MIPT and U.S. Partners Develop Precise Method for Calculating Nuclear Power Plant Seismic Resistance

Recently, the Science Communication Center of the Moscow Institute of Physics and Technology (MIPT) reported that Russian and American researchers have jointly developed a method capable of precisely calculating the seismic resistance of nuclear power plants, taking into account the heterogeneous structure of reinforced concrete, including the presence of individual rebar within walls and domes. The new method helps improve nuclear power plant safety by accounting for differences in how different types of seismic waves act on reinforced concrete.

Alena Favorskaya, a lead researcher at MIPT, stated that the study explicitly identifies metal rebar as heterogeneities in the computational domain rather than averaging them; the grid-characteristic method on Cartesian and curvilinear grids allows arbitrary specification of object geometry, variation of reinforcement ratio and seismic load type, while correctly calculating multiple reflections of elastic waves within the structure. Scientists noted that after the 2011 Fukushima Daiichi Nuclear Power Plant accident, improving the seismic resistance of nuclear power plants became a key issue in nuclear safety; the high cost of bench tests has driven the acquisition of information through computer modeling.

It is reported that past calculation results were insufficiently accurate because the interaction properties of longitudinal waves and transverse waves with concrete and steel differ significantly, and rebar in concrete often acts as a wave reflector, producing multiple reflections, which had not been fully considered previously. To address this, researchers adopted the grid-characteristic method and divided models into two types of grids based on the geometry of different nuclear power plant components, saving computational resources without reducing calculation accuracy. Using this method, scientists created computer models of reinforced concrete nuclear power plants with three different reinforcement ratios and tracked the effects of two types of seismic waves.

The calculations revealed differences in the nature of strong and weak earthquakes acting on nuclear power plant foundations, and indicated that damage caused by longitudinal and transverse waves has different characteristics. For example, transverse waves damage a larger foundation area, but longitudinal seismic vibrations are more dangerous to the integrity of the reactor compartment. It is reported that understanding these differences helps design more reliable nuclear power plants and invest an optimal amount of resources in construction, thereby enhancing the safety margin of nuclear power facilities under seismic conditions.