System-driven design of flexible nuclear power plant configurations with thermal energy storage

Abstract

Nuclear power plants are expected to make an important contribution to the decarbonisation of electricity supply, together with variable renewable generation. Previous work by the authors identified significant potential benefits of coupling nuclear reactors with thermal energy storage (TES) and secondary power generation cycle systems to improve the plant operational flexibility. This paper presents a system modelling approach to identifying configurations of flexible nuclear plants that minimise the investment and operation cost in a decarbonised energy system, effectively proposing a system-driven design of flexible nuclear technology. Case studies presented in the paper explore the impact of system features on plant configuration choices. The results suggest that cost-efficient flexible nuclear configurations should adapt to the system they are located in. In the main low-carbon and net-zero carbon scenarios and for a standard-size nuclear unit, it was found to be cost-efficient to install around 500 MWel of secondary generation capacity and 4.5 GWhth of TES capacity, resulting in an equivalent TES duration of 2.2 hours. Enhancing the nuclear plant flexibility was found to be less attractive when applied to a large number of nuclear units or when exposed to high interest rates, but more attractive if battery storage cost was higher or there was no option to invest in carbon offsetting technologies. Net system benefits per unit of flexible nuclear generation for the main scenarios were quantified at £29-33m/yr for a wind-dominated system and £19-20m/yr for a solar-dominated system.