%
!Phe nickel-base brazing alloys l i s t e d i n Table 3.4 have been shown t o be satisfactory i n contact with the saltmixt;Ure LiF-KF-I?aF-q i n t e s t s conducted at l5W0F for 100 hr. M e r two precious metal-base brazing alloys, 82$ Au-18$ N i and 80$ Au-20$ Cu, were unattaclsea in the LiF-KF-NaF-UFk salt e t e r 2000 hr at 1200째F. These two precious metal alloys were also tested in the LiF-BeF2-UFk mixture and again were not attacked.
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3.6.
Nondestructive Testing An ultrasonic inspection technique i s avaiuble for the detection af' $lam in plate, piping, and tubing, The water-immersed pulse-echo ultrasound eqtfignnent has been adapted t o high-speed use. Eddy current, dye penetrant, and radiographic inspection methods are also used as required. B e inspected materials have included Inconel, austenitic stainless steel, INOR-8, and the Eastelloy and other nickel-molybdenumbase alloys. ,
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Methods are being developed f o r the nondestructive testing of weldments during i n i t i a l construction and after replacement by remote mews i n a highdintensity radiation field, such as that which will be present if maintenance work i s required after operation of a molten-salt reactor. Th6 ultrasonic technique agpears t o be best suited t o semi-automatic and ranote operation, and it will probably be the least affected by radiation qf' any of the applicable methods. Studies have indicatedthat the difficulties encountered i n the ultrasonic inspection of Inconel welds and welds of same of the austenitic stainless steels because the weld struc'tures have hi& ultrasonic attenuation are not present in the inspection of INOR-8 welds. The high ultrasonic attenuation i s not present i n IIVOR-8 m e t a l are of the same camposfwelds because the base metal and the tion. The mechanical equipment desi for the m m t e welding operation will be useful f o r the inspection operation, *-
In the routine inspection of reactor-grade construction materials,
a tube, pipe, plate, or rod is rejected if' a void is detected that i s larger than 5$ of the thickness of the part being inspected. In the
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