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Choudhury TR, Ferdous J, Haque MM, Rahman MM, Quraishi SB, Rahman MS. Assessment of heavy metals and radionuclides in groundwater and associated human health risk appraisal in the vicinity of Rooppur nuclear power plant, Bangladesh. JOURNAL OF CONTAMINANT HYDROLOGY 2022; 251:104072. [PMID: 36084350 DOI: 10.1016/j.jconhyd.2022.104072] [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: 04/05/2022] [Revised: 08/18/2022] [Accepted: 08/28/2022] [Indexed: 06/15/2023]
Abstract
This study was carried out to assess the groundwater quality through estimating trace and heavy metal concentration and radionuclide levels in the vicinity of the Rooppur Nuclear Power Plant (RNPP) sites. Twenty-six (26) parameters, including major cations (K, Na, Mg, Ca) and anions (SO4-2, NO3-), trace and heavy metals (Mn, Fe, Zn, Ni, Co, Pb, Cd, As, Hg, Cu, Li, Be, B, V, Ga, Sr, Ag, Ba) and radionuclides (137Cs, 226Ra, 228Ra, and 40K) were estimated in water samples in the study area. This study revealed that the concentration values (μg/L) of Mn (667.091 ± 7.481), Fe (191.477 ± 3.756), Sr (105.218 ± 13.424), and Zn (23.493 ± 1.134) were the dominant metals in the study area. Different pollution evaluation indices (i.e., HPI, HEI, NI, Cd) data revealed that the study area was under a low to medium level of pollution due to the presence of metals in water. Subsequently, non-carcinogenic and carcinogenic health risks assessments for both adults and children were conducted, which indicated that health risk for the carcinogenic metals were below the threshold level except As through oral exposure for both adult and children. The activity concentrations of 226Ra, 228Ra, and 40K were measured to demonstrate probable radioactivity pollution using Gamma-ray spectrometry (High-resolution HPGe detector). The highest activity concentration of 226Ra, 228Ra, and 40K in groundwater samples were 4.9 ± 1.24 Bq/L (RNPP-15), 1.71 ± 0.43 Bq/L (RNPP-15), and 15.43 ± 3.08 Bq/L (RNPP-15). Among the three studied radionuclides, 40K has the highest average activity concentration. The radiological indicators referred to the annual effective dose (AED) is 0.4273 mSv yr-1, which implies no significant cause of radiological risks and hazards (UNSCEAR guideline value). This study provides a baseline of trace and toxic metal contamination, radioactivity, and radiation levels in the groundwater of the nuclear power plant (being built) area.
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Affiliation(s)
- Tasrina Rabia Choudhury
- Analytical Chemistry Laboratory, Chemistry Division, Atomic Energy Centre Dhaka, Bangladesh Atomic Energy Commission, Dhaka 1000, Bangladesh.
| | - Jannatul Ferdous
- Health Physics Division, Atomic Energy Centre Dhaka, Bangladesh Atomic Energy Commission, Dhaka 1000, Bangladesh
| | - Md Morshedul Haque
- Department of Environmental Sciences, Jahangirnagar University, Dhaka 1342, Bangladesh
| | - Md Mostafizur Rahman
- Department of Environmental Sciences, Jahangirnagar University, Dhaka 1342, Bangladesh
| | - Shamshad Begum Quraishi
- Analytical Chemistry Laboratory, Chemistry Division, Atomic Energy Centre Dhaka, Bangladesh Atomic Energy Commission, Dhaka 1000, Bangladesh
| | - M Safiur Rahman
- Water Quality Research Laboratory, Chemistry Division, Atomic Energy Centre Dhaka, Bangladesh Atomic Energy Commission, Dhaka 1000, Bangladesh
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Wu J, Zheng X, Chen J, Yang G, Zheng J, Aono T. Distributions and impacts of plutonium in the environment originating from the Fukushima Daiichi Nuclear Power Plant accident: An overview of a decade of studies. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2022; 248:106884. [PMID: 35398758 DOI: 10.1016/j.jenvrad.2022.106884] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 03/27/2022] [Accepted: 03/28/2022] [Indexed: 06/14/2023]
Abstract
This paper reviews the current knowledge on plutonium (Pu) isotopic composition (the atom or activity ratios) and activity concentrations of 238Pu, 239Pu, 240Pu, and 241Pu resulting from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident in 2011. In this critical review, we document the characteristic values of Pu atom or activity ratios (fingerprints) and present their spatial distributions around the FDNPP site. Based on multiple Pu fingerprints (238Pu/239+240Pu activity ratio, 240Pu/239Pu atom ratio, and 241Pu/239Pu atom ratio), we clarify that Pu contamination from the FDNPP accident occurred in a restricted terrestrial area, while Pu in the Northwest Pacific Ocean is still predominately sourced from the Pacific Proving Grounds (PPG) and global fallout. Using a simple two end-member mixing model, we calculate average contributions of Pu from the FDNPP accident of 13 ± 20% (n = 180) in soil samples, 55 ± 32% (n = 38) in leaf litter samples, and 67 ± 26% (n = 129) in air dust/black substances. In the marine environment, the PPG source average contributions are 45 ± 15% (n = 76) in seawater and 42 ± 12% (n = 48) in sediments. The spatial distributions of Pu atom or activity ratios based on existing studies suggest that: 1) in the terrestrial region investigated 80 km northwest of the FDNPP site, the Pu contamination is mainly observed in an area within a 50 km distance, and 2) in the terrestrial region investigated 60 km southwest of the FDNPP site, the Pu contamination is mainly observed in an area within a 30 km distance. Studies of Cs-bearing radioactive particles indicate that Pu occurs as Pu oxide, and the fuel fragments containing Pu that were released from the reactors to the surrounding environment are associated with micron-scale Cs-bearing radioactive particles. We note that the fractionation between Pu and other radionuclides occurred after release. These new findings about the Pu fingerprints around the FDNPP site will help researchers to establish a reference background database for future environmental risk assessment and geochemical study there.
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Affiliation(s)
- Junwen Wu
- Guangdong Provincial Key Laboratory of Marine Disaster Prediction and Prevention & Institute of Marine Sciences, Shantou University, Shantou, 515063, China; Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou, 511458, China
| | - Xuemin Zheng
- Guangdong Provincial Key Laboratory of Marine Disaster Prediction and Prevention & Institute of Marine Sciences, Shantou University, Shantou, 515063, China
| | - Jisheng Chen
- Guangdong Provincial Key Laboratory of Marine Disaster Prediction and Prevention & Institute of Marine Sciences, Shantou University, Shantou, 515063, China
| | - Guosheng Yang
- National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage, Chiba, 263-8555, Japan
| | - Jian Zheng
- National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage, Chiba, 263-8555, Japan.
| | - Tatsuo Aono
- National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage, Chiba, 263-8555, Japan
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Zuykov M, Fowler SW, Archambault P, Spiers G, Schindler M. Practical advice on monitoring of U and Pu with marine bivalve mollusks near the Fukushima Daiichi Nuclear Power Plant. MARINE POLLUTION BULLETIN 2020; 151:110860. [PMID: 32056642 DOI: 10.1016/j.marpolbul.2019.110860] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 12/23/2019] [Indexed: 06/10/2023]
Abstract
Following the Fukushima Daiichi nuclear power plant accident in 2011, some marine radionuclide monitoring studies report a lack of evidence for contamination of Japanese coastal waters by U and Pu, or state that marine contamination by them was negligible. Nevertheless, Fukushima-derived U and Pu were reported as associated with Cs-rich microparticles (CsMPs) found in local soil, vegetation, and river/lake sediments. Over time, CsMPs can be transported to the sea via riverine runoff where actinides, as expected, will leach. We recommend establishing a long-term monitoring of U and Pu in the nearshore area of the Fukushima Prefecture using marine bivalve mollusks; shells, byssal threads and soft tissues should all be analyzed. Here, based on results from Th biosorption experiments, we propose that U and Pu could be present at concentrations several times higher in shells with a completely destroyed external shell layer (periostracum) than in shells with intact periostracum.
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Affiliation(s)
- Michael Zuykov
- School of the Environment, Laurentian University, Sudbury, ON P3E 2C6, Canada.
| | - Scott W Fowler
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794-5000, USA
| | | | - Graeme Spiers
- School of the Environment, Laurentian University, Sudbury, ON P3E 2C6, Canada
| | - Michael Schindler
- Department of Geological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
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Igarashi Y, Kogure T, Kurihara Y, Miura H, Okumura T, Satou Y, Takahashi Y, Yamaguchi N. A review of Cs-bearing microparticles in the environment emitted by the Fukushima Dai-ichi Nuclear Power Plant accident. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2019; 205-206:101-118. [PMID: 31125755 DOI: 10.1016/j.jenvrad.2019.04.011] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 04/21/2019] [Indexed: 06/09/2023]
Abstract
Scientists face challenge in identifying the radioactive materials which are found as dotted images on various imaging plate (IP) autoradiographic photos of radioactively contaminated materials by the Fukushima Dai-ichi Nuclear Power Plant (F1NPP, or FDNPP) accident, such as air filter, fugitive dust, surface soil, agricultural materials, and water-shed samples. It has been revealed that they are minute particles with distinct morphology and elemental composition with high specific radioactivity, and different from those of the so-called Chernobyl hot particles. Basically, they are glassy particles once molten, composed of Si, O, Fe, Zn etc. with highly concentrated radiocaesium, which can be called as radiocaesium-bearing microparticles (CsMP). At present, CsMP can be classified into two types, Types-A and -B, which are characterized by different specific radioactivity, 134Cs/137Cs ratio, size and morphology, and geographic distribution around F1NPP. Such studies on the CsMP from various aspects have provided valuable information about what happened in the nuclear reactors during the F1NPP accident and fates of the CsMP in the environment. This review first provides a retrospective view on the research history of the CsMP, which is helpful to understand the unique character of the CsMP. Subsequently, more details about the current understanding of the natures of these hot particles, such as origin, morphology, chemical compositions, thermal properties, water-solubility, and secondary migration of CsMP in river and ocean systems are described with future prospects.
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Affiliation(s)
- Yasuhito Igarashi
- Graduate School of Science and Engineering, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, 310-8512, Japan; Institute for Integrated Radiation and Nuclear Science, Kyoto University, 2-chome, Asashiro-Nishi, Kumatori-cho, Sennan-gun, Osaka, 590-0494, Japan
| | - Toshihiro Kogure
- Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, Japan
| | - Yuichi Kurihara
- Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, Japan; Ningyo-toge Environmental Engineering Center, Japan Atomic Energy Agency, Tomata, Okayama, 708-0698, Japan
| | - Hikaru Miura
- Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, Japan; Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry, Abiko, Chiba, 270-1194, Japan
| | - Taiga Okumura
- Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, Japan
| | - Yukihiko Satou
- Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic, 1151, Japan.
| | - Yoshio Takahashi
- Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, Japan.
| | - Noriko Yamaguchi
- Institute for Agro-environmental Sciences, NARO, 3-1-1, Kannondai, Tsukuba, 305-8604, Japan
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Igarashi J, Zheng J, Zhang Z, Ninomiya K, Satou Y, Fukuda M, Ni Y, Aono T, Shinohara A. First determination of Pu isotopes ( 239Pu, 240Pu and 241Pu) in radioactive particles derived from Fukushima Daiichi Nuclear Power Plant accident. Sci Rep 2019; 9:11807. [PMID: 31413276 PMCID: PMC6694128 DOI: 10.1038/s41598-019-48210-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 07/25/2019] [Indexed: 11/13/2022] Open
Abstract
Radioactive particles were released into the environment during the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. Many studies have been conducted to elucidate the chemical composition of released radioactive particles in order to understand their formation process. However, whether radioactive particles contain nuclear fuel radionuclides remains to be investigated. Here, we report the first determination of Pu isotopes in radioactive particles. To determine the Pu isotopes (239Pu, 240Pu and 241Pu) in radioactive particles derived from the FDNPP accident which were free from the influence of global fallout, radiochemical analysis and inductively coupled plasma-mass spectrometry measurements were conducted. Radioactive particles derived from unit 1 and unit 2 or 3 were analyzed. For the radioactive particles derived from unit 1, activities of 239+240Pu and 241Pu were (1.70–7.06) × 10−5 Bq and (4.10–8.10) × 10−3 Bq, respectively and atom ratios of 240Pu/239Pu and 241Pu/239Pu were 0.330–0.415 and 0.162–0.178, respectively. These ratios were consistent with the simulation results from ORIGEN code and measurements from various environmental samples. In contrast, Pu was not detected in the radioactive particles derived from unit 2 or 3. The difference in Pu contents is clear evidence towards different formation processes of radioactive particles, and detailed formation processes can be investigated from Pu analysis.
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Affiliation(s)
- Junya Igarashi
- Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan.
| | - Jian Zheng
- Department of Radioecology and Fukushima Project, National Institutes for Quantum and Radiological Science and Technology, 491 Anagawa, Inage, Chiba, 263-8555, Japan.
| | - Zijian Zhang
- Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Kazuhiko Ninomiya
- Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Yukihiko Satou
- Collaborative Laboratories for Advanced Decommissioning Science, Japan Atomic Energy Agency, 790-1 Otsuka, Motooka, Tomioka, Futaba, Fukushima, 979-1151, Japan
| | - Miho Fukuda
- Department of Radioecology and Fukushima Project, National Institutes for Quantum and Radiological Science and Technology, 491 Anagawa, Inage, Chiba, 263-8555, Japan
| | - Youyi Ni
- Department of Radioecology and Fukushima Project, National Institutes for Quantum and Radiological Science and Technology, 491 Anagawa, Inage, Chiba, 263-8555, Japan.,State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing, 100871, China
| | - Tatsuo Aono
- Department of Radioecology and Fukushima Project, National Institutes for Quantum and Radiological Science and Technology, 491 Anagawa, Inage, Chiba, 263-8555, Japan
| | - Atsushi Shinohara
- Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
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Yang G, Hu J, Tsukada H, Tazoe H, Shao Y, Yamada M. Vertical distribution of 129I and radiocesium in forest soil collected near the Fukushima Daiichi Nuclear Power Plant boundary. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 250:578-585. [PMID: 31026706 DOI: 10.1016/j.envpol.2019.04.053] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 04/08/2019] [Accepted: 04/10/2019] [Indexed: 06/09/2023]
Abstract
Three soil core samples were collected from a forest located about 1.1 km south of the Fukushima Daiichi Nuclear Power Plant (FDNPP) boundary in 2017, and the vertical profiles of 129I from the FDNPP accident were determined by the combination of TMAH (tetramethyl ammonium hydroxide) extraction and ICP-MS/MS analysis. The humus layer above the soil layer was heavily contaminated with 134Cs (1983-5985 Bq g-1) and 137Cs (1947-5902 Bq g-1) (decay-corrected to March 11, 2011). The 129I activity concentrations decreased sharply with the soil depth, from 1894 to 34.1, from 9384 to 78.9, and from 2536 to 51.3 mBq kg-1, for the three sites. Downward migration of 129I was slightly faster than the one of 134Cs. In addition, the cumulative 129I inventories were observed to be 43.4 ± 1.0, 71.7 ± 1.8, and 56.5 ± 1.8 Bq m-2, respectively. Subsequently, the cumulative 131I inventories were estimated to be 1.76 ± 0.06, 2.90 ± 0.11, and 2.28 ± 0.10 GBq m-2 (decay-corrected to March 11, 2011), respectively. Finally, the total atmospheric deposition of 129I on the land of Japan due to the FDNPP accident was estimated to be around 1.09-1.71 kg (7.11-11.2 GBq).
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Affiliation(s)
- Guosheng Yang
- Institute of Radiation Emergency Medicine, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori, 036-8564, Japan
| | - Jun Hu
- Institute of Radiation Emergency Medicine, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori, 036-8564, Japan
| | - Hirofumi Tsukada
- Institute of Environmental Radioecology, Fukushima University, 1 Kanayagawa, Fukushima, 960-1296, Japan
| | - Hirofumi Tazoe
- Institute of Radiation Emergency Medicine, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori, 036-8564, Japan
| | - Yang Shao
- Institute of Radiation Emergency Medicine, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori, 036-8564, Japan; Beijing Engineering Research Center of Radiographic Techniques and Equipment, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China; School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Masatoshi Yamada
- Institute of Radiation Emergency Medicine, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori, 036-8564, Japan.
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Yang G, Rahman MS, Tazoe H, Hu J, Shao Y, Yamada M. 236U and radiocesium in river bank soil and river sediment in Fukushima Prefecture, after the Fukushima Daiichi Nuclear Power Plant accident. CHEMOSPHERE 2019; 225:388-394. [PMID: 30884300 DOI: 10.1016/j.chemosphere.2019.03.061] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 02/25/2019] [Accepted: 03/10/2019] [Indexed: 06/09/2023]
Abstract
Almost 8 years after the Japanese Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, data for 236U and 236U/238U have mainly remained limited to only a few heavily contaminated samples. In the present study, activities of 236U, 134Cs, and 137Cs, along with 234U, 235U, 238U, in 15 river bank soil and 10 river sediment samples, were measured by ICP-MS/MS and γ spectrometry. The 134Cs activities and 134Cs/137Cs activity ratios (decay-corrected to March 11, 2011) in these 15 river bank soil samples were from 74.8 to 3.88 × 105 Bq kg-1 and from 0.944 to 1.02, respectively; and in these 10 river sediment samples were from 87.1 to 1.86 × 105 Bq kg-1 and from 0.904 to 0.990, respectively. The 236U activities and 236U/238U atom ratios in these soil samples were in the respective ranges of (0.139-17.6) × 10-5 Bq kg-1 and (0.259-3.83) × 10-8; and in these sediment samples were in the respective ranges of (0.884-27.0) × 10-5 Bq kg-1 and (1.12-5.04) × 10-8. For one river sediment core sample, 134Cs and 236U activities decreased with the depth indicating 134Cs and 236U accumulated in the river sediment with time. Unlike 134Cs, no clear evidence of FDNPP accident-derived 236U has been found in this study, although further monitoring is encouraged to establish the background database on 236U/238U for its potential application as a tracer in environmental studies.
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Affiliation(s)
- Guosheng Yang
- Institute of Radiation Emergency Medicine, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori, 036-8564, Japan
| | - M Safiur Rahman
- Institute of Radiation Emergency Medicine, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori, 036-8564, Japan; Atmospheric & Environmental Chemistry Lab, Chemistry Division, Atomic Energy Centre, Dhaka, 1000, Bangladesh
| | - Hirofumi Tazoe
- Institute of Radiation Emergency Medicine, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori, 036-8564, Japan
| | - Jun Hu
- Institute of Radiation Emergency Medicine, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori, 036-8564, Japan
| | - Yang Shao
- Institute of Radiation Emergency Medicine, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori, 036-8564, Japan; Beijing Engineering Research Center of Radiographic Techniques and Equipment, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China; School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Masatoshi Yamada
- Institute of Radiation Emergency Medicine, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori, 036-8564, Japan.
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Zhang Z, Igarashi J, Satou Y, Ninomiya K, Sueki K, Shinohara A. Activity of 90Sr in Fallout Particles Collected in the Difficult-to-Return Zone around the Fukushima Daiichi Nuclear Power Plant. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:5868-5876. [PMID: 31034221 DOI: 10.1021/acs.est.8b06769] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident released abundant radioactive particles into the surrounding environment. Herein, we analyzed the activity of 90Sr in these particles to estimate the contribution of this radionuclide to the overall radiation exposure and shed light on the processes that occurred during the accident. Seven radioactive particles were isolated from the dust and soil samples collected from areas surrounding the FDNPP, and the minimum/maximum 137Cs activities were determined as 224/4,100 Bq. Based on the size, specific activity, and 134Cs/137Cs activity ratios, we concluded that six of the seven radioactive particles were released from the Unit 1 reactor, while one particle was released from the Unit 3 reactor by a hydrogen explosion. Strontium-90 was detected in all radioactive particles, and the minimal/maximal 90Sr activities were determined as 0.046/1.4 Bq. 137Cs/90Sr activity ratios above 1000 were observed for all seven particles, that is, compared to 137Cs, 90Sr had negligible contribution to the overall radiation exposure. The 137Cs/90Sr activity ratios of the radioactive particles were similar to those of terrestrial environmental samples and were higher for particles released from the Unit 1 reactor than for samples collected from the Unit 1 reactor building, which indicates possibility of additional 90Sr-rich contamination after release of the particles.
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Affiliation(s)
- Zijian Zhang
- Graduate School of Science , Osaka University , 1-1 Machikaneyama , Toyonaka , Osaka 560-0043 , Japan
| | - Junya Igarashi
- Graduate School of Science , Osaka University , 1-1 Machikaneyama , Toyonaka , Osaka 560-0043 , Japan
| | - Yukihiko Satou
- Collaborative Laboratories for Advanced Decommissioning Science (CLADS) , Japan Atomic Energy Agency , 790-1 Otsuka, Motooka , Tomioka , Fukushima 979-1195 , Japan
| | - Kazuhiko Ninomiya
- Graduate School of Science , Osaka University , 1-1 Machikaneyama , Toyonaka , Osaka 560-0043 , Japan
| | - Keisuke Sueki
- Center for Research in Isotopes and Environmental Dynamics (CRiED) , 1-1-1 Tennodai , Tsukuba , Ibaraki 305-8577 , Japan
| | - Atsushi Shinohara
- Graduate School of Science , Osaka University , 1-1 Machikaneyama , Toyonaka , Osaka 560-0043 , Japan
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