Modeling and Design of a Sensible Heat Thermal Energy Storage System for Small Modular Reactor

The contribution of intermittent (renewable) energy sources such as wind and solar continues to increase as renewables improve in efficiency and price-point. However, since renewables have grid priority the variability of renewables generates additional challenges for the electric grid in the form of rapidly varying net electric loads.;Proposed options for accommodating this net load have included operating nuclear reactors in a load follow mode, or operating the reactor at or near steady state and bypassing steam directly to the condenser. Both strategies result in lost energy potential. In addition to lost energy potential, load follow operation results in increased stress on the fuel and other mechanical components. A more attractive approach is to operate the reactor at or near steady state and bypass excess steam to a thermal energy storage system. The thermal energy can then be recovered later, either for electric generation during periods of peak electric demand, or for use in ancillary applications such as desalination and chilled water production. Such systems are known as nuclear hybrid energy systems (NHES). Various methods of Thermal Energy Storage (TES) can be coupled to nuclear (or renewable) power sources to help absorb grid instabilities caused by daily electric demand changes and renewable intermittency.;Sensible Heat Thermal Energy Storage is a mature technology currently used in solar energy systems. This research focuses on the design and coupling of such a system to Small Modular Reactors (SMRs), typical of Integral Pressurized Water Reactor (IPWR) designs currently under development.;The goal of the coupled system is to match turbine output with demand, bypass steam to the TES system for storage, and maintain reactor power at approximately 100%. Simulations of the NHES dynamics are run in a high-fidelity FORTRAN model developed at NCSU. Results reveal a sensible heat storage system is capable of meeting turbine demand and maintaining reactor power constant, while providing enough thermal energy to operate the TES system as an electric or steam peaking unit.