An Approach for Performance-Based Capacity Assessment of Prestressed Concrete Containment Vessels for Internal Accidents Application to VVER 1000 Containment Vessel

Abstract

A direct procedure is proposed for capacity assessment of prestressed concrete containment structures subjected to internal accident loads. The assessment procedure is based on graphical comparison between the structural capacity and the load intensity by plotting both parameters in the same “temperature gradient – overpressure” coordinate system. Furthermore, the capacity in terms of structural integrity and leak tightness is evaluated, corresponding to different limit states or performance levels. A new damage index is proposed in order to correlate the intensity of damages on the containment structure with the load intensity. The criteria for leak tightness and structural integrity are adopted for VVER-1000 containment structure. The ultimate pressure capacity, the failure mode and the capacity corresponding to different performance levels of the containment structure are assessed. The influence of the temperature load on the structure response is also studied. Conclusions are drawn on the VVER-1000 containment vessel overpressure capacity and its response to different design basis and severe accidents. The main failure mode and the critical zones of the structure are also determined.