[en] DOE has determined that additional capacity increases can be achieved by implementing various design strategies based on new concepts and/or the actual characteristics of the majority of the spent fuel to be shipped in the future. Implementating these design alternatives deviates from past regulatory practices and technical issues arise that must be resolved. Additional capacity increases can be achieved by taking credit for the burnup or reduced reactivity that results when fuel is used to produce power in a nuclear reactor. As the fuel is used, the volume of fissile material decreases, and other materials that tend to retard the fission process produced. These retardants are known as neutron absorbers or poisons. A number of opportunities exist to increase the productivity of the next generation of spent fuel shipping casks. Improving cask efficiency will not only reduce life cycle transportation costs but is also consistent with maintaining public and occupational risks (radiological and nonradiological) within the guidelines of the ''as low as reasonably achievable (ALARA)'' philosophy. Increases in cask capacities will reduce both the total number of shipments required to transport a given amount of fuel and the number of handling operations of both shipping and receiving facilities. 7 refs