CONSEQUENCES OF DROP TEST PARAMETER LIMITATIONS FOR SUBSEQUENT PACKAGE DESIGN SAFETY ANALYSIS

A drop test result represents only one “point” in the field of parameters, which a package design approval has to consider. One test parameter e. g. is ambient temperature condition. Using -40?C addresses the most severe embrittlement or stiffness of some cask components. Using maximum operational temperature, plastic deformations are of interest, particularly in the sealing areas to keep leak tightness. The real material properties of the drop test package model are an additional parameter with respect to the range of specified material properties due to quality assurance controls, which are the basis of the subsequent package design safety analysis. The relevance of scaling effects, influence of manufacturing processes, simulation of basket and radioactive content, questions of similarity, limited number of drop tests and drop test positions, temperature effects on impact limiter properties and some other aspects are presented in this paper. The given drop test parameter limitations require additional safety demonstrations for the package design besides the interpretation of drop test results. The definition of drop test parameters has a significant influence on subsequent package design safety analysis. It influences the safety analyses structure and dictates to what extent these analyses have to be presented in the safety analysis report. The presentation focuses on the consequences of limited results of drop tests due to the above mentioned limitations for subsequent package design safety analysis. This will be underlined by experiences during package design approvals including drop tests. Missing considerations concerning the selection of drop test parameters can provide severe consequences for subsequent package design safety analysis. Severe consequences, which could not only be provided due to the drop test program itself, but also due to an irrational extent of subsequent safety demonstrations up to the impossibility to demonstrate the compliance with the regulations at all. This leads usually to subsequent design changes, which costs a lot of time and money and rips into the heart of the project. This paper presents possible approaches for the check of parameters before starting drop test programs to avoid those severe consequences.