Radioactive Waste – The Safety of Disposal Facilities

A radioactive waste disposal facility must be designed and operated to protect people and the environment from the risks associated with the waste. The achievement of this objective is based on three main functions:

• isolation of waste from the environment readily accessible to man, the biosphere;

• containment of radionuclides contained in waste ;

• limiting water circulation in storage.

Whether for surface or deep disposal, the safety approach is developed by considering the following aspects:

• compliance with essential safety principles for the design of the storage system, in particular to ensure that the above-mentioned safety functions are carried out as effectively as possible in all conceivable circumstances;

• analysis of the safety of the storage system, which consists of assessing the appropriateness and effectiveness, in terms of safety, of the provisions implemented with regard to the aforementioned principles;

• radiological risk assessment for various possible situations.

The safety of a surface disposal facility, a concept used in several countries, is based on a three-barrier system: the waste packages, the storage structures and the site. Confidence in safety depends on quality assurance of the barriers, and on their monitoring and maintenance.

Assessing the safety of a deep geological repository depends first and foremost on the quality of the site and the design and construction of the structures, and secondly on the quality of the safety demonstration. Given the limited time available for monitoring and maintenance, confidence in safety will depend on the implementation of several robust barriers playing complementary roles to ensure that the main safety functions remain assured. The same applies to subsurface disposal of low-level, long-lived waste, where the isolation function is particularly important.