Abstract: Shielding and exhaust covers are disclosed herein which are mountable on the primary manways of a nuclear steam generator for protecting maintenance personnel from potentially harmful radiation during maintenance operations. Each of these doors includes mounting flanges which are detachably mountable to the manway flange. These mounting flanges include brackets for mounting a jewel rail track assembly which in turn slidably mounts two opposing quarter circle panels which, when slid together, form a semicircular shielding cover. The shielding and exhaust covers of the invention may be easily mounted over their respective manways by a single person, and may be opened or closed by a single person standing to the side of the manway and hence out of the radiation shine eminating therefrom. Finally, the shielding material contained in each of the covers is hermetically sealed within stainless sheet metal, which renders it mechanically strong and easily decontaminated.