This paper describes the reliability analysis of a concrete containment for VVER 440 under a high internal overpressure. The probabilistic safety assessment (PSA) level 3 aims at an assessment of the probability of the concrete structure failure under the excessive overpressure. The non-linear analysis of the concrete structure was considered. The uncertainties of the loads level (long-time temperature and dead loads), the material model (concrete cracking and crushing, behavior of the reinforcement and liner), degradation effects and other influences following from the inaccuracy of the calculated model and numerical methods were taken into account in the response surface method (RSM). The results of the reliability analysis of the NPP structues are presented. and Obsahuje seznam literatury
The paper presents the solution to the geodetic boundary value problem by the finite element method in area of Slovak Republic. Generally, we have made two numerical experiments. In the first one, Neumann BC in the form of gravity disturbances generated from EGM-96 is used and the solution is verified by the quasigeoidal heights generated directly from EGM-96. In the second one, Neumann BC is computed from gravity measurements and the solution is compared to the quasigeoidal heights obtained by GPS/leveling method.
This paper describes the probabilty analysis of reinforced concrete containment structure of NPP with the reactor VVER V-230 under high internal overpressure. The summary of calculation models and calculation methods for the probability analysis of the structural integrity in the case of the loss of coolant accident (LOCA) is showed. The probabilistic structural analysis (PSA) level 2 aims at an assessment of the probability of the concrete structure failure under excessive overpressure. In the non-linear analysis of the concrete structures a layered approximation of the shell elements with various material properties have been included. The uncertainties of longtime temperature and dead loads, material properties (concrete cracking and crushing, reinforcement, and liner) and model uncertainties were taken into account in the 106
direct MONTE CARLO simulations. The results of the probability analysis of the containment failure under excessive overpressure show that in the case of the LOCA accident at overpressure of 122,7 kPa the probability is smaller than the required 10-4 for design resistance. and Obsahuje seznam literatury
The influence of water environment on natural frequencies of a Francis pump-turbine runner with the shaft is analyzed. The computations are executed by ANSYS program package based on finite element method. The fluid ‘equivalent mass‘ matrix concept is used. For solution, the Euler approach is used. Obtained natural frequencies and vibration mode shapes of the turbine runner with shaft in vaccum, in air and in water are presented. Computed natural frequencies and vibration mode shapes of the turbine runner with shaft in vacuum are compared to computed natural frequencies and vibration mode shapes of the turbine runner without shaft. and Obsahuje seznam literatury