Development of Indigenous Instrument for Visual Inspection of Reactor Internals

Pre-commissioning and periodic in-service visual inspection of reactor vessel internals, of Prototype Fast Breeder Reactor (PFBR), is a mandatory regulatory requirement. An Indigenous Instrument (Periscope) is designed for this purpose. The instrument is accommodated within a tube of 400 mm outer diameter and has a length of 10 meters. The single tube contains viewing, illumination and the associated auxiliary systems. The Periscope is a sealed system and operates in Argon environment saturated with sodium aerosol at temperature of 150 Celsius and radiation field of 1.3R/hr. The Periscope has facility for focusing of image, scanning in vertical plane, image rotation and zooming to the area of interest. The Periscope can also be rotated around its axis through 360 degree for complete coverage of the reactor internals. Optical Relay lens based system is used to transfer the image from the objective prism to the eye piece. All the motions are motorized using high temperature stepping motors and position sensors. An additional viewing port is also provided for photography and video recording. The illumination level of 2500 Lux at 4 meter distance from Periscope, required for inspection is provided by combination of two lamps. Compact, short arc Ceramic Xenon lamps with integral reflector are used for the illuminator. Both the lamps are provided with motorized beam deflecting arrangement. The lamps are force cooled by Argon. An elaborate cooling arrangement is designed for this purpose. The Periscope is provided with PLC based controls. The control systems provide interface for operation of the periscope systems, display of status information and monitoring of the operation interlocks. The Periscope is designed for its designated handling and maintenance requirements that may arise during its life time. The Periscope is designed for operating life of 40 years, during which it is to be used for 20 planned inspections. Another 15 unplanned and exceptional operations are also envisaged. The paper presented here highlights the design aspects of the various sub-systems of the Periscope.