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Stäger F, Zok D, Schiller AK, Feng B, Steinhauser G. Disproportionately High Contributions of 60 Year Old Weapons- 137Cs Explain the Persistence of Radioactive Contamination in Bavarian Wild Boars. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:13601-13611. [PMID: 37646445 PMCID: PMC10501199 DOI: 10.1021/acs.est.3c03565] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 07/31/2023] [Accepted: 08/01/2023] [Indexed: 09/01/2023]
Abstract
Radionuclides released from nuclear accidents or explosions pose long-term threats to ecosystem health. A prominent example is wild boar contamination in central Europe, which is notorious for its persistently high 137Cs levels. However, without reliable source identification, the origin of this decades old problem has been uncertain. Here, we target radiocesium contamination in wild boars from Bavaria. Our samples (2019-2021) range from 370 to 15,000 Bq·kg-1 137Cs, thus exceeding the regulatory limits (600 Bq·kg-1) by a factor of up to 25. Using an emerging nuclear forensic fingerprint, 135Cs/137Cs, we distinguished various radiocesium source legacies in their source composition. All samples exhibit signatures of mixing of Chornobyl and nuclear weapons fallout, with 135Cs/137Cs ratios ranging from 0.67 to 1.97. Although Chornobyl has been widely believed to be the prime source of 137Cs in wild boars, we find that "old" 137Cs from weapons fallout significantly contributes to the total level (10-68%) in those specimens that exceeded the regulatory limit. In some cases, weapons-137Cs alone can lead to exceedances of the regulatory limit, especially in samples with a relatively low total 137Cs level. Our findings demonstrate that the superposition of older and newer legacies of 137Cs can vastly surpass the impact of any singular yet dominant source and thus highlight the critical role of historical releases of 137Cs in current environmental pollution challenges.
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Affiliation(s)
- Felix Stäger
- Institute
of Radioecology and Radiation Protection, Leibniz Universität Hannover, 30419 Hannover, Germany
| | - Dorian Zok
- Institute
of Radioecology and Radiation Protection, Leibniz Universität Hannover, 30419 Hannover, Germany
| | - Anna-Katharina Schiller
- Institute
of Radioecology and Radiation Protection, Leibniz Universität Hannover, 30419 Hannover, Germany
| | - Bin Feng
- Institute
of Inorganic Chemistry, Leibniz Universität
Hannover, 30167 Hannover, Germany
- TU
Wien, Institute of Applied Synthetic Chemistry & TRIGA Center
Atominstitut, 1060 Vienna, Austria
| | - Georg Steinhauser
- TU
Wien, Institute of Applied Synthetic Chemistry & TRIGA Center
Atominstitut, 1060 Vienna, Austria
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2
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Magre A, Boulet B, de Vismes A, Evrard O, Pourcelot L. Identification of the origin of radiocesium released into the environment in areas remote from nuclear accident and military test sites using the 135Cs/ 137Cs isotopic signature. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 329:121606. [PMID: 37087087 DOI: 10.1016/j.envpol.2023.121606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 03/15/2023] [Accepted: 04/07/2023] [Indexed: 05/03/2023]
Abstract
The isotopic signature of radionuclides provides a powerful tool for discriminating radioactive contamination sources and estimating their respective contributions in the environment. In this context, the 135Cs/137Cs ratio has been tested as a very promising isotopic ratio that had not been explored yet in many countries around the world including France. To quantify the levels of radioactivity found in the environment, a new method combining a thorough radiochemical treatment of the sample and an efficient measurement by ICP-MS/MS has been recently developed. This method was successfully applied, for the first time, to soil and sediment samples collected in France in two mountainous regions preferentially impacted either by global fallout from nuclear weapons testing (i.e., the Pyrenees) or by the Chernobyl accident (i.e., the Southern Alps). The 135Cs/137Cs ratios measured on twenty-one samples ranged from 0.66 ± 0.04 and 4.29 ± 0.21 (decay-corrected to January 1st, 2022) corresponding to the characteristic signatures of the fallout from Chernobyl and global fallout associated with the nuclear weapons testing, respectively. Moreover, large variations of both the 137Cs mass activity and the studied isotopic ratio recorded by most samples from the southern Alps suggest varying proportions of these two 137Cs sources. For these samples, the contribution of each source was estimated using this new tracer (135Cs/137Cs) and compared with the mixing contribution given by activity ratio: 239+240Pu/137Cs. This work has successfully demonstrated the applicability of the 135Cs/137Cs isotopic signature to nuclear forensic studies and could be extended to better evaluate the environmental impact of nuclear facilities (i.e., NPP, waste reprocessing).
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Affiliation(s)
- Anaelle Magre
- Laboratoire de Métrologie de la radioactivité dans l'environnement (PSE-ENV/SAME/LMRE), IRSN, 91400, Orsay, France; Laboratoire des Sciences du Climat et de l'Environnement (CNRS, CEA, UVSQ-IPSL), Université Paris-Saclay, 91191, Gif-sur-Yvette, France
| | - Beatrice Boulet
- Laboratoire de Métrologie de la radioactivité dans l'environnement (PSE-ENV/SAME/LMRE), IRSN, 91400, Orsay, France
| | - Anne de Vismes
- Laboratoire de Métrologie de la radioactivité dans l'environnement (PSE-ENV/SAME/LMRE), IRSN, 91400, Orsay, France
| | - Olivier Evrard
- Laboratoire des Sciences du Climat et de l'Environnement (CNRS, CEA, UVSQ-IPSL), Université Paris-Saclay, 91191, Gif-sur-Yvette, France
| | - Laurent Pourcelot
- Laboratoire d'étude et d'expertise sur la radioactivité de l'environnement (PSE-ENV/SEREN/LEREN), IRSN, 13108, Saint-Paul-lez-Durance, France.
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3
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Magre A, Boulet B, Isnard H, Mialle S, Evrard O, Pourcelot L. Innovative ICP-MS/MS Method To Determine the 135Cs/ 137Cs Ratio in Low Activity Environmental Samples. Anal Chem 2023; 95:6923-6930. [PMID: 37071760 DOI: 10.1021/acs.analchem.3c00207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2023]
Abstract
The 135Cs/137Cs isotopic ratio is a powerful tool for tracing the origin of radioactive contamination. Since the Fukushima accident, this ratio has been measured by mass spectrometry in several highly contaminated environmental matrices mainly collected near nuclear accident exclusion zones and former nuclear test areas. However, few data were reported at 137Cs environmental levels (<1 kBq kg-1). This is explained by the occurrence of analytical challenges related to the very low radiocesium content at the environmental level with the large presence of mass interferences, making 135Cs and 137Cs measurements difficult. To overcome these difficulties, a highly selective procedure for Cs extraction/separation combined with an efficient mass spectrometry measurement must be applied on a quantity of ca. 100 g of soil. In the current research, an innovative inductively coupled plasma-tandem mass spectrometry (ICP-MS/MS) method has been developed for the 135Cs/137Cs ratio measurement in low activity environmental samples. The use of ICP-MS/MS led to a powerful suppression of 135Cs and 137Cs interferences by introducing N2O, He, and, for the first time, NH3, into the collision-reaction cell. By adjusting the flow rates of these gases, the best compromise between a maximum signal in Cs and an effective interference elimination was achieved allowing a high Cs sensitivity of more than 1.105 cps/(ng g-1) and low background levels at m/z 135 and 137 lower than 0.6 cps. The accuracy of the developed method was successfully verified by analyzing two certified reference materials (IAEA-330 and IAEA-375) commonly used in the literature as validation samples and three sediment samples collected in the Niida River catchment (Japan) impacted by the Fukushima fallout.
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Affiliation(s)
- Anaelle Magre
- Laboratoire de métrologie de la radioactivité dans l'environnement (PSE-ENV/SAME/LMRE), IRSN, 91400 Orsay, France
- Laboratoire des Sciences du Climat et de l'Environnement (CNRS, CEA, UVSQ-IPSL), Université Paris-Saclay, 91191 Gif-sur-Yvette, France
| | - Beatrice Boulet
- Laboratoire de métrologie de la radioactivité dans l'environnement (PSE-ENV/SAME/LMRE), IRSN, 91400 Orsay, France
| | - Helene Isnard
- DES - Service d'Etudes Analytiques et de Réactivité des Surfaces (SEARS), CEA, Université Paris-Saclay, F-91191 Gif-Sur-Yvette, France
| | - Sebastien Mialle
- DES - Service d'Etudes Analytiques et de Réactivité des Surfaces (SEARS), CEA, Université Paris-Saclay, F-91191 Gif-Sur-Yvette, France
| | - Olivier Evrard
- Laboratoire des Sciences du Climat et de l'Environnement (CNRS, CEA, UVSQ-IPSL), Université Paris-Saclay, 91191 Gif-sur-Yvette, France
| | - Laurent Pourcelot
- Laboratoire d'étude et d'expertise sur la radioactivité de l'environnement (PSE-ENV/SEREN/LEREN), IRSN, 13108 Saint-Paul-lez-Durance, France
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Magre A, Boulet B, Pourcelot L, Roy-Barman M, de Vismes Ott A, Ardois C. Improved radiocesium purification in low-level radioactive soil and sediment samples prior to 135Cs/137Cs ratio measurement by ICP-MS/MS. J Radioanal Nucl Chem 2022. [DOI: 10.1007/s10967-022-08413-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Influence of extraction process on Cs isotope ratios for Fukushima Daiichi nuclear power plant accident-contaminated soil. J Radioanal Nucl Chem 2021. [DOI: 10.1007/s10967-021-07760-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Zhu L, Hou X, Qiao J. Determination of low-level 135Cs and 135Cs/ 137Cs atomic ratios in large volume of seawater by chemical separation coupled with triple-quadrupole inductively coupled plasma mass spectrometry measurement for its oceanographic applications. Talanta 2021; 226:122121. [PMID: 33676676 DOI: 10.1016/j.talanta.2021.122121] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 01/11/2021] [Accepted: 01/14/2021] [Indexed: 10/22/2022]
Abstract
Radioisotopes of cesium are powerful tracer for oceanographic studies. In this work, a novel method was developed for determination of ultra-low level 135Cs and 137Cs in seawater using triple-quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS). Cesium was pre-concentrated from up to 45 L seawater samples using ammonium molybdophosphate (AMP) adsorption, following a selective leaching of cesium using Sr(OH)2. The cesium was further purified from interfering elements using AMP-PAN and cation-exchange chromatography. Sr(OH)2 leaching was found to be an effective approach for selective exchange of cesium from the AMP sorbent without dissolution, which avoids the problem of separation of huge amount of NH4+ and MoO42- in the following steps. The decontamination factors for barium and rubidium with the developed method were more than 4 × 107 and 800, respectively. The separated 135Cs and 137Cs were measured using ICP-MS/MS by employing N2O as reaction gas to further elimination of isobaric (i.e. 135Ba and 137Ba) and polyatomic ions interferences. A detection limit of 1.5 × 10-16 g L-1 for 135Cs in seawater was achieved. The concentrations of 135Cs in seawater from Baltic Sea, Danish straits and Roskilde Fjord were determined using the developed method to identify the sources of 135Cs, the water masses exchange in this region was investigated using 135Cs and 137Cs.
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Affiliation(s)
- Liuchao Zhu
- Technical University of Denmark, Department of Environmental Engineering, Risø Campus, Roskilde, DK-4000, Denmark
| | - Xiaolin Hou
- Technical University of Denmark, Department of Environmental Engineering, Risø Campus, Roskilde, DK-4000, Denmark.
| | - Jixin Qiao
- Technical University of Denmark, Department of Environmental Engineering, Risø Campus, Roskilde, DK-4000, Denmark
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Zhu L, Hou X, Qiao J. Determination of 135Cs concentration and 135Cs/ 137Cs ratio in waste samples from nuclear decommissioning by chemical separation and ICP-MS/MS. Talanta 2021; 221:121637. [PMID: 33076157 DOI: 10.1016/j.talanta.2020.121637] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/29/2020] [Accepted: 09/04/2020] [Indexed: 11/29/2022]
Abstract
Determination of 135Cs concentration and 135Cs/137Cs atomic ratio is of great importance in characterization of radioactive waste from decommissioning of nuclear facilities. In this work, an effective analytical method was developed for simultaneously determination of 135Cs and 137Cs in different types of waste samples (steel, zirconium alloy, reactor coolant, ion exchange filter paper and spent ion exchange resin) by coupling AMP-PAN, AG MP-1M and AG 50 W-X8 chromatographic separation with ICP-MS/MS measurement. Decontamination factors of 7.0 × 106 for Co, 6.0 × 106 for Ba, 4.2 × 105 for Mo, 3.2 × 105 for Sn and 2.1 × 105 for Sb were achieved using the chemical separation procedure. The overall chemical yields of cesium were higher than 85%. A detection limit of 3.1 × 10-14 g/g for 135Cs was achieved for 0.2 g stainless steel sample or spent resin. The developed method was validated by analysis of standard reference materials (IAEA-375) and successfully applied for analysis of zirconium alloy, steel, ion exchange filter paper and spent ion exchange resin from nuclear power reactors. The obtained 135Cs can be used to evaluate the long-term environmental impact and provide useful information for waste disposal. The measured 135Cs/137Cs ratio in reactor coolant, as a characteristic information, might be useful for source identification and localization of leaked fuel element. The neutron flux of the leaked fuel element can be estimated based on the measured 135Cs/137Cs atomic ratios in the reactor coolant water. The developed method is simple and rapid (8 samples/day) for the determination of 135Cs concentrations and 135Cs/137Cs ratios in various waste samples from nuclear decommissioning.
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Affiliation(s)
- Liuchao Zhu
- Technical University of Denmark, Department of Environmental Engineering, Risø Campus, Roskilde, DK, 4000, Denmark
| | - Xiaolin Hou
- Technical University of Denmark, Department of Environmental Engineering, Risø Campus, Roskilde, DK, 4000, Denmark.
| | - Jixin Qiao
- Technical University of Denmark, Department of Environmental Engineering, Risø Campus, Roskilde, DK, 4000, Denmark
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8
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Zhu L, Hou X, Qiao J. Determination of Ultralow Level 135Cs and 135Cs/ 137Cs Ratio in Environmental Samples by Chemical Separation and Triple Quadrupole ICP-MS. Anal Chem 2020; 92:7884-7892. [PMID: 32367719 DOI: 10.1021/acs.analchem.0c01153] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An analytical method was developed for the determination of ultralow level 135Cs in environmental samples by chromatographic separation of cesium with AMP-PAN and AG50W-X8 columns and sensitive measurement of cesium isotopes with triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS). Cesium was simply released by acid leaching using aqua regia from environmental solid samples and preconcentrated on AMP-PAN column. The cesium adsorbed on the column was effectively eluted with NH4Cl solution without dissolving the AMP. The excessive amount of NH4Cl in the eluate was removed by sublimation in the presence of small amount of LiCl. The remaining barium and other interfering elements such as Mo, Sn, Sb, and Li were efficiently removed using cation exchange chromatography (AG50W-X8). The decontamination factors of this procedure are above 4 × 107 for barium and 4 × 105 for molybdenum; the chemical yields of cesium are more than 85% for samples of less than 10 g. This method enables to separate cesium from large size of samples for the determination of ultralow level 135Cs, avoiding the problem of removal of a huge amount of Mo in the dissolved AMP. Intrinsic 137Cs in the environmental samples measured by gamma spectrometry before and after separation was used as internal isotope dilution standard for quantitative determination of 135Cs without complete release and recover of radiocesium. The interference of barium (135Ba and 137Ba) to the ICP-MS measurement of 135Cs and 137Cs was further suppressed to 8 × 10-5 by using N2O as the reaction gas in ICP-MS/MS at a flow rate of 0.7 mL/min, so a total suppression of 2 × 10-12 for Ba was achieved, making the isobaric interference of Ba isotopes to the measurement of 135Cs and 137Cs in environmental samples negligible. A detection limit of 9.1 × 10-17 g/g for 135Cs and 137Cs was achieved for 60 g samples. The developed method was validated by analysis of standard reference materials (IAEA-375, IAEA-330, and IAEA-385) and successfully applied for the determination of 135Cs concentrations and 135Cs/137Cs ratios in soil samples collected from Denmark, Sweden, and Ukraine. The 135Cs/137Cs isotopic ratios in Danish soil (2.08-2.68) were significantly higher than that from Sweden and Ukraine (0.65-0.71), indicating different sources of radiocesium. This work demonstrated the application of 135Cs/137Cs as a unique fingerprint for discriminating the sources of radioactive contamination and estimating their contribution to the total inventory, which will be useful for nuclear forensics and environmental tracer studies.
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Affiliation(s)
- Liuchao Zhu
- Department of Environmental Engineering, Technical University of Denmark, Risø Campus, Roskilde DK-4000, Denmark
| | - Xiaolin Hou
- Department of Environmental Engineering, Technical University of Denmark, Risø Campus, Roskilde DK-4000, Denmark
| | - Jixin Qiao
- Department of Environmental Engineering, Technical University of Denmark, Risø Campus, Roskilde DK-4000, Denmark
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9
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Measurement of cesium isotopic ratio by thermal ionization mass spectrometry for neutron capture reaction studies on 135Cs. J Radioanal Nucl Chem 2020. [DOI: 10.1007/s10967-020-07198-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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10
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Zhu L, Xu C, Hou X, Qiao J, Zhao Y, Liu G. Determination of Ultratrace Level 135Cs and 135Cs/ 137Cs Ratio in Small Volume Seawater by Chemical Separation and Thermal Ionization Mass Spectrometry. Anal Chem 2020; 92:6709-6718. [PMID: 32270673 DOI: 10.1021/acs.analchem.0c00688] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The atomic ratio of 135Cs/137Cs is a powerful fingerprint for distinguishing the source terms of radioactive contamination and tracing the circulation of water masses in the ocean. However, the determination of the 135Cs/137Cs ratio is very difficult due to the ultratrace level of 135Cs (<0.02 mBq/m3) and 137Cs (<2 Bq/m3) in the ordinary seawater samples. In this work, a sensitive method was developed for determination of 135Cs concentration and 135Cs/137Cs ratio in seawater using chemical separation combined with thermal ionization mass spectrometry (TIMS) measurement. Cesium was first preconcentrated from seawater using ammonium molybdophosphate-polyacrylonitrile column chromatography and then purified using cation exchange chromatography to remove the interferences. With this method, decontamination factors of 6.0 × 106 for barium and 1800 for rubidium and a chemical yield of more than 60% for cesium were achieved. By using glucose as an activator, the ionization efficiency of cesium was significantly improved to 50.6%, and a constant high current of Cs+ (20 V) can be maintained for more than 180 min, which ensures sensitive and reliable measurement of low level 135Cs and 137Cs. Detection limits of 4.0 × 10-17 g/L for both 135Cs and 137Cs for 200 mL seawater were achieved, which enables the accurate determination of 135Cs concentration and 135Cs/137Cs ratio in a small volume of seawater samples (<200 mL). The developed method has been validated by analysis of seawater reference material IAEA-443. Seawater samples collected from the Greenland Sea, Baltic Sea, and Danish Straits have been successfully analyzed for 135Cs concentrations and 135Cs/137Cs ratios, and the results showed that 135Cs concentrations in the seawater of the Baltic Sea is much higher than that in the Greenland Sea, which is attributed to the high deposition of Chernobyl accident derived radiocesium in the Baltic Sea region.
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Affiliation(s)
- Liuchao Zhu
- Technical University of Denmark, Department of Environmental Engineering, Risø Campus, Roskilde DK-4000, Denmark
| | - Changkun Xu
- China Institute of Atomic Energy, Beijing 102413, China
| | - Xiaolin Hou
- Technical University of Denmark, Department of Environmental Engineering, Risø Campus, Roskilde DK-4000, Denmark
| | - Jixin Qiao
- Technical University of Denmark, Department of Environmental Engineering, Risø Campus, Roskilde DK-4000, Denmark
| | - Yonggang Zhao
- China Institute of Atomic Energy, Beijing 102413, China
| | - Guorong Liu
- China Institute of Atomic Energy, Beijing 102413, China
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Nakamura S, Shibahara Y, Kimura A, Iwamoto O, Uehara A, Fujii T. Measurements of thermal-neutron capture cross-section of Cesium-135 by applying mass spectrometry. J NUCL SCI TECHNOL 2019. [DOI: 10.1080/00223131.2019.1691077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Shoji Nakamura
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Naka-gun, Japan
| | - Yuji Shibahara
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka, Japan
| | - Atsushi Kimura
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Naka-gun, Japan
| | - Osamu Iwamoto
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Naka-gun, Japan
| | - Akihiro Uehara
- National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Toshiyuki Fujii
- Graduate School of Engineering, Osaka University, Osaka, Japan
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12
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Aspects of quality assurance and performance of strontium-selective resins under non-routine conditions: old resins, delayed elution. J Radioanal Nucl Chem 2019. [DOI: 10.1007/s10967-019-06484-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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13
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Dunne JA, Martin PG, Yamashiki Y, Ang IXY, Scott TB, Richards DA. Spatial pattern of plutonium and radiocaesium contamination released during the Fukushima Daiichi nuclear power plant disaster. Sci Rep 2018; 8:16799. [PMID: 30429490 PMCID: PMC6235829 DOI: 10.1038/s41598-018-34302-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 10/04/2018] [Indexed: 11/12/2022] Open
Abstract
Plutonium and radiocaesium are hazardous contaminants released by the Fukushima Daiichi nuclear power plant (FDNPP) disaster and their distribution in the environment requires careful characterisation using isotopic information. Comprehensive spatial survey of 134Cs and 137Cs has been conducted on a regular basis since the accident, but the dataset for 135Cs/137Cs atom ratios and trace isotopic analysis of Pu remains limited because of analytical challenges. We have developed a combined chemical procedure to separate Pu and Cs for isotopic analysis of environmental samples from contaminated catchments. Ultra-trace analyses reveal a FDNPP Pu signature in environmental samples, some from further afield than previously reported. For two samples, we attribute the dominant source of Pu to Reactor Unit 3. We review the mechanisms responsible for an emergent spatial pattern in 134,135Cs/137Cs in areas northwest (high 134Cs/137Cs, low 135Cs/137Cs) and southwest (low 134Cs/137Cs, high 135Cs/137Cs) of FDNPP. Several samples exhibit consistent 134,135Cs/137Cs values that are significantly different from those deposited on plant specimens collected in previous works. A complex spatial pattern of Pu and Cs isotopic signature is apparent. To confidently attribute the sources of mixed fallout material, future studies must focus on analysis of individual FDNPP-derived particles.
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Affiliation(s)
- James A Dunne
- School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UK. .,Bristol Isotope Group, University of Bristol, Wills Memorial Building, Queen's Road, Bristol, BS8 1RJ, UK.
| | - Peter G Martin
- Interface Analysis Centre, HH Wills Physics Laboratory, University of Bristol, Bristol, BS8 1TL, UK
| | - Yosuke Yamashiki
- Graduate School of Advanced Integrated Studies in Human Survivability, Kyoto University, Kyoto, 606-8501, Japan
| | - Ian X Y Ang
- Interface Analysis Centre, HH Wills Physics Laboratory, University of Bristol, Bristol, BS8 1TL, UK
| | - Tom B Scott
- Interface Analysis Centre, HH Wills Physics Laboratory, University of Bristol, Bristol, BS8 1TL, UK
| | - David A Richards
- School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UK. .,Bristol Isotope Group, University of Bristol, Wills Memorial Building, Queen's Road, Bristol, BS8 1RJ, UK.
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