| 1. |
- Waldner, L., et al.
(författare)
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The 2019-2020 EURADOS WG10 and RENEB Field Test of Retrospective Dosimetry Methods in a Small-Scale Incident Involving Ionizing Radiation
- 2021
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Ingår i: Radiation Research. - 0033-7587 .- 1938-5404. ; 195:3, s. 253-264
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Tidskriftsartikel (refereegranskat)abstract
- With the use of ionizing radiation comes the risk of accidents and malevolent misuse. When unplanned exposures occur, there are several methods which can be used to retrospectively reconstruct individual radiation exposures; biological methods include analysis of aberrations and damage of chromosomes and DNA, while physical methods rely on luminescence (TL/OSL) or EPR signals. To ensure the quality and dependability of these methods, they should be evaluated under realistic exposure conditions. In 2019, EURADOS Working Group 10 and RENEB organized a field test with the purpose of evaluating retrospective dosimetry methods as carried out in potential real-life exposure scenarios. A 1.36 TBq 192Ir source was used to irradiate anthropomorphic phantoms in different geometries at doses of several Gy in an outdoor open-air geometry. Materials intended for accident dosimetry (including mobile phones and blood) were placed on the phantoms together with reference dosimeters (LiF, NaCl, glass). The objective was to estimate radiation exposures received by individuals as measured using blood and fortuitous materials, and to evaluate these methods by comparing the estimated doses to reference measurements and Monte Carlo simulations. Herein we describe the overall planning, goals, execution and preliminary outcomes of the 2019 field test. Such field tests are essential for the development of new and existing methods. The outputs from this field test include useful experience in terms of planning and execution of future exercises, with respect to time management, radiation protection, and reference dosimetry to be considered to obtain relevant data for analysis.
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| 2. |
- Raeaef, C., et al.
(författare)
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Internal dose assessment of Gd-148 using isotope ratios of gamma-emitting Gd-146 or Gd-153 in accidently released spallation target particles
- 2020
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Ingår i: Scientific Reports. - : NATURE RESEARCH. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- The pure alpha emitter Gd-148 may have a significant radiological impact in terms of internal dose to exposed humans in case of accidental releases from a spallation source using a tungsten target, such as the one to be used in the European Spallation Source (ESS). In this work we aim to present an approach to indirectly estimate the whole-body burden of Gd-148 and the associated committed effective dose in exposed humans, by means of high-resolution gamma spectrometry of the gamma-emitting radiogadolinium isotopes Gd-146 and Gd-153 that are accompanied by Gd-148 generated from the operation of the tungsten target. Theoretical minimum detectable whole-body activity (MDA) and associated internal doses from Gd-148 are calculated using a combination of existing biokinetic models and recent computer simulation studies on the generated isotope ratios of Gd-146/Gd-148 and Gd-153/Gd-148 in the ESS target. Of the two gamma-emitting gadolinium isotopes, Gd-146 is initially the most sensitive indicator of the presence of Gd-148 if whole-body counting is performed within a month after the release, using the twin photo peaks of Gd-146 centered at 115.4 keV (MDA<1 Bq for ingested Gd-148, and<25 Bq for inhaled Gd-148). The corresponding minimum detectable committed effective doses will be less than 1 mu Sv for ingested Gd-148, but substantially higher for inhaled Gd-148 (up to 0.3 mSv), depending on operation time of the target prior to the release. However, a few months after an atmospheric release, Gd-153 becomes a much more sensitive indicator of body burdens of Gd-148, with a minimum detectable committed effective doses ranging from 18 to 77 mu Sv for chronic ingestion and between 0.65 to 2.7 mSv for acute inhalation in connection to the release. The main issue with this indirect method for Gd-148 internal dose estimation, is whether the primary photon peaks from (146) and Gd-153 can be detected undisturbed. Preliminary simulations show that nuclides such as Ta-182 may potentially create perturbations that could impair this evaluation method, and which impact needs to be further studied in future safety assessments of accidental target releases.
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| 3. |
- Bukartas, A., et al.
(författare)
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A Bayesian method to localize lost gamma sources
- 2019
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Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043. ; 145, s. 142-147
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Tidskriftsartikel (refereegranskat)abstract
- A feasibility study of a Bayesian based algorithm for orphan source localization by means of mobile gamma spectrometry is presented. The method was tested on three types of gamma sources (137Cs, 133Ba and 131I) using a HPGe detector mounted on a vehicle. Estimates on source activity and source locations were within 51% and 29% of actual values, respectively. Further studies are required to validate and develop this method for additional source-detector configurations and gamma radiation background conditions.
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| 4. |
- Hinrichsen, Y, et al.
(författare)
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Introducing the concept of the isodose for optimisation of decontamination activities in a radioactive fallout scenario
- 2018
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Ingår i: Journal of Radiological Protection. - : IOP Publishing. - 1361-6498 .- 0952-4746. ; 38:4, s. 1293-1310
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Tidskriftsartikel (refereegranskat)abstract
- In the recovery phase after a radioactive release incident, it is important to be able to focus decontamination operations on the areas that contribute most to the radiation dose. Monte Carlo simulations were applied to determine the shielding effect of a building against radiation from various directions, also giving information on the dose contributions at various locations inside the building from specific areas outside. The concept of the isodose was developed to optimise decontamination activities, and was applied as isodose lines to define the smallest areas that lead to a certain dose reduction through decontamination of areas surrounding the building. The shape and position of the isodose lines depend on the building's geometry, wall thickness, and material, and on the observation point inside the building. Calculations have been made with a surface resolution of 1 m2 for four observation points in a modular building, assuming depositions of 137Cs and 60Co on the ground surface and on the roof, as well as 1 cm below the ground surface to represent ground penetration. For example, a ten times as large area would have to be decontaminated to increase the dose reduction from 10% to 30%, if it is assumed that all the contamination is located at a depth of 1 cm.
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| 5. |
- Holm, Elis, et al.
(författare)
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Fallout of 238 Pu over Madagascar following the SNAP 9 A satellite failure.
- 2015
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Ingår i: Environmental Radiochemical Analysis V. P. Warwick (ed.). - UK : Royal Society of Chemistry, UK. - 9781782621553 ; :12, s. 44-49
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Bokkapitel (refereegranskat)abstract
- After the SNAP 9A satellite accident in 1964, the dispersion of Pu was investigated as a function of latitude North and South. It was obvious that most of the fallout of 238Pu was on the southern hemisphere. However no data from Madagascar, where the accident happened, were reported. This paper describes the analysis of peat bog samples for Pu-isotopes by alpha spectrometry after radiochemical separation. To investigate especially the presence of 239Pu, selected samples were analyzed for 239Pu and 240Pu using mass spectrometric analyses, AMS.
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| 6. |
- Magnusson, Åsa, et al.
(författare)
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Carbon-14 levels in the vicinity of the Lithuanian nuclear power plant Ignalina
- 2007
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 259:1, s. 530-535
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Tidskriftsartikel (refereegranskat)abstract
- Carbon-14 levels in the vicinity of the Lithuanian nuclear power plant Ignalina have been investigated. During 2001-2004, approximately 70 samples were collected and analysed using accelerator mass spectrometry. The study included samples of leaves, grass, moss, soil and aquatic plants, covering a distance up to 32 km from the power plant. The highest C-14 specific activities were found in soil samples from moss-covered sites close to the power plant, probably indicating the release of particulate material. The results are compared with those from studies around other types of reactors also investigated within the project. (c) 2007 Elsevier B.V. All rights reserved.
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| 7. |
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| 8. |
- Mantero, Juan, et al.
(författare)
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Pit lakes from Southern Sweden: natural radioactivity and elementary characterization
- 2020
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Natural radioactivity in the environment is a field gaining more attention in last decades. This work is focused on the study of natural radioactivity complemented with elementary characterization at former non-uraniferous mining areas in Sweden. This aim is addressed through the study of mining lakes, called pit lakes, which are water bodies generated after opencast mining. Environmental matrices (water, sediments and rocks) from 32 Swedish pit lakes, commonly used for recreational purposes were radiometrically characterized via alpha (238U, 234U, 232Th, 230Th, 210Po isotopes) and gamma spectrometry (238U and 232Th series radionuclides). Additionally, ambient dose rate equivalent in the immediate surrounding of each pit lake was quantified. Physico-chemical parameters (pH, specific conductivity, dissolved oxygen, oxidation–reduction potential) and elemental composition (major and trace elements by ICP-MS) were analysed in water samples and elementary composition of sediments/rocks was measured by XRF and SEM–EDX in some specific cases. A non-negligible number of pit lakes (26%) with enhanced U levels in water was found. At some sites, rocks contained up to 4% of U in areas with high degree of interaction with local population. Concerning the elementary perspective, another popular site (due to its turquoise water) was found to have elevated dissolved heavy metal levels. Results obtained in this work prove that measurement of natural radioactivity is another component that should be included in routine analysis of characterization in mining areas, especially if restauration of post-mining sites is intended for human recreational.
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| 9. |
- Nilsson, Jonas M.C., et al.
(författare)
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A rotating-slit-collimator-based gamma radiation mapper
- 2017
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Ingår i: Journal of Environmental Radioactivity. - : Elsevier BV. - 0265-931X. ; 177, s. 225-232
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Tidskriftsartikel (refereegranskat)abstract
- For situations with radioactive material out of control where it may be physically difficult or prohibited to access areas close to the source, measurements from distance may be the only way to assess the radiation environment. Using collimated detectors will provide means to locate the direction of the radiation from the source. To investigate the possibilities of mapping gamma emitting radioactive material in a closed non-enterable area, a tentative system for mapping radioactive materials from a distance was built. The system used a computer controlled cylindrical rotating slit collimator with a high purity germanium detector placed in the cylinder. The system could be placed on a car-towed trailer, with the centre of the detector about 1.4 m above ground. Mapping was accomplished by the use of a specially developed image reconstruction algorithm that requires measurements from two or more locations around the area to be investigated. The imaging capability of the system was tested by mapping an area, 25 by 25 m2, containing three 330 MBq 137Cs point sources. Using four locations outside the area with about 20 min measuring time in each location and applying the image reconstruction algorithm on the deconvoluted data, the system indicated the three source locations with an uncertainty of 1–3 m. The results demonstrated the potential of using collimated mobile gamma radiometry combined with image reconstruction to localize gamma sources inside non-accessible areas.
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| 10. |
- Pédehontaa-Hiaa, G., et al.
(författare)
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Tritium in urine from members of the general public and occupationally exposed workers in Lund, Sweden, prior to operation of the European Spallation Source
- 2020
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Ingår i: Journal of Environmental Radioactivity. - : Elsevier BV. - 0265-931X. ; 213
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Tidskriftsartikel (refereegranskat)abstract
- A powerful neutron source, the European Spallation Source (ESS), is currently under construction in Lund, Sweden (~90 000 inhabitants). Levels of tritium (3H) in urine were estimated in members of the public in Lund and employees at the ESS using liquid scintillation counting, to obtain baseline levels before the start of operation of the ESS. These were compared with levels in other occupationally exposed radiation workers. Both the spallation reaction in the ESS tungsten target and the activation of various materials by the protons produced by the 5 MW linear accelerator will generate tritium, which will be released into the atmosphere mainly as tritiated water (HTO). Urinary HTO activity concentrations were determined in a total of 55 individuals belonging to four different categories: ESS employees, neighbours of the ESS, members of the general public in Lund and exposed workers from other facilities. The participants were asked to provide information on their beverage intake the day before urine sampling. The urine samples were filtered on activated charcoal and distilled before analysis. The effect of sample preparation on the isotope fractionation of urine samples was investigated by isotope ratio mass spectrometry (IRMS) of 2H/1H, which showed no influence. IRMS was also used to investigate if the ratio between the stable hydrogen isotopes (2H/1H) could provide useful data of the origin, and hence the tritium concentration, of various types of drinking water. Urinary HTO activity concentrations determined using liquid scintillation counting (LSC) were found to be below the minimum detectable activity (MDA) of 2.1 Bq⋅L−1 for most of the participants. Five of the workers actively handling organic tritiated material were found to have activity concentrations between 3.5 and 11 Bq⋅L−1, which were higher than the average value in local tap water of 1.5 ± 0.6 Bq⋅L−1. The results will be used to evaluate the radiological impact on the population from future releases of tritium resulting from the operation of the ESS.
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