No abstract

No abstract

A seismic qualifi cation database being developed on the basis of proper experience and a large volume of results obtained in previous works (more than 5000 pieces of inspected equipment) can increase the effi cacy of computational-experimental evaluation of the seismic resistance of the equipment in commissioned power-generating units at NPPs and power units with extended service-life. The set of parameters to be included in the database and the structure of the database were determined on the basis of previously developed criteria and methods of reducing the labor intensiveness of the computational-experimental evaluation of the seismic resistance of the equipment in NPPs. The database can be used to systematize and colligate the results of computational-experimental examinations and to evaluate the seismic resistance of equipment by indirect methods.The computational-experimental substantiation of seismic resistance and stability against external actions is important for the safety of the equipment in NPP power-generating units which are being commissioned or whose service-life is to be extended. The proposed determination of the proper dynamical characteristics during assembly, disbracing, and pipeline bracing is regulated by federal regulatory documents and an industry regulatory and procedural document and is recommended by IAEA standards [1-7].The computational-experimental substantiation of the seismic resistance of equipment includes the following stages: 1) study of the design documentation pertaining to the equipment and system; 2) visual inspection of the equipment and evaluation of its conformity to the design specifications for assembly and disbracing;3) experimental determination of the dynamical characteristics of the equipment for the conditions of the plant systems; 4) development of computational models of the equipment on the basis of the installation blueprints and refined data on disbracing and bracing of the equipment; 5) calculation for seismic resistance of standard equipment and sections of pipelines; comparison of the computational results with the design validation; and 6) development of measures directed toward bringing the equipment up to the required level of seismic resistance. A significant volume of data on equipment certified for seismic resistance has now been accumulated: more than 5000 pieces of pipeline fixtures, pumps, heat-exchangers, backup diesel power plants and others at the stage of commissioning and service-like extension of NPP power-generating units. The data contain the design documentation, the physical and working parameters of the equipment, the results of dynamical tests and calculations, and technical solutions for the required

The classical problem of stability of a pipeline section with fluid flow is considered in this paper. The equation of perturbed motion is solved by a method of expansion by forms of natural oscillations with further application of the Bubnov — Galerkin method. The boundary of the stability domain on the plane of fluid flow parameters is determined using the Raus — Hurwitz criterion for non-conservative stability problems. For fixed values of the relative mass, the trajectories of characteristic indicators are constructed as functions parametrically dependent on the velocity of the fluid flow. The frequency of pipeline oscillations in the event of loss of stability is determined by the flutter type. Flutter modes at various points of the boundary of the stability domain are examined. Flutter modes are represented by a beam of curved axes of the pipeline at discrete points of time throughout one period.

No abstract