The electricity market is changing with decreasing markets for base-load electricity. Changes in nuclear power plants are required to match changes in markets. Nuclear energy produces heat that is then converted to electricity. Heat storage is cheaper than electricity storage (batteries, pumped storage, etc.). There is the option to incorporate heat storage into the power plant design to enable variable electricity output to maximize revenue while operating the reactor at base load to minimize costs.

We examine options for heat storage coupled to reactors with sodium or salt in the secondary heat transfer loop. The three classes of storage technologies are described: bulk hot salt or sodium storage, sensible heat storage (steel or other solid), and latent heat storage with another material.

Heat storage can enable the power plant to operate as a battery or pumped hydro station. At times of low electricity prices there is the option to divert heat from the reactor to heat storage while operating the power turbine at minimum load. Keeping the turbine on line allows rapid return to full electricity output to meet demand during high prices. The low-value electricity from the plant and added low-value electricity from the grid can be used to electrically resistance heat the heat storage media. When electricity prices increase, heat from the reactor and storage goes to the turbine for peak electricity production to maximize revenue.