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This paper provides surface-clearance levels for 413 radionuclides for the normal reuse of objects leaving the controlled area of a nuclear facility. Four sets of surface-specific clearance levels are derived based on choices of dose coefficients (DCs) in probabilistic dose assessments using the SUrface DOse QUantification model (SUDOQU; van Dillen and van Dijk 2018 J. Radiol. Prot. 38 1147–203). The general dose criteria for clearance, extended with a suitable dose constraint for the concept of the representative person, are applied in the derivations. These clearance levels apply to the total of fixed and removable radioactive contamination on the surface of objects. The results are discussed in the context of conservatism of the exposure scenarios (parameters, DCs), and guidance is given on the selection and application of the values.

In this paper, we describe a practical and convenient method to include the contribution of the ingrowth of radioactive progeny in dose assessments of the corresponding parent nuclides. This method modifies the dose coefficients (DCs) of parent nuclides by adding weighted DCs of the corresponding daughter nuclides to them. Based on the decay kinetics of serial nuclear transformations, the progeny weighting factors, with values between 0 and 1, are derived by analysis of the time-integrated activity of each nuclide in the (branched) decay chain headed by a parent nuclide. Using the electronic, nuclear-decay database of Publication 107 of the International Commission on Radiological Protection (ICRP 2008), DC weighting factors for annual dose assessments are calculated for all daughter radionuclides in the decay chains and are tabulated in this paper. Weighting factors based on integration periods other than one year, ranging from 1 h–70 years, are also provided (see the supplementary material). With a priori established weighting factors, dose assessments become significantly simplified by considering the decay kinetics of only the parent nuclides and by applying the modified DCs. This ensures that the ingrowth of progeny is taken into account realistically. In some cases, one requires a conservative estimate of the dose, for instance when dealing with issues of the clearance of materials under regulatory control. Therefore, we adapted the weighting-factor method to derive conservative DC weighting factors for dose evaluations. These values are calculated for various integration periods and compared with those from an existing method adopted by the Euratom Article 31 Group of Experts and by the International Atomic Energy Agency. Identical progeny weighting factors are obtained for long-lived parent radionuclides, whereas for short-lived parent radionuclides, the new method can yield significantly larger values. For example, the weighting factor of I-131 (daughter of parent Te-131) increases from 0.002 to 1.0 based on an integration period of 1 year. The progeny DC weighting factors, derived based on nuclear transformations in exit-only decay chains, may not always be suitable for use in radiological dose evaluations. For instance, when environmental removal pathways are dominant, the application of these weighting factors may have its limitations. This paper, therefore, provides guidance on the proper selection and application of weighting factors.

A new methodology has been developed for the assessment of the annual effective dose resulting from removable and fixed radiological surface contamination. It is entitled SUDOQU (SUrface DOse QUantification) and it can for instance be used to derive criteria for surface contamination related to the import of non-food consumer goods, containers and conveyances, e.g., limiting values and operational screening levels. SUDOQU imposes mass (activity)-balance equations based on radioactive decay, removal and deposition processes in indoor and outdoor environments. This leads to time-dependent contamination levels that may be of particular importance in exposure scenarios dealing with one or a few contaminated items only (usually public exposure scenarios, therefore referred to as the 'consumer' model). Exposure scenarios with a continuous flow of freshly contaminated goods also fall within the scope of the methodology (typically occupational exposure scenarios, thus referred to as the 'worker model'). In this paper we describe SUDOQU, its applications, and its current limitations. First, we delineate the contamination issue, present the assumptions and explain the concepts. We describe the relevant removal, transfer, and deposition processes, and derive equations for the time evolution of the radiological surface-, air- and skin-contamination levels. These are then input for the subsequent evaluation of the annual effective dose with possible contributions from external gamma radiation, inhalation, secondary ingestion (indirect, from hand to mouth), skin contamination, direct ingestion and skin-contact exposure. The limiting effective surface dose is introduced for issues involving the conservatism of dose calculations. SUDOQU can be used by radiation-protection scientists/experts and policy makers in the field of e.g. emergency preparedness, trade and transport, exemption and clearance, waste management, and nuclear facilities. Several practical examples are worked out demonstrating the potential applications of the methodology.

Atherosclerosis is the development of lipid-laden plaques in arteries and is nowadays considered as an inflammatory disease. It has been shown that high doses of ionizing radiation, as used in radiotherapy, can increase the risk of development or progression of atherosclerosis. To elucidate the effects of radiation on atherosclerosis, we propose a mathematical model to describe radiation-promoted plaque development. This model distinguishes itself from other models by combining plaque initiation and plaque growth, and by incorporating information from biological experiments. It is based on two consecutive processes: a probabilistic dose-dependent plaque initiation process, followed by deterministic plaque growth. As a proof of principle, experimental plaque size data from carotid arteries from irradiated ApoE\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{{-/-}}$$\end{document}-/- mice was used to illustrate how this model can provide insight into the underlying biological processes. This analysis supports the promoting role for radiation in plaque initiation, but the model can easily be extended to include dose-related effects on plaque growth if available experimental data would point in that direction. Moreover, the model could assist in designing future biological experiments on this research topic. Additional biological data such as plaque size data from chronically-irradiated mice or experimental data sets with a larger variety in biological parameters can help to further unravel the influence of radiation on plaque development. To the authors’ knowledge, this is the first biophysical model that combines probabilistic and mechanistic modeling which uses experimental data to investigate the influence of radiation on plaque development. Electronic supplementary material The online version of this article (doi:10.1007/s00411-017-0709-2) contains supplementary material, which is available to authorized users.

Epidemiological miner cohort data used to estimate lung cancer risks related to occupational radon exposure often lack cohort-wide information on exposure to tobacco smoke, a potential confounder and important effect modifier. We have developed a method to project data on smoking habits from a case-control study onto an entire cohort by means of a Monte Carlo resampling technique. As a proof of principle, this method is tested on a subcohort of 35,084 former uranium miners employed at the WISMUT company (Germany), with 461 lung cancer deaths in the follow-up period 1955-1998. After applying the proposed imputation technique, a biologically-based carcinogenesis model is employed to analyze the cohort's lung cancer mortality data. A sensitivity analysis based on a set of 200 independent projections with subsequent model analyses yields narrow distributions of the free model parameters, indicating that parameter values are relatively stable and independent of individual projections. This technique thus offers a possibility to account for unknown smoking habits, enabling us to unravel risks related to radon, to smoking, and to the combination of both.

The Fukushima nuclear accident (Japan, 11 March 2011) revealed the need for well-founded criteria for surface contamination and associated screening levels related to the import of non-food (consumer) goods, containers and conveyances. The only available European-harmonised criteria are those laid down in the IAEA transport regulations, but these criteria date back from the early 1960s and only apply to the safe transport of radioactive materials. The main problem is that a generic dose-assessment model for consumer products is missing. Therefore, RIVM (National Institute for Public Health and the Environment) developed a new methodology entitled SUDOQU (SUrface DOse QUantification) to calculate the annual effective dose for both consumers and non-radiological workers, addressing issues of removability of surface contamination. The methodology can be used to derive criteria and screening levels for surface contamination and could serve as a useful tool for policy-makers and radiation-protection specialists.

Breast cancer incidence in a tuberculosis fluoroscopy cohort has been modelled with a two-stage carcinogenesis model. The relatively simple model, in which hormonal influences only affect the number of sensitive target cells, fits the data very well. Under the assumption that individual hormonal differences average out, and with a relative biological effectiveness for mammographic X rays of 1, the model yields ∼10 fatal breast cancer cases induced by the entire Dutch screening programme over a period of 25 y. This is much lower than derived from standard ICRP risk estimates and should be compared with the number of lives saved, which is estimated at ∼350 y(-1). As the extent of screening is currently being reconsidered in The Netherlands and elsewhere, this is an important result.

A method is presented to control the in-plane ordering, size, and interparticle distance of nanoparticles fabricated by evaporation through a mask of colloidal particles. The use of optical tweezers combined with critical point drying gives single-particle position control over the colloidal particles in the mask. This extends the geometry of the colloidal masks from (self-organized) hexagonal to any desired symmetry and spacing. Control over the mask's hole size is achieved by MeV ion irradiation, which causes the colloids to expand in the in-plane direction, thus shrinking the size of the holes. After modification of the mask, evaporation at different angles with respect to the mask gives additional control over structure and interparticle distance, allowing nanoparticles of different materials to be deposited next to each other. We demonstrate large arrays of metal nanoparticles with dimensions in the 15-30 nm range, with control over the interparticle distance and in-plane ordering.

An MeV ion beam penetrating an amorphous material causes rapid heating of a cylindrically shaped region around the ion track, which leads to anisotropic deformation: the irradiated material shrinks in the direction of the ion beam and expands perpendicular to it. This provides a unique way to tailor the shape of colloidal materials. Spherical silica particles are transformed into oblate ellipsoids, with anisotropy tuned by ion fluence. Ellipsoid suspensions can be used to test theories of colloidal phase transformations. Photonic crystals of ellipsoidal colloids can have enlarged optical band gaps. Deforming metal-silica or silica-metal core-shell particles leads to control over their surface plasmon resonance frequency. Two-dimensional colloidal crystals show complex deformation behavior, providing unique masks for nanolithography.

Epidemiological miner cohort data used to estimate lung cancer risks related to occupational radon exposure often lack cohort-wide information on exposure to tobacco smoke, a potential confounder and important effect modifier. We have developed a method to project data on smoking habits from a case-control study onto an entire cohort by means of a Monte Carlo resampling technique. As a proof of principle, this method is tested on a subcohort of 35,084 former uranium miners employed at the WISMUT company (Germany), with 461 lung cancer deaths in the follow-up period 1955-1998. After applying the proposed imputation technique, a biologically-based carcinogenesis model is employed to analyze the cohort's lung cancer mortality data. A sensitivity analysis based on a set of 200 independent projections with subsequent model analyses yields narrow distributions of the free model parameters, indicating that parameter values are relatively stable and independent of individual projections. This technique thus offers a possibility to account for unknown smoking habits, enabling us to unravel risks related to radon, to smoking, and to the combination of both.

Spherical silica (SiO2), zinc sulfide (ZnS), and core-shell particles of these materials undergo substantial anisotropic plastic deformation under high-energy ion irradiation. Individual particles can be turned into oblate or prolate ellipsoids with exact control over the aspect ratio. In this letter, we report on the fabrication and optical characterization of thin three-dimensional photonic crystals of spherical particles, which have been anisotropically deformed into spheroidal oblates by means of ion irradiation. As a result of the collective deformation process, both the unit cell symmetry and the particle form factor have been changed leading to appreciable tunability in the optical properties of the photonic crystal.

A biologically based two-stage carcinogenesis model is applied to epidemiological data for lung cancer mortality in a large uranium miner cohort of the WISMUT company (Germany). To date, this is the largest uranium miner cohort analyzed by a mechanistic model, comprising 35,084 workers among whom 461 died from lung cancer in the follow-up period 1955-1998. It comprises only workers who were first employed between 1955 and 1989 and contains information on annual exposures to radon progeny. We fitted the model's free parameters, including the average growth time of one malignant cell into a lethal tumor. This lag time has an extraordinary value of 13 to 14 years, larger than that previously used or found in miner studies. Even though cohort-wide information on smoking habits is limited and the calendar-year dependence of tobacco smoke exposure was only implicitly accounted for by a birth cohort effect, we find good agreement between the modeled (expected) and empirical (observed) lung cancer mortality. Model calculations of excess relative lung cancer death risk agree well with those from the descriptive, BEIR VI-type exposure-age-concentration model for WISMUT miners. The large variety of exposure profiles in the cohort leads to a well-determined mechanistic model that in principle allows for an extrapolation from occupational to indoor radon exposure.

A mechanistic two-stage carcinogenesis model has been applied to model lung-cancer mortality in the largest uranium-miner cohort available. Models with and without smoking action both fit the data well. As smoking information is largely missing from the cohort data, a method has been devised to project this information from a case-control study onto the cohort. Model calculations using 256 projections show that the method works well. Preliminary results show that if an explicit smoking action is absent in the model, this is compensated by the values of the baseline parameters. This indicates that in earlier studies performed without smoking information, the results obtained for the radiation parameters are still valid. More importantly, the inclusion of smoking-related parameters shows that these mainly influence the later stages of lung-cancer development.

Mammography screening is an accepted procedure for early detection of breast tumors among asymptomatic women. Since this procedure involves the use of X rays, it is itself potentially carcinogenic. Although there is general consensus about the benefit of screening for older women, screening practices differ between countries. In this paper radiation risks for these different practices are estimated using a new approach. We model breast cancer induction by ionizing radiation in a cohort of patients exposed to frequent X-ray examinations. The biologically based, mechanistic model provides a better foundation for the extrapolation of risks to different mammography screening practices than empirical models do. The model predicts that the excess relative risk (ERR) doubles when screening starts at age 40 instead of 50 and that a continuation of screening at ages 75 and higher carries little extra risk. The number of induced fatal breast cancers is estimated to be considerably lower than derived from epidemiological studies and from internationally accepted radiation protection risks. The present findings, if used in a risk-benefit analysis for mammography screening, would be more favorable to screening than estimates currently recommended for radiation protection. This has implications for the screening ages that are currently being reconsidered in several countries.

Photonic crystals are regular three-dimensional (3D) structures with which the propagation and spontaneous emission of photons can be manipulated in new ways if the feature sizes are roughly half the wavelength and the coupling with the electromagnetic radiation is sufficiently strong. ‘Early’ speculation on these new possibilities can be found in the Refs.1–4 A more recent overview can be found in Ref.5 and, of course, the other chapters in this book. A useful analogy to guide thinking about the properties and the applications of photonic crystals is the propagation of electrons in a semiconductor in comparison to the propagation of photons scattered by a regular 3D dielectric material. An example is the possibility of opening up a region of energy, a photonic band gap, for which the propagation of photons is forbidden, in analogy to the electronic band gap present in semiconductors. However, there are also important differences; for instance, the scattering of photons cannot be described well by scalar wave equations because the polarization of light cannot be neglected. Most theoretical and experimental work for visible light applications have until now focused on pure dielectric structures, interestingly, recent calculations have shown that metallo-dielectric structures should also be considered as having very interesting photonic properties in the visible, including, if one neglects absorption, a complete band gap.6–8 And even with absorption taken into account, it seems that for relatively thin photonic crystals most of the interesting optical properties remain.8