Heat-Only Small Modular Reactors Vs. Nuclear Combined Heat and Electricity: Concepts and Economics

Abstract

There is a growing interest in the heat-only small modular reactor concept for clean, efficient, and economic district heating applications. On the other side, there is an argument that upgrading the existing nuclear power plants (NPPs) to a combined heat and electricity generation (CHP) mode could be a competitive option. Upgrading NPPs to CHP generation requires several pieces of equipment, such as heat exchangers and often a long-distance heat transportation pipeline. Furthermore, the maximum electrical power generation capacity is decreased when the power plant is operated in CHP mode. While the capital cost of heat-only SMR could be higher, the optimum siting could reduce the heat transportation construction and operation cost, and the integration with secondary thermally driven applications could significantly improve the overall economics of the system. In order to compare the feasibility of these two scenarios, considering a typical heat-demand profile, the design and operation of both systems are optimized, and their economics are compared based on several sensitivity analyses. Based on findings, nuclear heating scenarios (CHP or heat-only SMR) are much superior to gas-based DHSs, even when heat transportation over long distances up to 100 km is required. Compared to CHP, the results are promising for the expansion of heat-only SMRs for district heating applications in a wide range of cases. The loss of electricity due to the reduction of electricity generation efficiency represents the critical drawback factor of CHP-based district heating. At the same time, the advantage of flexible siting of heat-only SMRs, as close as possible to heat demand, could result in a considerably lower heat-transportation cost and levelized cost of heat. For example, the installation of Teplator heat-only SMR modules at a distance of 20 km from demand is found to be more economical than upgrading an NPP (located 40 km than the heat demand) to CHP when the average market electricity is higher than (55 €/MWeh).