Repository
Safety Design
According to the overall objective of radioactive waste management, human beings and the environment shall be protected from current and future impacts of waste disposal practises. To this end, the Vaalputs site has been selected by means of a regional survey and further detailed suitability and characterisation studies in accordance with internationally acceptable selection criteria.
A repository isolation concept is required that provides effective isolation from the biosphere for the duration of the operational and institutional control period, after closure of the repository. The current disposal concept for the LLW is near surface disposal consisting of near surface trenches located in the region above the groundwater table.
For Vaalputs reliance is placed on the multi-barrier systems approach where the site characteristics together with the waste packages all contribute to the isolation of the waste from the environment for time periods sufficiently long for radio nuclides to decay to acceptable levels.
The long-term safety performance of the repository takes cognisance of the defence in depth principle whereby the multiple barrier system (MBS) approach is incorporated. The MBS consists of two main components, i.e., the natural barrier system (NBS) and the engineered (man-made) barrier system (EBS). The quality of these barrier systems influences the long-term safety performance of the facility.
The institutional control period commences after repository closure and is assumed to be three hundred years for the Vaalputs near surface repository given the current operational constraints and source term.
- Provide a high level of operational and long-term safety.
- Allow a convincing demonstration of compliance with performance standards, thus ensuring public confidence in the disposal system.
- Ensure safety without placing excessive financial burdens on the current and future generations.
- Prevents or substantially delays movement of water or radionuclides toward the accessible environment.
- The repository system design incorporates the near field, geosphere, biosphere at Vaalputs as well as the manufacture and conditioning of waste packages at the predisposal operator’s site.
- Specify the maximum potential exposure to the highest exposed group of individuals amongst the public.
- Mandate the use of the “As Low as Reasonably Achievable” (ALARA) principle.
- Require the “defence in depth” principle to be implemented.
- Comply with international acceptable risk.
- Embracing the IAEA safety principles, fundamentals and guidelines.