Nicolas Solente Workshop on Regulatory Requirements to Ensure Safe Disposal of Disused Sealed Sources for Operators and Regulators Amman, JORDAN 7-11 April 2014 Role of the Safety Case in disposal programmes

Outline of the presentation Objectives of the Safety Case Contents of a Safety Case SC flow diagram The disposal programme planning Safety Functions and Disposal programme The safety case and the site selection The safety case and the initial disposal facility design The safety case and the detailed disposal facility design The Safety case and the scientific and R&D programme The Safety Case and disposal operations Conclusions

Objectives of the Safety Case Fundamental safety objective of disposal programme: “to protect people and the environment from harmful effects of ionizing radiation” The operator of the facility is responsible for safety, and must assess the safety of the facility demonstrate that the design and operation of the facility are compliant with the relevant safety requirements The Safety case (SC), including a Safety Assessment (SA) is developed to o provide evidence to demonstrate that the disposal facility will be safe to operate, will remain safe after its closure and complies with all applicable regulatory requirements.

Contents of a Safety Case A typical disposal facility SC will comprise: An Operational SC: demonstrates that the construction and operations of the facility will be safe for the workers, the public and the environment A Long Term, post-closure SC: demonstrates that the Radionuclides will not present an unacceptable risks in the future Scientific and engineering supporting material: a comprehensive collection of evidence providing the basis and justification for the SA Other information (local and national context, managerial decisions…) supporting decision making

SC flow diagram

The disposal programme planning

Safety Functions and Disposal programme During the start-up and initial phases, a safety concept is selected and developed. The concept relates to specific safety functions, such as confine RN, prevent intrusion, isolate from water…. The safety functions are defined to prevent or reduce the risks, and thus provide the required level of safety. The safety functions are an important component of the SA/SC Simultaneously, a disposal concept is chosen, such as borehole, deep geological, surface disposal The safety functions are fulfilled by the repository system, subsystems and components. The safety functions and their implementation in the disposal system will be a constant link between the disposal programme and the SC

The safety case and the site selection The site selection is a complex process that considers many factors. A number of those factors are safety related and define some of the selection criteria, The site selection criteria are established to eliminate those sites where some safety functions could not be provided or would require to consider a different disposal concept (seismicity, flooding, population…) Disposal concept and selection criteria are interdependent, and the availability of the required environment (geology, hydrogeology, surface water bodies, population) should be a major contributing factor in the disposal concept selection

The safety case and the initial disposal facility design 1.Conceptual design: a generic design is selected, with regards to The waste inventory (quantity + RN contents) The available geology (from desktop studies at this stage) The national policy, including RAW management and safety policies An initial safety case should be performed to validate the concept selection, using generic/preliminary parameters. Output: Are the preliminary Waste Acceptance Criteria, issued from the Preliminary SC consistent with the waste inventory?

The safety case and the detailed disposal facility design 1.Functional analysis  defines all functions of the facility 2.Functions attributed to components (systems, sub- systems) 3.Safety functions attributed to single or multiple systems/subsystems 4.Quantitative assessment of the performance of the repository and its components – identification and quantification of the uncertainties 5.Verification of the robustness of the systems (defense in depth, compatibility, interdependencies…) 6.Modification of the systems 7.Back to step 3 until Performance and robustness demonstrated

Interdependencies & iterations The design and the decision-making processes are iterative and shall incorporate safety aspects in most cases. Revisions in design will trigger modification of the SC, as changes in the safety strategy, or in the SA (models, uncertainty management) will trigger modifications of the design

The Safety case and the scientific and R&D programme A scientific programme is required to provide the parameters and data needed to model the behavior of the facility in its environment and evaluate its performance indicators (dose, RN flow...) The SC is a demonstration of compliance to safety objectives, and must be based on undisputable data (geology, corrosion, cement, waste composition, rad & non-rad…) The required quality and quantity of data will increase as the project and the SC progress. Data acquisition will be largely driven by SA considerations. Ex: The geological investigations must be designed with a view on providing data in a quality and a quantity sufficient to the demonstration of safety and the modelling of the subsurface. Several survey campaigns may be necessary.

The Safety Case and disposal operations Waste acceptance Criteria evolutions Disposal of new waste streams, new DSRS types require that their acceptability is verified and, occasionally, that WAC are modified. The consequences on the safety assessment of the new conditions (RN, waste form, chemical composition) must be evaluated, in the framework of the initial safety case The SC must be regularly updated, to reflect the changes to the facility or the waste, and to take advantage of new scientific results, international practice, regulations…

Conclusions The SC controls several aspects of any disposal programme: Site selection and facility design are justified for a large extent by compliance to safety objectives. For a similar objective of safety, the level of performance required must remain commensurate with the hazards associated with the waste Waste acceptance Criteria are directly related to the SA/SC The acceptable RN inventory is directly related to the SA/SC The management of uncertainties commands the extent of the scientific/R&D programme …