Quintessa Update
Spring 2004.

Welcome to the Spring 2004 edition of Quintessa Update, the electronic newsletter of Quintessa Limited.

TESLA - The Evidence Support Logic Application Quintessa is pleased to announce the release of TESLA 1.2, a decision support modelling tool based on Evidence Support Logic. TESLA is designed to assist in the evaluation of complex decisions where there are multiple and sometimes conflicting sources of evidence, as well as residual uncertainty. Sensitivity analyses can be performed to identify key components and a variety of graphical outputs are available to aid communication with stakeholders. TESLA assists systems modellers and decision makers to document the logic and justification that underpins their reasoning, to identify and visualise potential sources of bias and their implications, and to provide a well documented audit trail back to the raw data. For more information, please contact tesla@quintessa.org.

Training Courses and Workshops Quintessa staff have extensive experience in the development and presentation of technical training courses and workshops for a range of subjects such as safety assessment of radioactive waste, the remediation of contaminated land and the application of environmental software. As well as developing and presenting material for organisations such as the IAEA and ITC, custom courses have been tailored to the specific needs of clients. For example, a 5 day course was given to UKAEA staff on the use of performance assessment (PA) to determine short- and long-term safety and environmental impacts from radioactive waste disposal, contaminated land and authorised radioactive discharges. The course demonstrated the structured and systematic approach to PA through lectures and practical exercises. Further information about the provision of training courses and workshops can be obtained from Richard Little or James Penfold.

Raiden3 - fully coupled reactive geochemical transport and flow code Raiden3 is the latest version of Quintessa's fully coupled reactive geochemical transport and flow code for geochemically evolving regions. Varying assumptions on the form of reactive geochemistry can be made, with the possibility of modelling heterogeneous regions in which physical parameters vary across the domain. Raiden3 uses a finite difference discretisation of the underlying equations based on a compartmental spatial grid to offer great flexibility when modelling complex 3D geometries. Standard grid-based discretisations of 2D and 3D systems can also be made. Previous versions of Raiden have been used on a variety of projects for Japanese and European organisations; for example to model the geochemical evolution of engineered barriers, natural analogues and CO2 sequestration scenarios. Geochemical evolution can be modelled using a range of user-defined kinetic mechanisms, instantaneous reaction mechanisms and ion exchange for minerals, and coupled porewater chemistry. Flows in the system are fully coupled to the evolving geochemistry through variations in porosity, but can be decoupled and imposed on the system if desired. Geochemical properties and transport properties can be specified to be time/temperature/chemistry dependent using user-defined expressions. For more information please contact Steven Benbow.

PRISM Foodchain Modelling Software The UK Food Standards Agency has placed a contract with Quintessa to develop the PRISM 2.0 software package including up-to-date models for soil and plant transfers in the terrestrial foodchain, which will enable assessments to be undertaken for heavy metals and radionuclides. For further information please contact Philip Maul.

New Faces Quintessa is pleased to welcome Andrew Martin, a geologist with particular interests in volcanism and collision tectonics; and Claire Watson, a mathematician with interests in environmental software and modelling.