A SIMPLE NONLINEAR MODEL FOR PENDULAR CHAOTIC OSCILLATIONS OF REACTOR CORE BARREL

摘要

We propsoe a non-linear model reproducing the unidirectional (quasi)pendular moton of pressurized water reactor (PWR) core barrel (CB), which is in intermittent contact with reactor pressurevessel (RPV) in places of lower fastenings. Analtyic formulae are obtained, which allow one to elucidate the infleunce of reactor parameters on the character of motion. We show by the example of the WWER-1000 reactor that, in the framework of our model, there exists a possibiltiy of chaotic pendular oscillations in the certain region of three parameters, namely, (i) the pendualr oscillation frequency, (ii) the resulting force acting on the CB at the main circulation pump (MCP) frequency from the coolant flows of opposite legs, and (iii) the clearance between the CB and RPV.