▎ 摘　　要

NOVELTY - A sheath material comprises 30-40 pts. wt. polyolefin, 10-20 pts. wt. silicone rubber, 2-10 pts. wt. hybrid graphene multifunctional additive, 40-50 pts. wt. microencapsulated flame-retardant, 1-5 pts. wt. flame-retardant shell forming additive, 1-3 pts. wt. polyfunctional crosslinking agent, 0.5-2 pts. wt. lubricant and 1-4 pts. wt. antioxidant (A). The hybrid graphene multifunctional additive comprises nanoparticle anti-irradiation agent, antioxidant (B) and graphene. The nanoparticle anti-irradiation agent is chosen from one or more of tungsten oxide, bismuth oxide, bismuth carbonate, rare earth metal oxide and nano-silica. The rare earth metal in the rare earth metal oxide comprises one of lanthanum, cerium, praseodymium, neodymium, promethium, samarium and europium. The antioxidant (A) is 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl chloride. USE - Sheath material for nuclear power plant. ADVANTAGE - The sheath material utilizes hybrid graphene multifunctional additive, microencapsulated flame-retardant and flame-retardant shell forming additive which have excellent synergistic effect and anti-aging performance. The sheath material has excellent flame retardance, acid and alkali resistance, radiation resistance and prolonged service life. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of sheath material, which involves adding polyolefin, silicone rubber and hybrid graphene multifunctional additive to mixer, mixing at 140-200 degrees C, adding microencapsulated flame-retardant, flame-retardant shell forming additive, polyfunctional crosslinking agent, antioxidant (A) and lubricant, mixing, extruding, granulating at 140-200 degrees C to form a sheath pellets, using prepared sheath pellets as an outer sheath layer of conductive core of a cable, irradiating and cross-linking under an electron beam of 10 KW and 10 MeV when the sheath pellet is used as a covering material for the inner sheath layer of conductive core of a cable.