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Yamano, Hidemasa; Takai, Toshihide; Emura, Yuki; Higashi, Hideo*; Fukuyama, Hiroyuki*; Nishi, Tsuyoshi*; Ota, Hiromichi*; Morita, Koji*; Nakamura, Kinya*; Fukai, Hirofumi*; et al.
no journal, ,
A research project has been conducting thermophysical property measurement of a eutectic melt, eutectic melting experiments and material analysis, physical model development for the eutectic melting reaction, and reactor application analysis in order to simulate the eutectic melting reaction and relocation behavior of boron carbide as a control rod material and stainless steel during a core disruptive accident in an advanced sodium-cooled fast reactor designed in Japan. This paper describes the project overview and progress until JFY2020.
Sato, Rina; Yoshimura, Kazuya; Sanada, Yukihisa; Sato, Tetsuro*; Takagi, Marie*
no journal, ,
no abstracts in English
Futagami, Satoshi; Ando, Masanori; Yamano, Hidemasa
no journal, ,
To enhance resilience of next-generation nuclear power plants, the authors have performed a three-dimensional analysis of structures with an earthquake-resistant lower support structure, assuming a protected loss of heat sink event, which may cause all decay heat removal systems to lose their functions immediately after reactor shutdown. The results show how the reactor vessel and guard vessel deform at extremely high temperatures.
Okada, Toyofumi; Shibanuma, Tomohiro; Honda, Fumiya; Komeno, Akira; Kikuno, Hiroshi
no journal, ,
Am is generated by beta-decay of Pu. In the case of treating MOX, it is important for shielding about 60keV gamma-ray emitted by Am. Also getting dose rate data of MOX containing Am is valuable. In this work, we measured gamma-ray dose rate from MOX containing Am by changing thickness of shielding materials and range between MOX and measuring instruments. Also we confirmed that calculating analysis is useful for evaluation of shielding material's performance.
Demachi, Kazuyuki*; Kuwabara, Yuto*; Chen, S.*; Kasahara, Naoto*; Nishino, Hiroyuki; Onoda, Yuichi; Kurisaka, Kenichi
no journal, ,
no abstracts in English
C-SS eutectic molten materialsFukuyama, Hiroyuki*; Higashi, Hideo*; Yamano, Hidemasa
no journal, ,
The purpose of this study is to develop the thermophysical property model needed to simulate the behavior of the eutectic compound of the control rod material (boron carbide (BC)) and the structural material of a reactor vessel (stainless steel: SUS316L (SS)) during a core disruptive accident in a sodium-cooled fast reactor. This paper describes the liquidus temperature, density and surface tension of the molten compound of 15mass% BC-SS systematically measured with the High-Temperature Thermophysical Property Measurement System (PROSPECT).
Suzuki, Risa; Nomi, Takayoshi; Nagatani, Taketeru; Shiromo, Hideo; Shiba, Tomooki; Kaburagi, Masaaki; Okumura, Keisuke; Kosuge, Yoshihiro*; Takada, Akira*; Nauchi, Yasushi*
no journal, ,
no abstracts in English
Ueki, Taro
no journal, ,
In the power spectrum measurement of natural and engineering phenomena, there are upper and lower limits in the frequency domain variables. Therefore, in this excerpt, we report that the randomized Weierstrass function for the modelling of inverse power law spectrum has been extended so that the range of frequency domain variable can be set arbitrarily. This extension is born out of breaking the relationship with the convergence issue in the fractalness of Weierstrass function and thus named an incomplete randomized Weierstrass function (IRWF). An example of the uncertainty evaluation of neutron effective multiplication factor using IRWF is shown for fuel debris in a sufficiently water-moderated environment.
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.
Narukawa, Takafumi; Udagawa, Yutaka
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no abstracts in English
Pd in radioactive rubbles by ICP-MS/MSIwahashi, Hiroyuki; Do, V. K.; Furuse, Takahiro; Ota, Yuki; Homma, Shunta; Kurosawa, Kiyoko*; Motoki, Yoshiaki*; Hirosawa, Takashi
no journal, ,
The radiometric determination of beta emitting Pd (half-life of 6.5 million years) requires a multiple-step chemical separation and a time-consuming radioactive measurement. Inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) with recent technological advances in interference removal by two quadrupole mass filters and a collision/reaction cell could be an alternative for highly sensitive analysis of long-lived radionuclides. In this study, we have developed an analytical method for the determination of Pd in concrete rubble by ICP-MS/MS combined with single-column chromatographic separation. A simplified procedure for the separation of Pd from concrete matrices was developed. The measurement condition was optimized to completely suppress the interference including the isobar Ag and the sample matrices. The application of the developed method to radioactive concrete rubble is under consideration.
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.
Miyazaki, Yasunori; Okamura, Nobuo; Watanabe, Masayuki; Sano, Yuichi
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no abstracts in English
Kinase, Sakae; Mikami, Satoshi; Ando, Masaki; Saito, Kimiaki
no journal, ,
no abstracts in English
-isosaccharinic acid, 2Iwata, Hajime; Kimuro, Shingo; Kitamura, Akira; Miyabe, Shunsuke*; Maeno, Mamiko*; Tanaka, Takeru*; Hieda, Manami*
no journal, ,
The effect of -isosaccharinic acid (ISA) on the solubility of palladium (Pd) in alkaline aqueous solution (pH 8.5, 10.0) was investigated by solubility experiments. The Pd concentration increased with the increase of ISA concentration. The equilibrium constant was calculated from the solubility data obtained in this study.
Kimura, Shun; Takeda, Masaki; Motoshima, Takayuki*; Dan, Hanae*
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no abstracts in English
Nagai, Haruyasu; Furuta, Yoshihiro*; Satoh, Daiki; Nakayama, Hiromasa
no journal, ,
no abstracts in English
Kawato, Takaya*; Ishida, Keisuke*; Yamamoto, Takeshi*; Minato, Daisuke*; Fujisaki, Kiyoshi*; Hamamoto, Takafumi*; Mihara, Morihiro
no journal, ,
no abstracts in English
Futemma, Akira; Kudo, Tamotsu
no journal, ,
During a nuclear emergency, aerial radiation monitoring (ARM) via manned helicopters could be utilized as a way of radiation measurement. Natural background radiation maps surrounding twelve nuclear facilities in Japan are developed by ARM to contribute to make an appropriate evaluation of the environmental radiological effect during a nuclear emergency.