The radiation barrier alloy (RBA) concept is a method for introducing radioactive, chemical, and physical barriers for storing weapons-grade plutonium, and yet still allowing for accurate material control and accountability, as well as for retrieving the material by the host nation if desired. The radioactive and chemical barriers are achieved by fabricating the plutonium in the form of a plutonium-beryllium compound (PuBe13), which results in neutron emission resulting from (α,n) reactions within the compound and multiplication from (n,fission) processes in the plutonium. Preliminary physics analyses have been completed, as well as a general review of fabrication techniques and availability of the required materials. These studies revealed that dose levels in excess of 500 rem/h at a 1-m distance from the surface of the RBA assembly can be obtained. However, essential for achieving these dose levels is operation at a high level of neutron multiplication (keff∼0.9). Criticality concerns, even under flooded conditions, can be eliminated through the use of a thermal-neutron-absorbing material (e.g., cadmium) either as a cladding material or a container material surrounding the RBA assembly. Fabrication techniques for the Pu-Be compound are well demonstrated and fully compatible with the RBA assembly fabrication. Data from disassembly of Pu-Be sources indicate that the compound is stable and no significant physical degradation occurs over a 40-yr timeframe. There is no reason to believe that any additional problems exist for longer time frames, given that the components are designed for the appropriate lifetimes (i.e., adequately account for gas production). The materials required for RBA implementation are available in the required quantities, and cost of these materials is not prohibitive. The possible exception is tantalum, although its use is nonessential for RBA performance and hence it will probably be eliminated from future RBA designs. Additional physical barriers can be added by welding the assembly together and encasing the assembly in an outer container. If desired, the assembly (inside the outer container) can also be immersed in a neutronically inert matrix such as lead. The lead serves a dual role in that in makes it difficult to move because of the additional weight, and it increases safety by reducing the possibility of a criticality accident resulting from flooding or assembly crushing. To further the RBA preconceptual analyses, a baseline design based on physics performance was developed. For the baseline RBA configuration, approximately six RBA assemblies, each 31 m3 in volume, would be required to store 50 Mt of weapons-grade plutonium.