in core monitor housings a vibration sensor is attached to an inside diameter of a cylindrical housing a signal cable is coupled to the vibration sensor and extends into an exterior of the reactor pressure vessel a protective assembly minimizes the damage inflicted on the signal cables during handling the signal cables are helically wound in an annular space between a pair of concentric thin walled tubes and then passed through cable penetration bores formed in the body of a flange insert the flange insert supports the concentric tube assembly and is sandwiched between the housing flange and the in core monitor instrument flange of a conventional in core monitor assembly application_number US 22774794 A description the present invention is a method and a device for facilitating installation and removal of instrumentation and associated equipment for monitoring flow induced vibrations in an in core monitor housing of a boiling water reactor bwr during reactor operation the fluid flow in a boiling water reactor will be generally described with reference to fig1 feedwater is admitted into a reactor pressure vessel rpv 10 via a feedwater inlet 12 and a feedwater sparger 14 which is a ring shaped pipe having suitable apertures for circumferentially distributing the feedwater inside the rpv a core spray inlet 11 supplies water to a core spray sparger 15 via core spray line 13 the feedwater from feedwater sparger 14.