Tests of the reactor building containment for strength and tightness have been completed at unit 1 of the Akkuyu NPP under construction by Rosatom in Türkiye. Experts tested the ability of the structure to withstand the loads stipulated by the project design and to maintain tightness when pressure increases in emergency situations.
The tests were carried out continuously for eight days. To test the strength, the air pressure inside the containment was gradually increased to 0.46 MPa. This is 15% higher than the design pressure of 0.4 MPa, for which the tightness of the structure was assessed. At the peak of the pressure set, the load on each square metre of the containment surface was equivalent to the weight of a cargo weighing about 47 tonnes. After reaching the maximum level, the pressure was gradually reduced. At all stages, specialists monitored the condition of the shell – the stresses arising in it and changes in shape and size under load.
The programme checked the tightness both at high pressure and at rarefaction (below atmospheric pressure). The test results confirmed that the structure fully meets the design requirements for strength and tightness and is able to withstand excessive internal pressure.
“A series of control tests is being carried out sequentially at unit 1. The equipment, structural elements, and security systems are being checked,” said Sergey Butskikh, Director General of project company Akkuyu Nukleer. “We have successfully tested the main protective barrier of the power unit. The results confirm the high quality of the work on the construction of the sealed shell and allow us to move on to the next stage of pre–commissioning in the near future – the cold and hot running-in of the reactor plant.”
The double containment is one of the design features of power units with VVER-1200 reactors. The inner containment surrounds the main equipment of the reactor plant and serves as a barrier preventing the release of radioactive substances into the environment. Strength is provided by a reinforced concrete structure with a prestressing system with reinforced coils, and tightness is provided by an internal steel lining. The outer containment is formed of reinforced concrete and is designed to withstand extreme external influences: earthquakes up to magnitude 9, tsunamis, hurricanes, and combinations thereof.
Akkuyu NPP will eventually host four Russian-designed VVER-1200 reactors. The pouring of first concrete for unit 1 took place in April 2018, for unit 2 in June 2020, for unit 3 in March 2021, and for unit 4 in July 2022. Rosatom is constructing the reactors according to a build-own-operate model. Unit 1 is currently preparing for commissioning.
