Localized vacuum removal of steam generator deposits

Abstract

A method of cleaning sludge from the top of tube sheet ( 34 ′) of a nuclear steam generator ( 10 ) includes introducing a moveable suction apparatus ( 120 ) having attached vacuum inlets ( 148 ), said moveable suction apparatus introduced through handholes ( 62 ) in the side of the generator and into either the no tube lane ( 60 ) or the circumferential annulus, and sludge vacuuming the top of the tube sheet ( 34 ′).

What is claimed is: 
     
         1 . A method of sludge removal from the top tube sheet surface in a tubular steam generator having a plurality of entry handholes allowing access to the no-tube lane and to the circumferential annulus, consisting of:
 1) opening at least one handhole, allowing access to the no-tube lane and/or to the circumferential annulus;   2) introducing at least one moveable sludge suction apparatus within the no-tube lane and/or the circumferential annulus, said apparatus includes a suction head with at least one vacuum inlet; and   3) sludge vacuuming of the top of tube sheet surface with the moveable sludge suction apparatus.   
     
     
         2 . The method of  claim 1 , including inspecting the top of tube the sheet surface by at least one optical scanning device mounted on or in the suction head. 
     
     
         3 . The method of  claim 1 , including lighting the path of the suction head with a lighting device mounted on or in the suction head. 
     
     
         4 . The method of  claim 1 , where a wand connects the suction head to the moveable sludge suction apparatus. 
     
     
         5 . The method of  claim 1 , wherein the moveable sludge suction apparatus is introduced into the no tube lane. 
     
     
         6 . The method of  claim 1 , wherein the moveable sludge suction apparatus is introduced into the circumferential annulus. 
     
     
         7 . The method of  claim 1 , wherein a wand connects the suction head to the moveable sludge suction apparatus, which wand moves the suction head between tubes of the tube bundle. 
     
     
         8 . The method of  claim 1 , wherein the sludge is aqueous sludge wherein the water level is maintained by a separate injector header. 
     
     
         9 . The method of  claim 1 , wherein a pump is used to remove sludge. 
     
     
         10 . A moveable sludge suction apparatus, wherein said apparatus is able to deliver a wand and a suction head assembly into a tube bundle, in a tubular steam generator having a tube sheet, and has optional light and visual means, where the wand connects the suction head to the suction apparatus and the light device acts to inspect sludge removal from the top of the tube sheet.