The most critical challenge in the nuclear industry is the safe long-term operation of existing nuclear power plants (NPPs) and the development of new, safe, and efficient NPPs. Ensuring safety requires effective aging management. The identification of structural degradation caused by aging in the internal components of light water reactor (LWR) pressure vessels will become increasingly important as the average age of NPPs worldwide continues to rise. This is also essential for predicting the long-term durability of newly developed nuclear power plants.
The project “Safety Enhancement of Reactor Pressure Vessel Internals (SAFE-Rx)” aims to address the growing issues related to reactor pressure vessel internal components, which have led to an increased number of failures over the past decade. The main objectives of the project are to provide comprehensive information on flow fields and the dynamic response of reactor internal components to these flows, in order to manage degradation mechanisms in both existing and newly designed nuclear power plants.
Within this project, it is planned to develop high-resolution, high-accuracy numerical solution methods based on the finite element method (FEM) for investigating vibrations of reactor internal components, taking into account fluid–structure interaction (FSI). The finite element models will be validated using experimental data obtained under real reactor operating conditions.
For potential participation in the SAFE-Rx project, the following equipment is being procured:
“Functional upgrade of a high-speed stereo digital image correlation (3D-DIC) system with synchronized residual stress and temperature measurements.”
The equipment to be acquired, “High-Speed Stereo Digital Image Correlation (DIC) System with Synchronized Residual Stress and Temperature Measurements (VIC-3D Blue-Falcon ReSA System; VIC-3D High-Speed DIC System; VIC-3D Infrared DIC System)”, will significantly expand the university’s experimental research infrastructure and enable high-resolution dynamic measurements.
The equipment package includes:
• a Residual Stress Analysis (ReSA) system with an automatically controlled translation stage,
• an extended infrared (IR) measurement system,
• and expansion modules for a stereo high-speed camera system.
This equipment will be fully integrated into the existing 3D-DIC system, forming a unified experimental research platform.
Residual stresses and associated thermal effects are among the most critical factors influencing the mechanical behavior, durability, and lifetime of materials and structures. Their impact is particularly significant under cyclic loading, vibration, thermal loads, and aggressive service environments. Therefore, the ability to synchronously measure strain, residual stress, and temperature at high acquisition rates is essential for advanced scientific and applied research in fields such as:
• energy,
• transportation,
• aerospace,
• mechanical engineering,
• and additive manufacturing.
Currently, neither the university nor Lithuania possesses an equivalent integrated system that enables high-resolution residual stress measurements using the hole-drilling method in combination with a 3D-DIC system, while simultaneously capturing dynamic and thermal processes. Such methodology is used in leading laboratories worldwide and is considered one of the most accurate and versatile approaches for residual stress analysis in isotropic and anisotropic materials and structures, including:
• hybrid composites,
• coatings,
• welded structures,
• and additively manufactured materials, where thermal processes induce significant internal stress states.
The acquisition of this equipment will significantly strengthen the quality of ongoing and planned research activities and will enable the development of new research directions. This is particularly important in the context of international collaboration.
For example, partners within the ECIU network, such as INSA (Institut National des Sciences Appliquées), are conducting projects focused on additively manufactured structures, which require precisely such measurements of residual stresses and dynamic deformations. The acquired system will enable the university to actively participate in such initiatives and strengthen its position in international consortia.
Project funding:
The project is financed with the funds of the Economic Recovery and Resilience Facility under the “New Generation Lithuania” plan and with the funds of the state budget of the Republic of Lithuania.
Project results:
Project Outcomes
• To acquire the measurement system “Functional upgrade of a high-speed stereo digital image correlation (3D-DIC) system with synchronized residual stress and temperature measurements” in order to enhance R&D activities and competitiveness;
• To expand the university’s experimental research infrastructure, enabling high-resolution measurements of dynamic processes;
• To develop a methodology for synchronized high-speed measurements of strain, residual stress, and temperature;
• To develop a methodology for high-resolution residual stress measurements while simultaneously capturing dynamic and thermal processes;
• To develop a non-invasive monitoring system capable of capturing the dynamic response of internal components under flow-induced vibration loading;
• To actively engage in scientific research in the field of advanced measurement technologies and strengthen the university’s position in international research consortia.
The acquired equipment also has clear applied potential in collaboration with industry. Together with the KTU Ultrasound Institute, R&D activities are being carried out for Lithuanian Railways in the field of rolling stock lifetime assessment. Companies such as Astra LT and Carlsen Baltic have expressed a need to investigate the impact of residual stresses generated during welding on structural reliability. Until now, due to the lack of appropriate measurement infrastructure, it has not been possible to perform certain complex investigations. The acquisition of this equipment will therefore fill a critical technological gap.
The selected approach for upgrading the equipment is rational and economically justified, as it involves a targeted functional extension of the existing 3D-DIC system rather than a complete system replacement. This ensures:
• optimal use of existing resources,
• reduced investment costs,
• and compatibility with existing laboratory infrastructure.
The acquired advanced equipment complies with international research standards and provides the capability to perform state-of-the-art experimental research, competitive with leading laboratories worldwide.
Period of project implementation: 2026-04-20 - 2027-01-31
Project coordinator: Kaunas University of Technology
