1
|
Martinsson J, Pédehontaa-Hiaa G, Malmborg V, Madsen D, Rääf C. Experimental wildfire induced mobility of radiocesium in a boreal forest environment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 792:148310. [PMID: 34146801 DOI: 10.1016/j.scitotenv.2021.148310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 04/08/2021] [Accepted: 06/02/2021] [Indexed: 06/12/2023]
Abstract
Wildfires are expected to increase with warmer climate, which can contribute to the mobility and the resuspension of long-lived and potentially hazardous radionuclides. The release of 137Cs during combustion of dried litter, forest floor organic soil, and peat was investigated in a small-scale experimental set-up. Combustion conditions were varied to simulate different wildfire scenarios, and the fuels were dried organic material collected in a boreal environment of Sweden that was contaminated following the Chernobyl accident in 1986. The combustion-related release of 137Cs to the air was on average 29% of the initial fuel content, while 71% of the initial 137Cs remained in the ashes after the combustion. Peat and forest soil had the highest releases (39% and 37%, respectively), although these numbers should be viewed as potential releases since authentic wildfire combustion of these fuels are usually less effective than observed in these experiments. These results indicates that the 137Cs has migrated downwards in the organic material, which imply potentially significantly more 137Cs emissions in severe wildfires with intense combustion of the organic vertical profile in peatbogs and forests. More 137Cs tended to be released during intense and efficient combustion processes, although no significant differences among combustion intensities were observed. The generated experimental data was used in an emission scenario to investigate the possible range in 137Cs emissions from a wildfire. Our study shows that a severe wildfire in a contaminated area of 10,000 ha could potentially release up to 7 TBq of 137Cs. This is the first laboratory study to investigate 137Cs release upon varying combustion conditions using real fallout contaminated organic material obtained from a boreal environment.
Collapse
Affiliation(s)
- Johan Martinsson
- Medical Radiation Physics, Lund University, Lund, Box 118, 221 00, Sweden.
| | | | - Vilhelm Malmborg
- Ergonomics and Aerosol Technology, Lund University, Lund, Box 118, 221 00, Sweden
| | - Dan Madsen
- Division of Fire Safety Engineering, Lund University, Lund, Box 118, 221 00, Sweden
| | - Christopher Rääf
- Medical Radiation Physics, Lund University, Lund, Box 118, 221 00, Sweden
| |
Collapse
|
2
|
Velasco H. Temporal Attenuation of Gamma Dose Rate in Air Due to Radiocesium Downward Mobility in Soil. HEALTH PHYSICS 2021; 120:163-170. [PMID: 33044422 DOI: 10.1097/hp.0000000000001294] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
ABSTRACT The Chernobyl and Fukushima Dai-ichi Nuclear Power Plant accidents have demonstrated that radiocesium deposited on the ground was one of most important pathway contributions to the air dose rate. Cesium-134 contributes more significantly in the first period of 2-3 y. However, 137Cs external exposure may remain relevant for decades. The contribution to the air dose rate attributable to these radionuclides is maximum at the deposition time and then usually decreases over time. The dose rate temporal reduction is a consequence of both the radionuclide physical decay and the radionuclide downward mobility in soil. In this investigation, this decreasing behavior of the air dose rate is approached using an empirical attenuation function, and its coefficients are computed in terms of the effective diffusion coefficient and downward migration rates of radiocesium in soil. The methodology is tested for different hypothetical scenarios and in real situations, including areas affected by the two major accidents at nuclear power plants.
Collapse
Affiliation(s)
- Hugo Velasco
- Instituto de Matemática Aplicada San Luis, Universidad Nacional de San Luis/CONICET, Ejército de los Andes 950, San Luis, Argentina
| |
Collapse
|
3
|
Ramzaev V, Bernhardsson C, Dvornik A, Barkovsky A, Vodovatov A, Jönsson M, Gaponenko S. Calculation of the effective external dose rate to a person staying in the resettlement zone of the Vetka district of the Gomel region of Belarus based on in situ and ex situ assessments in 2016-2018. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2020; 214-215:106168. [PMID: 32063294 DOI: 10.1016/j.jenvrad.2020.106168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 01/09/2020] [Accepted: 01/13/2020] [Indexed: 06/10/2023]
Abstract
The aim of this study was to perform a preliminary assessment of the expected effective dose rate from external exposure to an adult individual staying at that part of the radioactively contaminated territory of the Vetka district of the Gomel region of the Republic of Belarus, from where residents had been resettled after the Chernobyl accident. For this assessment, in summer 2016 and 2018 soil samples were taken from 19 sites located in forests (7 plots), virgin meadows (4 plots), cultivated meadows (6 plots) and vegetable gardens (2 plots), with the subsequent estimation of the inventory and vertical distribution of 137Cs in the soil. The values of 137Cs inventory in the soil ranged from 452 to 1620 kBq m-2 (mean = 904 kBq m-2, median = 964 kBq m-2). The results of the measurement of soil samples were used to calculate values of the air kerma rate, normalized to the inventory of radioactive caesium in the soil. On average, the normalized indicator of the air kerma rate from the man-made source was higher in forests (1.13 nGy h-1 per kBq m-2) compared to virgin meadows (0.95 nGy h-1 per kBq m-2). Normalized air kerma rate in cultivated meadows and vegetable gardens was approximately two times lower than the corresponding indicator for virgin meadows. Using a field gamma spectrometer-dosemeter, ambient dose equivalent rate of gamma radiation in the air was measured at the surveyed sites and the contributions of the technogenic and natural components to the dose rate were estimated. Additionally, such measurements were performed on asphalted surfaces (5 sites) and inside two wooden houses. The measured values of the total ambient dose equivalent rate at a height of 1 m above the ground, asphalted surface or house floor varied from 160 to 2260 nSv h-1. The lowest levels were recorded over asphalted surfaces and inside houses, and the highest ones at forest and virgin meadow sites. The contribution of the technogenic component to the total dose rate varied from 61.9% to 98.8% (mean = 88.9%; n = 26). The effective dose of anthropogenic radiation calculated from the results of in situ measurements in a forest, virgin meadow, cultivated meadow, kitchen garden, asphalted area and house was 0.59, 0.80, 0.34, 0.29, 0.06 and 0.06 μSv h-1, respectively. Similar values for land plots were calculated based on ex situ analysis of soil samples. It can be expected that, starting from 2020, the average effective external dose of a person staying in the resettlement zone of the Vetka district will not exceed 1 mSv year-1.
Collapse
Affiliation(s)
- V Ramzaev
- Saint-Petersburg Research Institute of Radiation Hygiene after Professor P.V. Ramzaev, 8 Mira Str., Saint-Petersburg, Russia.
| | - C Bernhardsson
- Medical Radiation Physics, Department of Translational Medicine, Lund University, SE-205 02, Malmö, Sweden
| | - A Dvornik
- Institute of Radiobiology of the National Academy of Sciences of Belarus, 4 Fedyuninskogo Str., Gomel, Belarus
| | - A Barkovsky
- Saint-Petersburg Research Institute of Radiation Hygiene after Professor P.V. Ramzaev, 8 Mira Str., Saint-Petersburg, Russia
| | - A Vodovatov
- Saint-Petersburg Research Institute of Radiation Hygiene after Professor P.V. Ramzaev, 8 Mira Str., Saint-Petersburg, Russia
| | - M Jönsson
- Medical Radiation Physics, Department of Translational Medicine, Lund University, SE-205 02, Malmö, Sweden
| | - S Gaponenko
- Institute of Radiobiology of the National Academy of Sciences of Belarus, 4 Fedyuninskogo Str., Gomel, Belarus
| |
Collapse
|
4
|
Influence of the migration of radioactive contaminants in soil, resident occupancy, and variability in contamination on isodose lines for typical Northern European houses. Sci Rep 2019; 9:7876. [PMID: 31133735 PMCID: PMC6536529 DOI: 10.1038/s41598-019-44392-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 05/15/2019] [Indexed: 11/08/2022] Open
Abstract
In the remedial phase following an accidental radioactive release, it is important that soil decontamination measures are carried out on the areas that contribute most to the radiation dose. In this study, the newly developed concept of isodose lines was applied to the area around typical Swedish dwellings to identify these areas. The influence of the most common building materials in Sweden, wood and brick, and the importance of the positions of doors and windows on the isodose lines were demonstrated for specific positions inside the houses, as well as for the entire house, assuming the residents exhibit typical resident occupancy. Decontamination of the areas within certain isodose lines was shown to result in a greater dose reduction than decontaminating the same area of soil within a certain distance of the house. Furthermore, the impact of vertical migration of the radioactive contaminants in the soil on the isodose lines was studied, showing that the area enclosed by isodose lines decreases over time as the contaminants migrate deeper into the soil. The resulting isodose lines and their change over time are dominated by the downward movement of the contamination in the upper layer of soil. The impact of the variability in contamination on the final isodose lines and their dependence on building materials are demonstrated.
Collapse
|
5
|
Varley A, Tyler A, Bondar Y, Hosseini A, Zabrotski V, Dowdall M. Reconstructing the deposition environment and long-term fate of Chernobyl 137Cs at the floodplain scale through mobile gamma spectrometry. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 240:191-199. [PMID: 29738947 DOI: 10.1016/j.envpol.2018.04.112] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 04/20/2018] [Accepted: 04/24/2018] [Indexed: 06/08/2023]
Abstract
Cs-137 is considered to be the most significant anthropogenic contributor to human dose and presents a particularly difficult remediation challenge after a dispersal following nuclear incident. The Chernobyl Nuclear Power Plant meltdown in April 1986 represents the largest nuclear accident in history and released over 80 PBq of 137Cs into the environment. As a result, much of the land in close proximity to Chernobyl, which includes the Polessie State Radioecology Reserve in Belarus, remains highly contaminated with 137Cs to such an extent they remain uninhabitable. Whilst there is a broad scale understanding of the depositional patterns within and beyond the exclusion zone, detailed mapping of the distribution is often limited. New developments in mobile gamma spectrometry provide the opportunity to map the fallout of 137Cs and begin to reconstruct the depositional environment and the long-term behaviour of 137Cs in the environment. Here, full gamma spectrum analysis using algorithms based on the peak-valley ratio derived from Monte Carlo simulations are used to estimate the total 137Cs deposition and its depth distribution in the soil. The results revealed a pattern of 137Cs distribution consistent with the deposition occurring at a time of flooding, which is validated by review of satellite imagery acquired at similar times of the year. The results were also consistent with systematic burial of the fallout 137Cs by annual flooding events. These results were validated by sediment cores collected along a transect across the flood plain. The true merit of the approach was confirmed by exposing new insights into the spatial distribution and long term fate of 137Cs across the floodplain. Such systematic patterns of behaviour are likely to be fundamental to the understanding of the radioecological behaviour of 137Cs whilst also providing a tracer for quantifying the ecological controls on sediment movement and deposition at a landscape scale.
Collapse
Affiliation(s)
- Adam Varley
- Department of Biological and Environmental Sciences, University of Stirling, Stirling FK9 4LA, United Kingdom.
| | - Andrew Tyler
- Department of Biological and Environmental Sciences, University of Stirling, Stirling FK9 4LA, United Kingdom
| | - Yuri Bondar
- Norwegian Radiation Protection Authority, Grini Næringspark 13, 1332 Østerås, Norway
| | - Ali Hosseini
- Polessie State Radiation-Ecological Reserve, Tereshkovoy Street 7, Khoiniki, Gomel Region, Belarus
| | - Viachaslau Zabrotski
- Norwegian Radiation Protection Authority, Grini Næringspark 13, 1332 Østerås, Norway
| | - Mark Dowdall
- Polessie State Radiation-Ecological Reserve, Tereshkovoy Street 7, Khoiniki, Gomel Region, Belarus
| |
Collapse
|
6
|
Varley A, Tyler A, Dowdall M, Bondar Y, Zabrotski V. An in situ method for the high resolution mapping of 137Cs and estimation of vertical depth penetration in a highly contaminated environment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 605-606:957-966. [PMID: 28688353 DOI: 10.1016/j.scitotenv.2017.06.067] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 06/06/2017] [Accepted: 06/08/2017] [Indexed: 06/07/2023]
Abstract
The Chernobyl nuclear power plant meltdown has to date been the single largest release of radioactivity into the environment. As a result, radioactive contamination that poses a significant threat to human health still persists across much of Europe with the highest concentrations associated with Belarus, Ukraine, and western Russia. Of the radionuclides still prevalent with these territories 137Cs presents one of the most problematic remediation challenges. Principally, this is due to the localised spatial and vertical heterogeneity of contamination within the soil (~10's of meters), thus making it difficult to accurately characterise through conventional measurement techniques such as static in situ gamma-ray spectrometry or soil cores. Here, a practical solution has been explored, which utilises a large number of short-count time spectral measurements made using relatively inexpensive, lightweight, scintillators (sodium iodide and lanthanum bromide). This approach offers the added advantage of being able to estimate activity and burial depth of 137Cs contamination in much higher spatial resolution compared to traditional approaches. During the course of this work, detectors were calibrated using the Monte Carlo Simulations and depth distribution was estimated using the peak-to-valley ratio. Activity and depth estimates were then compared to five reference sites characterised using soil cores. Estimates were in good agreement with the reference sites, differences of ~25% and ~50% in total inventory were found for the three higher and two lower activity sites, respectively. It was concluded that slightly longer count times would be required for the lower activity (<1MBqm-2) sites. Modelling and reference site results suggest little advantage would be gained through the use of the substantially more expensive lanthanum bromide detector over the sodium iodide detector. Finally, the potential of the approach was demonstrated by mapping one of the sites and its surrounding area in high spatial resolution.
Collapse
Affiliation(s)
- Adam Varley
- Department of Biological and Environmental Sciences, University of Stirling, Stirling FK9 4LA, United Kingdom.
| | - Andrew Tyler
- Department of Biological and Environmental Sciences, University of Stirling, Stirling FK9 4LA, United Kingdom
| | - Mark Dowdall
- Norwegian Radiation Protection Authority, Grini næringspark 13, 1332 Østerås, Norway
| | - Yuri Bondar
- Polessie State Radiation-Ecological Reserve, Tereshkovoy Street 7, Khoiniki, Gomel Region, Belarus
| | - Viachaslau Zabrotski
- Polessie State Radiation-Ecological Reserve, Tereshkovoy Street 7, Khoiniki, Gomel Region, Belarus
| |
Collapse
|
7
|
Ramzaev V, Bernhardsson C, Barkovsky A, Romanovich I, Jarneborn J, Mattsson S, Dvornik A, Gaponenko S. A backpack γ-spectrometer for measurements of ambient dose equivalent rate, H˙∗(10), from 137Cs and from naturally occurring radiation: The importance of operator related attenuation. RADIAT MEAS 2017. [DOI: 10.1016/j.radmeas.2017.10.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
8
|
Nilsson JMC, Finck RR, Rääf CL. A rotating-slit-collimator-based gamma radiation mapper. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2017; 177:225-232. [PMID: 28711774 DOI: 10.1016/j.jenvrad.2017.07.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 07/04/2017] [Accepted: 07/05/2017] [Indexed: 06/07/2023]
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.
Collapse
Affiliation(s)
- Jonas M C Nilsson
- Medical Radiation Physics, Department of Translational Medicine, Lund University, Skåne, University Hospital, S-205 02 Malmö, Sweden
| | - Robert R Finck
- Medical Radiation Physics, Department of Translational Medicine, Lund University, Skåne, University Hospital, S-205 02 Malmö, Sweden
| | - Christopher L Rääf
- Medical Radiation Physics, Department of Translational Medicine, Lund University, Skåne, University Hospital, S-205 02 Malmö, Sweden.
| |
Collapse
|
9
|
Östlund K, Samuelsson C, Mattsson S, Rääf CL. The influence of 134Cs on the 137Cs gamma-spectrometric peak-to-valley ratio and improvement of the peak-to-valley method by limiting the detector field of view. Appl Radiat Isot 2017; 128:249-255. [PMID: 28743069 DOI: 10.1016/j.apradiso.2017.07.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 06/22/2017] [Accepted: 07/04/2017] [Indexed: 10/19/2022]
Abstract
The peak-to-valley method was investigated under laboratory conditions and in situ with respect to both 134Cs perturbation of the 137Cs valley and use of collimation. The 134Cs perturbation is significant down to 134Cs:137Cs activity ratios of 1:100. In these cases the full energy peaks from 134Cs (796 and 802keV) and associated valley should be used instead of the peak and valley from the 137Cs 662keV peak. Use of collimators in situ outside Fukushima Daiichi significantly increased PTV for 134Cs.
Collapse
Affiliation(s)
- Karl Östlund
- Medical Radiation Physics, Department of Translational Medicine, Lund University, Skåne University Hospital, Malmö, SE-205 02 Malmö, Sweden.
| | - Christer Samuelsson
- Medical Radiation Physics, Department of Translational Medicine, Lund University, Skåne University Hospital, Malmö, SE-205 02 Malmö, Sweden
| | - Sören Mattsson
- Medical Radiation Physics, Department of Translational Medicine, Lund University, Skåne University Hospital, Malmö, SE-205 02 Malmö, Sweden
| | - Christopher L Rääf
- Medical Radiation Physics, Department of Translational Medicine, Lund University, Skåne University Hospital, Malmö, SE-205 02 Malmö, Sweden
| |
Collapse
|
10
|
Biological dosimetry to assess risks of health effects in victims of radiation accidents: Thirty years after Chernobyl. Radiother Oncol 2016; 119:1-4. [DOI: 10.1016/j.radonc.2016.02.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Accepted: 02/29/2016] [Indexed: 01/22/2023]
|
11
|
Pichierri F. Computational design of cucurbituril-acene hybrids for the optical detection of cesium ions: DFT and TD-DFT studies. Theor Chem Acc 2016. [DOI: 10.1007/s00214-016-1824-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|