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An urgent problem of increasing the operational performance of steel-zirconium adapters, made by diffusion welding in vacuum, in RBMK process channels is decreasing the tendency toward intercrystallite corrosion of their steel parts and increasing the corrosion resistance of the zirconium parts. Previous investigations have shown that the heat treatment (annealing at 580°C for 10 h) which is currently used to increase the corrosion resistance of electron-beam weld seams and the zirconium parts of adapters can make the steel more sensitive.In the present work, decreasing the annealing temperature in the most dangerous spot (in the zone of the steel-zirconium joint) by disconnecting the heater of the annealing vacuum furnace on the adapter (only the heater in the zone of the electron-beam weld seam was switched on) was tested. The record of the thermal cycles, which was obtained with thermocouples, showed that in this case the temperature in the zone of the joint is 520-550°C.The tendency of steel to undergo intercrystallite corrosion was investigated by the method of electrochemical potentiodynamic reactivation [1]. The corrosion resistance of the zirconium parts of the adapters was estimated from the results of tests performed under autoclave conditions with the parameters of the process channels without irradiation. In addition, x-ray phase analysis of the metal of the zirconium part of the adapter ~10 mm from the joint was performed.As Table 1 shows, the weakest sensitization was observed for annealing with the heater section turned off. As Table 2 shows, the corrosion resistance of the zirconium parts of an adpater treated using all regimes studied (an assessment was made according to the color of the oxide film) is quite high (the thickness of the oxide film is not determined metallographically). It should be noted that the corrosion resistance of the surfaces subjected to rolling before annealing is

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