Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Yomogida, Takumi; Ouchi, Kazuki; Oka, Toshitaka; Kitatsuji, Yoshihiro; Koma, Yoshikazu; Konno, Katsuhiro*
Scientific Reports (Internet), 12(1), p.7191_1 - 7191_10, 2022/05
Times Cited Count：5 Percentile：50.82(Multidisciplinary Sciences)Particles containing alpha (
) nuclides were identified from sediment in stagnant water at the torus room of the Fukushima Dai-ichi Nuclear Power Station (FDiNPS)'s Unit 2 reactor. Several uranium-bearing particles were identified by SEM observation. These particles contained Zr and other elements which constituted fuel cladding and structural materials. The 
U/
U isotope ratio in the solid fractions that included U particles was consistent with the nuclear fuel in the Unit 2 reactor, which indicated that the U particles had been derived from nuclear fuel. The particles with alpha-emitters detected by alpha track analysis were several tens to several hundred 
m in size. The EDX spectra showed that these particles mainly comprised iron, which indicated Pu, Am, and Cm were adsorbed on the Fe-baring particles. This study clarifies that the major morphologies of U and other -nuclides were differed in the sediment of stagnant water in the torus room of FDiNPS's Unit 2 reactor.
Ouchi, Kazuki; Yomogida, Takumi; Oka, Toshitaka; Kitatsuji, Yoshihiro; Koma, Yoshikazu; Konno, Katsuhiro*
no journal, ,
In order to grasp the existence state of -nuclides contained as particulate solids in the contaminated water, -nuclide concentrations in the solids and the filtrate which classified according to particle size using filters with pore sizes of 10, 1, 0.1 and 0.02 m were quantitatively analyzed by ICP-MS. Reactor-derived U was detected in the particulate solids in the contaminated water, and most of them settled deeply as coarse particles of 
10 m. U existing in the water as fine particles and ions was also confirmed.
-emitters by SEM-EDX and alpha trackYomogida, Takumi; Ouchi, Kazuki; Oka, Toshitaka; Kitatsuji, Yoshihiro; Koma, Yoshikazu; Konno, Katsuhiro*
no journal, ,
It has been revealed from the analysis results of ICP-MS and -ray spectrometry that the contaminated water at the torus room of Unit 2 reactor contains -nuclides which were derived from nuclear fuels. To investigate the morphology of these -nuclides, we tried to detect particles containing -nuclides by scanning electron microscopy-X-ray detection (SEM-EDX) and the alpha track method. As a result of SEM-EDX observation, several sub-m to several m size particles containing U were identified. These particles contain elements derived from fuel cladding materials such as Zr, suggesting the possibility that these particles are fine fuel debris. The particles containing alpha emitters were identified by alpha-track method. These particles with few hundred m in diameter were mainly composed of iron oxide, which suggest Pu, Am, Cm were attached to the surface of these particles. These results indicated that the forms of U and other -nuclides were different.
Kitatsuji, Yoshihiro; Ouchi, Kazuki; Yomogida, Takumi; Oka, Toshitaka; Nitta, Ayako; Hinai, Hiroshi; Koma, Yoshikazu; Konno, Katsuhiro*
no journal, ,
In order to clarify the chemical species of alpha nuclides in the contaminated water of the Fukushima Daiichi Nuclear Power Station, sludge was classified by particle size. The concentration of alpha radioisotope was measured and the particles were investigated. Most alpha particles were larger than 10 micrometers and settled at the bottom of the torus chamber.
Yomogida, Takumi; Ouchi, Kazuki; Oka, Toshitaka; Kitatsuji, Yoshihiro; Koma, Yoshikazu; Konno, Katsuhiro*
no journal, ,
As part of the decommissioning work of the Fukushima Daiichi Nuclear Power Plant (1F), disposal of stagnant water existing in the basement of the turbine building is underway. Higher concentrations of alpha nuclides have been detected in the stagnant water in the reactor building than in the downstream buildings. It is necessary to consider technology to effectively remove -nuclides to proceed with the disposal of the stagnant water in the reactor buildings. We focused on particulate -nuclides in the stagnant water in the torus room of Unit 2, and analyzed and investigated their particle size, chemical form, etc to understand morphology of -nuclides. We detected particles containing -nuclides by SEM-EDX and alpha-track detection. The results showed that U is in particle form, ranging from a few hundred nm to a few m. Other -nuclides (Pu, Am, and Cm) were distributed on iron oxide particles.
-emitting nuclides analysis of the stagnant water including sediments in Fukushima Daiichi NPS, 1; -emitting nuclides in the stagnant water at the unit 3 reactor of Fukushima Dai-ichi NPSOuchi, Kazuki; Oka, Toshitaka; Yomogida, Takumi; Morii, Shiori; Kitatsuji, Yoshihiro; Koma, Yoshikazu; Konno, Katsuhiro*
no journal, ,
To understand the existence of -nuclides in the particulate solids contained in the stagnant water in the unit 3 reactor of Fukushima Daiichi Nuclear Power Station, the stagnant water was classified by particle size using filters with pore diameters of 10, 1, 0.1, and 0.02~m, and U and Np concentrations in the solid fraction and filtrate were investigated using ICP-MS. Both nuclides were present in large particles larger than 10~m, and some were present in the stagnant water on fine particles or ions smaller than 0.02~m.
-emitting nuclides analysis of the stagnant water including sediments in Fukushima Daiichi NPS, 2; Detection of fine particle containing -emitters by SEM-EDX and alpha TrackYomogida, Takumi; Ouchi, Kazuki; Morii, Shiori; Oka, Toshitaka; Kitatsuji, Yoshihiro; Koma, Yoshikazu; Konno, Katsuhiro*
no journal, ,
To investigate the morphology of -nuclides in solid fraction of the stagnant water in the Fukushima Dai-ichi nuclear Power Station's Unit 3 reactor, we tried to detect particles containing -nuclides by scanning electron microscopy-X-ray detection (SEM-EDX) and the alpha track method. As a result of SEM-EDX observation, several sub-m to 10 m size particles containing U were identified. The particles containing alpha emitters were identified by alpha-track method. These particles with few hundred m in diameter were mainly composed of iron.
-emitting nuclides analysis of the stagnant water including sediments in Fukushima Daiichi NPS, 3; Chemical state analysis of -emitting nuclide particles obtained from unit #3 stagnant water sludgeUsui, Akane; Yamaguchi, Yukako; Sekio, Yoshihiro; Maeda, Koji; Koma, Yoshikazu; Konno, Katsuhiro*
no journal, ,
no abstracts in English
-emitting nuclides analysis of the stagnant water including sediments in Fukushima Daiichi NPS, 6; Chemical state analysis of -emitting nuclide particles obtained from unit #3 stagnant water sludge (Part 2)Nitta, Asahi; Usui, Akane; Yamaguchi, Yukako; Sekio, Yoshihiro; Maeda, Koji; Koma, Yoshikazu; Konno, Katsuhiro*
no journal, ,
no abstracts in English
-emitting nuclides analysis of the stagnant water including sediments in Fukushima Daiichi NPS, 7; Analysis of U and Np in the stagnant water at the Unit 1 reactorMorii, Shiori; Ouchi, Kazuki; Yomogida, Takumi; Oka, Toshitaka; Kitatsuji, Yoshihiro; Koma, Yoshikazu; Konno, Katsuhiro*
no journal, ,
The existence of -emitting nuclides on the sediment contained in the stagnant water of the Unit 1 reactor of Fukushima Daiichi Nuclear Power Station was investigated. The stagnant water was fractionated using filters and U and Np concentrations in the solid fraction and filtrate were determined using ICP-MS. Most of them were present in the fraction which pore size is larger than 10 m, like those in the Units 2 and 3. Some were present in the stagnant water on fine particles or ions smaller than 0.1 m.
-emitting nuclides analysis of the stagnant water including sediments in Fukushima Daiichi NPS, 9; Analysis of fine particle containing -emittersYomogida, Takumi; Ouchi, Kazuki; Morii, Shiori; Oka, Toshitaka; Kitatsuji, Yoshihiro; Koma, Yoshikazu; Konno, Katsuhiro*
no journal, ,
Fine particles containing -nuclides in sediment of stagnant water of Unit 1 were analyzed. We have detected several sub-m to a few m size particles containing U by SEM-EDX, these particles contain elements derived from fuel cladding materials such as Zr, suggesting the possibility that these particles are fine fuel debris. On the other hand, by the alpha-track method, we have detected fine particles main composed of iron oxide with a diameter from 10 m to a few hundred m, which attached Pu, Am and Cm on their surface. These results indicated that the existence forms of -nuclides were similar to those in the stagnant water of torus room in Units 2 and 3.
-emitting nuclides analysis of the stagnant water including sediments in Fukushima Daiichi NPS, 10; Chemical state analysis of -emitting nuclide particles obtained from stagnant water sludge sampled from Unit #1 and centralized radioactive waste treatment facilityToyota, Chihiro; Nitta, Asahi; Usui, Akane; Sekio, Yoshihiro; Maeda, Koji; Koma, Yoshikazu; Konno, Katsuhiro*
no journal, ,
no abstracts in English
