Conversion of Ford nuclear reactor shim-safety rod magnets from subsurface to above surface

The conversion from subsurface to above-surface shim-safety rod magnets was implemented for several reasons: (1) improved reliability when compared to subsurface magnets; (2) reduction in radiation exposure during repair to the activated subsurface magnets and associated magnet contact switches; (3) reduction in radiation exposure during shim-safety rod inspections; (4) reduction in radiation exposure by having a single top for control rod elements that enables them to be used under rods and in other core locations; and (5) absorption of the impact of scrammed shim-safety rods in the rod holddown device rather than the control fuel element, reducing the possibility of element damage.