Publications

Chlorine-36 in the Biosphere

A number of tasks have been undertaken on Chlorine-36 in the biosphere as part of the BIOPROTA work programme. Those for which reports are currently available are detailed below.

  • International Forum on Chlorine-36 in the Biosphere

A forum on the behaviour of Cl-36 in the biosphere was held from 27 - 28 September 2006 at Chatenay-Malabry near Paris and was hosted by ANDRA. The workshop was well attended by 33 participants from nine countries, including operators and regulators. Various participants presented their current models for assessing the radiological impact of Cl-36 ranging from those models using equilibrium concentration ratios those using dynamic specific activity approaches. The chlorine cycle and the behaviour of organic and inorganic chlorine was also discussed. The workshop report is available here.

  • Chlorine-36 Accumulation in Soil and Crop Uptake

The BIOPROTA programme recently completed a study of Cl-36 behaviour in soils and uptake into plants. Within this study, a significant range of model types and alternative data assumptions were described and compared, demonstrating the degree of understanding of the likely behaviour of Cl-36 in soil and uptake into plants. Quantitative estimates were presented and compared for Cl-36 concentrations in crops based on contaminated water entering surface soil in irrigation water and via upward migration processes from below. Both deterministic and probabilistic assessments were demonstrated and a wide range of sensitivity calculations was also presented. Despite the variations in the models, the results for concentrations in crops were generally within about an order of magnitude of each other. The spread of results obtained in probabilistic calculations did not indicate much greater variation for a given set of site conditions. The report published by ANDRA is available to download.

A further project on chlorine-36, which extends the scope to include dose assessment, is currently in progress. Further information is provided in our current work programme.


Workshop reports and other publications of interest

The following workshop reports and other publications of interest are made available for use of others, but the participants and supporting organisations take no responsibility for the use of the material.

  • International Forum on Selenium-79 in the Biosphere

Selenium-79 (Se-79) is an important radionuclide in some types of radioactive waste. It is mobile and long-lived and potentially could migrate into the biosphere following release from radioactive waste disposal facilities. Special attributes are its complex chemistry, notably the chemical form is dependent upon the redox state with some compounds being volatile. Selenium is an essential element, but can also be toxic with only a small concentration range between deficiency and toxicity.

The data necessary for radiological assessment of Se-79 are scarce and can be unreliable, particularly in relation to its behaviour in the terrestrial soil-plant system.

A workshop was therefore held to discuss those attributes of Se-79 of particular relevance to radiological assessments for geological waste repositories. The objective was to provide an open forum for presentation and discussion of the behaviour of selenium in the biosphere, with particular focus on the environmental processes involved in selenium migration and accumulation in the biosphere and how radioecological assessments of Se-79 could be improved.

The workshop was held on 5-6 May 2008, hosted by Nagra, Wettingen, Switzerland, and involved both presentation and discussion of data requirements for dose assessment and knowledge and on-going research in the field of Se-79 behaviour in the biosphere. The workshop report is now available here.

  • International Forum on Application of Guidance and Methodologies for Assessing Radiation Impacts on Non-Human Biota (NHB) from Radioactive Waste Disposal Facilities (PROBIOTA)

A forum on the application of guidance and methodologies for assessing radiation impacts on non-human biota from radioactive waste disposal facilities was held from 31 January to 1 February 2007 at Lappeenranta, Finland, hosted by Posiva. The workshop was attended by 15 participants from six countries. Presentations were made by participants on developments in international methods for assessing impacts of ionising radiation on NHB and national experience in the application of methods to waste disposal facilities. The workshop report is now available here.

  • International Forum on Chlorine-36 in the Biosphere

A forum on the behaviour of Cl-36 in the biosphere was held from 27 - 28 September 2006 at Chatenay-Malabry near Paris and was hosted by ANDRA. The workshop was well attended by 33 participants from nine countries, including operators and regulators. Various participants presented their current models for assessing the radiological impact of Cl-36 ranging from those models using equilibrium concentration ratios those using dynamic specific activity approaches. The chlorine cycle and the behaviour of organic and inorganic chlorine was also discussed. The workshop report is available here.

  • Evaluation of codes for geosphere and biosphere compartmental contaminant transfer modelling

One of the goals of BIOPROTA is the search for opportunities of synergies. A task currently under development within the forum is therefore an inter-comparison of codes and their flexibilities for model development and implementation.

The current wealth of models and codes is a sign of healthy independent development by various agencies. Most agencies are moving away form hard coded models, since they allow for little model flexibility, requiring the user to modify the source code in order to adapt the model.

Comparing codes, illustrating their capacities, giving examples of their strengths and weaknesses could enhance code refinement and help point towards future development. A workshop on code comparisons was held at ANDRA in September 2005, which provided a platform for knowledge exchange on various codes and set the stage for synergy exploitation in the fields of code, model and data base development.

Anyone interested in finding out more information should contact Achim.Albrecht[at]andra.fr.


Work programme themes

The initial BIOPROTA work programme was organised in three themes. Details of these, and the publications within those themes, can be viewed below. The BIOPROTA output is made available for use of others, but the participants and supporting organisations take no responsibility for the use of the material. Please view either of the themes below.

  • Theme 1: Development of a Database for Key Radionuclides and Process Data

The overall objective of the BIOPROTA Database is to provide data and supporting information relating to key Features, Events and Processes (FEPs) and the behaviour of key radionuclides in the biosphere. Enviros have collated parameter information for inclusion in a database to support BIOPROTA forum members in biosphere modelling exercises.

  • Theme 2: Modelling Testing and Development Tasks

Theme 2 investigated the mathematical and conceptual modelling assumptions of key biosphere processes. There were six tasks under Theme 2:

Theme 2: Task 1 - Irrigation

The objective of this task was to investigate the calculation of doses arising from interception by growing crops using contaminated irrigation water and the consequent contamination of the food consumed by humans. The Theme 2 Task 1 report can be downloaded here.

Theme 2: Task 2 - Inhalation

The objective of this task was to investigate further the calculation of doses arising from inhalation of particles suspended from soils within which long-lived radionuclides, particularly alpha emitters, had accumulated. The Theme 2 Task 2 report can be downloaded here.

Theme 2: Task 3 - Model Review and Comparison for C-14 Dose Assessment

The objective of this task was to be able to model the transport and fate of C-14 and account for the treatment of C-14 processes, pathways and accumulation in the biosphere, including equilibration times between the newly arriving C-14 and stable C (C-13 and C-12) of the biosphere and its component system/ compartments. The Theme 2 Task 3 report can be downloaded here.

Theme 2: Task 4 - Model Comparison for Radionuclide Accumulation in Soils

The objective of this task was to discuss the objectives, definitions and results of an assessment model intercomparison. Focus was given to the long-term accumulation of long lived radionuclides in soils. Two often used scenarios were adapted as means of contamination, the well scenario, where contaminated well water is used for irrigation of agricultural land and a river scenario, where contaminated river water floods the agricultural land. The Theme 2 Task 4 report can be downloaded here.

Theme 2: Task 5 - Analogues

Analogue information can increase our conceptual understanding of long term repository behaviour and behaviour of radionuclides in the environment in support of post closure performance assessment. They can also provide quantitative data for Performance Assessment (PA) models and are a communication method to pass on information to a non-specialist audience.

The objective of this Task was to review past and present use and understanding of natural analogues relating to biotically-influenced biosphere processes with the intention of promoting considered application of them in future safety assessments and public communication. The Theme 2 Task 5 report can be downloaded here.

Theme 2: Task 7 - Geosphere-Biosphere Interface Zone (GBIZ)

The objective of Task 7 within Theme 2 was to support better account of the treatment of radionuclide transfer through the geosphere-biosphere interface zone, and the related accumulation/dispersion/dilution processes which should be considered in order to provide appropriate confidence in PA results. The Theme 2 Task 7 report can be downloaded here.

  • Theme 3: Site Characterisation, Experiments and Monitoring

The objective of Theme 3 is to provide advice about the biosphere features of a site which it may be useful to determine because they are especially relevant to the evaluation of radiation exposures over the long term. In addition, advice is also to be prepared concerning the setting up of experiments and field measurements so that the output can be relevantly interpreted for use in radiological assessments. The Theme 3 report can be downloaded here.

A further work programme on site characterisation is ongoing, which aims to take account of experience at particular sites, in terms of recognition of difficult areas as well as successes.