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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 | Andersson K.G.,Technical University of Denmark | Palsson S.E.,Institute for Energy Technology of Norway | Singh Sidhu R.,Icelandic Radiation Safety Authority
Applied Radiation and Isotopes | Year: 2010

The past years have seen a broadening in the focus of emergency preparedness and first response towards situations involving the malevolent use of radioactive materials in a variety of contexts. Many of these contexts are such that first responders and responsible authorities may be faced with isotopes and activities that present significant challenges with respect to identification and quantification using gamma ray spectrometry. The MALRAD international exercise was designed to provide a practice opportunity for authorities and laboratories to work with synthetic gamma-spectrometric data generated in response to seven hypothetical scenarios involving radioactive materials. Scenarios were based as far as practical upon earlier events and participants had one week to provide as much information as possible about the sources based on the provided data. Results indicate that in cases of single isotopes, irrespective of the detector type involved, all participants were in a position to identify sources and provide estimates of activity. For situations involving shielded sources or special nuclear materials most participants were in a position to provide indications as to what the sources were but only a few participants were in a position to provide detailed information. © 2010 Elsevier Ltd.


Hansen H.S.,Norwegian Radiation Protection Authority | Hansen H.S.,Nord-Trøndelag 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.


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.


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.


Andersson K.G.,Technical University of Denmark | Nielsen S.P.,Technical University of Denmark | Thorring H.,Norwegian Radiation Protection Authority | Joensen H.P.,Sudan University of Science and Technology | And 5 more authors.
Radioprotection | Year: 2011

The European decision support systems ARGOS and RODOS rely on the ECOSYS model for prognoses of ingestion doses. ECOSYS needs an update of various parameter values to provide reliable estimates. This paper reports on some results of a Nordic initiative to derive parameter values that are specific to Nordic conditions, as well as to improve generic parameter values in ECOSYS, taking into account the host of useful measurement data accumulated since ECOSYS was created. © 2011 EDP Sciences.


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.


Andersson K.G.,Technical University of Denmark | Nielsen S.P.,Technical University of Denmark | Thorring H.,Norwegian Radiation Protection Authority | Hansen H.S.,Norwegian Radiation Protection Authority | And 5 more authors.
Journal of Environmental Radioactivity | Year: 2011

The ECOSYS model is the ingestion dose model integrated in the ARGOS and RODOS decision support systems for nuclear emergency management. The parameters used in this model have however not been updated in recent years, where the level of knowledge on various environmental processes has increased considerably. A Nordic work group has carried out a series of evaluations of the general validity of current ECOSYS default parameters. This paper specifically discusses the parameter revisions required with respect to the modelling of deposition and natural weathering of contaminants on agricultural crops, to enable the trustworthy prognostic modelling that is essential to ensure justification and optimisation of countermeasure strategies. New modelling approaches are outlined, since it was found that current ECOSYS approaches for deposition and natural weathering could lead to large prognostic errors. © 2011 Elsevier Ltd.


Palsson S.E.,Icelandic Radiation Safety Authority | Howard B.J.,Icelandic Radiation Safety Authority | Howard B.J.,UK Center for Ecology and Hydrology | Gudnason K.,Icelandic Radiation Safety Authority | Sigurgeirsson M.A.,Icelandic Radiation Safety Authority
Environmental Monitoring and Assessment | Year: 2012

The aim of this study was to provide improved information on the long-term transfer of global nuclear weapons 137Cs fallout to cow's milk in Iceland many years after deposition. The spatial variation in deposition was confirmed to be explained by precipitation. Soil samples showed a significant difference in 137Cs deposition density between the main agricultural areas, with the South having the highest values, then the West and North and the lowest in the Northeast. There was no significant difference between the effective halflives in 137Cs activity concentrations in milk and milk powder from themain dairies in Iceland based on data for milk from 1990 to 2007 and for milk powder from 1986 to 2007. There was, however, a significant difference between the effective half-lives obtained for these two regions, 13.5 years for the Northern and 10.5 years for the Southern regions. These half-lives for global fallout are longer than those previously reported for similar time periods in other Arctic areas. The transfer of 137Cs to cow's milk was quantified for different agricultural regions using aggregated transfer coefficients (Tag) for the period of peak global fallout soil inventory in 1965- 1967. The values ranged from 2.8×10-3 to 10.6× 10-3 m2kg-1. By 2001-2004, the Tag values had only declined, in the main agricultural areas, to 0.6×10-3- 1.0×10-3 m2kg-1. Long-term transfer rates to milk many years after deposition were high in Iceland compared with most other reported data. The transfer is potentially relevant for some of the contaminated areas around the Fukushima Nuclear Power Plant after the accident in March 2011 since limited information is available on uptake from Andosols and associated effective half-lives. © Springer Science+Business Media B.V. 2012.


PubMed | Icelandic Radiation Safety Authority
Type: | Journal: 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 (90)Sr and (137)Cs 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 (r(0.2-0.6) 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.

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