In the FIGES NT Department, thermal hydraulic analyses of nuclear components, design and safety analyses are carried out. In this context, the flow characteristics of cooling cycle, stress analyses, seismic analyses, vibration and fatigue analyses, dispersion analyses, aircraft impact analyses and system behavior in the post-accident phase are investigated by computational tools using appropriate numerical methods.
In recent years, the growing demand for advanced nuclear reactor safety analyses has led to a rapid development of methods for multi-dimensional thermal-hydraulic analyses. These methods have become more and more complex in order to take into account the expected physical phenomena under steady-state conditions and time-dependent reactor conditions. There are various software and codes used for advanced thermal-hydraulic calculations throughout the world.
Objectives of subchannel analysis;
- Determination of fuel temperatures
- Determination of the temperature of the fuel claddings
- Detection of coolant temperatures
- Flow area calculations
Analyses of System Elements
Thermal-fluid analyses are carried out for a large part of the elements forming the nuclear reactor system. These analyses can be performed with using ANSYS software for steam generators, circulation pumps, passive cooling systems, pressurizers and pipes used in fluid transport by FIGES NT department.
CFD (Computational Fluid Dynamics) is the most appropriate tool for complex flow analyses, such as Nuclear Systems. However, it should be kept in mind that the use of this tool requires knowledge, attention and experience in identifying appropriate boundary conditions, creation of mesh and correctly interpreting the results.
The following calculations can be made for the Nuclear Power Plants with CFD analyses in the NT department;
- Steady state or time dependent fluid behavior
- Pressure, velocity and temperature distributions
- Heat transfer calculations
- Single and multi-phase flows
- Radiological fallout analyses
Design based or beyond design safety calculations and accident scenarios for nuclear power plants are carried out by the thermal hydraulic codes and structural analyses of the reactor. By using thermal hydraulic codes, the safety calculations can be made for loss of fluid circulating the reactor due to a large or small fractures or leaks which may take place in any part of the reactor. The structures of the power plant are analyzed for resistance to any aircraft crash and this ensures the safety of the reactor building.
Design and modeling of nuclear system elements such as reactor vessel, steam generator and pressurizer are made. Various software and simulation tools are used for design improvements and increasing the performance of these elements. In addition, structural strength analyses of all pressure vessels in the system, fatigue analyses of moving and stationary system parts, seismic analyses of the nuclear power plant site and acoustic analyses are also performed.
Technical Support Organization-TSO
Since 2007, the Secretariat of the International Atomic Energy Agency (IAEA) has been encouraging Member States to establish Technical and Scientific Support Organizations (TSOs) in the light of Strengthening of Nuclear Safety principles as required by the previous General Conference resolutions.
Following discussions with Turkey nuclear licensing organization during 2017 and 2018, contacts have been established with German Federal Organization for Reactor Safety (GRS) and steps are determined in the aim of bringing FIGES to the level of TSO of Turkey in nuclear safety.
In order to become a TSO, the necessary infrastructure works within FIGES are started and preparations are made for further steps. Thus, the relevant departments, especially the Nuclear Technology Department ” in FIGES will be able to provide technical support in the safety analysis and licensing procedures of nuclear reactors and other facilities in Turkey taken as basis the “nuclear safety culture”.