Flexible nuclear co-generation plant combined with district heating and a large-scale heat storage

The paper presents a concept of flexible nuclear co-generation. A plant operating according to the concept can vary its production of heat and electricity by utilising steam on different pressure levels. It is also connected to a district heating system and utilises a large-scale heat storage. France has set long-term targets to increase the share of solar and wind power in the power mix, consequently reducing the share of nuclear power. The flexible co-generation can help the nuclear fleet cope with this change while potentially reducing emissions from the heating sector. High utilisation rate, efficiency and more stable reactor output is targeted. The concept is studied with an optimisation model within the French operational environmental in three case studies of Paris, Lyon and Dunkirk. Total efficiencies of 70%, 54% and 34% are reached, respectively. Cases represent systems with different heat loads and distances from nearby DH systems. Result indicate that both operational flexibility and large-scale storages are heavily utilised. However, compared to the flexibility required by a high-renewable power system, the plants can only play a small part. Also, the current district heating systems need development to utilise a large-scale heat source such as nuclear co-generation.