On February 20, an earthquake of 6.4 magnitude occurred in Hatay. After the earthquake felt in Mersin, no abnormality or damage was detected as a result of the rapid investigation in the Akkuyu NPP site. Construction and assembly works in the field continue. All stages of construction at the Akkuyu NPP site are closely monitored by independent inspection organizations and the Turkish Nuclear Regulatory Authority (NDK), the national regulatory agency.
The Mobilization Unit and the Civil Defense and Emergency Situations Unit, which are the emergency units of AKKUYU NÜKLEER A.Ş, cooperate with the Turkish Ministry of Interior Disaster and Emergency Management Presidency (AFAD). AKKUYU NÜKLEER A.Ş continues to support those affected by the earthquakes in the Republic of Turkey.
Information note: Akkuyu NPP site is located in the fifth degree earthquake zone, which is considered the safest according to the earthquake zones classification in the “Turkey Earthquake Map” prepared by AFAD. According to the observations made in the region, no major and destructive earthquakes have been observed in the 50 km area around the site during the observation history. However, the design of the Akkuyu NPP project was made according to the maximum earthquakes of magnitude 9. During the construction of the NPP, seismic activities are regularly monitored. There are 2 seismic measurement stations inside the site. There are 40 more in an area of 12 kilometers. The data received from the stations are collected and transmitted to the Turkish data processing center of the Kandilli Observatory and Earthquake Research Institute (KRDAE). Analysis of the seismic activity at the site is done to clarify and verify the terrain parameters. All buildings and structures on site are designed for specific loads depending on their category. If during monitoring it turns out that the parameters have changed according to the design, a recalculation will be made immediately and, if necessary, measures will be taken to strengthen certain structures.
In the period from 2011 to 2017, a series of engineering studies were conducted at the Akkuyu NPP site in line with the modern requirements of the legislation of the Republic of Turkey, the Russian Federation and the recommendations of the IAEA. These studies were carried out in regional areas (within a radius of 300 km), nearby areas (within a radius of 25 km), adjacent to the construction site (within a radius of 5 km) and where the nuclear power plant is located.
In order to verify the reliability of the information and to eliminate the possibility of error, studies on earthquake threat were carried out by four independent research groups: Boğaziçi University Kandilli Observatory Earthquake Research Institute (Turkey), Russian Academy of Sciences - World Physics Institute (Russia), Worley Parsons (Europe) and RIZZO (US). Studies have confirmed that the parameters of the Akkuyu field comply with all current legal requirements for the construction of a nuclear power plant.
Following the reassessment of nuclear power plant designs following the Fukushima incident, additional tests were conducted for earthquakes exceeding the Maximum Design Earthquake (MDE) for Akkuyu by 40%. Evaluation results show that main systems, structures and equipment have sufficient reserves to absorb MRZ earthquake loads and are resistant to MRZ+40% loads. The containment shell will remain tight in such an impact and the reinforced concrete structures of the reactor building will remain intact. As a result of a seismic effect of MRZ+40%, there is no release of radioactive materials out of the enclosure shell.
The main buildings and structures of Akkuyu NPP are at an altitude of 10,5 m above sea level. At the same time, the height of the protection dam under construction will be +12,5 m above sea level. A number of engineering protection measures at the Akkuyu NPP construction site provide protection from the effects of precipitation, mudflows and flooding, as well as rising sea levels.
In accordance with current requirements, the Republic of Turkey National Report on stress testing of Akkuyu NPP has been prepared for evaluation by Ensreg, the European Nuclear Safety Inspection Group. According to the report, the Akkuyu NPP design has a reserve of 1 m for world sea level rise during the entire life cycle of global warming. At the same time, the project considers the possibility of a combination of factors including sea level rise, wind wave formation, tides, storm surge, barometric effects and seasonal fluctuations in water levels. As a result of considering the combination of these factors, the Akkuyu NPP site will also be protected in case the sea level rises by 8,63 m. Considering the effect of the hydraulic structures of the facility in the open sea, the maximum height of a potential tsunami in the region where the NPP construction site is located, according to the calculations, such a tsunami is predicted to be up to 10.000 m with a probability of only once in 6,55 years.