Electron beam welding of control rod drive components for the WWER-1000 reactor

A technology has been developed for the electron-beam welding of drive components intended for the vertical displacement of control rods in the WWER-1000 reactor. The drive housing of dissimilar steels OKh17N and 08Kh18N10T is at the same time a stator of a linear step motor. The stator is made in the form of a welded tubular structure from four-phases of steel OKh17N, separated by four longitudinal circular inserts from austenitic steel 08Kh18N10T. The longitudinal and circular welds of magnet-soft steel OKh17N and nonmagnet steel 08Kh18N10T are made by using an electron-beam welder. The optimum heat treatment conditions of the welded joints for these steels (680 deg C for 5 h) have been found, ensuring levelling their hardness and increasing impact viscosity and intercrystalline corrosion-resistance properties in the heat-affected zone. Tests of the samples have confirmed the operation reliability and performance of the welded joints