Investigation of Thermal-Hydraulic Parameters Combinations Which Increase the Flow Induced Stresses in Nuclear Reactor Structures

摘要

The research results present the factors determining nature and a level of cyclic dynamic loads of NPP equipment and reactor internals. Paper show, that the dominant effects on the vibration level are imposed by the pressure oscillations of coolant under critical combination of thermalhydraulic and operating parameters. As an example of this phenomenon the number of operating regimes of WWER-1000 is analyzed. The analysis shows that the formation of defects in reactor lid unit of WWER-1000 reactor occurs at the definite unfavorable operating condition of reactor. The obtained results illustrate the existence of the concealed physical phenomena and processes in thermal hydraulic circuits of reactors, which can’t be foreseen in design and normative documents and not predicted by the thermal hydraulic computer codes. The approach is discussed to achieve service life prolongation, improvement of reliability and safety that could be of great importance for Space Reactor for Power and Thermal Propulsion