Practical successes in reinforcing the thread detachable joints for nuclear reactor installations can be achieved by a method of brazing using amorphous and microcrystalline filler metals produced by a rapid melt solidification. Compositions and technology of nickel-based filler metals in the form of amorphous foils 30-40 μm thick and 20 mm wide were developed for brazing a superalloy Nimonic with molybdenum. Conditions of vacuum brazing of the specified joints by STEMET 1342 and STEMET 1309 filler metals, ensuring wetting and reliable joining of based materials, were set up. Metallography and microprobe X-ray analysis of brazed joints were carried out. The superalloy - molybdenum mock-up of thread-brazed joints was manufactured using the STEMET 1309 filler metal, and effects of the clearance size and a filler metal position on the brazing quality were investigated. The best characteristics of the brazed joints were provided at a minimal clearance size and deposition of the filler metal foil into a technological groove inside the thread.