Radiation resistant cable

High Energy Accelerator Research Organization (KEK) and Japan Atomic Energy Agency (JAEA) are promoting jointly the construction of Japan Proton Accelerator Research Complex (J-PARC) in Tokai-mura, Ibaraki prefecture since 2001. In general, polymeric cable installed in heavy radiation environment, such as nuclear power plant or radiation research facility as the J-PARC, deteriorates its performance by the effect of radiation damage. The deterioration conducts a decrease of mechanical property and of flame retardant characteristics that require the replacement of the cable within a certain period of time to keep the basic function as insulation or non-flammability. This report explains the development of radiation resistant polymeric material and cable by the examination of sample gamma-ray irradiation method based on the joint research agreement with JAEA toward the J-PARC application. We studied the irradiation effect in the combination of light stabilizer and ultraviolet absorber. A current non-halogen sheath material observed severe damage on the mechanical property by the irradiation dose of 0.5 MGy. While the developed material demonstrated excellent performance as the elongation brake more than 50%, which corresponding to the self-diameter bending, kept after the irradiation dose of 2.5 MGy. The new cable manufactured with the advanced sheath material maintained at the vertical tray flame test of JIS C 3521, and accomplished to a bending test, in case the cable was bent to a diameter four times of the cable outer diameter, as well as all of the development objectives were achieved successfully. The developed cable is being applied to the J-PARC in these years. (author)