Which continuous-loop system utilizes a slender inconel tube packed with thermally sensitive eutectic salt?

The continuous-loop fire detection system that utilizes a slender inconel tube packed with thermally sensitive eutectic salt is known as the Fenwal system. This type of system works by monitoring changes in temperature that can indicate the presence of a fire. The inconel tube is specially designed to be heat-sensitive, with the eutectic salt inside melting at a specific temperature. When a fire occurs, and the temperature rises to the melting point of the salt, the system triggers an alarm, indicating that a fire may be present.

This mechanism is crucial since it allows for reliable and early detection of fire, providing an important safety measure in powerplants. The continuous-loop design ensures that the system can monitor a large area without the need for multiple individual sensors, making it efficient and effective in fire detection. Other systems listed do not employ this specific method of using a eutectic salt in an inconel tube, thus distinguishing Fenwal as the correct choice.