SEISMIC RESPONSE MEASUREMENT OF UNDERWATER SPENT FUEL STORAGE TRAYS THROUGH HIGH SPEED IMAGE PROCESSING

摘要

Seismic stability of spent fuel storage trays stacked in a water pool is an important aspect of nuclear waste management. Seismic stability of the trays stack cannot be easily evaluated through finite element analysis, due to the various imperfections like friction and slip and, other non-linearities in the system. Hence shake table testing is considered to be the best alternative for evaluating the seismic stability. For checking the seismic stability of a trays stack, a series of shake table tests have been conducted. Conventional displacement sensors including LVDTs require a stationary platform near the measurement point as a reference. The two ends of the sensors are to be fastened to this reference point and the measurement point, respectively; the distance between these points is not easily adjustable because of the nature of the mechanism of the sensor. For underwater displacement measurement, conventional displacement sensors, which work on electrical principles, will not serve. This limits the application of LVDTs in several situations for displacement measurement. This paper presents the vision based displacement measurement of underwater storage trays tested on shake table. High speed video camera is used to record the motion of the trays stack during shaking. The video images are processed and displacement of the underwater trays stack is measured using motion tracking algorithm. Sloshing effect on trays stack and free vibration of trays stack, after the end of the shaking is studied and damping is calculated. Vital information of underwater motion of the spent fuel storage trays is obtained.