Safety Assessment Methodologies and Implementation of Monitoring and Control Programmes Dr. Japie van Blerk AquiSim Consulting (Pty) Ltd Wednesday, 24 March 2010 Leriba Lodge Centurion, Gauteng

Introduction Application of Safety Assessment Process (IAEA Glossary, 2007)  Facilities and activities (existing and new, utilized for peaceful purposes) General term encompassing any human activity that may cause people to be exposed to radiation risks arising from naturally occurring or artificial sources Nuclear facilities Irradiation installations Mining and raw material processing facilities; Radioactive waste management facilities; and Any other places where radioactive material is produced, processed, used, handled, stored or disposed of — or where radiation generators are installed …on such a scale that consideration of protection and safety is required… Occupational (worker ) and public safety assessments Operational and post closure phases

Introduction Application of Safety Assessment Process (IAEA Glossary, 2007)  Facilities and activities (existing and new, utilized for peaceful purposes) General term encompassing any human activity that may cause people to be exposed to radiation risks arising from naturally occurring or artificial sources Nuclear facilities Irradiation installations Mining and raw material processing facilities; Radioactive waste management facilities; and Any other places where radioactive material is produced, processed, used, handled, stored or disposed of — or where radiation generators are installed …on such a scale that consideration of protection and safety is required… Occupational (worker ) and public safety assessments Operational and post closure phases

Introduction Application of Safety Assessment Process (IAEA Glossary, 2007)  Facilities and activities (existing and new, utilized for peaceful purposes) General term encompassing any human activity that may cause people to be exposed to radiation risks arising from naturally occurring or artificial sources Nuclear facilities Irradiation installations Mining and raw material processing facilities; Radioactive waste management facilities; and Any other places where radioactive material is produced, processed, used, handled, stored or disposed of — or where radiation generators are installed …on such a scale that consideration of protection and safety is required… Occupational (worker ) and public safety assessments Operational and post closure phases

Introduction Safety Assessment (IAEA Glossary, 2007)  Assessment of all aspects of a practice that are relevant to protection and safety; for an authorized facility, this includes siting, design and operation of the facility  Analysis to predict the performance of an overall system and its impact, where the performance measure is the radiological impact or some other global measure of the impact on safety Safety Standards (Regulation No. 388)  Systematic process to ensure that all the relevant safety requirements are met by the proposed (or actual) design. Safety assessment includes, but is not limited to, the formal safety analysis

Introduction The Scientific Committee 87-3 established by the National Council on Radiation Protection (NRCP) (Kennedy, 1997)  Portrayed a post-closure safety assessment as a multidisciplinary, iterative process focussed on regulatory compliance rather than an analysis of a disposal system for the purpose of predicting its actual behaviour  With this in mind, they defined a post-closure safety assessment as: ‘the iterative process involving site-specific, prospective evaluations of the post-closure phase of the system’ with the primary objectives to  determine whether reasonable assurance of compliance with quantitative performance objectives can be demonstrated,  identify data, design and other needs to reach defensible decisions about regulatory compliance

Introduction The NRCP Scientific Committee 87-3 Definition  Iterative process: expect that a safety assessment will have to be repeated two or more consecutive times  Site-specific prospective evaluations: include data from the actual system assessed Not with the intent to predict its actual behaviour in the future, but rather to understand the behaviour of the system better and to reflect on the importance of specific components with respect to the compliance criteria  Reasonable assurance: emphasizes the inexact nature of the procedure Reach defensible decisions on the extent to which the disposal system may comply with the regulatory criteria  A decision tool to determine the conditions for which reasonable assurance of compliance with safety objectives can be provided; not a method to predict the actual behaviour of a disposal system into the future

Introduction Safety Assessment in the Context of a Safety Case  Definition of Safety Case (IAEA Glossary, 2007) A collection of arguments and evidence in support of the safety of a facility or activity This will normally include the findings of a safety assessment and a statement of confidence in these findings For a repository, the safety case may relate to a given stage of development. In such cases, the safety case should acknowledge the existence of any unresolved issues and should provide guidance for work to resolve these issues in future development stages  IAEA PRISM and GEOSAF Projects

Safety Assessment and Exact Sciences An exact science is any field of science capable of accurate, quantitative expression or precise predictions and rigorous methods of testing hypotheses, especially reproducible experiments involving quantifiable predictions and measurements  Unlike purely scientific areas of study, the radiological public safety assessment process cannot be considered what one would describe as an exact science  The assessment process draws from the fundamental principles of exact sciences, and parts of the assessment methodology are sometimes amenable to normal scientific approaches  The time scales, space scales, uncertainties in boundary conditions, and uncertainties in future human behaviour make it impossible to test and verify (or falsify) the overall assessment

Safety Assessment and Exact Sciences  The inherent nature of the assessment methodology - from the release of radioactive contaminants, the migration of these contaminants into the environment, the subsequent uptake of radionuclides into the human body to pose a radiological exposure - in itself is not an exact science  Safety assessment is a process to develop an understanding of the limits of potential radiological exposure to members of the public for an assumed set of conditions and parameter values  By examining a range of potential conditions of concern, it is possible to develop confidence that the public will be protected from radiation, even though exact statements about future exposures cannot be made

Safety Assessment Methodologies Developed and improved significantly since 1980s Radioactive waste management  Geological disposal  Near surface disposal Mining and mineral processing facilities  Difference in characteristics and timescales IAEA Coordinated Research Projects  NSARS  ISAM, ASAM  PRISM  GEOSAF

Safety Assessment Methodologies

Regulatory Framework System Description  Process, site, waste, facilities and human behavior  Incremental contribution to radiation exposure (historical perspective)  Source identification and description Primary and secondary sources  Pathway analysis Atmospheric pathway Aquatic (groundwater and surface water) pathways Definition and justification of exposure conditions and scenarios

Safety Assessment Methodologies Model Development  Conceptual and mathematical models  Comprehensive and transparent Approach to System Modeling  Complex systems Introduce simplifying assumptions Decouple system processes Combination of above  Compartmental approach  Coupled modeling approach Sensitivity and uncertainty analysis  Improve confidence in the assessment

Monitoring and Control Programme What is the Purpose of a Monitoring Programme?  Environmental monitoring (IAEA Glossary, 2007) The measurement of external dose rates due to sources in the environment or of radionuclide concentrations in environmental media Safety Standards (Regulation No. 388)  An appropriate environmental monitoring and surveillance programme must be established, implemented and maintained to verify that the storage, disposal or effluent discharge of radioactive waste complies with the conditions of the nuclear authorization  Source monitoring (IAEA Glossary, 2007) The measurement of activity in radioactive material being released to the environment or of external dose rates due to sources within a facility or activity

Monitoring and Control Programme What is the purpose of a monitoring programme?  Demonstrate compliance with the conditions of the nuclear authorization System behave as designed  Determine the current status of the system  System characterization  Input data for the safety assessment process  Validation of system models used in safety assessment  Develop stakeholder confidence

Monitoring and Control Programme Use safety assessment as a tool to developed the monitoring programme  Safety assessment helps to understanding system behavior Understand environmental pathways of concern (Historical perspective)  Atmospheric pathway  Aquatic (surface water and groundwater) pathways  Requirements for the atmospheric pathway monitoring different from the groundwater pathway  Recognize the differences between a radioactive waste disposal facility and a mining and mineral processing operation Different pathway of concern Slow migration processes Contribution from facilities and activities, but also natural background radiation  Background reference site

Safety Case and Safety Assessment The Safety Case and Safety Assessment for Radioactive Waste Disposal (IAEA Draft Safety Guide DS355)  Safety case...is the collection of scientific and technical arguments and evidence in support of the safety of a disposal facility covering the suitability of the site and the design, construction and operation of the facility, the assessment of radiation risk and assurance of the quality of all the safety related work associated with the disposal facility  Safety assessment...a systematic assessment of radiation hazards, is an important component of the safety case. It involves the quantification of radiation dose and risk that may arise from the disposal facility for comparison with dose and risk criteria, and provides an understanding of the behaviour of the disposal facility under normal and disruptive conditions, considering the timeframes over which the radioactive waste remains hazardous

Safety Case and Safety Assessment Stakeholder Confidence in Facilities and Activities  The NEA (NEA, 1999) defines confidence as “…to have reached a positive judgement that a given set of conclusions are well-supported…”

Safety Case and Safety Assessment Stakeholder Confidence in Facilities and Activities  Stakeholders (target audience) Regulatory authorities, local, regional and national government Public and environmental interest groups Management  Confidence in the safety assessment Confidence in the safety assessment methodology, approach and results Identification and handling of unresolved issues  Confidence in the management and performance of the facilities or activities Monitoring and surveillance programme Supporting arguments

Safety Case and Safety Assessment PRISM Proposal for Discussion Purposes ONLY  Safety assessment is part of a process  Monitoring programme in support of confidence building and safety arguments  Integration of safety arguments in support of the safety case for the facilities and activities

Conclusion Safety Assessment Process is not an Exact Science Integration and Assessment of the Environmental Pathway into the Assessment Process Focus on the Safety Case and not on the Safety Assessment  Monitoring programme in support of safety arguments  Stakeholder confidence

Thank You for Your Attention!