Characterisation of the Geology of the UK Low Level Waste Repository

2011 ◽  
Author(s):  
John Shevelan ◽  
Nicholas T. Smith
Keyword(s):  
Site Investigation ◽  
Environmental Safety ◽  
Geological Model ◽  
Hydrogeological Model ◽  
Geological Interpretation ◽  
Low Level ◽  
Geological Models ◽  
Waste Repository ◽  
Site Characterisation ◽  
The Uk

The UK Low Level Waste Repository Ltd (LLWR) submitted an Environmental Safety Case (ESC) for the disposal of low-level waste (LLW) to the UK Environment Agency on the 1st of May 2011. As part of the ESC, the LLWR have to demonstrate that a programme of site investigation and site characterisation has been carried out to provide the requisite information for the ESC and support facility design and construction. This paper explains the development of the site investigation programme and how the understanding of the geology of the site has developed. The geological environment in the region of the LLWR consists of Quaternary age deposits overlying older bedrock. The site has been subjected to a series of site investigation programmes from 1939 to the present day. The development of 3-D geological models was necessary to integrate data from boreholes, trial pits, geophysical investigations and beach exposures and data gained from site operations. The understanding of the geology has developed with each new set of data. Early simple interpretations from a few boreholes have been superseded by a series of more complex interpretations each incorporating the increasingly detailed observations. Initial attempts to develop a lithostratigraphic representation of the geology proved difficult. It was also difficult provide a clear link between the geology and the hydrogeology using a lithostratigraphic approach as required for the development of hydrogeological models. A lithofacies approach to characterising the geology was adopted in 2007, which has allowed the grouping of geological units with similar hydraulic properties and the development of a regional 3-D geological model. The 3-D geological model has been used as the framework for the development of a hydrogeological model for the site. The development of the 3-D geological models has been iterative. It was observed that there are differences between models developed using solely mathematical interpolation and those controlled by geological interpretation. The different representations of the geological information have been used to consider the effects of uncertainty in the geological interpretation in the hydrogeological modelling.

An Assessment of the Radiological Impact of Human Intrusion at the UK Low Level Waste Repository (LLWR)

2011 ◽  
Author(s):  
Tim. Hicks ◽  
Tamara Baldwin ◽  
Richard Cummings ◽  
Trevor Sumerling
Keyword(s):  
Environmental Safety ◽  
Assessment Model ◽  
Disposal Site ◽  
Barrier Materials ◽  
Low Level ◽  
Geotechnical Investigations ◽  
Safety Case ◽  
Waste Repository ◽  
The Uk

The UK Low Level Waste Repository Ltd submitted an Environmental Safety Case for the disposal of low-level waste (LLW) to the Environment Agency on the 1st of May 2011. The Environmental Safety Case (ESC) presents a complete case for the environmental safety of the Low Level Waste Repository (LLWR) both during operations and in the long term (Cummings et al, in these proceedings). This includes an assessment of the long-term radiological safety of the facility, including an assessment of the potential consequences of human intrusion at the site. The human intrusion assessment is based on a cautiously realistic approach in defining intrusion cases and parameter values. A range of possible human intrusion events was considered based on present-day technologies and credible future uses of the site. This process resulted in the identification of geotechnical investigations, a housing development and a smallholding as requiring quantitative assessment. A particular feature of the site is that, because of its proximity to the coast and in view of expected global sea-level rise, it is vulnerable to coastal erosion. During such erosion, wastes and engineered barrier materials will be exposed, and could become targets for investigation or recovery. Therefore, human intrusion events have been included that are associated with such activities. A radiological assessment model has been developed to analyse the impacts of potential human intrusion at the site. A key feature of the model is the representation of the spatial layout of the disposal site, including the engineered cap design and the large-scale spatial heterogeneity of radionuclide concentrations within the repository. The model has been used to calculate the radiation dose to intruders and to others following intrusion at different times and at different locations across the site, for the each of the selected intrusion events, considering all relevant exposure modes. Potential doses due to radon and its daughters in buildings constructed on excavated spoil from the repository are a particular concern. Options for managing the emplacement of the radium-bearing waste packages with regard to human intrusion have been assessed. These calculations show that a managed waste emplacement strategy can ensure that calculated doses are consistent with regulatory guidance levels.

Update on the Review of the LLWR 2011 Environmental Safety Case

2013 ◽  
Author(s):  
Richard Cummings ◽  
Amy Huntington ◽  
John Shevelan ◽  
Andrew J. Baker ◽  
Trevor Sumerling ◽  
...  
Keyword(s):  
Environmental Safety ◽  
Acceptance Criteria ◽  
Low Level ◽  
Additional Work ◽  
Local Stakeholders ◽  
Safety Case ◽  
Waste Repository ◽  
Environment Agency ◽  
The Uk

The UK Low Level Waste Repository has submitted a fully revised Environmental Safety Case (ESC) to the Environment Agency for the continued operation of the site. The Environment Agency is reviewing the submission. As part of the review of the ESC, we have been engaging with the Environment Agency to answer questions and provide further clarification where required. Once the review is complete, LLWR will apply for a revised permit for the continued operation of the site. We are required by our current Permit to operate the site in accordance with the assumptions of the ESC. We have developed a process for the implementation and maintenance of the ESC as a ‘live’ safety case under formal change control, and the development of waste acceptance arrangements identified as necessary to ensure that the repository is operated in a safe and optimised way, consistent with the assumptions and results of the ESC. Engagement with waste consignors has been essential in the development of revised waste acceptance criteria. Additional work has also been carried out in the development of an Article 37 submission, presenting the ESC to local stakeholders and developing of waste emplacement strategies.

Use of a Shielded Low Resolution Gamma Spectrometer for Segregation of Free Release and Low Level Waste

2007 ◽  
Author(s):  
C. G. Wilkins ◽  
E. Alvarez ◽  
J. Cocks ◽  
L. Davison ◽  
A. Mattinson
Keyword(s):  
High Efficiency ◽  
Specific Activity ◽  
Performance Testing ◽  
Low Resolution ◽  
Measurement Sensitivity ◽  
Radiation Background ◽  
Low Level ◽  
Monitoring Process ◽  
Waste Repository ◽  
The Uk

In the UK, low level radioactive waste (LLW) is sent to the national Low Level Waste Repository (LLWR) at Drigg in Cumbria. Strict rules limit the specific activity of waste that is sent to the LLW Repository and waste producers and consignors have to demonstrate that the waste they send to the repository meets its conditions for acceptance. However, the limited capacity of the Low Level Waste Repository means that it is just as important for waste consigners to ensure that inactive ‘free release’ or ‘exempt’ waste is not inadvertently sent to the repository. Incorrect segregation of waste in a decommissioning activity can mean that large amounts of the waste produced is below the exemption limit and could therefore be disposed of in conventional landfill. Sellafield Ltd. is using a pair of Canberra WM2750 Clearance Monitors to assay 100 litre packages of soft waste produced in some of their decommissioning activities at Sellafield. The WM2750 uses low resolution gamma spectrometry (LRGS) to determine the radionuclide content of packages or drums of LLW up to a maximum of 140 litre capacity. It uses a lead shielded measurement chamber to reduce the local radiation background along with high efficiency sodium iodide (NaI) detectors in order to obtain the measurement sensitivity required to be able to distinguish between LLW and exempt waste in a measurement time of less than 1 minute per package. This paper describes the waste monitoring process and the design of the clearance monitor — in particular how it was calibrated and the performance testing that was carried out to ensure that waste items identified by the monitors as being exempt waste are suitable for disposal to a conventional landfill site.

Strategic Environmental Assessment for UK LLW Management

2009 ◽  
Author(s):  
Andrew Craze ◽  
Pete Davis ◽  
Matthew Clark
Keyword(s):  
Environmental Assessment ◽  
Waste Treatment ◽  
Treatment Options ◽  
Environmental Safety ◽  
Nuclear Industry ◽  
Strategic Environmental Assessment ◽  
Low Level ◽  
Metal Recycling ◽  
The Uk ◽  
Implementation Of The Strategy

NDA is delivering a Strategic Environmental Assessment (SEA) to underpin the UK Nuclear Industry Low Level Waste Strategy. The purpose of this assessment is embed sustainability issues into our decision making and to fulfil our requirements under the European Union’s Strategic Environmental Assessment (SEA) Directive (2004/42/EU) and transposing UK Regulations, and to underpin the development of the strategy. The outputs of the SEA have provided input into particular aspects of the strategy, leading to a more robust and better informed result. Development of options to be assessed under the SEA has looked at a number of factors, including: • what the strategy is aiming to achieve; • expectation from stakeholders as to what should be addressed; • consideration of tactical approaches to implementation of the strategy in addition to high level strategic issues; • links to other projects and programmes (for example the Environmental Safety Case for the Low Level Waste Repository. The SEA aims to provide a robust assessment of the environmental and sustainability impacts of alternative strategies for providing continued capability and capacity for the management and disposal of LLW in the UK. The assessment also considers other, more tactical, issues around implementation of the strategy, for example: issues around the location of LLW management facilities; the environmental impacts of alternative waste treatment options (metal recycling etc); considerations of alternative approaches to the classification of radioactive waste and opportunities that would result. Critical to the development of the SEA has been the involvement of statutory and non-statutory stakeholders, who have informed both the output and the approach taken.

Characterization and Assessment of the Groundwater Pathway for the Low Level Waste Repository, UK

2011 ◽  
Author(s):  
Lee J. Hartley ◽  
Martin James ◽  
Peter Jackson ◽  
Matt Couch ◽  
John Shevelan
Keyword(s):  
Radioactive Waste ◽  
Groundwater Flow ◽  
Environmental Safety ◽  
Long Term Evolution ◽  
Low Level ◽  
Term Evolution ◽  
Groundwater Flow Modelling ◽  
Safety Case ◽  
Waste Repository

The Low Level Waste Repository (LLWR) is the UK’s principal facility for the disposal of solid low-level radioactive waste and is operated by LLW Repository Limited. Presently, LLWR Ltd is establishing the long-term environmental safety of disposals of solid radioactive waste at the LLWR, through the submission of the 2011 Environmental Safety Case for the LLWR. This Environmental Safety Case addresses the Environment Agency Guidance on Requirements for Authorisation. Aspects of the submission consider improved vault design, closure design, and quantitative assessments. Each of these issues requires an understanding of the movement of water through the facility and the surrounding geology during operations and following facility closure. Groundwater flow modelling has been used extensively in support of the interpretation of field investigations, the development of the engineering design, and an assessment of the groundwater pathway as one of the major pathways by which contaminants may reach the environment. This paper describes these important aspects of the Environmental Safety Case. The geological environment in the region of the LLWR consists of Quaternary age deposits overlying older bedrock. The facility involves shallow excavations into the Quaternary deposits, originally for trenches, with disposals to a vault system beginning in 1988. In the post-closure phase these disposals are covered by a cap and surrounded by a cut-off wall to minimise the water flow around or through the waste. An innovative modelling methodology has been developed to represent the range of scales that have to be considered from the regional groundwater flow patterns over several kilometres, the scale of tens of metres around the immediate site area, and down to about 1 metre for details of flows within the repository itself in three dimensions. Detailed finite-element models of the flow through geological media and the engineered features are used to interpret site data and assess a credible set of post-closure situations and model cases. In the radiological assessment, a more simplified compartment model is used to assess uncertainties in hydrogeological properties and the long-term evolution of the engineered barriers. Together the approach provides flexible tools for understanding and assessing a comprehensive range of aspects including details of flows within the repository, dilution and migration in the external geology, the long-term evolution of the hydrogeological system, the implications of spatial variability and alternative geological models, and effects of uncertainties.

The Role of the National Low Level Waste Repository Operator in Delivering New Solutions for the Management of Low Level Wastes in the UK

2009 ◽  
Author(s):  
Martin Walkingshaw
Keyword(s):  
Radioactive Waste ◽  
Alternative Treatment ◽  
Parent Body ◽  
Low Level ◽  
The United Kingdom ◽  
Waste Repository ◽  
The Uk ◽  
The Village ◽  
Low Level Radioactive Waste

The UK National Low Level Waste Repository (LLWR) is located near to the village of Drigg in West Cumbria. It is the principal site for disposal of solid Low Level Radioactive Waste (LLW) in the United Kingdom. This paper describes the program of work currently being undertaken by the site’s operators, (LLW Repository Ltd and its newly appointed Parent Body Organisation), to extend the life of the LLWR and reduce the overall cost of LLW management to the UK taxpayer. The current focus of this program is to prevent disposal capacity being taken up at LLWR by waste types which lend themselves to alternative treatment and/or disposition routes. The chosen approach enables consignors to segregate LLW at source into formats which allow further treatment for volume reduction or, (for wastes with lower levels of activity), consignment in the future to alternative disposal facilities. Segregated waste services are incorporated into LLW Disposal commercial agreements between the LLWR operator and waste consignors.

An Assessment of the Radiological Impact of Coastal Erosion of the UK Low-Level Waste Repository

2011 ◽  
Author(s):  
Trevor Sumerling ◽  
Paul Fish ◽  
George Towler ◽  
James Penfold ◽  
John Shevelan ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Erosion ◽  
Assessment Model ◽  
Coastal System ◽  
Future Evolution ◽  
Low Level ◽  
Waste Repository ◽  
The Uk ◽  
The Impact

The UK Low Level Waste Repository Ltd submitted an Environmental Safety Case for the disposal of low-level waste to our regulator, the Environment Agency, on the 1st of May 2011. This includes assessments of the long-term radiological safety of past and future disposals. A particular feature of the Low Level Waste Repository (LLWR) is that, because of its proximity to the coast, the site is vulnerable to coastal erosion. Our present understanding is that the site will be eroded on a timescale of a few hundred to a few thousand years, with consequent disruption of the repository, and dispersal of the wastes. We have undertaken a programme of scientific research and monitoring to characterise the evolution and function of the current coastal system that provides a basis for forecasting its future evolution. This has included modelling of contemporary hydrodynamics, geomorphological mapping, repeat LiDAR and aerial photographic surveys to detect patterns and rates of change, coastal inspections and reconstructions of post-glacial (i.e. last 15,000 years) sea levels and sediment budgets. Estimates of future sea-level rise have been derived from international sources and consideration given to the impact of such on the local coastline. Two alternative models of coastal recession have then been applied, one empirical and one physical-process based, taking account of the composition of Quaternary-age sediments between the coast and the site and uncertainties in future local sea level change. Comparison of the ranges of calculated times to site contact with sea-level rise indicate that the repository is most likely to be disrupted by undercutting of the engineered vaults and of the trenches. A novel and flexible radiological assessment model has been developed to analyse the impacts of the erosion of the repository and subsequent dispersal of wastes. The model represents the spatial layout of the site and distribution of radionuclides within the repository and is able to take account of a range of uncertainties. These include uncertainties related to the rate of erosion through the facility, amounts of co-erosion of geological and cap materials, alternative assumptions for residence of waste materials on the beach, alternative waste form associations, the wider dispersion of the eroded materials and marine sorption/desorption processes. Results indicate assessed annual doses and risks that are consistent with regulatory guidance levels.

Development and Validation of a Model of Uranium Release to Groundwater From Legacy Disposals at the UK Low Level Waste Repository

2008 ◽  
Vol 1107 ◽  
Author(s):  
J.S. Small ◽  
C. Lennon ◽  
S. Kwong ◽  
R.J. Scott
Keyword(s):  
Geochemical Model ◽  
3 Dimensional ◽  
Low Level ◽  
Waste Repository ◽  
Chemical Conditions ◽  
Safety Features ◽  
The Uk ◽  
Development And Validation ◽  
Physical And Chemical ◽  
Low Solubility

AbstractA previous radiological assessment of the UK Low Level Waste Repository (LLWR) has considered how the prevailing reducing chemical conditions in disposal trenches, may limit uranium release through the extreme low solubility of U(IV) solids. This study considers the additional effects that the physical and chemical nature of the uranium wastes may have on the release of uranium. Fluoride process residues produced by refining of uranium metal comprise the majority of the legacy inventory. Based on historic records and descriptions of the uranium wastes a conceptual model has been developed which bounds the release rate of uranium present as inclusions and dissolved in the solid residues by the dissolution rate of a magnesium fluoride matrix. The model is represented in a 3-dimensional groundwater flow and geochemical model. Initial findings indicate that the model correctly represents the range of fluoride and uranium concentrations that are measured in leachate from the LLWR trenches. Incorporation of this model in future safety assessments, together with a reduction in the derived inventory of uranium, is likely to result in a significant lowering of the peak groundwater dose to acceptable levels, even in the case that the site re-oxidizes. The study builds confidence in the inherent safety features that are provided by the sparingly soluble uranium waste residues and the reducing chemical conditions of the LLWR trenches.

Research in support of the 2011 environmental safety case for the Low Level Waste Repository

2012 ◽  
Vol 76 (8) ◽  
pp. 3465-3474 ◽  
Author(s):  
A. Baker ◽  
R. Cummings
Keyword(s):  
Peer Review ◽  
Research Priorities ◽  
Research Programme ◽  
Environmental Safety ◽  
Group Key ◽  
Review Group ◽  
Safety Issues ◽  
Low Level ◽  
Safety Case ◽  
Waste Repository

AbstractThis paper provides a summary of the research programme undertaken in support of the Low Level Waste Repository's 2011 environmental safety case (ESC). The programme has been developed, based on an understanding of safety issues and the requirements of the ESC. The research requirements to underpin the safety case have been identified by means of an auditable process, and subjected to scrutiny by both the regulators and a peer review group. Key research priorities for the future are identified.

Study of Scale-Down Method for Dense Grid Points

2013 ◽  
Vol 734-737 ◽  
pp. 3011-3015
Author(s):  
Sheng Yun Yu ◽  
Chang He Song ◽  
Hai Ying Xu
Keyword(s):  
Numerical Simulation ◽  
Geological Model ◽  
Three Dimension ◽  
Reservoir Heterogeneity ◽  
Geological Models ◽  
Scale Down ◽  
Dense Grid ◽  
Grid Points ◽  
Renormalization Method

The data of three-dimension geological models are very large, this kind of three -dimension geological model can not be directly used for numerical simulation and must be scaled down. The reservoir parameters, especially permeability, are scaled down by the simple renormalization method. The interbeds and parts of strong heterogeneity are filled back. The simple renormalization method is good through evaluation , not only it reduces the number of grid points, but also retains reservoir heterogeneity.

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