Social and scientific issues in the acceptibility of radiation risks

Ionising radiation hazards are perhaps the most documented and regulated occupational and environmental hazard. In the radiological protection field a single expert advisory organisation has had an unusually large influence on the international standard setting process. This is the International Commission on Radiological Protection (ICRP). Two common, and opposing views, exist over the formulation of protection recommendations by the ICRP. The first, and most widely accepted, is that its recommendations are scientifically determined. The second view, is that its recommendations are politically or socially determined. Neither of these analyses adequately accounts for the complex process in which protection recommendations are formulated. A third view, provided by studies of the origins of scientific controversy, suggests that both science and social factors are important in the assessment and limitation of risk. The aim of this thesis is not simply to examine the origin of controversy. Issues of equal, if not more, importance are the resolution of controversy, the formation of consensus and the maintenance of expert authority and influence. These issues form the central focus of this thesis. The aim is to assess the process through which the ICRP formulates its radiological protection recommendations and comment on the extent that these are influenced by the affiliations of its members. This thesis concludes that the ICRP's recommendations have been shaped by a complex relationship of scientific and social considerations, in which a socio-technical commitment to nuclear energy has played a key role. The Commission has responded to new scientific data by making complex changes to its philosophy and methods of describing risk. Where reductions in numerical limits have been applied they have been accompanied by practical measures designed to limit the impact of the change and provide continuity with the old limits and flexibility in the application of the new recommendations.

Highly radiation sensitive type IA FBGs for future dosimetry applications

We have studied Co60 gamma-irradiation effect on the characteristics of Type IA fiber Bragg gratings. A record Bragg peak shift of 190 pm was observed for a grating written in Fibercore PS-1250/1500 photosensitive fiber at a radiation dose of 116 kGy. Type IA and Type I gratings show different kinetics under radiation and during post-radiation annealing, which can be used for the design of a grating based dosimetry system.

Size-dependent radiation tolerance in ion irradiated TiN/AlN nanolayer films

Interface effects on ion-irradiation tolerance properties are investigated in nanolayered TiN/AlN films with individual layer thickness varied from 5 nm to 50 nm, prepared by pulsed laser deposition. Evolution of the microstructure and hardness of the multilayer films are examined on the specimens before and after He ion-implantation to a fluence of 4 × 10 m at 50 keV. The suppression of amorphization in AlN layers and the reduction of radiation-induced softening are observed in all nanolayer films. A clear size-dependent radiation tolerance characteristic is observed in the nanolayer films, i.e., the samples with the optimum layer thickness from 10 nm to 20 nm show the best ion irradiation tolerance properties, and a critical layer thickness of more than 5 nm is necessary to prevent severe intermixing. This study suggests that both the interface characteristics and the critical length scale (layer thickness) contribute to the reduction of the radiation-induced damages in nitride-based ceramic materials. © 2013 Elsevier B.V. All rights reserved.

Highly radiation sensitive type IA FBGs for future dosimetry applications

We have studied Co60 gamma-irradiation effect on the characteristics of Type IA fiber Bragg gratings. A record Bragg peak shift of 190 pm was observed for a grating written in Fibercore PS-1250/1500 photosensitive fiber at a radiation dose of 116 kGy. Type IA and Type I gratings show different kinetics under radiation and during post-radiation annealing, which can be used for the design of a grating based dosimetry system.