Squeezing Water from a Stone: Why Thermal Storage Does Not Remove the Mismatch Between Nuclear Plants and Solar-Heavy Grids

A 2026 study proposes to make a nuclear plant dispatchable by inserting a thermal energy storage unit between the reactor and the turbine. The reactor keeps running at constant power, surplus heat is stored in a tank of molten salt, and in the evening the turbine draws both the reactor heat and the stored reserve. This paper examines what the proposal changes and what it leaves in place. The plant produces no additional energy: the same kilowatt-hours are moved to a different hour. The turbine must be larger than the reactor, so the storage unit is in effect a second plant built around the first, and its cost falls on the buyer of the electricity. The problem it addresses is created by uncontrollable generation on the same grid, and each layer added to solve it requires another layer. We contrast this path with ARBOK LONGBATTERY (ALB), a modular source that delivers as much energy as the market requests and therefore needs no storage to level its output. Keywords: nuclear power; thermal energy storage; molten salt reactors; grid flexibility; ARBOK LONGBATTERY