Extreme or Severe Loads

These loads include extreme environmental conditions, such as tornadoes and the safe shutdown earthquake postulated to oeeur during the life of the faeility. Also included are effeets resulting from a postulated rupture of a high-energy system during normal operation, startup or shutdown of the plant or other postulated design basis aeeident. 

determination of static and dynamic characteristics of underlying materials  

historical listings of all earthquakes which may have affected the site  

The direction of motion for SSE shall generally be assumed as resultant motion to correspond with one of the principal horizontal directions of the structure for the facility being analysed. 

The vertical motion associated with SSE can be established on the basis of the information developed from the above-mentioned investigation. The value should not be less than 2/3 of the maximum horizontal ground acceleration of the SSE. The frequency strength is between 3.5 and 33 Hz. The vertical acceleration shall be equal in intensity to the horizontal component. 

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