Year
2016
Abstract
The 9975 shipping package, a robust drum-style Type B Fissile Package, is used for transport and storage of Plutonium metals and oxides. At Savannah River Site (SRS), plutonium metals and oxides are stored in a triple-nested 3013 container assembly housed inside the 9975 double-containment vessel (CV). The shipping package structural components include the outer drum shell, fiberboard, primary and secondary CV, lead shielding, plates, and impact limiters made of aluminum-honey combs. The 9975 shipping package storage life was developed based on the Container Qualification Program (CQP) which used a systematic approach to provide needed information for the safety analysis process by evaluating container functions, requirements and qualification bases. The functions include containment, criticality prevention, and impact and fire resistances. The qualification for the storage period was also provided by the monitoring requirements of the Storage and Surveillance Program (SSP). The 9975 shipping package SSP performs surveillance and accelerated aging tests to ensure any degradation due to aging is detected in advance of such degradation occurring in service. Although the Program has demonstrated that the 9975 package has a robust design that can perform under a variety of conditions, the package was not specifically designed for long term nuclear material storage. Since the existing 9975 Model service storage life of 15 years is due to expire in mid-2017 for the oldest shipping packages, life time extension (LTE) analysis is needed to extend the storage life for the second time. Therefore, the 9975 shipping package LTE requires a relatively new comprehensive approach which combines existing material data to be used in the package thermal and structural analyses in order to determine the use of the shipping package for long term safe storage of nuclear materials. The 9975 Model storage life extension evaluation can be divided in two general steps. The initial step is to collect material property data based on three elements: beginning-of-life conditions, as-found surveillance data, and experimental aging studies. The material data are then modified as applicable to be used in the 9975 Model thermal and structural analyses models. This submittal primarily focuses on the ongoing LTE prediction efforts of the 9975 shipping packages using the new approach and also documents the progress made to date. In addition, the comprehensive approach can be applicable to other similar shipping package designs.