3　Basic Requirements

3.1　Technical Principles

3.1.1　The seismic investigation and evaluation of a nuclear power plant shall find out the seismic and geologic conditions of the region，near region and site vicinity of the plant，identify capable faults，determine the ground motion parameters of the site and assess the earthquake-induced geological disasters.

3.1.2　In the seismic investigation and evaluation，existing information shall be fully collected and analyzed，major problems shall be identified and studied according to the complexity of seismic and geological conditions，and specific working plans shall be worked out according to the basic working procedures for seismic investigation and evaluation and necessary investigation，exploration and analysis technical means be used either individually or in combination，to complete the investigation and evaluation.

3.1.3　The scopes of seismic investigation and evaluation shall be classified as region，near region and site vicinity scopes.The scopes shall respectively comply with the following provisions:

1　The regional scope shall be the area with a radius no less than 150km with the site as the center.

2　The near region scope shall be the area with a radius no less than 25km with the site as the center.

3　The site vicinity scope shall be the area with a radius no less than 5km with the site as the center.

3.1.4　The scopes of seismic investigation and evaluation and the corresponding investigation objectives shall comply with the following provisions:

1　For regional scope，data of geological structure framework，seismic activities and geodynamic background of the region shall be surveyed and provided，and the geological and seismic features affecting the seismic safety of the site shall be assessed.

2　For near region scope，more detailed geologic structure and seismic activity data shall be investigated and obtained，the seismotectonic characteristics in the near region be identified and the seismogenic structure in this scope shall be indicated in detail.

3　For site vicinity scope，capable faults shall be investigated and identified to assess the potential earthquake-induced geological disasters in the site area.

3.1.5　The scale of main drawings obtained through seismic investigation and evaluation shall comply with the following provisions:

1　It shall be no less than 1∶1000000 for regional scope.

2　For near region scope，it shall be no less than 1∶200000 in preliminary feasibility study phase；and no less than 1∶100000 in feasibility study phase.

3　For site vicinity scope，it shall be no less than 1∶50000 in preliminary feasibility study phase；and no less than 1∶25000 in feasibility study phase.

3.1.6　The horizontal acceleration peak value of SL-2 design basis ground motion of site shall be no less than 0.15g.