The staged, passively functioning engineered barriers contribute to the post-closure safety of the deep geological repository (Explanatory Report on the General Licence Applications, NTB 24-12, Chapter 5).

The engineered barriers contribute to the containment, immobilisation and retention of radionuclides (Sicherheitsbericht (“Safety Report” (in German)), NTB 24-01, Section 4.2). The majority of radionuclides decay within the engineered barriers (Sicherheitsbericht (“Safety Report” (in German)), NTB 24-01, Section 4.6.1).

The engineered barriers are made up of the waste matrix, disposal canister, and the backfill and sealing system. The staged, passively functioning engineered barriers are important for the post-closure safety of a deep geological repository (Post-Closure Safety Report, NTB 24-10, Section 6.1). Together with the Opalinus Clay, they ensure that the protection criteria are met with regard to the expected evolution, also when considering alternative conceptualisations and hypothetical assumptions (Post-Closure Safety Report, NTB 24-10, Chapter 8). The engineered barriers are designed in such a way that, each forming an element of a multi-barrier system, they ensure optimum performance.

In accordance with the regulatory requirements of the Swiss Federal Nuclear Safety Inspectorate (ENSI) set out in ENSI pdf Guideline G03(590 KB) , the disposal canisters for high-level waste will completely contain the waste for at least one thousand years (Design and Performance Assessment of Disposal Canisters for High-Level Waste, pdf NTB 24-20, Chapter 6(15.88 MB) ).

The understanding of the performance, functioning and expected evolution of the engineered barriers has a solid scientific and technical foundation (Synthesis of the Performance Assessment for a Deep Geological Repository for Radioactive Waste, pdf NTB 24-22, Chapter 3(53.01 MB) ).