The power increase in the nuclear power plants has been investigated for the safety aspect. Most equipment could be affected by the power uprate, which could increase the electricity power level. The quantification of the uprate reliability is performed by the system dynamics method, which is processed by the feedback and accumulation algorithms. The Vensim software package is used for the simulations, which is made by the Monte Carlo method. There are two kinds of considerations as the economic and safety properties. The result shows the stability of the operations when the power can be decided. This shows the higher efficiency of the reactor. The maximum value of risk is 157,887 in 2065 and the minimum value is 2 in 2010. Thus, the risk of the power uprate increases 78,954 times higher than the initial value in this study.