced, which can be applied to the spacing calculation of condenser half side operation at nuclear power units. Taking a PWR nuclear power project as an example the different condensers cooling pipe evaluation models is verified by using actual working condition data of half side operation in the nuclear power plant. It is proposed that Connors coefficient K_C value is 2.3 and the risk factor is 0.8, which can be applied to the evaluation criteria for condenser safe operation in the nuclear power plant. The minimum condenser spacing is 556mm based on the vibration impact wear theory. The actual amplitude measurement results also confirm that this model is conservative enough, which can be used for design reference verification in condenser spacing design.