FABRICATION OF THE MOLTEN-SALT REACTOR EXPERIMENT HEAT EXCHANGER CORE INVOLVES A NOVEL WELDED AND BACK-BRAZED JOINT DESIGN FOR TUBE-TO-TUBE SHEET JOINTS

Journal Article · Sat Feb 01 00:00:00 EST 1964 · Welding J. (N.Y.)

OSTI ID:4083229

Donnelly, R G; Slaughter, G M

The INOR-8 tube bundle of the primary heat exchanger of the Molten-Salt Reactor Experiment contains 163 1/2 in. dia x 0.042 in. wall U-tubes welded to a 1 1/2 in. thick tube sheet 18 in. in dia. Procedures were successfully developed for welding and back brazing the 326 closely spaced tube-to-tube sheet joints in the unit, and the actual tube bundle was fabricated without incident. The welded and back-brazed design provides a double seal between the fuel and coolant salts and was used because of the necessity for high joint integrity. Trepan grooves were machined in the weld side of the tube sheet so that lowrestraint edge-type welds could be made. This technique greatly reduces the cracking problems associated with welding thin-walled tubes to thick tube sheets. Welding and assembly procedures were developed, which provided welds of high quality with a minimung of roll-over. The 82 Au--18 Ni (wt. %) brazing alloy used is corrosion resistant, ductile, and produces joints exhibiting satisfactory mechanical strength. A unique joint design incorporating a trepan groove and feeder holes was used for the braze side, the purpose being to prevent preferential flow of alloy on the relatively thin-walled tubes. After the determination of exact welding and brazing conditions on several subsize and full-size mockup samples, the actual unit was constructed. Nondestructive inspection of the welds revealed no defects. Good general flow of the brazing alloy was evident, and ultrasonic examination of brazed joints showed only minor scattered porosity. The completed unit passed both helium leak and 800 psi hydrostatic tests. (auth)

• Research Organization: Oak Ridge National Lab., Tenn.
• NSA Number: NSA-18-010512
• OSTI ID: 4083229
• Journal Information: Welding J. (N.Y.), Vol. Vol: 43; Other Information: Orig. Receipt Date: 31-DEC-64
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

METALS, CERAMICS, AND OTHER MATERIALS
ALLOYS
BRAZING
CHROMIUM ALLOYS
COOLANTS
CORROSION
CRACKS
DEFECTS
DUCTILITY
FABRICATION
FUELS
FUSED SALTS
GOLD ALLOYS
HEAT EXCHANGERS
HELIUM
INOR-8
JOINTS
MATERIALS TESTING
MECHANICAL PROPERTIES
MOLYBDENUM ALLOYS
NICKEL ALLOYS
PLANNING
POROSITY
PRESSURE
QUANTITATIVE ANALYSIS
SEALS
SHEETS
STABILITY
THICKNESS
TUBES
ULTRASONICS
WELDING
WELDS