Central and Eastern United States Seismic Source Characterization for Nuclear Facilities: Maximum Magnitude Distribution Evaluation

Introduction

In mid-2014, an error was identified in the published maximum magnitude (Mmax) distributions for a number of the CEUS seismotectonic model zones. The error was promptly communicated to utility seismic hazard representatives, NRC and DOE representatives, and key technical experts involved in the development of the CEUS SSC model. EPRI published a report (EPRI Product ID: 3002005684) to document reviews performed to determine the extent of condition of the Mmax error and the potential impacts of the error on seismic hazard calculations. The EPRI report documents the originally published and corrected Mmax values and the results of evaluations performed to assess impacts on the recurrence parameters, seismic hazards, and ground motion response spectra (GMRS) estimates at two sites within or near the affected seismotectonic zones. The evaluations were performed in close consultation with the three CEUS SSC sponsors (NRC, DOE, and EPRI) and represent consensus conclusions.

Minor Mmax distribution corrections were identified for the PEZ-N, PEZ-W, IBEB, SLR and MidC A through D seismotectonic zones. Sensitivity studies at two sites showed there are negligible impacts on the recurrence parameter results as well as calculated seismic hazard and GMRS results. These impacts are within the level of precision associated with the standard reporting of GMRS, which leads to the conclusion that it is NOT necessary to incorporate the corrected Mmax values into the CEUS model or the published CEUS SSC report.