Element immersed in coolant of nuclear reactor
This paper describes the method of processing a coolant-displacement rod of a nuclear reactor, preparatory to the installation of the rod in the nuclear reactor, to preclude the formation undesirably of an unsupported permanent axial gap in the cladding of the rod over the anticipated time of use of the rod in the nuclear reactor by reason of neutron bombardment of the rod. The gap would be collapsible under the force exerted by the coolant of the nuclear reactor, the rod including a stack of zirconium-oxide pellets in cladding of an alloy of zirconium, the inner surface of the cladding prior to the processing being spaced from the outer surfaces of the pellets. It comprises: mounting the rod in a container and evacuating the container from atmospheric pressure to a pressure such that the rod is in an attenuated atmosphere containing residual oxygen not combined chemically with any other chemical element. Thereafter it conducts electrical current only through the cladding to heat the cladding to a temperature at which the yield strength of the cladding is substantially reduced and, while the rod is maintained at the temperature adding a gas to apply pressure uniformly to the cladding of a magnitude sufficient at the temperature to collapse the cladding uniformly on the outer surface of the pellets of the stack while the rod maintains its radial symmetry. The outer surface of the cladding is oxidized at the temperature by the residual oxygen, the the processing, precluding the formation, by exposure to neutron flux, over the period of time over which the rod will later be in use in a reactor, of an unsupported axial gap in the cladding which would collapse under the pressure and at the temperature, of the coolant of the nuclear reactor.
- Assignee:
- Westinghouse Electric Corp., Pittsburgh, PA (USA)
- Patent Number(s):
- US 4938918; A
- Application Number:
- PPN: US s 7-405597
- OSTI ID:
- 6547340
- Country of Publication:
- United States
- Language:
- English
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Element immersed in coolant of nuclear reactor
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Related Subjects
220300* -- Nuclear Reactor Technology-- Fuel Elements
CHALCOGENIDES
CLADDING
COOLANTS
DEPOSITION
FUEL ELEMENTS
FUEL PELLETS
FUEL RODS
OXIDES
OXYGEN COMPOUNDS
PELLETS
REACTOR COMPONENTS
SURFACE COATING
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES