1. WORKING GROUP 4 KEY DISCUSSION RESULTS TOPICS 2 & 3 International Workshop on the Safe Disposal of Low Level Radioactive Waste 03 to 05 February 2015, Montrouge, France

2. Topic 2 – Challenges in Safety Case Development (1)  Time frames for assessment  Limited by uncertainties  Some countries use long assessment time frames of 1000 years and more for above surface facilities – important to indicate that results are no predictions of future situation  FEPs  Scenarios usually developed by FEP screening  International FEP lists (ISAM, NEA) somewhat convoluted and complicated to use  Countries use their own FEP lists and use the international lists for checking completeness  Improvements of international lists would be beneficial IAEA Workshop Paris - February 2015 2

3. Topic 2 – Challenges in Safety Case Development (2)  Scenario definition and analysis of results  Normal and alternate evolution, what-if scenarios  Approaches usually conservative (i.e. alternate evolution scenarios defined to cover any perceivable situation)  What-if scenarios to test robustness of facility design  Results can be extremely conservative  Interpretation of results requires a balancing of arguments as part of the integration of safety arguments  Difficulty often arises in risk based approaches to distinguish between normal evolution and failure scenarios IAEA Workshop Paris - February 2015 3

4. Topic 2 – Challenges in Safety Case Development (3)  Management of uncertainties  Need to be resolved in the integration of safety arguments  Integration of safety arguments requires qualified personnel  Updating of safety case  Required each five or ten years and at licensing steps  Also required when significant changes (e.g. new waste or different waste containers) are planned  Applies to the whole integration of safety arguments IAEA Workshop Paris - February 2015 4

5. Topic 2 – Challenges in Safety Case Development (3)  Public involvement  In many countries early involvement of public (community consultation) has proven beneficial  Early meetings of all involved parties (i.e. operator, regulator, public)  Importance to not compromise the independence of the regulator  Successful approach in several countries like Sweden, Belgium and Canada: Operator (through Government) supplies funding to locals and environmental groups to develop their own expertise IAEA Workshop Paris - February 2015 5

6. Topic 4 – Licensing Process and Responsibilities for Safety  Responsibilities defined by Safety Requirements  Regulatory process:  Skills of personnel very important  Through cost recovery from operator sufficient resources are made available  Good project planning needed in regulatory body  Important aspects for regulator and operator:  Regulator and operator may use input from external experst, but should not become dependent on them  Continuity of available expertise in particular for disposal projects with lifetime of many decades very important IAEA Workshop Paris - February 2015 6