Nuclear energy plays a fundamental role in significantly reducing greenhouse gas emissions and in improving independence, security and diversity of energy supply throughout Europe.
nuclear energy in europe
60% of Generation II and III reactors in Europe have almost reached the end of their lifetimes. Immediate replacement is not an option, yet operations must be sustained over the next several decades until the deployment of Generation IV reactors.
long term operation
Long Term Operation (LTO), the lifetime extension of nuclear power plants to or beyond 60 years, is common practice in countries with established nuclear programmes and a means of achieving intermediate decarbonisation targets.

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.

ensuring safety

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 tools

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.

previous research

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.

remaining issues

Though significant progress was made in previous projects, continuous research is essential to addressing several remaining issues.

Non-consensus on the embrittlement damage mechanisms and the influence of chemical elements causing RPV embrittlement at high fluences

The applicability of sub-size specimen testing methods for assessing LTO safety need to be validated due to limited availability of surveillance materials

Need to validate existing prediction tools for LTO beyond 60 years

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.