Fundamental Study of Tandem Electron Beam Welding for Nuclear Fusion and Fission Reactors

As the important part of the life extension program for nuclear fission reactors and that of the maintenance scheme of blanket of fusion reactors, repair welding technique of neutron damaged materials is recognized to be one of the most urgent subjects to be established. This work provides the potentiality and the critical issues of "Tandem electron beam welding technique" when it is applied to heavily neutron damaged materials. Where mechanical property degradation due to the displacement damage and helium production from (n, α) reaction makes it very difficult to produce sound welded joint. This paper presents the preliminary results to see the elementary characteristics of the welded joints produced by Tandem electron beam welding technique. Not only for the stainless steel nor high-nickel alloys, also for stainless steel to high-nickel alloy welded joints were studied. The tandem electron beam welding was done at JWRI, Osaka University. By optimizing the drilling effect from the leading electron beam and the weld defect suppression effect from the secondary electron beam , weld defect free welded joints were obtained with the excellent joint strength and ductility. The weld bead shape and penetration characteristics are also provided. The present results are quite promising to apply "Tandem electron beam welding" to heavily neutron damaged metallic structures and components

Synthesis and Properties of Polysilsesquioxanes Having Ethoxysulfonyl Group as a Side Chain

Polysilsesquioxane having an ethoxysulfonyl group as a side chain was synthesized to prepare a proton-conductive film composed of a main chain of siloxane. At first, sodium 4-(2-methylallyloxy)benzenesulfonate was chlorinated with thionyl chloride. Next, hydrosilylation with trichlorosilane was carried out in the presence of platinum catalyst followed by treatment with ethanol. Finally, the hydrolytic polycondensation was carried out to provide poly(3-(4-ethoxysulfonylphenoxy)-2-methylpropyl)silsesquioxane. This polysilsesquioxane was heated to form a free-standing film that was brittle and brown in color