All salt piping and vessels must be heated to prepare for salt filling and to keep the salt molten when there is no nuclear power. The pipes and components of the two salt systems were heated electrically. In the much larger and more compactwith its three salt systems and numerous heat exchangers the reactor and heat exchanger compartments are heated by circulating the compartment atmosphere, which is nitrogen, over electrical heaters. Circulation is by three large blowers discharging gas at 566 0C into the reactor compartment which has outlets to the heat exchanger compartments and the drain tank compartments.
    The warship design follows  heating philosophy and one of the main challenges facing the naval architect is to incorporate into the hull design the interconnected compartments containing the reactor plant and auxiliary systems which require a large temperature range: from an operating temperature of 538 0C down to ambient conditions, when access by remote operated tooling is required for maintenance. The compartment boundaries incorporate thermal insulation, radiation shielding and external cooling.