SEISMIC ISOLATION OF SAFETY-CLASS EQUIPMENT IN ADVANCED NUCLEAR POWER PLANTS

Seismic isolation can substantially reduce earthquake loadings on structores, systems, components (SSCs), and equipment, and is being considered for application to advanced nuclear reactors. The conveotional implementstion isolates the reactor building at its base and was the focus of several completed research projects funded by the U.S. Departmeot of Energy (DOE) and U.S. Nuclear Regolatory Commission (NRC). An alternate implementation of seismic isolation involves protection of SSCs and equipment inside a reactor building, which is the focus of an on going MEITNER project funded by the DOE Advanced Research Projects Ageocy - Energy (ARPA-E). The MEITNER project includes an experimental program that is investigating the application of seismic isolation to equipment. Four models are being evaluated, with three isolated at the base, and one isolated at its mid-height. 1hls paper presents data on the seismic response of a cylindrical vessel isolated at its mid-height The test specimeo was 240 inches tall and had an outer diameter of 60 inches. The vessel was supported on a stiff steel frame by three equally spaced mounts. Friction Pendulum bearings were installed between each mount and the steel frame. The test specimen was subjected to three component ground motions using a 6 DOF earthquake simulator. The vessel was filled with water and sample internals were attached to the vessel head. Three configorations were tested, non-isolated, isolated using single Friction Pendulum beariogs, and isolated using triple Friction Pendulum bearings. Data from the experiments show that mid-height isolation enables siguificant reductions in seismic demands in both the vessel and its internals.