Climate changes, ice ages, human intrusions, changing of host rock properties, crack-formation, water ingress and others may have effects on the integrity of the waste package.

The design of the repository has to fulfil fundamental SAFETY CRITERIA:

  • REDUNDANCY which is provided by a MULTIPLE BARRIER system
  • DIVERSITY by a COMBINATION of natural and technical barriers
  • The FAIL SAFE criterion for passive systems like barriers must be fulfilled by ROBUSTNESS
  • To mitigate the consequences of damages from COMMON MODE FAILURE two measures can be foreseen:
    • a limitation of activity inventory per each waste package and
    • spatially separated disposal

Safety requirements include

  • continuous optimization of the waste disposal concept from planning to final closure of  the repository (in the extreme case of total reversibility: take-out the canisters)
  • retrieve ability of waste packages during operation time of repository as well as
  • control and safety system for the time post closure: identification of a waste package
  • recovery by miners for long years after final closure (German Safety Requirements: 500 years)

Nevertheless, for a given site, many “what if’s” and uncertainties exist, considering a timeframe of 1 Mio years.

In the case of water access corrosion takes place with loss of integrity, chemical reactions with canister surface, hydrogen generation, crack formation …