Experimental methods for detecting types of motion within and surrounding reactor cores were employed, including the dominating influence of noise analysis techniques and the associated theoretical bases underlying these methods. Out of extensive tabulations of demonstrated applications, particular attention was given to specific methods for measuring core barrel motions, in-core instrument vibrations, steam void velocity, fuel motions, and control rod vibrations. Selected features of types of in-vessel motion monitoring programs found in commercial power reactors were noted along with their motivations. Advantages and disadvantages can be cited for specific techniques.