Analysis of Mechanisms for Early Waste Package / Drip Shield Failure

The purpose of this analysis is to evaluate the types of defects or imperfections that could occur in a waste package or a drip shield and potentially lead to its early failure, and to estimate a probability of undetected occurrence for each type. An early failure is defined as the through-wall penetration of a waste package or drip shield due to manufacturing or handling-induced defects, at a time earlier than would be predicted by mechanistic degradation models for a defect-free waste package or drip shield. A single waste package design has been specified with several configurations for the various waste forms as cited in Total System Performance Assessment Data Input Package for Requirements Analysis for DOE SNFIHLW and Navy SNF Waste Package Overpack Physical Attributes Basis for Performance Assessment (SNL 2007 [DIRS 179567], Table 4-1, Item 03-02). The waste package consists of a stainless steel inner shell and an outer corrosion barrier. For this analysis, the transportation, aging, and disposal (TAD) canister type waste package is a surrogate for all of the waste package configurations since all the configurations are subject to the same fabrication and handling processes. The scope of this analysis is limited to the manufacturing or handling-induced defects that might lead to the early failure of the waste package outer corrosion barrier and drip shield. The structural (stainless steel) vessel of the waste package was not analyzed.