All nuclear plant discharge low-level radiation (LLR) to the environment. The problem that the thesis addresses is that of the definition of LLR risk. This thesis is a study of the nature of the LLR risk conflict, and how opposing views about LLR risk are brought to bear at both local and global levels. In other words, the thesis empirically explores the basis of this conflict by embedding a set of linked local risk controversy case studies within the global fundamental LLR risk scientific debate. My position is that risk and safety knowledge is conceived, produced, and deployed in particular ways. In this context, I have conflated the notions of conception, production and deployment of LLR risk knowledge by coining the neologism: the 'performance ofLLR risk'. To this end, the thesis has mapped out the performance of knowledge by and between actors/actants involved in the LLR risk debate. In other words, the thesis has attempted to explore (via case study research) the traces left by the pathways along which differing quantities and qualities of anthropogenic ionising radiation insults are delivered to differing receiving populations and individuals - and various responses to those insults. Further, (via the interrogation of a set of analytical themes) I have explored a number of meanings that adhere to fundamental experimental data. What is significant about elements of the fundamental institutional judgements, are their inherently subjective nature (in the context of complex, uncertain, indeterminate and latent phenomena). In practice, the end-points of these negotiations are institutionally reified as radiation protection risk factors, which are then translated into models of environmental management. Thus, somewhere along the continuum that stretches from fundamental science to rad-risk regulation 'on the ground', the statement 'LLR may be risky', is transformed into 'LLR is relatively safe'. The thesis problematises the appearance of closure (LLR is safe) as a unified truth that is reified in industrial and regulatory products, processes and procedures; by invoking the ANT concept of 'translation', whereby the disappearance of the network of contingent assumptions, negotiations, extrapolations, justifications and uncertainty that comprise that claim is replaced by a black-boxed knowledge construct that is patterned, disciplined, strong and durable. My primary conclusion is that, for the purposes of institutional radiation protection, fundamental epistemological scientific uncertainty about LLR risk knowledge is potentially problematically translated into regulatory certainty. In other words, I present evidence which suggests that the risk communication 'LLR is potentially risky' (via fundamental science) translates into 'LLR is acceptably safe' (for the purposes of radiation protection regUlation). Or more precisely, whilst the institutional radiation protection community remain unsure about the determination of LLR risk (because, at present, knowledge of the action ofLLR and the tools employed to determine that risk, are not sufficiently developed) - for regulatory radiation protection purposes LLR is assumed to be relatively safe. Thus, I argue that there exist profound uncertainty and indeterminacy about the (over)simp1ification of the complex and potentially problematic latent phenomena that comprise the institutional network LLR risk judgement. I contend that these risk definitions seem dependent on the relative strengths or weaknesses of the various natural and social associations that are corralled enrolled and mobilised. The powerful institutional network rests with the LLR safety claim. For counter groups a causative connection between chronic LLR discharge by nuclear facilities and childhood leukaemia clusters and increased cancer incidence in young people in communities near to those facilities remain phantom intermediaries - excluded and excised from the institutional LLR risk definition. However, evidence presented in this thesis problematises the institutional safety claim, and replaces it with another truth claim: that LLR may be unacceptably risky.

Naturally Occurring Radioactive Material (NORM) is produced as scale in several industrial and oil processes and represents a risk for the public health and the environment due to the high levels of hazardous radionuclides (the main species are ²²⁶Ra and ²²⁸Ra and daughters).

A hyper-pure germanium detector-based, gamma-ray spectroscopy, low-background counting system was used to determine the level of natural radioactivity from beach sand samples collected from various locations along the Andaman coast of Thai peninsula following the 2004 tsunami. The activity concentrations of 226Ra, 232Th and 40K were found to lie in the range of 1.6±0.1↔52.5±0.8, 0.3±0.1↔73.9±1.5 and 2.8±0.1 ↔1,111.9±116.5 Bq.kg-1 respectively for the west coast and 3.5±0.1 ↔83.1±1.2, 4.5±0.1 ↔42.0±0.9, and 9.6±1.1 ↔1,376±144 Bq.Kg-1 respectively for the east coast. The radioactivity concentrations of 226Ra, 232Th and 40K along the Andaman coast are comparable to that of the east coast, which was not exposed to the tsunami. The activity concentration of artificial radionuclides (ie.137Cs) was found to be below the minimum detectable activity. The derived values for external and internal hazard indices for sand samples obtained in this study ranges from 0.01-0.50 and 0.01-0.72 respectively while the radium equivalent activity varied from 2.8-184.8 Bq-kg-1 which are lower than the internationally approved values of <1 for Hex and Hm and <370 Bq.kg-1 for Raeg. None of beach sand samples which were studied could be considered as a radiological hazard to people who were exposed to them. The monitored areas are at the typical local level of radioactivity from natural background radiation. The gamma absorbed dose rates due to 226Ra, 232Th and 40K in the sand samples varied in the range 1.3±0.1 to 86.4±2.5 nGy.h-1 with an average value of 48±1 nGy.h-1. Assuming a 20% outdoor occupancy factor, the corresponding annual effective dose varied from 1.6±0.1 to 105.9±3.1 μSv.y-1 with a mean value of 59.1±0.3 μSv.y-1, significantly lower than the worldwide average value of 0.07 mSv.y-1 for the annual outdoor effective dose as reported by UNSCEAR(2000).

This thesis describes the development of a system to assist the design of long-term remediation strategies for radioactively contaminated land. Existing radiological models, that estimate the uptake of radionuclides by plants and the doses arising from exposure to external radiation, were combined with a spatially implemented food-chain model, to allow the temporal and spatial variation of radionuclide transport through the terrestrial environment, and the resulting doses of exposed human populations, to be estimated. Doses are estimated using a novel method for the simulation of human populations, which includes the generation of sub-populations by Monte-Carlo sampling and consideration of the geographical origins of consumed food products. Various simulated radiological countermeasures have been incorporated into the system (e.g. clean-feeding of livestock), allowing the effects of potential remediation strategies to be assessed. Furthermore, a method has been developed which efficiently identifies the optimum set of countermeasures for a given scenario according to a defined merit function using cost benefit analysis, which can be extended to include terms that account for the preference for averting high levels of individual dose, and the social costs of a number of countermeasure side-effects (e.g. disruption of normal daily life). To assess the applicability of the system, it was used to evaluate potential remediation strategies for hypothetical, large-scale nuclear accidents within two contrasting case study sites (Cumbria, UK and Zaragoza, Spain). In both case studies the system successfully identified optimal remediation strategies which were, according to the defined merit function, significant improvements upon simple food and dose rate restriction strategies.

Die Rückstände des Uranbergbaus in Sachsen wurden in der Vergangenheit bewusst oder unbewusst als Baumaterial im Straßen- und Wegebau, zum Planumsausgleich für Flächen und beim Hausbau verwendet. Die Broschüre richtet sich an Planungsbüros, Antragsteller sowie Ausführende im Bau- und Straßenbau und liefert umfassende Informationen für eine strahlenschutzgerechte, sichere und kostengünstige Verwertung oder Beseitigung dieser Stoffe. Enthalten sind Hinweise zu Planung, Antragstellung, Voruntersuchung, strahlen-schutzfachlicher Baubegleitung und Dokumentation von Baumaßnahmen, bei denen mit radioaktiven Stoffen zu rechnen ist.

Die Rückstände des Uranbergbaus in Sachsen wurden in der Vergangenheit bewusst oder unbewusst als Baumaterial im Straßen- und Wegebau, zum Planumsausgleich für Flächen und beim Hausbau verwendet. Die Broschüre richtet sich an Planungsbüros, Antragsteller sowie Ausführende im Bau- und Straßenbau und liefert umfassende Informationen für eine strahlenschutzgerechte, sichere und kostengünstige Verwertung oder Beseitigung dieser Stoffe. Enthalten sind Hinweise zu Planung, Antragstellung, Voruntersuchung, strahlen-schutzfachlicher Baubegleitung und Dokumentation von Baumaßnahmen, bei denen mit radioaktiven Stoffen zu rechnen ist.