Joining techniques for core flow test loop fuel rod simulators

Journal Article · Fri Jan 01 04:00:00 EST 1982 · Nucl. Technol.; (United States)

OSTI ID:6768171

Moorhead, A J; McCulloch, R W

Laser welding and furnace brazing techniques have been developed to join subassemblies for fuel rod simulators (FRSs) that have survived up to 1000-h steady-state operation at 700 to 1100/sup 0/C cladding temperatures and over 5000 thermal transients, ranging from 10 to 50/sup 0/C/s. A pulsed-laser welding procedure uses small diameter filler wire to join one end of a resistance heating element to a tubular conductor. The other end of the heating element is laser welded to an end plug, which in turn is welded to a central conductor. Before these welding operations, the intermediate material conductors (either tubular or rod) are vacuum brazed to matching copper leads. On room temperature tensile testing, 10 of 11 brazements between copper and nickel rods failed in the copper rather than the brazement. The thin walls and ductility of the copper and nickel tubular conductors caused joint machining and fitup problems. Accordingly, it has not been possible to consistently produce tensile test samples of brazed dissimilar metal tubular conductors that will fail outside the joint area. A unique tubular electrode carrier has also been developed for gas tungsten arc welding FRSs to the tubesheet of a test assembly. Two seven-rod mockups of the simulator-to-tubesheet joint area were welded and successfully cycled 500 times from 370/sup 0/C (698/sup 0/F) down to 100/sup 0/C (212/sup 0/F) with an internal pressure of 11.72 MPa (1700 psi). No leakage was detected by helium mass spectrometry, either before or after testing. Modified versions of the electrode carrier were developed for brazing electrical leads to the upper ends of the FRSs. Satisfactory brazes have been made on both single-rod mockups and arrays of simulators.

• Research Organization: Oak Ridge National Laboratory Metals and Ceramics Division, Oak Ridge, Tennessee 37830
• OSTI ID: 6768171
• Journal Information: Nucl. Technol.; (United States), Journal Name: Nucl. Technol.; (United States) Vol. 56:1; ISSN NUTYB
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
220300* -- Nuclear Reactor Technology-- Fuel Elements
ANALOG SYSTEMS
ARC WELDING
BRAZING
COPPER
DUCTILITY
ELECTRIC CONDUCTORS
ELECTRIC HEATING
ELEMENTS
FABRICATION
FAILURES
FLUIDS
FUEL ASSEMBLIES
FUEL CANS
FUEL ELEMENTS
FUEL RODS
FUNCTIONAL MODELS
GAS TUNGSTEN-ARC WELDING
GASES
HEATING
HELIUM
HIGH TEMPERATURE
JOINING
LASER WELDING
LEAK TESTING
MASS SPECTROSCOPY
MATERIALS TESTING
MECHANICAL PROPERTIES
MECHANICAL TESTS
METALS
NICKEL
NONMETALS
RARE GASES
REACTOR COMPONENTS
RESISTANCE HEATING
SIMULATORS
SPECTROSCOPY
TENSILE PROPERTIES
TESTING
THERMAL CYCLING
TRANSITION ELEMENTS
TUBES
VERY HIGH TEMPERATURE
WELDING