An exergy and a thermoeconomic analyses are carried out to a high temperature gas-cooled reactor (HTGR) direct combined cycle. The thermoeconomic approach used is the H&S Model, which is based on the disaggregation of physical exergy into its enthalpic and entropic terms. This approach allows the isolation of dissipative components of the productive structure, as condensers. The goal is to calculate the irreversibilities of each subsystem and the exergetic unit cost of each internal flow and product of the system.
Results show that the H&S Model yields consistent results, because exergetic unit costs of internal flows are greater than one and product-fuel ratio of each productive unit are less than one. Besides the allocation of external fuels of the plant, i.e., the nuclear fuel and the fossil fuel, it is shown that the H&S Model can be used in order to quantify both internal and external irreversibilities, as well as the conventional exergy analysis, because the differences between the defined fuels and products of each unit or subsystem of the productive structure are equal to the sums of the exergy destruction and exergy loss values of each unit of the physical structure evaluated by the exergy balance.