Patent Number: 
Section: claims

1. A control rod drive mechanism comprising:a shaft elongated along an axis and comprising engagement recesses formed along the axis on a circumference thereof;a supporting member defining an elongated channel for receiving the shaft, the supporting member comprising a latch opening therethrough;a latch assembly comprising a latch mechanism and a latch operably connected to the latch mechanism, the latch mechanism disposed outside the shaft in a radial direction from the axis, the latch comprising a latch tip extending into the elongated channel via the latch opening and configured to latch the shaft by engagement with one of the engagement recesses;a latch housing located outside the supporting member in the radial direction and housing the latch mechanism, wherein the latch housing comprises a latch housing wall disposed outside the latch assembly in the radial direction; anda plurality of coil housings disposed outside the latch assembly in the radial direction, each coil housing comprising an inner wall facing the shaft, the inner wall comprising a non-magnetic wall portion and a magnetic wall portion, wherein the plurality of coil housings are arranged along the axis together with the latch housing wall such that the inner walls of the plurality of coil housings and the latch housing wall together provide non-magnetic wall portions and magnetic wall portions that are alternatingly arranged along the axis while facing the shaft. 2. The control rod drive mechanism of claim 1, wherein each of the coil housings comprises an outer wall connected to the inner wall and facing away from the inner wall. 3. The control rod drive mechanism of claim 2, wherein non-magnetic wall portion of each coil housing overlaps a corresponding coil when viewed in a viewing direction perpendicular to the axis. 4. A control rod drive mechanism comprising:a shaft elongated along an axis and comprising engagement recesses formed along the axis on a circumference thereof;a latch assembly comprising a latch mechanism and a latch operably connected to the latch mechanism, the latch mechanism disposed outside the shaft in a radial direction from the axis, the latch comprising a latch tip extending toward the shaft and configured to latch the shaft by engagement with one of the engagement recesses;a latch housing located outside the latch mechanism in the radial direction and housing the latch mechanism, wherein the latch housing comprises non-magnetic wall portions and magnetic wall portions that are alternatingly arranged along the axis while facing the shaft; anda plurality of coil housings located outside the latch housing in the radial direction and arranged along the axis.