Additional safety measures will be introduced to the current safety system of NPP that enables operation to run safer. As a result of the severe accident in Fukushima Dai-ichi Nuclear Power Plant in 11 March 2011 the European Nuclear Safety Regulators Group (ENSREG) made a decision to carry out “stress tests” in all European nuclear power facilities.

This review process in Hungary is officially referred to as Targeted Safety Re-Assessment (TSR). According to the requirements of the TSR, Paks NPP was obliged to prepare a project called Prevention of overpressure of the containment (containment: the reactor vessel and the adjacent steel and concrete elements in the reactor building) where MVM ERBE Ltd. (member of the MVM Holding) is the project leader, as EPC Contractor.

After the flooding of the reactor cavity, the residual heat of the molten core in the reactor pressure vessel warms up the coolant in the cavity by heat transfer trough the wall of the vessel. As the evaporation rate of the coolant increases, the quantity of steam in the containment also raises. If the sprinkler (water-based operation) system is not operable, the containment pressure will gradually increase.

Following a long preparation phase (conceptual design, final implementation design, licensing and authorization process as well as the procurement and manufacturing process) the project officially entered the execution phase in 2021. As of August 2022, an important milestone was passed when 2 sets of air coolers and their steel structures were lifted on the top of the reactor buildings (Block 2 and 3). Such works will be carried out in Block 1 and 4 in 2023. The project life cycle will end in 2024.

Photo: MVM Paks NPP Ltd.