METHOD OF AND DEVICE FOR FILLING FUEL ELEMENTS WITH GAS Russian patent published in 1996 - IPC

FIELD: manufacture of fuel elements, fuel rods with burnable absorbers, etc. SUBSTANCE: through microchamber with evacuation and gas-filling systems is placed directly under welding head. Microchamber case has upper hinged cover with end seal secured under welding head. Microchamber case is provided with inner separate side channels for evacuation and filling it with gas. Bottom part of microchamber houses shell with hold-down ring accommodating flexible sealing member of crimping type. Device has also fuel element vertical displacement assembly placed coaxially in respect to microchamber. Method for filling fuel elements with gas followed by their sealing involves placing fuel element with preinstalled end cap having axial hole inside microchamber, evacuating inner space of fuel element through axial hole in end cap, filling fuel element with gas under pressure higher than that required inside fuel element after sealing; after fuel element is filled with gas, it is transferred to welding head and cladding is welded with end cap simultaneously withe sealing this hole to form single weld. Desired gage pressure Pgage and time of fuel element transfer to welding head τ_tr are interrelated by equation Pgage = A.τ_tr, where A = (0.08-0.12).10⁵ Pa/s. EFFECT: improved reliability of fuel element sealing upon filling it with gas. 7 cl, 2 dwg