Time filter

Source Type

Szabo Z.,Lithosphere Fluid Research Laboratory | Szabo Z.,Hungarian Academy of Sciences | Jordan G.,Hungarian Academy of Sciences | Szabo C.,Lithosphere Fluid Research Laboratory | And 6 more authors.
Isotopes in Environmental and Health Studies | Year: 2014

Radon and thoron isotopes are responsible for approximately half of the average annual effective dose to humans. Although the half-life of thoron is short, it can potentially enter indoor air from adobe walls. Adobe was a traditional construction material in the Great Hungarian Plain. Its major raw materials are the alluvial sediments of the area. Here, seasonal radon and thoron activity concentrations were measured in 53 adobe dwellings in 7 settlements by pairs of etched track detectors. The results show that the annual average radon and thoron activity concentrations are elevated in these dwellings and that the proportions with values higher than 300 Bq m-3 are 14-17 and 29-32% for radon and thoron, respectively. The calculated radon inhalation dose is significantly higher than the world average value, exceeding 10 mSv y-1 in 7% of the dwellings of this study. Thoron also can be a significant contributor to the inhalation dose with about 30% in the total inhalation dose. The changes of weather conditions seem to be more relevant in the variation of measurement results than the differences in the local sedimentary geology. Still, the highest values were detected on clay. Through the year, radon follows the average temperature changes and is affected by the ventilation, whereas thoron rather seems to follow the amount of precipitation. © 2013 © 2013 Taylor & Francis.

Palsson S.E.,Icelandic Radiation Safety Authority | Howard B.J.,UK Center for Ecology and Hydrology | Bergan T.D.,Directorate for Civil Protection and Emergency Planning | Paatero J.,Finnish Meteorological Institute | And 2 more authors.
Journal of Environmental Radioactivity | Year: 2013

Atmospheric testing of nuclear weapons began in 1945 and largely ceased in 1963. Monitoring of the resulting global fallout was carried out globally by the Environmental Measurements Laboratory and the UK Atomic Energy Research Establishment as well as at national level by some countries. A correlation was identified between fallout deposition and precipitation and an uneven distribution with latitude.In this study, the available data from 1954 to 1976 for 90Sr and 137Cs were reanalysed using analysis of covariance (ANCOVA) and logarithmically transformed values of the monthly deposition density as the response variable. Generalized additive models (GAM) were used to explore the relationship of different variables to the response variable and quantify the explanatory power that could be achieved. The explanatory variables which consistently explained most of the variability were precipitation at each site, latitude and change with time and a simple linear model was produced with similar explanatory power as the GAM. The estimates improved as the temporal resolution of the precipitation data increased.A good log-log fit could be obtained if a bias of about 1-6 mm precipitation per month was added, this could be interpreted as dry deposition which is not otherwise accounted for in the model. The deposition rate could then be explained as a simple non-linear power function of the precipitation rate (r0.2-0.6 depending on latitude band). A similar non-linear power function relationship has been the outcome of some studies linking wash-out and rain-out coefficients with rain intensity. Our results showed that the precipitation rate was an important parameter, not just the total amount. The simple model presented here allows the recreation of the deposition history at a site, allowing comparison with time series of activity concentrations for different environmental compartments, which is important for model validation. © 2012 Elsevier Ltd.

Dowdall M.,Norwegian Radiation Protection Authority | Smethurst M.A.,University of Exeter | Watson R.,Geological Survey of Norway | Mauring A.,Norwegian Radiation Protection Authority | And 3 more authors.
Journal of Environmental Radioactivity | Year: 2012

In recent years car-borne gamma spectrometry has expanded from its role as a geological survey platform to being a useful asset in searching for orphan sources and for surveying in the aftermath of an incident involving the release of radioactive materials. The opportunities for gaining practical experience in the field however are limited by cost considerations and practicability. These limitations are exacerbated by the fact that field data can differ significantly from data generated in the laboratory. As a means of exercising existing emergency measuring/surveying capability and introducing car-borne measurements to a larger group, a virtual exercise was devised. The exercise ORPEX (Orphan Sources and Fresh Fallout Virtual Exercise in Mobile Measurement) featured two typical emergency scenarios: a search for orphan sources and surveying to delineate fallout from a local release point. Synthetic spectral data were generated for point sources and inserted into genuine car-borne measurement data. Participants were presented with a typical software tool and data and were asked to report source locations and isotopes within a time limit. In the second scenario, synthetic data representing fallout from a local fire involving radioactive material were added to real car-borne data, participants being asked to produce maps identifying and characterising the regions of contamination. Fourteen individual organisations from seven different countries supplied results which indicated that for strong sources of isotopes with simple spectra featuring high energy peaks, location and identification was not a problem. Problems arose for isotopes with low energy signals or that presented a weak signal even when visible for extended periods. Experienced analysts tended to perform better in identification of sources irrespective of experience with mobile measurements whereas those with experience in such measurements were more confident in providing more precise estimates of location. The results indicated the need for the inclusion of less frequently encountered sources in field exercise related to mobile measurements. © 2011 Elsevier Ltd.

Dowdall M.,Norwegian Radiation Protection Authority | Mattila A.,Radiation and Nuclear Safety Authority | Rameback H.,Swedish Defence Research Agency | Aage H.K.,Danish Emergency Management Agency | Palsson S.E.,Icelandic Radiation Safety Authority
Journal of Radioanalytical and Nuclear Chemistry | Year: 2015

The capabilities of a number of national reach-back entities in situations involving possible interdiction of nuclear materials was assessed. The assessment was conducted as a training exercise using simulated gamma spectra of a range of materials typical of those that may trigger border alarms, some of which included nuclear materials of various types. Responses indicated that the majority of participants were in a position to highlight the potential presence of such materials even in the presence of shielding or masking materials. Cases where participants had greater difficulty in indicating the presence of nuclear material involved materials with which the majority of participants were unfamiliar. Even though conducted as an exercise, results indicate that national reach-back entities can perform adequately but further enhancement of capabilities through training assessments may increase the efficacy of the expert assistance they provide to first responders. © 2014, Akadémiai Kiadó, Budapest, Hungary.

Hansen H.S.,Norwegian Radiation Protection Authority | Hansen H.S.,Nord-Trondelag University College | Nielsen S.P.,Technical University of Denmark | Andersson K.G.,Technical University of Denmark | And 7 more authors.
Radiation Protection Dosimetry | Year: 2010

The ECOSYS model is used to estimate ingestion dose in the ARGOS and RODOS decision support systems for nuclear emergency management. It is recommended that nation-specific values for several parameters are used in the model. However, this is generally overlooked when the systems are used in practice. We have estimated first year ingestion doses in two scenarios with wet and dry deposition of 137Cs, using the ECOSYS model. We calculated doses for each country using national dietary data while keeping all other parameters at their default values. These dose calculations were then used to estimate the variation in ingestion doses resulting from the variation in the diets only. The dietary data demonstrated that the average consumption of milk, meat and vegetables varied by a factor of 2-4 among the Nordic countries. For both scenarios, the ingestion doses varied by a factor of about 2, among the countries. For all countries, the model predictions were most sensitive to changes in milk, beef and wheat consumption. The results demonstrate that recent and reliable dietary data are required to reliably estimate ingestion doses. © The Author 2010. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org.

Discover hidden collaborations