Year
2018
Abstract
Radiological sources are common in many countries because of beneficial uses in medical and industrial applications. Some of the radioisotopes used in these applications have relatively short half-lives—e.g. 73.8 days for Ir-192 and 5.27 years for Co-60—while others have much longer half-lives—e.g. 30.17 and 28.79 years, respectively, for Cs-137 and Sr-90. These radioisotopes are high-energy β-? emitters, and the lack of a disposition pathway for the disused radiological sources poses a significant risk in terms of inadvertent or deliberate misuse of the material and other problems. The U.S. Department of Energy has planned since the mid-1980s to dispose of all high-level radioactive waste (HLW) and spent nuclear fuel (SNF), regardless of commercial, defense, or research origin, in a common mined geologic repository. A separate mined repository was proposed in 2015 for DOE-managed SNF and HLW, as well as an option for deep borehole disposal of “small” waste forms, such as the Cs and Sr capsules currently stored in pool cells at Hanford’s Waste Encapsulation Storage Facility. This paper presents the design and structural analysis of a compact Type B packaging that can be used for transportation and storage of the disused radiological sources, as well as for direct disposal at a mined geological repository, or a deep borehole, without repackaging. Structural analysis was performed by using finite element code ABAQUS. The results showed that the structural performance of the packaging meets the regulatory requirements under both normal conditions of transport (NCT) and hypothetical accident conditions (HAC), as prescribed in the U.S. federal regulations 10 CFR 71 Packaging and Transportation of Radioactive Material. The all stainless-steel structure materials (i.e., 304/304L stainless steels for the packaging components) and the packaging design also provide adequate heat dissipation and radiation shielding for the disused radiological sources, as well as excellent long-term performance against general corrosion and stress corrosion cracking during extended dry storage. Moreover, the packaging design is suitable for subsequent transportation and direct disposal, without repackaging. Finally, the compact Type B packaging design enables optional use of the ARG-US remote monitoring system, which enhances safety and security during extended storage, transportation, and disposal.