A composite-wall radiation-shielded cask and method of assembly having an inner shell surrounding a containment volume, and two or more non-annular sections of a radiation-shielding material secured with a fastener or strap to the inner shell to form a bound inner assembly. The bound inner assembly is inserted into an outer shell to form a clearance gap between the inner assembly and the outer shell. And the clearance gap is then filled with filler material capable of transferring mechanical and thermal loads between the bound inner assembly and the outer shell.
 The United States Government has rights in this invention pursuant to Contract No. W-7405-ENG-48 between the United States Department of Energy and the University of California for the operation of Lawrence Livermore National Laboratory.