Why are nuclear-powered ballistic-missile submarines difficult for enemies to locate?

Nuclear-powered ballistic-missile submarines are difficult to locate primarily because they are designed to operate continuously while submerged, eliminating the need to expose themselves on the surface. Their stealth is maintained through extensive silencing measures, which are critical because modern detection relies heavily on passive sonar to identify noises emanating from a vessel.123

To minimize their acoustic signature, engineers have implemented several design strategies:
* Machinery Isolation: Critical components, such as reactor coolant pumps, have been redesigned to be quieter, and machinery is often mounted on sound-absorbing supports to prevent vibrations from reaching the hull.23
* Hull Coatings: Submarines are frequently coated with specialized sound-absorbing materials that reduce the effectiveness of detection and homing torpedoes.23
* Natural Circulation: There is a design preference for natural-circulation power plants, which reduce the reliance on noisy mechanical pumps.23

These efforts are essential because, while nuclear power allows for effectively unlimited range, any increase in speed or mechanical output can generate noise, making the submarine easier for an enemy to detect.45