Waste Technology Section

Underground Research Facilities Network (URF)


Enhancing Confidence in Geological Disposal of Radioactive Waste: The Role of Natural Analogues and Safety Indicators

28 November — 2 December 2011, Nottingham, United Kingdom


day 1

Session I: Introduction
Welcome and introductions

Session II: Introducing the Safety Case
Safety Philosophy (F. Neall)
  • Basic IAEA Safety Principles and Standards
  • Concept of GD Safety Case (detailed below)
  • Concept of repository system Safety Functions
  • Different safety measures and indicators at different times
  • The concept of exposed groups and individuals
Post-closure safety targets for GD: national examples

Nature of the Safety Case (R. Alexander)
  • The “safety case” is generally defined as a collection of arguments in support of the safety of the repository, which can be developed for both the operational and post-closure phases
  • A safety case also includes both the findings of PA/SA and a statement of confidence in these findings
  • It should also acknowledge the existence of any unresolved issues and provide guidance for work to resolve these issues in future development stages
  • For social acceptance, it is critical not only to make a technical safety case, but also to explain it to key stakeholders
A safety case is refined stepwise throughout repository development with increased system understanding based on site characterization information and iteratively conducted design and PA/SA studies

The Place of Safety Assessment (SA) in the Safety Case (F. Neall)
  • Setting the objectives of a SA
  • Defining the system and what is being analysed
  • A safety case also includes both the findings of PA/SA and a statement of confidence in these findings
  • Establishing the starting point (initial state conditions) and end points (uptake and dose estimates)
  • Structuring the assessment: FEPs, scenarios and calculation cases
  • Incorporating the biosphere into the analysis
What the regulator should expect to receive: degree of detail of analysis, treatment of uncertainty, alternative views/models

Session III: natural safety indicators: how can analogues help?
Natural safety indicators and methods to present relative dose and risk in a safety case (F. Neall and R. Alexander)
Natural safety indicators and methods to present relative dose and risk in a safety case: discussion (guided by the use of decision tree software)


day 2

Session IV: Group exercise
How to design a Safety Case incorporating alternative safety indicators for your national programme (F. Neall and R. Alexander)

Group Exercise I: designing a Safety Case incorporating alternative safety indicators

Group presentations: designing a Safety Case incorporating alternative safety indicators


day 3

Session V: field trip
Cementitious systems: short description of existing work (T. Milodowski)

Visit Pooles Caves in Derbyshire where 200 years of industrial lime wastes have interacted with the rock and groundwater in a manner analogues to a cementitious repository. How could a site like this be used in repository performance assessment?


day 4

Session VI: cementitious systems
Cementitious systems: where are we, what do we still need to do? (R. Alexander)

Cementitious systems: discussion (guided by the use of decision tree software): could you build a programme to support the Safety Case using Poole Caves? How could you integrate it with existing data?

The current status of the UK national radioactive waste disposal programme (C. Tweed)


day 5

Session VII: The use of palaeohydrogeology in repository development: previous use and future promise
The use of palaeohydrogeology in repository development: previous use and future promise (F. Neall and R. Alexander)

Palaeohydrogeology: discussion (guided by the use of decision tree software): where can we go from here?

Wrap-up, close the course

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