Abstract: A basket for a cask for transporting, storing, and containing pressurized water nuclear fuel assemblies, including an internal assembly of sleeves has a plurality of sleeves arranged in a uniform pattern and secured within a cylindrical shell. Each of the plurality of independent sleeves being sized to secure and contain a fuel assembly. The internal assembly of sleeves includes a set of single sleeves centrally positioned in the basket, a set of corner sleeves including a single sleeve in each corner of the basket, and a set of double sleeves. An internal support structure is positioned within the basket and includes a cross-shaped central support element and four angle shaped corner supports. Neutron poison material for absorbing neutrons is secured to an inner wall of each of the plurality of sleeves for maintaining fission reactions within the basket below a critical level necessary to sustain a fission reaction.