The invention relates to nuclear engineering and can be used in the manufacture of fuel elements for nuclear reactors. Essence of the invention: variants of a welded join between a fuel element casingand a plug which are made of high-chromium steel are proposed, providing for more reliable sealing of nuclear reactor fuel elements as a result of the production of a high quality welded join betweenthe casing and the plug without the need for subsequent heat treatment of the weld seam, which simplifies the manufacturing process. This is achieved through the formation of a ferrite phase in the metal of the seam by adjusting the structure of a join between a casing and a plug made of ferrite-martensite and ferrite steels in different combinations and by observing the necessary size ratio parameters to ensure the formation of the aforesaid phase.