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Brown J.E.,Norwegian Radiation Protection Authority | Gjelsvik R.,Norwegian Radiation Protection Authority | Roos P.,Technical University of Denmark | Kalas J.A.,Norwegian Institute for Nature Research | And 2 more authors.
Journal of Environmental Radioactivity | Year: 2011

Recent developments regarding environmental impact assessment methodologies for radioactivity have precipitated the need for information on levels of naturally occurring radionuclides within and transfer to wild flora and fauna. The objectives of this study were therefore to determine activity concentrations of the main dose forming radionuclides 210Po and 210Pb in biota from terrestrial ecosystems thus providing insight into the behaviour of these radioisotopes. Samples of soil, plants and animals were collected at Dovrefjell, Central Norway and Olkiluoto, Finland. Soil profiles from Dovrefjell exhibited an approximately exponential fall in 210Pb activity concentrations from elevated levels in humus/surface soils to " supported" levels at depth. Activity concentrations of 210Po in fauna (invertebrates, mammals, birds) ranged between 2 and 123Bqkg-1d.w. and in plants and lichens between 20 and 138Bqkg-1d.w. The results showed that soil humus is an important reservoir for 210Po and 210Pb and that fauna in close contact with this media may also exhibit elevated levels of 210Po. Concentration ratios appear to have limited applicability with regards to prediction of activity concentrations of 210Po in invertebrates and vertebrates. Biokinetic models may provide a tool to explore in a more mechanistic way the behaviour of 210Po in this system. © 2010 Elsevier Ltd.

Beresford N.A.,UK Center for Ecology and Hydrology | Yankovich T.L.,Environment Canada | Wood M.D.,University of Salford | Fesenko S.,International Atomic Energy Agency | And 3 more authors.
Science of the Total Environment | Year: 2013

The application of the concentration ratio (CR) to predict radionuclide activity concentrations in wildlife from those in soil or water has become the widely accepted approach for environmental assessments. Recently both the ICRP and IAEA have produced compilations of CR values for application in environmental assessment. However, the CR approach has many limitations, most notably, that the transfer of most radionuclides is largely determined by site-specific factors (e.g. water or soil chemistry). Furthermore, there are few, if any, CR values for many radionuclide-organism combinations. In this paper, we propose an alternative approach and, as an example, demonstrate and test this for caesium and freshwater fish. Using a Residual Maximum Likelihood (REML) mixed-model regression we analysed a dataset comprising 597 entries for 53 freshwater fish species from 67 sites. The REML analysis generated a mean value for each species on a common scale after REML adjustment taking account of the effect of the inter-site variation. Using an independent dataset, we subsequently test the hypothesis that the REML model outputs can be used to predict radionuclide, in this case radiocaesium, activity concentrations in unknown species from the results of a species which has been sampled at a specific site. The outputs of the REML analysis accurately predicted 137Cs activity concentrations in different species of fish from 27 Finnish lakes; these data had not been used in our initial analyses. We recommend that this alternative approach be further investigated for other radionuclides and ecosystems. © 2013 Elsevier B.V.

Jordan D.,University of Valencia | Algora A.,University of Valencia | Algora A.,Institute of Nuclear Research | Tain J.L.,University of Valencia | And 43 more authors.
Physical Review C - Nuclear Physics | Year: 2013

The β-feeding probabilities for three important contributors to the decay heat in nuclear reactors, namely 102,104,105Tc, have been measured using the total absorption spectroscopy technique. For the measurements, sources of very high isobaric purity have been obtained using a Penning trap (JYFLTRAP). A detailed description of the data analysis is given and the results are compared with high-resolution measurements and theoretical calculations. © 2013 American Physical Society.

Algora A.,University of Valencia | Jordan D.,University of Valencia | Tain J.L.,University of Valencia | Rubio B.,University of Valencia | And 38 more authors.
Physical Review Letters | Year: 2010

The β feeding probability of Tc102,104,105,106,107, Mo105, and Nb101 nuclei, which are important contributors to the decay heat in nuclear reactors, has been measured using the total absorption technique. We have coupled for the first time a total absorption spectrometer to a Penning trap in order to obtain sources of very high isobaric purity. Our results solve a significant part of a long-standing discrepancy in the γ component of the decay heat for Pu239 in the 4-3000s range. © 2010 The American Physical Society.

Niemela I.,STUK
11th International Probabilistic Safety Assessment and Management Conference and the Annual European Safety and Reliability Conference 2012, PSAM11 ESREL 2012 | Year: 2012

This article presents an isolation of I&C model from PRA model as implemented in FinPSA software. The I&C system is modeled using communication vectors, which are suitable for modeling large distributed control systems. The modeling is compact and allows convenient expression of large systems. On top of the I&C system, control tasks are defined, and fault trees link to control tasks. The I&C model can link to fault trees to introduce dependencies, for example electric power or room cooling. Thus, the interface between system fault trees and I&C model is twofold: fault refer to I&C tasks, and I&C model refers to fault trees of its support systems.

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