Methods of the Strength Computation for the Covers, Bottoms, Assemblies and Elements of the Structure of Steam Generators Used by the Two-Loop Nuclear Power Plants with BBEP-1000 Reactors

Abstract

This scientific paper gives a review of the available methods and approaches used for the strength computation of the covers, bottoms, assemblies and elements of the structures of steam generators of the two-loop NPPs with BBEP-1000 reactors. For most assemblies and elements of the structures of steam generators of NPPs, the main strains arising in them are the consequences of the uniform internal and external pressures. However, in many cases the assemblies and elements of the structures of steam generators of NPPs can also be exposed to additional loads (weight loads, efforts and moments that result from nonhomogeneous thermal expansion of different parts of steam generator, etc.). The values of the strains caused by additional loads can sometimes exceed the value of the main strain. These can be decreased by the arrangement of additional supports or compensators or by changing the structure configuration. Sometimes, it is reasonable to increase the wall thickness of the calculated elements of the structures in order to reduce the strains caused by additional loads. Before getting to the strength computations for the assemblies and elements of the structures of steam generators we need to define first the character of the external loads on them (constant or cyclic load) and the deformability of their structural materials (ductile material, brittle material or limited plasticity material) and then to select the method for their strength computation. To provide a reliable operation of the steam generators of NPPs it is important to provide appropriate strength characteristics for all its assemblies and elements. These elements include process pipelines that are connected to the steam generator structure. These represent a spatially branched pipeline systems of a different technological purpose whose structures are supported by special fastening elements (the supports of different types, spring suspenders, etc.). The strength computations done for such systems include static and cyclic strength computations, seismic action computations, etc.