DELISA-LTO (DEscription of the extended LIfetime and its influence on the SAfety operation and construction materials performance - Long Term Operation with no compromises in the safety) is a project under call HORIZON-EURATOM-NRT-01. The project with four years of duration (2022-2026) is focused on WWER (eastern) type reactors. The DELISA–LTO Project brings opportunity to obtain components from the selected decommissioned Nuclear Power Plants (NPPs) and analyze them. The main aim of the DELISA-LTO Project is to test these materials and study the thermal ageing phenomena. Testing of the harvested material subjected to real operating conditions is promising opportunity to acquire new information about material degradation in real operated NPPs. Obtained information will be important to assure Long Term Operation (LTO) in case of lifetime extension NPPs which are currently in operation.