Title:
NUCLEAR FUEL AGGREGATE
Document Type and Number:
Japanese Patent JPS63121787
Kind Code:
A
Abstract:
A device for relieving thermally induced stresses developed in a nuclear fuel assembly during reactor heatup is disclosed herein. The device generally comprises a stress relieving fastener capable of connecting a fuel assembly top nozzle, which may be stainless steel, to a threaded stud, which may be Zircaloy. The stud is attached to a fuel assembly channel. The fastener includes a threaded nut having a deformable portion for relieving thermally induced stresses developed in the stud by the differential thermal expansion of the top nozzle and stud. In a first embodiment of the nut, the deformable portion comprises a circumferential, deformable ridge which is substantially recessed from the marginal edge of the nut and which is disposed on the bottom most surface of the nut. The ridge contacts the top nozzle when the nut threadedly engages the stud. A second embodiment of the nut is similar to the first embodiment except that the deformable ridge is disposed flush with the marginal edge of the nut. The deformable portion in the second embodiment may also include a circumferential, deformable first groove which is formed in the lower portion of the nut. In addition, the second embodiment may include a deformable second groove formed in the bottom most surface of the nut. During reactor heatup, thermally induced stresses may develop in the stud. The deformable portion of the nut deforms, thereby relieving the thermally induced stresses.
Inventors:
CHIYAN KII RUI
RENAADO TOOMASU JIESHINSUKII
RENAADO TOOMASU JIESHINSUKII
Application Number:
JP27363887A
Publication Date:
May 25, 1988
Filing Date:
October 30, 1987
Export Citation:
Assignee:
WESTINGHOUSE ELECTRIC CORP
International Classes:
G21C3/324; G21C3/30; (IPC1-7): G21C3/30
Attorney, Agent or Firm:
Mitsuteru Soga (3 outside)