Experimental investigation of a mid-height seismic isolation for slender safety-class equipment in advanced nuclear power plants

Published June 3, 2022

Graduate Student: Kaivalya M. Lal

Principal Investigator: Andrew S. Whittaker

Co-Principal Investigator: Michael C. Constantinou

Project Completion Date: June 2022

Summary

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Recent studies have shown that the seismic load case can substantially increase the overnight capital cost (OCC) of safety-class equipment in advanced nuclear power plants. Seismic isolation can substantially reduce earthquake loadings on structures, systems, components (SSCs), and equipment, and is being considered for application to advanced nuclear reactors. The conventional implementation isolates the reactor building at its base and was the focus of completed research projects funded by the U.S. Department of Energy (DOE) and U.S. Nuclear Regulatory Commission (NRC). An alternate implementation of seismic isolation involves protection of SSCs and equipment inside a conventionally founded reactor building. Although seismic isolation has not been used to protect individual pieces of safety-class equipment in a nuclear power plant, its use for non-nuclear applications has been studied, with a focus on power transformers. Substantial reductions in cost may be realized if safety-class equipment is isolated, because seismic demands can be significantly reduced, and equipment standardized, but this has yet to be proven by physical experiments.

The DOE Advanced Research Projects Agency – Energy (ARPA-E) funded a MEITNER project with the goal of reducing the OCC of advanced reactors using equipment-level seismic protective systems. The MEITNER project includes proof-of-concept experiments on seismically isolated equipment. One experiment involved a 240-inch tall cylindrical vessel with an outer diameter of 60 inches, representing either a steam generator or a high temperature gas reactor, was tested in non-isolated and isolated configurations. The vessel was supported on a steel frame at its mid-height, near its center of gravity, and subjected to three component ground motions using a six degree-of-freedom earthquake simulator at the University at Buffalo. Two types of Friction Pendulum isolators were utilized to isolate the vessel: single concave Friction Pendulum (SFP) isolators and triple Friction Pendulum (TFP) isolators. The vessel was filled with water to simulate the in-service condition and mass distribution.

The data generated from the earthquake-simulator experiments demonstrate that mid-height seismic isolation is feasible for tall vessels and enables significant reductions in seismic demands. The data is being used to validate numerical models and will be made available to analysts and engineers via DesignSafe.

Publications

1.   Lal, K. M., Whittaker, A. S., and Constantinou, M. C. (2021). "Seismic isolation of safety-class equipment in advanced nuclear power plants."  Proceedings: 17th World Conference on Earthquake Engineering (WCEE), Sendai, Japan.

2.   Lal, K. M., Whittaker, A. S., and Constantinou, M. C. (2022). "Protection of safety-class equipment in advanced reactors using seismic isolation."  Proceedings: 12th National Conference on Earthquake Engineering (NCEE), Salt Lake City, Utah.

Sponsor

This project was supported by Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000978.

Video

Photos

Figure 2a. SFP bearing (top) on a load cell (bottom) in the isolated configurations of the vessel.

Figure 2b. TFP bearing (top) on a load cell (bottom) in the isolated configurations of the vessel