An important area in activities of the State Scientific and Technical Center for Nuclear and Radiation Safety (SSTC NRS) is computer analysis of reactor transient and emergency modes and further strength calculations for individual reactor components under these modes. Implementation of the qualitative engineering analysis at the enterprise is provided by used computer codes. They include, in particular the ANSYS software package, whose tools allow solving a whole range of engineering challenges: simulation of neutronic processes, issues of thermohydraulics, structural analysis, seismic strength, etc.
During the workshop on new ANSYS-2019R1 version, which was held in late March in Kyiv, developers and users showed the capabilities of ANSYS computer functionality to solve specific issues in various engineering areas. The experts familiarized visitors with new technologies and tools for computer simulation of stress-strain and thermal state, liquid and gas flows, low and high frequency electromagnetic phenomena, as well as aspects of geometric modeling.
Representatives of SSTC NRS, Paton Electric Welding Institute of the National Academy of Sciences of Ukraine, National Technical University “Kharkiv Polytechnic Institute”, Energoatom, Pivdenne Design Office shared the experience on practical use of the products.
SSTC NRS researcher Marat Mustafin and Head of the NPP Lifetime Department of the Paton Electric Welding Institute Volodymyr Diemienkov presented the concept of an integrated approach to assess the integrity of NPP primary equipment and piping using correlated calculations in ANSYS and Relap Code.
At the first stage of the presented approach, the experts developed a global finite element model of reactor equipment and piping, which allows analyzing the stress-strain state taking into account distribution of the main environmental parameters for selected nonstationary operation modes. The model was validated and parametrically correlated to Relap5 used in SSTC NRS. The second stage was based on an example of safety valve integrity assessment taking into account nonstationary force factors defined at the first stage.
The idea to develop such an “integrated” approach is primarily caused by the need to justify lifetime extension for reactor equipment at Ukrainian NPPs, taking into account rapid development of the capabilities of the used software packages.
According to experts, the related calculations allow simulation of any nonstationary emergency processes and provide a comprehensive approach, which in turn allows obtaining a realistic stress-strain state of the studied reactor components for further analysis.