DEVELOPMENT OF THE CRITICALITY CONTROL OVERPACK PAYLOAD CONTAINER FOR TRANSPORT OF EXCESS PLUTONIUM OXIDES IN THE TRUPACT-II AND HALFPACT PACKAGINGS

A new transuranic (TRU) waste payload container has been developed for the shipment of a target waste stream consisting of approximately 9 metric tonnes of excess plutonium oxides in the TRUPACT-II and HalfPACT Type B packages. The Criticality Control Overpack (CCO) is designed to increase the authorized fissile material content of each package by a factor of 1.9 times the current limits with a 30% reduction in fabrication costs as compared to existing authorized fissile material centric payload container options. Confinement and separation of fissile material within and between individual CCOs in 14 pack and 7 pack arrays of payload containers results in a 239Pu fissile gram equivalent (FGE) limit per package of 5,320 and 2,660 FGE for the TRUPACT-II and HalfPACT packages, respectively. Hypothetical Accident Condition (HAC) 30 foot drop certification testing of the CCO was performed at elevated normal conditions of transport (NCT) temperatures to demonstrate the ability of the payload container design to perform its safety-significant criticality control function. The CCO design consists of a steel 55-gallon drum overpacking an inner stainless steel Criticality Control Container (CCC) (constructed from 6” class 150 standard ASME pipe and flange components) and impact-attenuating upper and lower plywood dunnage assemblies. This paper discusses the design, development, structural certification testing, and thermal and criticality analysis of the new CCO payload container.