METHOD FOR REMOVING DEFECTIVE SPENT FUEL ASSEMBLIES Russian patent published in 2000 - IPC

FIELD: nuclear power engineering. SUBSTANCE: method for removing spent fuel assemblies from floating depot storage tank involves removal of safety plugs from filler holes of storage tank turning plate; while the latter is turned, open filler hole is brought in alignment with boxes accommodating fuel assemblies. Boxes proper are mounted in tube plate of tank via through bushings whose flanges are welded to tube plate and to boxes. Boxes holding defective fuel assemblies are detected and removed through filler hole. To this end, annular drilling is made in tube plate and in bushing flange around box through mentioned hole; inner diameter of drilling should be slightly greater than outer diameter of bushing and its depth is to be greater than welding penetration in tube plate. Then box is gripped through auxiliary slots on its top and extracted together with spent fuel assembly and bushing. Procedure does not require removal of turning plate and removal of defective fuel assembly held in box without disturbing its integrity. EFFECT: reduced emission of radioactive products into environment. 4 dwg