Typical uniform hazard spectra for eastern North American sites at low probability levels

Seismic design for nuclear power facilities is generally based on a prescribed earthquake response spectrum, which defines the response of a simple oscillator of a given natural frequency to the expected motions. To develop standard designs that may be suitable in a number of possible future locations, it is useful to develop standard spectra that describe typical environments. The adequacy of the standard design for a particular location may then be judged based on comparison of the standard spectrum with a site-specific "uniform hazard spectrum" (UHS). In this paper, UHS results from selected publicly available studies are used to develop a standard spectral shape that describes moderate-seismicity sites in eastern North America, on hard-rock site conditions. Compared with a standard spectrum that has been suggested for future nuclear plants on rock sites (modified Canadian Standards Association CSA/CAN-N289.3), the spectral shape proposed herein has higher amplitudes at high frequencies and lower amplitudes at low frequencies.