GEOSAF Part II - demonstration of the operational and long-term safety of geological disposal facilities for radioactive waste
The International Intercomparison and Harmonisation Project On Demonstrating the Safety of Geological Disposal
Background - International intercomparison and harmonization projects are one of the mechanisms developed by the IAEA for examining the application and use of its safety standards, with a view to ensuring their effectiveness and working towards harmonization of approaches to the safety of radioactive waste management.
The international intercomparison and harmonization project GEOSAF project ran from 2008 to 2011 to work towards harmonization in approaches to demonstrating the safety of geological disposal with a special emphasis on the expectations from the regulatory authorities engaged in the licensing process with respect to the development of the safety case. The GEOSAF project focused on the safety case for geological disposal facilities, a concept that has gained in recent years considerable prominence in the waste management area and is addressed in several international safety standards (e.g. SSR-5, GSR Part 5, SSG-14, GSG-3).
On the request of the participants to the initial project, a follow- up project has been developed and the inaugural meeting of the new project – GEOSAF Part II - took place in IAEA headquarters from 19 to 23 March 2012. GEOSAF Part II was initiated with the objective to reach a joint understanding and work towards harmonization of views and expectations regarding the safety of the operational phase for geological disposal of radioactive waste with regards to post-closure safety. More specifically the approach taken in GEOSAF Part II is to address operational safety for geological disposal working on the development and review of an overall safety case that integrates both operational and post closure aspects.
As indicated in the IAEA Safety Requirements on Disposal of Radioactive Waste, it is convenient to identify three periods with the development, operation and closure of a disposal facility: the pre-operational period, the operational period and the post-closure period.
Until recently, the demonstration of safety of geological disposal of radioactive waste in the Member States mainly addressed the post-closure period of the disposal facilities with a little focus on the operational period. In relation to that the safety cases and safety assessments supporting this demonstration of safety were also mainly focused on post-closure safety. International requirements and guidance related to the safety of disposal facilities address the development of safety case and safety assessment, but even if operational safety is considered in these standards, further exchanges and potential additional specific guidance could be developed on that topic, in particular on the implications of operational safety on long term safety for geological disposal.
A particular challenge to be addressed in the process to implement geological disposal facilities for radioactive waste is to define the interface between the operational and post-closure safety.
The GEOSAF Part II project was established to address this issue and more specifically to elaborate on a structure and methodology to define an overarching safety case supporting the demonstration of safety of geological disposal, integrating both the operational and post-closure phases.
The GEOSAF Part II project takes as its starting point the concept of an "initial state" that is required at the commencement of the post-closure phase and which is required to be delivered by all the components of the phase(s) before closure. As the geological disposal project advances through a number of licensing and approval steps and as further information becomes available, the operator will be able to evaluate and verify that the assumed initial state will be achieved.
At the time of closure of the disposal facility, the final safety case will have to demonstrate that:
- the operational safety case has delivered the safety functions required to achieve the initial state
- the post-closure safety case (starting from the initial state) will deliver the required level of protection to humans and the environment
A particular challenge to be addressed in the process to implement geological disposal facilities for radioactive waste is to define the interface between operational and post-closure safety.
GEOSAF Part II provides a forum to exchange ideas and experience on the development and review of an integrated operational and post-closure safety case for geological disposal facilities. It also aims at providing a platform for knowledge transfer.
The target audience for the project comprises government and industry representatives: senior policymakers, regulators and facility operators, and their technical experts. The project is of particular interest to regulatory authorities, technical safety organizations and waste management organizations responsible for the development and operation of geological disposal facilities.
The project is planned for a period of at least 2 years starting in 2012. The working methodology for the project consists of core group meetings during which basic supporting material on various relevant issues is developed. This material is then distributed amongst the Member States participating in plenary meetings organized every year. During these plenary meetings the material prepared by the core group is commented, discussed and improved. The plenary meetings should also allow defining the work to be carried out by the core group prior to the next plenary meeting both to improve the existing material and to potentially address new topics.
The next plenary meeting of GEOSAF Part II will take place from 13 to 17 May 2013 in IAEA headquarters in Vienna.
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