Modeling Based Study of Impact Loads Generated by Tornadoes and Hurricanes on Safety-critical Structures for Nuclear Structures

— Safety-related buildings and structures for nuclear plants require the design and analysis of tornado and hurricane generated missile impact load. Several Canadian provinces, including Ontario, Quebec, Manitoba, Saskatchewan and Alberta are tornado prone. In Canada during the years 1980 to 2009, a total of 1,217 tornados were observed, including one F5 scale, five F4 scale, 24 F3 scale and 119 F2 scale tornadoes. These tornadoes pose critical risks to nuclear infrastructure due to the potential for missile generated impact loads from debris present in the tornado that can impact the nuclear structures. During the years, 1918 to 2014, seven F4 scale, 18 F3 scale and 126 F2 scale tornadoes were observed in Ontario. Meanwhile, several hurricanes hit the Eastern region provinces of Canada in recent history, including Hurricane Juan in September 2003 in Nova Scotia and Prince Edward Island, and four hurricanes in Nova Scotia and New Brunswick in 1963. In this work, an ANSYS based advanced computational simulation model framework was developed to investigate the effect of the tornado and hurricane generated missile impact load on nuclear structures. The explicit dynamics module in the ANSYS software was used for simulations and the preliminary results are presented. A database of materials and potential missile impact loads were identified for future investigations. For example, concrete, reinforced concrete, steel, and reinforced concrete walls with steel liner are relevant for further study. The 0.158 meter diameter and 4.58 meter long steel pipe missiles in 103 m/sec, 89 m/sec and 72 m/sec maximum wind speeds were also identified for further investigation. Lab based impact loading tests on scaled down samples were also studied.