Use of LLNL and EPRI probabilistic seismic hazard curves interim position

The issue of the seismic hazard to be used in safety or risk assessments has recently been raised at a number of DOE facilities. One of the technical issues associated with this topic is the existence and use of two different methodologies for the development of seismic hazard curves by Lawrence Livermore National Laboratory (LLNL) and the Electric Power Research Institute (EPRI). Experience to date has shown that application of these methodologies can yield significantly different results. In response to this situation, a Seismic Working Group (SWG) has been formed at DOE Headquarters to coordinate the application of these methodologies within DIE in a consistent manner, and to cooperate in an effort to address the differences between the two methodologies. The difference between the LLNL and EPRI studies takes on Departmental importance for several reasons: (1) results from these studies are applicable to locations in the Eastern United States (east of 104W) and have been used by a number of DOE sites and contractors; (2) the current usage of these studies is inconsistent from site to site; (3) the Department General Design Criteria (DOE Order 6430.1A) requires that seismic design be evaluated based on probabilistic seismic hazard without explicitly identifying what methodology should be used; and (4) various Departmental organizations are using safety goals to evaluate facility performance and design which can be sensitive to the probabilistic seismic hazard curve used