Validation of Monte Carlo Activation Calculation for V1 NPP Reactor Concrete Shaft

29th Symposium of AER on VVER Reactor Physics and Reactor Safety (2019, Energoland, Mochovce NPP, Slovakia)
[2] reactor physics experiments and code validation


Michal Šnírer, Kristína Krištofová, Gabriel Farkas, Vladimír Slugeň


The aim of this work was to create a model of the VVER-440/V-230 reactor in the MCNP code, to calculate the induced activity in ex-vessel structural components and to validate obtained results. The internal reactor components, reactor pressure vessel and external shielding of the V1 NPP reactor were examined and the material composition of the individual components was determined on the basis of available documents. At the same time, material vectors of components entering the physical model were determined. A survey of the V1 reactor operating history revealed that after 12 campaigns shielding assemblies were introduced into the core due to the gradual radiation embrittlement of the pressure vessel, thereby reducing the core and reducing the neutron flux density in the sample volume area. On this basis, representative campaigns were set up for given time periods. A model of the V1 reactor at the core level was created, taking into account the specifics of the V-230 type. At the same time, the choice of the method of scatter reduction was taken into account, which was also reflected in the creation of the geometric model. Based on the proposed methodology, the activation of the reactor concrete shaft at the sample volume location was performed using the MCNP5 with the ENDF/B-VII.1 cross section library. The activities of selected radionuclides were determined based on which it was possible to verify the correctness of the results with respect to the measurements of samples performed by Wood Nuclear Slovakia s.r.o. and measurements performed at the UJFI FEI. The conformity of the calculated values with the measured values demonstrates the correctness of the calculation model. In this way, the validation of the MCNP model for calculating the induced activity of the reactor components of the V1 NPP was achieved.