A closure device for containers for transporting radioactive substances, having a first and a second component each with a comb-like portion, wherein the comb-like portions, with the closure device locked, has a bolt element passing through them. The bolt element has a head with an accommodating recess running transversally to the longitudinal axis of the bolt element, that one of the components has a through-opening which, with the bolt passing through the comb-like portions, is aligned with an accommodating recess.