Seismic hazard evaluation for the high-flux isotope reactor (HFIR) Oak Ridge National Laboratory, Oak Ridge, Tennessee

This study investigates the probabilistic hazard of earthquake-induced ground shaking at the HFIR facility, Oak Ridge, Tennessee. These results will be used to calculate plant response and potential effects in a Probabilistic Risk Assessment (PRA). For this purpose, several guidelines apply to this work. First, both the frequency of exceedance and the uncertainty in frequency of exceedance of various ground motion levels must be represented. These are required by the PRA so that the frequency and uncertainty of various possible plant states can be expressed. Second, there is a deliberate attempt to provide an unbiased distribution of frequencies of exceedance, i.e. to present results that are neither conservative nor unconservative. This is consistent with the goals of a PRA, to provide unbiased estimates of plant effects from which appropriate decisions (for instance about evaluating existing levels of seismic design) can be reached. Recent intensive studies of seismic hazard in the central and eastern United States (CEUS) have been completed by the Electric Power Research Institute (EPRI). These studies represent major efforts to characterize the seismic hazard for nuclear power plants in the CEUS, and use the most recent, up-to-date understandings of seismicity and ground motion relations for the region. With these studies as a resource, the current effort relies exclusively on the seismicity and ground motion assumptions therein to formulate seismic hazard curves for the HFIR facility. The interpretation of these studies to derive seismic hazard curves in a format suitable for input to a PRA is described in this report. 29 refs., 40 figs., 22 tabs