Generation IV nuclear reactors will not be implemented unless they enable lower production costs than with the current systems. In such a context, considering only technical issues such as the performances of the plant is not entirely satisfactory since maximizing the system efficiency does not guarantee a minimum cost. Consequently, a technoeconomic optimization method was developed and then applied to the power conversion system of a very high temperature reactor.

Technoeconomic optimization consists in minimizing an objective function that depends on technical and economic variables. The advantage of the technoeconomic optimization compared to classical optimizations based on the efficiency is that it can take into account both investment costs and operating costs.

A technoeconomic model was implemented in a specific optimization software named Vizir, which is based on genetic algorithms. The calculation of the thermodynamic cycle is performed by a software named Tugaz.

The results are the values of the decision variables that lead to a minimum cost, according to the model. The total production cost is evaluated. The consequences of different modifications of the model are discussed.