Investigations at Nuclear Power plant Sites
Before deciding on locating a nuclear power plant at a site the site and its adjoining areas are investigated in detail to determine the geology and tectonics of the site area for determining the maximum earthquake potential of the area, the probable values of different components of earthquake ground motion - acceleration, velocity and displacement - and suitability of the site to support the plant structures.
Approach to Seismic Risk Assessment
Epicenters of past earthquakes occurring within a 300 kilometers distance from the site under consideration, and having magnitudes above 3 are superimposed on a plot of lineaments/faults on a 1:1,000,000 scale map.
Divide the 300 kilometer radius into tectonic provinces.
Identify significant tectonic features (lineaments, which could be considered or suspected to be the surface expressions of a geological fault.
Associate as many earthquakes as possible with the known tectonic structures.
Estimates occurrence rates (in time and space) of earthquakes of different magnitudes associated with each tectonic structure or province.
Estimate the maximum earthquake potential which can be associated with each known tectonic structure.
Identify the earthquakes which cannot be associated with known tectonic structures.
Investigate the area through satellite imageries and aerial photographs, detailed geological maps and ground truth verification to determine if additional tectonic structures, which could be considered the sources of the unidentified earthquakes, could be found. And if they are faults establish the geological characteristics.
Set up an attenuation law for each source-site combination to translate the earthquake effects into vibratory ground motions at the site.
Select a methodology through which values of acceleration, velocity and displacement from future earthquakes could be estimated.
Setup a model through which the influence of the local geology in modifying the base ground motions at the site may be characterized.
Estimate the differences between the free field motions and those due to the presence of engineering structures at or near the site to arrive at the design basis ground motions.
This page was updated on 12 January 2011