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Smith G.M.,GMS Abingdon Ltd. | Smith K.L.,RadEcol Consulting Ltd. | Kowe R.,Radioactive Waste Management Directorate | Thorne M.,Mike Thorne and Associates Ltd. | And 3 more authors.
Journal of Environmental Radioactivity | Year: 2014

Decisions on permitting, controlling and monitoring releases of radioactivity into the environment rely on a great variety of factors. Important among these is the prospective assessment of radionuclide behavior in the environment, including migration and accumulation among and within specific environmental media, and the resulting environmental and human health impacts. Models and techniques to undertake such assessments have been developed over several decades based on knowledge of the ecosystems involved, as well as monitoring of previous radionuclide releases to the environment, laboratory experiments and other related research.This paper presents developments in the assessment of radiation doses and related research for some of the key radionuclides identified as of potential significance in the context of releases to the biosphere from disposal facilities for solid radioactive waste. Since releases to the biosphere from disposal facilities involve transfers from the geosphere to the biosphere, an important aspect is the combined effects of surface hydrology, near-surface hydrogeology and chemical gradients on speciation and radionuclide mobility in the zone in which the geosphere and biosphere overlap (herein described as the geosphere-biosphere subsystem). In turn, these aspects of the environment can be modified as a result of environmental change over the thousands of years that have to be considered in radioactive waste disposal safety assessments. Building on the experience from improved understanding of the behavior of the key radionuclides, this paper proceeds to describe development of a generic methodology for representing the processes and environmental changes that are characteristic of the interface between the geosphere and the biosphere. The information that is provided and the methodology that is described are based on international collaborative work implemented through the BIOPROTA forum, www.bioprota.org. © 2013 Elsevier Ltd.


PubMed | Institute for Radiological Protection and Nuclear Safety, RadEcol Consulting Ltd, CEFAS, International Atomic Energy Agency and 11 more.
Type: | Journal: Radiation protection dosimetry | Year: 2016

During the past decades, many specialised networks have formed to meet specific radioecological objectives, whether regional or sectorial (purpose-oriented). Regional networks deal with an array of radioecological issues related to their territories. Examples include the South Pacific network of radioecologists, and the European network of excellence in radioecology. The latter is now part of the European platform for radiation protection. Sectorial networks are more problem-oriented, often with wider international representativeness, but restricted to one specific issue, (e.g. radioactive waste, low-level atmospheric contamination, modelling). All such networks, while often working in relative isolation, contribute to a flow of scientific information which, throughUnited Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEARs) efforts of synthesis, feeds into the radiation protection frameworks of protecting humans and the environment. The IUR has therefore prompted a co-construction process aimed at improving worldwide harmonisation of radioecology networks. An initiative based on an initial set of 15 networks, now called the IUR FORUM, was launched in June 2014. The IUR Forum agreed to build a framework for improved coordination of scientific knowledge, integration and consensus development relative to environmental radioactivity. Three objectives have been collectively assigned to the IUR FORUM: (1) coordination, (2) global integration and construction of consensus and (3) maintenance of expertise. One particular achievement of the FORUM was an improved description and common understanding of the respective roles and functions of the various networks within the overall scene of radioecology R&D. It clarifies how the various networks assembled within the IUR FORUM interface with UNSCEAR and other international regulatory bodies (IAEA, ICRP), and how consensus on the assessment of risk is constructed. All these agencies interact with regional networks covering different geographical areas, and with other networks which address specific topics within radiation protection. After holding its first Consensus Symposium in 2015, examining the possible ecological impact of radiation from environmental contamination, the IUR FORUM continues its work towards improved radiation protection of humans and the environment. We welcome new members.


Smith K.,Eden Nuclear and Environment Ltd. | Jackson D.,Eden Nuclear and Environment Ltd. | Smith G.,GMS Abingdon Ltd. | Norris S.,Campus Management
Mineralogical Magazine | Year: 2012

Carbon-14 has been identified as one of the more significant radionuclides in solid radioactive wastes in a repository, due to the potential radiological impact arising if 14C were to be released and enter the biosphere. However, the assessment of radiation doses is complicated by the major role of carbon in biological processes, and this has tended to lead to the adoption of a cautious assessment approach. An international comparison of five models used to predict uptake of 14C to agricultural crops has been undertaken, within the BIOPROTA framework. Processes investigated include conversion of 14C-labelled CH4 into CO2 in soils, carbon accumulation in and release from soil carbon pools, gaseous emanation to, and dispersion from, the plant canopy atmosphere and, incorporation into plants by photosynthesis. For a unit rate of entry of 14C to soil, modelled activity concentrations in cereal crops differ by three to five orders of magnitude. This reflects, in part, differing assumptions for mixing and dispersion of air above the soil surface and within the crop canopy layer. For a unit activity concentration of 14C in air, the modelled uptake to cereal crops converges significantly. Following an assumed irrigation of crops with groundwater containing unit activity of 14C, the predicted uptake to crops varied by two to four orders of magnitude, again largely dominated by assumptions regarding the canopy atmosphere. In all cases, there is some convergence in model predictions as field size increases. A continuing programme of field research is being undertaken in parallel with the assessment work. © 2012 The Mineralogical Society.


Smith K.,Eden Nuclear and Environment Ltd. | Smith G.M.,GMS Abingdon Ltd. | Norris S.,Campus Management
Mineralogical Magazine | Year: 2012

Consideration of the biosphere is important in the post-closure safety assessment of a geological disposal facility (GDF) as the biosphere acts as the receptor for any contaminants that may be released from the geosphere. Considerable uncertainty exists in the characteristics of the biosphere at times in the far future when any contaminant releases from a GDF would reach the accessible environment. These uncertainties include human behaviour, affecting environmental change as well as exposure modes. A number of critical scientific issues have been identified through the practical application of the International Atomic Energy Agency reference biosphere approach within both site generic and site specific repository assessment projects. These issues are being addressed through an international collaboration programme, BIOPROTA. The purpose of this paper is to describe the BIOPROTA programme, its objectives and typical working method. The approach is illustrated with examples from the recent work programme including model intercomparison studies for the radionuclides 36Cl and 79Se. © 2012 The Mineralogical Society.


Sneve M.K.,Norwegian Radiation Protection Authority | Smith G.,GMS Abingdon Ltd
Radiation Protection Dosimetry | Year: 2015

Past development of processes and technologies using radioactive material led to construction of many facilities worldwide. Some of these facilities were built and operated before the regulatory infrastructure was in place to ensure adequate control of radioactive material during operation and decommissioning. In other cases, controls were in place but did not meet modern standards, leading to what is now considered to have been inadequate control. Accidents and other events have occurred resulting in loss of control of radioactive material and unplanned releases to the environment. The legacy from these circumstances is that many countries have areas or facilities at which abnormal radiation conditions exist at levels that give rise to concerns about environmental and human health of potential interest to regulatory authorities. Regulation of these legacy situations is complex. This paper examines the regulatory challenges associated with such legacy management and brings forward suggestions for finding the path from: legacy recognition; implementation, as necessary, of urgent mitigation measures; development of a longerterm management strategy, through to release from regulatory control. © The Author 2014.


Smith K.,RadEcol Consulting Ltd. | Smith G.,GMS Abingdon Ltd. | Perez-Sanchez D.,CIEMAT
15th International High-Level Radioactive Waste Management Conference 2015, IHLRWM 2015 | Year: 2015

BIOPROTA is an international collaborative forum, started in 2002, designed to support resolution of key issues in biosphere aspects of the assessment of the long-term impacts of potential contaminant releases associated with solid radioactive waste disposal. The focus is on the application of good science to provide a good understanding of relevant biosphere system processes and address important uncertainties. This in turn supports decision making related to waste management and the appropriate allocation of resources to solve problems. The forum is tailored to enable opportunities for sharing, reviewing and interpretation of information used in the biosphere component of post-emplacement assessments of solid radioactive waste disposal. This includes methods for system characterization and description, modelling of system evolution subject to assumptions for environmental change, exposure modelling according to those possibilities for evolution, and data to support all the assessment assumptions and model parameter selection. The working method is based on an annual meeting for information exchange and identification of key issues of common interest. Out of that discussion, opportunities for collaborative projects and topical workshops are developed. This paper reviews recent progress in BIOPROTA and related international and national level activities, and present ideas for the focus of future work.


PubMed | Norwegian Radiation Protection Authority and GMS Abingdon Ltd
Type: Journal Article | Journal: Radiation protection dosimetry | Year: 2015

Past development of processes and technologies using radioactive material led to construction of many facilities worldwide. Some of these facilities were built and operated before the regulatory infrastructure was in place to ensure adequate control of radioactive material during operation and decommissioning. In other cases, controls were in place but did not meet modern standards, leading to what is now considered to have been inadequate control. Accidents and other events have occurred resulting in loss of control of radioactive material and unplanned releases to the environment. The legacy from these circumstances is that many countries have areas or facilities at which abnormal radiation conditions exist at levels that give rise to concerns about environmental and human health of potential interest to regulatory authorities. Regulation of these legacy situations is complex. This paper examines the regulatory challenges associated with such legacy management and brings forward suggestions for finding the path from: legacy recognition; implementation, as necessary, of urgent mitigation measures; development of a longer-term management strategy, through to release from regulatory control.


This paper describes the development and evolution of the Electric Power Research Institute's (EPRI) post-closure dose assessment for potential releases of radionuclides from the proposed High Level Waste repository at Yucca Mountain. The starting point for this work was the 1995 publication of Technical Bases for Yucca Mountain Standards by the Commission on Geosciences, Environment and Resources of the National Research Council. This report proposed the development and application of an individual risk-based standard for releases from the repository to replace the existing one, which was based on radionuclide release limits. This in turn implied the development and application of methods to assess radiation doses to humans. Accordingly, EPRI produced a methodology for such dose assessment as part of its Total System Performance Assessment program for the proposed Yucca Mountain repository site. The methodology initially addressed releases via groundwater and then releases associated with extrusive igneous events. The methodology was updated and applied over the following years to take account of regulatory developments, changes in estimates of the source term to the biosphere, peer review through international model comparison exercises, new site generic data, and new data concerning conditions at the point of compliance in Amargosa Valley. The main outputs were Biosphere Dose Conversion Factors, which relate radionuclide levels in environmental media to the annual individual doses to a member of a hypothetical critical group and to the regulator-defined Reasonably Maximally Exposed Individual. Most recently, consideration has been given to uncertainty in the dose estimates based on a probabilistic analysis. The paper provides a perspective on the evolution of the dose assessments in response to the developments listed above. Copyright © by the Health Physics Society.


Smith G.,GMS Abingdon Ltd
15th International High-Level Radioactive Waste Management Conference 2015, IHLRWM 2015 | Year: 2015

Many countries have operated research reactors safely for many years. The scale and design of these reactors varies considerably according the objectives of the research programs that they were intended to support. The amount of spent fuel arising is relatively small, compared to that linked to commercial and military reactors. However, in countries which do not have commercial or military programs, only research reactors, the management of the spent fuel presents a significant challenge. It is also the case that research reactor fuel does not present a single set of characteristics relevant to its management. Coupled with other regional and local factors as widely disperse as geography, regulatory framework and policy, this means that no single solution is likely to emerge that is effective in all cases. This paper reviews those issues and provides some illustrative discussion and conclusions.


Thome M.C.,Mike Thorne and Associates Ltd | Smith G.M.,GMS Abingdon Ltd
15th International High-Level Radioactive Waste Management Conference 2015, IHLRWM 2015 | Year: 2015

In post-closure radiological safety assessments of geological disposal facilities for radioactive wastes, models are developed and applied for transport of radionuclides through the engineered barriers and surrounding host rock towards the biosphere. Whereas the role of the engineered barriers and host rock is generally to prevent or retard the migration of radionuclides, in the more superficial strata retardation may be of less importance compared with dilution and dispersion. However, in determining the radiological impacts of possible releases of radionuclides in relation to the regulatory criteria typically employed, there is a need to evaluate the degree of dilution and dispersion in the superficial strata, together with any re-concentration that may occur. This means that appropriate conceptual and mathematical models are required to define the region between the deeper geosphere and the superficial biosphere. This region is described as the geosphere-biosphere interface and its characterization is discussed herein, based on work carried on work carried out with the BIOPROTA international collaborative forum.

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