In this paper, according to the discussion of improving the safety of nuclear power plants (NPPs) according to reports and findings of Fukushima accident, a model for the economic analysis of a NPP with a higher level of safety in an electricity power market is provided. Therefore, a solution to determine the balance between safety and economy to deal with station black-out (SBO) accident in a pressurized water reactor (PWR) nuclear power plant is presented. A supply function equilibrium (SFE) that takes into account carbon tax in the power market is used to calculate the profit of each power generation firm. A hierarchical innovative approach is used to make decisions about improving the safety of NPP. In this method, breakeven point (BEP) is used as the decision criterion to compare the safety improvement costs and profit of NPP in the power market. This method is used to add an emergency diesel generator (EDG) and a mobile heat exchanger to a NPP that examines the impact of investment costs and profits. The result shows that with the addition of an EDG to the NPP, the BEP of investment costs and net profit of the NPP is one month later. Finally, it can be suggested to the investor of the NPP to add EDG to improve safety, so that the implementation of this proposal leads to a slight increase in payback period, but greatly reduces core damage frequency (CDF) of NPP reactor in SBO accident. Manuscript profile