Effect of Applied Stress during Irradiation at 5 K on the Shear / Compression Strength of Bonded Specimens

Insulation and bonding materials which are used to construct superconducting magnets for use in fusion reactors, such as ITER, will be subjected to an applied mechanical stress and also to intense neutron irradiation. There is little design information available on the effects of ionising radiation on materials when they are subjected to low temperatures and to an applied stress. The work reported was undertaken to assess the effects of a stress applied to the specimen during irradiation at 5 K. Specimens of commercially pure titanium were prepared and bonded in a geometry which would induce combined shear and compression stresses when the samples were mechanically loaded. A number of specimens were bonded using S2 glass fabric pre-impregnated with an epoxide resin and others were prepared using dry glass fabric followed by vacuum impregnation with an epoxide resin. Test specimens based on both types of resin were reactor irradiated at 4 K, with and without an applied stress of 30 MPa. A series of specimens, were cooled to 5 K and retained as non-irradiated controls.