One main issue preventing LTO is the embrittlement of the Reactor Pressure Vessel (RPV), a non-replaceable component whose mechanical properties degrade over time. RPVs must be able to safely withstand both emergency and normal conditions for the extended period of operation.
Nuclear reactors must undergo thorough analyses and follow strict procedures to be approved for LTO. Complex prediction tools that take into account a variety of factors are used to determine the durability, resistance, and ultimately, the safety of RPVs.
Current prediction tools have been developed based on data generated from reactors with typical 40-year lifetimes. To determine the durability and resistance of RPVs with extended lifetimes, these prediction tools must be validated and adapted if necessary.
Several R&D efforts have been initiated at industrial, national and European levels to provide decision makers with relevant information and ensure safe Long Term Operation (LTO). A number of research projects in previous Euratom programmes specifically focused on RPV embrittlement and ageing mechanism issues.
Ageing management programmes and the implementation of regulator guidelines for extending the operating licenses of nuclear power plants up to 60 years were significantly improved.
Though significant progress was made in previous projects, continuous research is essential to addressing several remaining issues.
STRUMAT-LTO aims to fill remaining gaps to ensure compliance with safety standards and prepare decision makers for potential lifetime extensions of European nuclear power plants beyond 60 years.