EURAD-2 - Deliverable 7.2 - Representative conditions and identification of the key parameters influencing the long-term behaviour of LL-ILW

EURAD2_WP7 L’OPERA Task 3 aims to identify and evaluate the representative environmental conditions of disposal facilities for the long-term management of low- and intermediate-level waste (LILW). This involves understanding the key parameters that influence the durability and stability of various waste matrices and waste forms and characterising the environmental conditions prevailing in disposal facilities. The deliverable begins with an introduction Section 1, outlining the scope and objectives of L’OPERA and Task 3. Section 2 provides a concise overview of the radioactive waste disposal strategies employed by partner countries. This summary aids in selecting the appropriate boundary conditions that align with the scope of L’OPERA for assessing the durability of waste forms and waste matrices. Section 3 outlines waste acceptance criteria in partner countries and their national requirements for the stability of matrices and waste forms relevant to the system being investigated in WP7. Section 4 summarises the key parameters of waste forms and representative conditions of disposal facilities for the long-term management of LILW to be considered in L’OPERA: • Section 4.1 emphasises the importance of durability in matrices and waste forms, focusing on properties to be investigated in L’OPERA from the perspectives of chemical, physical, and mechanical properties. This highlights the need for waste forms to resist chemical reactions between waste and matrices, as well as between waste forms and the environment, to prevent radionuclide release. Physical integrity is another critical aspect, with studies assessing factors such as porosity, density, homogeneity, and resistance to structural alterations. Waste forms must withstand environmental conditions, such as temperature fluctuations, humidity, and radiation, over extended periods. Mechanical durability is also crucial, with evaluations focusing on the compressive strength, flexural strength, and resistance to mechanical stress. Ensuring that waste forms retain their structural integrity under anticipated load conditions is essential for long-term containment and confinement. • Section 4.2 presents the characterised representative conditions of disposal facilities, focusing on key geochemical parameters for leaching tests and long-term environmental conditions for ageing tests. These conditions are critical for understanding how waste forms interact with their surroundings and ensuring their long-term stability. These findings serve as a basis for proposing protocols for Task 5, which focuses on waste form durability and stability testing. The conclusion, presented in Section 5, offers recommendations for defining experimental protocols and procedures. Furthermore, several perspectives for future research are included. In summary, EURAD-2 WP7 T3 provided valuable insights into the key parameters influencing the long- term behaviour of waste forms and matrices. These findings underscore the importance of chemical, physical, and mechanical stability, as well as the need for standardised protocols and collaborative research to ensure the safe and effective management of radioactive waste.