A significant component of the UK baseline inventory is separated uranium. The vast majority of this separated uranium is Depleted, Natural and Low Enriched Uranium (DNLEU). If all of the DNLEU contained in the current baseline inventory were to be disposed of in a Geological Disposal Facility, DNLEU wastes would represent a significant fraction of the disposed volume. In a recent study for the Nuclear Decommissioning Authority Radioactive Waste Management Directorate (NDA RWMD), Quintessa assessed the key controls on the performance of a number of different disposal concept options (combinations of wasteform, waste container and backfill) that might be considered for DNLEU.
The approach taken in this study was to develop an understanding of the safety functions that each of the... Full Details
A major update of Quintessa's decision support software (TESLA Version 2.1) has been released incorporating a host of new features designed to make it easier to analyse, present and audit decisions.
TESLA is a software tool that supports the structured analysis of complex decisions using an approach founded on Evidence Support Logic (ESL). This approach has proved invaluable to decision makers faced with complex problems drawing on multiple and uncertain sources of evidence, such as encountered at the back end of the nuclear fuel cycle and the geological storage of gases and hazardous wastes. Full Details
Quintessa has undertaken a study for the Nuclear Decommissioning Authority Radioactive Waste Management Directorate (NDA RWMD) to examine the post-closure safety implications of proposals for the direct packaging of Intermediate Level Waste (ILW) in standard containers without the use of any encapsulant material.
In a recent report (PCPA: Consideration of Non-encapsulated ILW in the Phased Geological Repository Concept) conceptual models for radionuclide release and transport in groundwater and gas were developed for non-encapsulated wastes with a range of backfill materials, together with a base case model of cement-encapsulated wastes for comparison purposes. Radionuclide releases in gas were examined qualitatively and... Full Details
Quintessa has delivered an updated version of the PRISM food chain modelling software to the UK Food Standards Agency (FSA).
PRISM allows probabilistic simulations to be carried out of the distribution and transport of contaminants in agricultural systems following routine and accidental releases of radionuclides to the atmosphere. The code models the deposition, interception and inhalation of 42 elements and 129 associated radionuclides and their subsequent behaviour in agricultural systems. A broad range of complex source terms and agricultural scenarios can be represented. The models and data are fully documented in FSA reports. Full Details
At the British Carbon Group conference "Modelling and Measuring Reactor Core Graphite Properties and Performance" held at Aston University, Quintessa presented two software applications (CHANSELA and PANDA) designed for visualising data relating to graphite reactor cores.
Periodic inspections are carried out on the cores of the British fleet of Advanced Gas-Cooled Reactors. Each graphite reactor core is comprised of about 300 fuel channels, but it is possible to inspect only a small fraction of these during a single outage. Decisions on which channels to inspect and take samples from require a balance to be struck between many competing requirements for data, as well as operational considerations. Full Details
A recent paper published in the Journal of Radiological Protection provides an illustrative assessment of human health issues arising from the potential release of chemotoxic and radioactive substances from a generic geological disposal facility for radioactive waste. The paper summarises the results of a study by Quintessa working with the Nuclear Decommissioning Authority Radioactive Waste Management Directorate (NDA RWMD).
The assessment uses a source-pathway-receptor methodology and estimates exposures for a number of human exposure pathways, which are consistent with authoritative toxicological assessment criteria. Also, the possibility of additive and synergistic effects resulting from exposures to mixtures of chemical contaminants... Full Details
Quintessa provides post-closure radiological modelling support to the National Cooperative for the Disposal of Radioactive Waste (Nagra), the organisation responsible for preparing the technical and scientific basis for the safe, long-term management of radioactive waste in Switzerland.
Quintessa has implemented Nagra's post-closure biosphere assessment model in a new software tool, the Swiss Biosphere Assessment Code (SwiBAC).