SIMULATION OF TRANSIENT PROCESS ON WWER-1000 USING COUPLED APPROACH

Abstract

Research and modeling of thermohydraulic processes in NPP equipment is necessary for a deep and improved justification of reliable and safe operation of nuclear installations. Taking into account the accumulated experience and the latest technologies, the study of thermohydraulic processes is developing in the direction of applying innovative approaches to conducting both experimental studies and expanding the calculation capabilities of thermohydraulic codes. The article presents an approach to the decomposition of the thermohydraulic model of the WWER-1000 reactor plant on submodels, which are calculated in coupling with separate instances of the system thermohydraulic code RELAP5/Mod 3.2. Coupling is implemented using a specially developed module. This approach allows you to "bypass" the internal limitations of RELAP5 in the number of components (hydrodynamic volumes, thermal structures, "trips" and control variables) that can be used for computational analysis. As a result, it becomes possible to achieve a higher degree of detail for the entire reactor installation. In addition, the article confirms the possibility of applying the previously developed coupling module to such a non-equilibrium model as a nuclear reactor model. At the same time, the use of the RELAP5 model as a reactor model makes it possible to avoid inaccuracies that arise when applying assumptions about the transverse profiles of the input variables of the CFX model, as well as to perform the validation of the RELAP5 model of the RU loops. Coupled calculation of stationary and transient mode of reactor installation WWER-1000 is performed. The reliability of calculation results obtained in conjugation is evaluated by comparing them with the results of autonomous calculations in RELAP5. The analysis of the results of computational modeling confirms the possibility of applying the developed coupling module to such a non-equilibrium model as a model of a nuclear reactor, and also confirms the correctness of the RELAP5 model of the loops of the reactor plant obtained on the basis of the modification of the full-fledged RELAP5 model.