Regulatory Review of Safety Cases for Radioactive Waste Disposal Facilities

1. Regulatory Review of Safety Cases for Radioactive Waste Disposal Facilities David G Bennett 7 April 2014

2. Introduction to the Safety Case • Radioactive waste must be managed in such a way as to avoid imposing an undue burden on future generations • The generations that produce the waste have to seek and apply safe, practicable and environmentally acceptable solutions for its long term management • IAEA safety requirements for radioactive waste disposal require that a safety case (including a supporting safety assessment) be developed

3. Introduction to the Safety Case • The safety case is: • the collection of scientific, technical, administrative and managerial arguments and evidence in support of the safety of a disposal facility • The arguments cover the suitability of the site and the design, construction and operation of the facility, the assessment of radiation risks and the assurance of the adequacy and quality of all of the safety related work associated with the disposal facility • a well-defined, formal set of documents produced by the operator and reviewed by the regulator

4. Introduction to the Safety Case • Safety assessment is an integral part of the safety case • It provides an understanding of the behaviour of the disposal facility under normal conditions and disturbing events, considering the time frames over which the radioactive waste remains hazardous • It includes a systematic quantification of radiation doses and risks that may arise from the disposal facility for comparison with dose and risk criteria

5. Safety Case Components

6. Introduction to the Safety Case • For disposal facilities the regulator shall: • Establish regulatory requirements for the development of different types of disposal facility for radioactive waste • Set out the procedures for meeting the requirements for the various stages of the licensing process • Set conditions for the development, operation and closure of each individual disposal facility • Carry out such activities as are necessary to ensure that the conditions are met

7. Regulatory Review • The regulatory authorities will need to make formal reviews of the safety case and issue appropriate licences and conditions • Such reviews may need to be conducted several times during the life of any particular disposal facility • Regulators need to have (and maintain) sufficient competence • A defined process of review should be followed, leading to clearly communicated results • Interactions with the operator and other stakeholders should be expected and managed • Safety case reviews can be lengthy complex projects

8. Regulatory Review • IAEA ASAM Project • Regulatory Working Group • Detailed review guidance • Review questions covering all areas of safety assessment

9. Attributes of Regulatory Review • The conduct of a high-quality regulatory review enhances confidence in the credibility of the regulator, in the review findings and in any associated regulatory decisions • Regulatory review should be: • Independent from the work of the operator and any peer reviews undertaken on behalf of the operator • Well-defined in scope and objectives • Made against clearly defined regulatory requirements, expectations and acceptance criteria • Conducted using structured, traceable review procedures with clearly defined roles and responsibilities and decision-making steps • Adequately resourced, commensurate with the complexity of the safety assessment and the risks associated with the facility • Open and transparent with well-defined consultation steps

10. Management of the Review Process • The management of a regulatory review procedure should reflect the principles of good project management • The objectives and scope of the review should be clearly defined • A review plan should be developed. The plan should define the project schedule, allocate resources and assign roles and responsibilities review tasks • Use suitably qualified and experienced reviewers • A project manager should be appointed to: • Co-ordinate review tasks, communication between reviewers and dialogue with the operator and other stakeholders • Identify and deal with any areas of regulatory uncertainty • Review and integrate documents generated during the review • Synthesise and communicate the review findings

12. Regulatory Review of the Safety Case • The review should work systematically to assess each component of the safety case • Has it been developed under suitable management and quality systems? • Is the safety case context appropriate for the decision step in hand? • Is the safety case sufficiently complete (consistent with the context)? • Does the safety case demonstrate understanding of the disposal system? • Is the safety strategy clear and logical? • Is the safety assessment based on appropriate assumptions, scenarios, models and parameter values? Is it transparent in its presentation of data, models and information? • Are uncertainties sufficiently addressed? • Does the safety case include an adequate consideration of optimisation? • Does it define an adequate programme of work for improving the safety case, setting limits etc., and managing the disposal facility?

13. Review of the Context • Have regulatory requirements and criteria been identified, correctly interpreted and addressed? • Does the safety case (and associated licensing documentation) clearly and correctly describe the purpose of the assessment or the permission being sought? • Is the purpose of the safety assessment clear? • Are the timeframes considered appropriate? • Does the safety assessment present the correct end-points (dose, risk, fluxes etc)?

14. Assessment Purpose • The views formed during regulatory review will differ according to the purpose of the assessment, for example: • Testing of initial ideas and safety concepts • Demonstration of disposal facility safety • Optimisation of facility design • Definition of waste acceptance criteria and radiological capacity • Justification of the duration of the institutional control period • Periodic re-assessment as required by law or regulation • Application to extend the facility • Application to close of facility • It is important, therefore, that the assessment purpose is clear and agreed

15. Assessment Timeframes • What timeframes have been considered and why? • Are the timeframes prescribed by regulation? • Do the half-lives of the relevant radionuclides dictate any of the assessment timeframes? • Is the peak of the predicted dose or risk within the defined timeframes? If not, why not? • Have the assessment timeframes taken into account the uncertainty associated with long term prediction? • Are assessment timescales dictated by disruptive events (glaciation, volcanism, erosion)? If so, how were such events defined and treated in the safety assessment? • Was overall timeframe separated into shorter time-windows for modelling or presentational reasons?

16. Assessment End-Points • What are the relevant assessment end-points for radiological protection? • Absorbed dose, effective dose, risk • Has the appropriate end-point been assessed for the exposure situation under consideration? • Have alternative end-points been calculated? • Radionuclide concentrations/fluxes • Non-radiological contaminants concentrations/fluxes • Have the assessed end points been compared properly to the regulatory criteria? • Were different end-points calculated for different timeframes?

17. Regulatory Review - Conclusions • Regulators need to be ready to make safety case reviews • Developing an appropriate regulatory framework and guidance • Establishing and maintaining sufficient competence (staff and contractors) • Defining and managing the review process • Working systematically through the safety case • Focussing effort on the most important issues to safety • Operators need to be ready to provide the regulators with the information they need