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Review and Development of Methodologies for Modelling with Uncertainty and Variability

Objective

Any assessment of the safety of an underground repository for radioactive waste must consider various types of uncertainties. These uncertainties arise in each step of the assessment process: information gathering; experimentation; modelling; interpretation of results; and decision making.
These uncertainties are of many types, and are addressed with a variety of tools and techniques. For example, scenario analysis is widely used to tackle uncertainties in the future evolution of a site, and probabilistic calculations are often used for treating uncertain data.
The objective of this project os to review and investigate the types of uncertainties and techniques for handling them. In particular, an aim is to demonstrate techniques which are currently not widely used within the radioactive waste disposal community.
A particular area in which some potentially useful techniques are applied is that of Artificial Intelligence. The use of fuzzy logic is also a potentially useful area.
Any assessment of the safety of an underground repository for radiactive waste must consider various types of uncertainty. These uncertainties arise in each step of the assessment process: information gathering; experimentation; modelling; interpretation of results; and decision making. The objective of this project is to review and investigate the types of uncertainties and techniques for handling them. In particular, an aim is to demonstrate techniques which are currently not widely used within the radioactive waste disposal community. A particular area in which some potentially useful techniques are applied is that of artificial intelligence. The use of fuzzy logic is also a potentially useful area.

A review of types of uncertainty and techniques for their treatment has been completed. Alternative approaches to handling uncertainties are considered. Of these, the fuzzy set concept is clearly applicable and is discussed further. Voting theory offers a cautionary tale when trying to rank options. The use of fractals to model spatial variability is also seen as worthy of serious study. A section on performance measures shows that measures other than the maximum expected value are less prone to risk dilution. A review of methods and tools for handling uncertainty in safety assessments has begun and various new approaches to the management of uncertainty have been proposed.
Work programme:

B.1 Review
This phase consists of an in-depth review of:

types of uncertainties encountered in safety assessments internationally;
tools and techniques for handling uncertainties, including those currently used in radioactive waster disposal and in other fields;
available data sources and their uses, including experiment, expert judgement, detailed simulation;
presentational methods for displaying uncertainties in inputs and outputs of assessments.

B.2 Definition and investigation of important test cases
In this phase, test cases will be defined to cover the types of uncertainties and techniques identified as being most important in the first phase of the project. The aim is to demonstrate the practicalities of implementing various methodologies.

B.3 Investigation of further cases and lessons for general methodology
In this third phase, the focus is on recommendations for novel methodologies which could be used to address important issues. These will be based on the experience gained in the trial applications of the previous phase.

Coordinator

Intera Information Technologies Ltd
Address
Chiltern House 45 Station Road
RG9 1AT Henley-on-thames
United Kingdom

Participants (3)

Fril Systems
United Kingdom
Address
St Annes
BS4 4AB Bristol
UNIVERSITE LIBRE DE BRUXELLES
Belgium
Address
50,Avenue Franklin Roosevelt 50, Cp 194/6
1050 Bruxelles
University of Bristol
United Kingdom
Address
University Walk
BS8 1TH Bristol