A Method for the Coupled Thermal-Structural Analysis of Radioactive Material Shipping Packages in Hypothetical Accident Conditions: Part 1—NCT Thermal Load and Some HAC Mechanical Loads

Abstract

The design of radioactive material (RAM) shipping packages are designed to withstand the mechanical and thermal loads specified in Title 10 Code of Federal Regulations Part 71 (10CFR71). The Hypothetical Accident Conditions (HAC) specified in 10CFR71 include a 30-foot free drop, a crush by an 1100-pound plate, a 40-inch free drop onto a round bar and a 30-minite fire. Furthermore, in accordance with the Nuclear Regulatory Commission Guide 7.8, these loads should be applied sequentially. The current common practice is to base the thermal modeling on the un-deformed (or un-damaged) packaging configuration and thermal stresses are neglected in structural analyses. This paper presents a methodology to simulate the coupled thermal and structural responses and to evaluate the accumulated damages caused by both sequentially applied thermal and mechanical loads of the Hypothetical Accident Conditions. Part 1 of the paper discusses the thermal analysis for the Normal Conditions of Transport (NCT) to establish the initial temperatures of the shipping package. It also discusses the subsequent analyses of closure-bolt tightening preload analysis and 30-foot drop analysis.