One type of graphene tape would be loaded with 95% uranium 235. One type would bring in Polonium. One type would bring in Beryllium. The fourth and final type of graphene tape would be impregnated with pure Copper which is a relatively cheap, fairly heavy, and not very toxic metal. You need lots of heat … Continue reading A rocket nozzle with 4 types of ultra-thin graphene tape fed into a vise-tamper would be a nuclear rocket.