The group’s mission is to conduct state-of-the-art research and develop applied programs to evaluate the safety of complex structures and structural components when subjected to severe operational and environmental loads, including earthquakes. Much of this work is conducted for the U.S. Nuclear Regulatory Commission (NRC), in support of its primary objective to ensure protection of the public and the environment from the effects of radiation exposure. The group’s research programs have contributed significantly to the development of current regulatory requirements and guidance for ensuring the safety of critical nuclear power plant structures, including the primary containment structure. Among the group’s focus areas are the seismic safety of new and emerging plant designs, the effects of aging degradation on plant safety, and collaboration with Japanese and Korean researchers on seismic and structural issues.
Since the mid-1990s, the Group has been conducting research and developing applied programs directed toward understanding the structural and seismic response of proposed new nuclear plant designs. The group conducted the initial research and design review to establish the structural and seismic adequacy of concrete-filled steel modules proposed for use in AP600 and AP1000 reactors. The group is currently identifying the unique structural and seismic analysis issues posed by proposed small modular reactor designs, and is investigating the applicability of existing analysis methods for determining the realistic seismic response of these structures.
For more than 10 years, the Group has been conducting research on the effects of environmental degradation in reducing safety margins for critical plant structures, systems and components. This research has focused on identifying the structural elements that are most vulnerable to environmental degradation, characterizing the degradation mechanisms, estimating rates of degradation, predicting safety margins as a function of time, and evaluating the consequences of degradation on overall plant safety.
For more than 20 years, the Group has assisted the NRC in a collaborative effort with Japan to share information on seismic issues of common interest. During the recently completed five-year program, the collaboration activities included concrete shear wall tests, ultimate strength and degraded piping tests, and equipment fragility testing. The collaboration activities during the current program include several new areas, such as behavior of concrete- filled steel members and upgrading seismic response analysis methods for buildings.
In 2007, the Group entered a five-year collaboration agreement with Korea Atomic Energy Research Institute (KAERI), to develop seismic capability evaluation technology for degraded structures and components. Based on the success of this collaboration, another five-year agreement with KAERI began follow-up research on seismic probabilistic risk assessment technology for large earthquakes.