The dosimetry of internal exposure to radionuclides is performed on the basis of biokinetic and dosimetric models. For prospective purpose, the organ or effective dose resulting from potential conditions of exposure can be calculated by applying these models with dedicated software. However, it is acknowledged that a significant uncertainty is associated with such calculation due to the variability of individual cases and to the possible lack of knowledge about some factors influencing the dosimetry. This uncertainty has been studied in a range of situations by modeling the uncertainty on the model parameters by probability distributions and propagating this uncertainty onto the dose result by Monte Carlo calculation. However, while probability distributions are well adapted to model the known variability of a parameter, they may lead to an unrealistically low estimate of the uncertainty due to a lack of knowledge about some input parameters. Here we present a mathematical method, based on the Dempster-Shafer theory, to deal with such imprecise knowledge. We apply this method to the prospective dosimetry of inhaled uranium dust in the nuclear fuel cycle when its physico-chemical properties are not precisely known. The results show an increased estimation of the range of uncertainty as compared to the application of a probabilistic method. This Dempster-Shafer method may valuably be applied in future prospective dosimetry of internal exposure in order to more realistically estimate the uncertainty resulting from an imprecise knowledge of the parameters of the dose calculation.
Journal Article Invited Paper A structured approach for the assessment of internal dose: the IDEAS guidelines Get access H. Doerfel, H. Doerfel * 1Forschungszentrum Karlsruhe GmbH, Karlsruhe, Germany *Corresponding author: info@idea-system.com Search for other works by this author on: Oxford Academic PubMed Google Scholar A. Andrasi, A. Andrasi 2KFKI Atomic Energy Research Institute, Budapest, Hungary Search for other works by this author on: Oxford Academic PubMed Google Scholar M. Bailey, M. Bailey 3Radiation Protection Division, Health Protection Agency, Chilton, Didcot OX11 0RQ, UK Search for other works by this author on: Oxford Academic PubMed Google Scholar V. Berkovski, V. Berkovski 4Radiation Protection Institute, Kiev, Ukraine Search for other works by this author on: Oxford Academic PubMed Google Scholar E. Blanchardon, E. Blanchardon 5Institut de Radioprotection et de Sûreté Nucleaire, Fontenay-aux-Roses, France Search for other works by this author on: Oxford Academic PubMed Google Scholar C.-M. Castellani, C.-M. Castellani 6ENEA Radiation Protection Institute, Bologna, Italy Search for other works by this author on: Oxford Academic PubMed Google Scholar R. Cruz-Suarez, R. Cruz-Suarez 7International Atomic Energy Agency, Vienna, Austria Search for other works by this author on: Oxford Academic PubMed Google Scholar C. Hurtgen, C. Hurtgen 8SCK•CEN Belgian Nuclear Research Centre, Mol, Belgium Search for other works by this author on: Oxford Academic PubMed Google Scholar B. LeGuen, B. LeGuen 9Electricite de France, Saint-Denis, France Search for other works by this author on: Oxford Academic PubMed Google Scholar I. Malatova, I. Malatova 10NRPI, Prague, Czech Republic Search for other works by this author on: Oxford Academic PubMed Google Scholar ... Show more J. Marsh, J. Marsh 3Radiation Protection Division, Health Protection Agency, Chilton, Didcot OX11 0RQ, UK Search for other works by this author on: Oxford Academic PubMed Google Scholar J. Stather, J. Stather 3Radiation Protection Division, Health Protection Agency, Chilton, Didcot OX11 0RQ, UK Search for other works by this author on: Oxford Academic PubMed Google Scholar J. Zeger J. Zeger 7International Atomic Energy Agency, Vienna, Austria Search for other works by this author on: Oxford Academic PubMed Google Scholar Radiation Protection Dosimetry, Volume 127, Issue 1-4, November 2007, Pages 303–310, https://doi.org/10.1093/rpd/ncm405 Published: 12 October 2007
In the event of an accident involving radioactive material, there could potentially be a large number of people requiring internal contamination monitoring.To answer to this challenge, the IRSN, the French institute for radiological protection and nuclear safety, has developed since 2007 a fleet of 10 body counting mobile units: 8 light and heavy emergency units and 2 expertise mobile units, unique in Europe, allowing on-site monitoring of up to 2500 people per day.Their use for the follow up of French nationals coming back from Japan after the Fukushima Accident is described and discussed.
Purpose: Epidemiological studies of the French uranium miners and the plutonium workers at the Mayak nuclear facility have provided excess relative risk (ERR) estimates per unit absorbed lung dose from alpha radiation. The aim of this paper was to review these two studies and to derive values of the relative biological effectiveness (RBE) of alpha particles for the induction of lung cancer.Materials and methods: We examined and compared the dosimetry assumptions and methodology used in the epidemiological studies of uranium miners and the plutonium workers. Values of RBE were obtained by comparing risk coefficients including comparison of lifetime risks for a given population. To do this, preliminary calculations of lifetime risks following inhalation of plutonium were carried out.Results and conclusions: Published values of risk per unit dose following inhalation of radon progeny and plutonium were in agreement despite the very different dose distributions within the lungs and the different ways the doses were calculated. Values of RBE around 10–20 were obtained by comparing ERR values, but with wide uncertainty ranges. Comparing lifetime risks gave similar values (10, 19 and 21). This supports the use of a radiation weighting factor of 20 for alpha particles for radiation protection purposes.
The ventral lateral neurons (LNvs) of the Drosophila brain that express the period (per) and pigment dispersing factor (pdf) genes play a major role in the control of circadian activity rhythms. A new P-gal4 enhancer trap line is described that is mostly expressed in the LNvs This P-gal4 line was used to ablate the LNvs by using the pro-apoptosis gene bax, to stop PER protein oscillations by overexpressing per and to block synaptic transmission with the tetanus toxin light chain (TeTxLC). Genetic ablation of these clock cells leads to the loss of robust 24-h activity rhythms and reveals a phase advance in light-dark conditions as well as a weak short-period rhythm in constant darkness. This behavioural phenotype is similar to that described for disconnected1 (disco1) mutants, in which we show that the majority of the individuals have a reduced number of dorsally projecting lateral neurons which, however, fail to express PER. In both LNv-ablated and disco1 flies, PER cycles in the so-called dorsal neurons (DNs) of the superior protocerebrum, suggesting that the weak short-period rhythm could stem from these PDF-negative cells. The overexpression of per in LNs suppresses PER protein oscillations and leads to the disruption of both activity and eclosion rhythms, indicating that PER cycling in these cells is required for both of these rhythmic behaviours. Interestingly, flies overexpressing PER in the LNs do not show any weak short-period rhythms, although PER cycles in at least a fraction of the DNs, suggesting a dominant role of the LNs on the behavioural rhythms. Expression of TeTxLC in the LNvs does not impair activity rhythms, which indicates that the PDF-expressing neurons do not use synaptobrevin-dependent transmission to control these rhythms.
In the scope of the IDEAS project to develop General Guidelines for the Assessment of Internal Dose from Monitoring data, two databases were compiled. The IDEAS Bibliography database contains references dealing with problems related to cases of internal contamination. The IDEAS Internal Contamination Database now contains more than 200 cases of internal contamination. In the near future, the IDEAS Internal Contamination database will be made available to the internal dosimetry community. The database has several potential applications, including: training, testing biokinetic models, testing software for calculating intakes and doses from bioassay data, comparison of data from a new accidental intake with that from previous exposures to similar materials. The database is by no means complete, and this presentation is also an appeal for internal contamination cases to extend and update it.
Some beaches in the south of France present high levels of natural radioactivity mainly due to thorium (Th) and uranium (U) present in the sand. Risk assessment after internal exposure of members of the public by either inhalation or ingestion of black sand of Camargue was performed. This evaluation required some information on the human bioavailability of U and Th from this sand. In vitro assays to determine the solubility of U, Th and their progeny were performed either in simulated lung fluid, with the inhalable fraction of sand, or in both simulated gastric and intestinal fluids with a sample of the whole sand. The experimental data show that the bioavailability of these radionuclides from Camargue sand is low in the conditions of the study. Prospective dose assessment for both routes of intake show low risk after internal exposure to this sand.
The individual monitoring of internal exposure of workers comprises two steps: measurement and measurement interpretation. The latter consists in reconstructing the intake of a radionuclide from the activity measurement and calculating the dose using a biokinetic model of the radionuclide behavior in the human body. Mathematically, reconstructing the intake is solving an inverse problem described by a measurement-model equation. The aim of this paper is to propose a solution to this inverse problem when the measurement-model parameters are considered as uncertain. For that, an analysis of the uncertainty on the intake calculation is performed taking into account the dispersion of the measured quantity and the uncertainties of the measurement-model parameters. It is shown that both frequentist and Bayesian approaches can be used to solve the problem according to the measurement-model formulation. A common calculation algorithm is proposed to support both approaches and applied to the examples of tritiated water intake and plutonium inhalation by a worker.
