Preparations are underway in the Paks II. project in order to start the construction of the baseplate of the nuclear island of Unit 5 the with the first concrete pour at the end of this year. To this end, the experts have carried out a mock-up test, i.e. a 1:1 construction of a smaller excerpt of the reactor building's baseplate, which has the size of around 4x8 m and is 3 m thick. The purpose of the test, which was carried out in the presence of the professionals of the Hungarian Atomic Energy Authority, was to model the construction, in particular the mass concrete nature of the thick structures. The volume of work carried out on the external site is illustrated by the fact that 6 m³ of sub-base concrete, 90 m³ of concrete, 26 tonnes of rebar and half a tonne of tie wire were used to make the model of the base plate.

Prior to the mock-up test, a smaller 3×3 m „pre-mock-up concrete block” was also prepared to identify any possible defects and deficiencies.