MODEL-IN-THE-LOOP CONTROL DESIGN FOR SEISMIC TESTING OF BASE-ISOLATED NUCLEAR EQUIPMENT

To date, safety-related equipment in nuclear facilities is seismically qualified by either physical testing or numerical analysis. This paper investigates an alternate strategy for seismic qualification, namely, Model-in-the-loop (MIL) simulation, which integrates physical testing and numerical simulations in real time. The effects of the boundary environment on the test specimen are realized by a system of actuators that are driven by numerical models in the loop. In this paper, MIL is conceptualized for 1D base-isolated equipment wherein the equipment is physically tested and the seismic isolation system at the base is represented by numerical models. The equipment is mounted atop a uniaxial hydraulic shake table and controls are designed such that the shake table mimics the isolated boundary conditions at the base of the equipment. The test system modeling, control design philosophy and verification for this MIL problem are discussed. MIL could be an efficient qualification strategy for such configurations because an equipment could be tested and qualified for boundary conditions corresponding to different isolation systems by simply switching computer models, thereby eliminating the need for constructing multiple test fixtures. The MIL concepts presented here could be extended for the qualification of other safety-related equipment, including internals in reactor vessels and steam generators.