Decoupling Criteria with respect to Structural response of aNuclear Power Plant Structure

摘要

An attempt has been made to study the structural response of calandria vault (CV) supporting the calandriaendshield assembly (CEA) of pressurized heavy water reactor (PHWR). The entire structure has been considered asa multi-degree of freedom system with coupled and uncoupled CEA with CV. It has been found that theacceleration level at the point of coupling the subsystem varies with the two models studied. However, the responseat the base of the structure does not alter significantly. The shear forces above and below the level of CEA aremodified locally with the presence of coupled CEA, but the overall response does not alter. It has also beenobserved that the mass of the structure above the CEA also plays a major role in altering the overall structuralresponse. In conclusion, the present study indicates, that, i) a detailed study for evaluating the de-coupling criteriaof structures and equipment has to be established based on the mass distribution of the structure above and belowthe point where the secondary system is to be coupled or decoupled; and ii) revision of codal specifications toinclude the mass distribution in primary system and multi-point attachment of secondary system with the primarysystem