Abe, Hironobu; Hatakeyama, Nobuya; Yamazaki, Masanao; Okuzono, Akihiko*; Sakai, Tetsuo*; Inoue, Masahiro*
JAEA-Research 2009-019, 192 Pages, 2020/02
Construction of the underground facility is on going at the Horonobe Underground Research Center, a division of the Japan Atomic Energy Agency. The facility is consisted of three shafts and horizontal drifts at the completion of construction and it is excavated in geological environment with methane gas, so it is important to secure the workers and visitors security in case of fire in the underground. However, it is known that the fire gas such as methane shows a complicated behavior by drift effect and so on and very difficult to predict its behavior, even if under enforced ventilation. In order to construct new prediction method of the fire gas behavior, the model scaled experiments were conducted by using the basic model which consists of shafts and drifts. As a results, fundamental data of the fire gas behavior was grasped and complicated behavior of the fire gas such as three-dimensional backflow and main flow inversion phenomena at the underground structure were ascertained. A new fire gas behavior analysis system has been designed and a prototype system has been programmed which is able to simulate the phenomena noted above. Coupling analysis method is adapted to the system, which consists of mainly one-dimensional ventilation network analysis and simplified computational fluid dynamics program named M-CFD. To minimize calculation time, M-CFD was designed as two-dimensional calculation with simulators multi area analysis system. Using the prototype system, several experimented models representing typical behavior of fire gas have been simulated for model scaled experiments. The system qualitatively reappeared the phenomena such as back flow or main flow inversion, and most of calculations completed in expected time. This indicates appropriateness of the prototype system, but some upgrade such as heat conductivity analysis in the wall rock mass transfer calculation, user friendly interface system and others will be required.
Watanabe, Takayoshi; Oyama, Takuya; Ishii, Yasuo; Niizato, Tadafumi; Abe, Hironobu; Mitachi, Katsuaki; Sasaki, Yoshito
KEK Proceedings 2017-6, p.122 - 126, 2017/11
no abstracts in English
Das, S. K.*; Fukuda, Tomokazu*; Mizoi, Yutaka*; Ishiyama, Hironobu*; Miyatake, Hiroari*; Watanabe, Yutaka*; Hirayama, Yoshikazu*; Jeong, S. C.*; Ikezoe, Hiroshi*; Matsuda, Makoto; et al.
Physical Review C, 95(5), p.055805_1 - 055805_4, 2017/05
Sasaki, Yoshito; Ishii, Yasuo; Abe, Hironobu; Mitachi, Katsuaki; Watanabe, Takayoshi; Niizato, Tadafumi
Horticulture Journal, 86(2), p.139 - 144, 2017/04
To examine the translocation of radiocesium (Cs) scattered by the Fukushima Daiichi Nuclear Power Plant accident that occurred in March 2011 to the Japanese chestnut, we investigated the autoradiography and radiocesium concentration in each part of the Japanese chestnut. The Japanese chestnut fruit has a thin skin between the kernel (cotyledons) and shell; the kernel of the fruit is edible. Cs concentration in each part of the fruit was found to be almost the same at about 1.010 Bqkg. Radiocesium concentration in chestnut weevil larvae found on the fruit was approximately one-seventh of that in the kernel.
Sasaki, Yoshito; Abe, Hironobu; Mitachi, Katsuaki; Watanabe, Takayoshi; Ishii, Yasuo; Niizato, Tadafumi
Journal of Environmental Radioactivity, 161, p.58 - 65, 2016/09
We report the behavior of radiocesium on the tree bark and its transfer into the stemflow of chestnut in a forest in Fukushima. The radiocesium concentration is greatest in 2-cm stem, less in 5-mm stem, and least in the leaves. In the 2-cm stem, the radiocesium concentration of the bark was approximately 10 times that of wood. The average Cs-137 concentration of the dissolved fraction of stem flow was about 10 Bq/L; the pH was nearly constant at 5.8. A strong positive correlation was observed between the radiocesium concentration and the electrical conductivity of the dissolved fraction of stemflow; this result suggests that radiocesium and electrolytes have the same elution mechanism from the tree. Some of the particles in the particulate fraction of the stem flow was strongly adsorbed radiocesium.
Niizato, Tadafumi; Abe, Hironobu; Mitachi, Katsuaki; Sasaki, Yoshito; Ishii, Yasuo; Watanabe, Takayoshi
Journal of Environmental Radioactivity, 161, p.11 - 21, 2016/09
Estimations of radiocesium input and output budgets concerning the forest floor in a mountain forest region have been conducted in the north and central part of the Abukuma Mountains of Fukushima, after 2 to 3 year period following the TEPCO Fukushima Dai-ichi Nuclear Power Plant accident. The radiocesium input and output associated with surface washoff, throughfall, stemflow, and litterfall processes at the experimental plots have been monitored on a forest floor of evergreen Japanese cedar and deciduous Konara oak forests. The results at both monitoring locations show the radiocesium input to be 4-50 times higher than the output during the rainy season in Fukushima. These results indicate that the radiocesium tend to be preserved in the forest ecosystem due to extremely low output ratios. Thus, the associated fluxes throughout the circulation process are key issues for the projecting the environmental fate of the radiocesium levels.
Ishiyama, Hironobu*; Jeong, S.-C.*; Watanabe, Yutaka*; Hirayama, Yoshikazu*; Imai, Nobuaki*; Jung, H. S.*; Miyatake, Hiroari*; Oyaizu, Mitsuhiro*; Osa, Akihiko; Otokawa, Yoshinori; et al.
Nuclear Instruments and Methods in Physics Research B, 376, p.379 - 381, 2016/06
Ishii, Yasuo; Abe, Hironobu; Niizato, Tadafumi
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 3 Pages, 2015/05
As part of the project entitled "Long-Term Assessment of Transport of Radioactive Contaminant in the Environment of Fukushima" (F-TRACE project), JAEA has researched since November 2012 to predict the transport behavior of radioactive caesium, which now Cs-134 and Cs-137 are the main radiological contribution, from contaminated mountain forests to estuary and coast through dam, pond, river etc. based on their investigated data survey data in the Fukushima prefecture. In this study, we report characterization and radio assay of the surface run-off substances obtained (or collected) at the forest observation plots in the Ogi district of Kawauchi-mura and the Yamakiya district of Kawamata-machi, and at the soil-saving dam in the Ogaki district of Namie-machi, Fukishima prefecture, Japan.
Ishiyama, Hironobu*; Jeong, S.-C.*; Watanabe, Yutaka*; Hirayama, Yoshikazu*; Imai, Nobuaki*; Miyatake, Hiroari*; Oyaizu, Mitsuhiro*; Katayama, Ichiro*; Osa, Akihiko; Otokawa, Yoshinori; et al.
Japanese Journal of Applied Physics, 53(11), p.110303_1 - 110303_4, 2014/11
Ishibashi, Kenji*; Uesaka, Mitsuru*; Morita, Koji*; Sato, Yasushi*; Iimoto, Takeshi*; Watanabe, Yukinobu*; Unesaki, Hironobu*; Yamano, Hidemasa
Nippon Genshiryoku Gakkai-Shi, 55(7), p.403 - 406, 2013/07
Japan-Korea Exchange program has been successful and their joint sessions have been accompanying conferences. With this background, younger generation's communication has been recognized as important role in Japan and Korea's joint cooperation. Thus students and young researchers support program has started. Understanding the achievements and the current status is important, expecting unrelated areas and working groups to show interest and hopefully join this area of work.
Sonoda, Tetsu*; Wada, Michiharu*; Tomita, Hideo*; Sakamoto, Chika*; Takatsuka, Takaaki*; Furukawa, Takeshi*; Iimura, Hideki; Ito, Yuta*; Kubo, Toshiyuki*; Matsuo, Yukari*; et al.
Nuclear Instruments and Methods in Physics Research B, 295, p.1 - 10, 2013/01
no abstracts in English
Hirayama, Yoshikazu*; Mihara, Mototsugu*; Watanabe, Yutaka*; Jeong, S. C.*; Miyatake, Hiroari*; Momota, Sadao*; Hashimoto, Takashi*; Imai, Nobuaki*; Matsuta, Kensaku*; Ishiyama, Hironobu*; et al.
European Physical Journal A, 48(5), p.54_1 - 54_10, 2012/05
Ishiyama, Hironobu*; Yamaguchi, Kanako*; Mizoi, Yutaka*; Watanabe, Yutaka*; Das, S. K.*; Hashimoto, Takashi*; Miyatake, Hiroari*; Hirayama, Yoshikazu*; Imai, Nobuaki*; Oyaizu, Mitsuhiro*; et al.
Journal of Instrumentation (Internet), 7(3), p.C03036_1 - C03036_14, 2012/03
We developed an active-target type gas counter operating with low He/CO (10%) detector gas for application in studying low-energy nuclear reactions using radioactive beams. A 400-m-thick gas electron multiplier (THGEM) was used as the proportional counter for high injection rate capability. We examined the gas gain stability and the influence of ion feedback on particle tracks at high beam injection rates of up to 10 particles per second (pps) using a low-energy C beam. From the result of this examination, we found that the THGEM was found to be applicable for our active target at high injection rates of up to 10 pps.
Okada, Masashi*; Niki, Kazuaki*; Hirayama, Yoshikazu*; Imai, Nobuaki*; Ishiyama, Hironobu*; Jeong, S. C.*; Katayama, Ichiro*; Miyatake, Hiroari*; Oyaizu, Mitsuhiro*; Watanabe, Yutaka*; et al.
Physical Review Special Topics; Accelerators and Beams, 15(3), p.030101_1 - 030101_10, 2012/03
Iwatsuki, Teruki; Sato, Haruo; Nohara, Tsuyoshi; Tanai, Kenji; Sugita, Yutaka; Amano, Kenji; Yabuuchi, Satoshi; Oyama, Takuya; Amano, Yuki; Yokota, Hideharu; et al.
JAEA-Research 2011-009, 73 Pages, 2011/06
The research and development plan in Horonobe Underground Research Laboratory are summarized according to the 2nd Midterm Plan till 2014 fiscal year of JAEA. In this midterm, galleries and the infrastructures for the research and development up to the depth of 350 m are constructed by Private Financial Initiative (PFI). Additionally Phase 3: Operation phase at the galleries begins in parallel to Phase 2: Construction phase. In these phases various research and development including collaboration with other institutes are conducted at the galleries. Generallic applicable techniques on the subject of the investigation of geological environment, facility construction in deep underground and the reliability of geological deposal are developed during the phase. The feasibility and reliance of various technologies concerning geological disposal is demonstrated by widely opening the outcome to the public in the society.
Ota, Kunio; Abe, Hironobu; Kunimaru, Takanori
JAEA-Research 2010-068, 370 Pages, 2011/03
The Horonobe Underground Research Laboratory (URL) Project is a comprehensive research and development project aimed at studying the host sedimentary formations at Horonobe in Hokkaido, northern Japan. In phase I, following the selection of the URL area and site in Horonobe, stepwise surface-based investigations were carried out from March 2001 to March 2005. The relevant surface-based investigation techniques were developed and the design and safe construction plans for the URL finalised. Integration of the results ensures that the phase I goals were successfully achieved and identifies key issues that need to be addressed in phases II and III. More importantly, efforts have been made to summarise as many lessons learnt from the phase I investigations as possible to form a "knowledge base" that will reinforce the technical basis for both implementation and the formulation of safety regulations. The present report summarises the results of the phase I geoscientific research.
Imai, Nobuaki*; Hirayama, Yoshikazu*; Ishiyama, Hironobu*; Jeong, S.-C.*; Miyatake, Hiroari*; Watanabe, Yutaka*; Makii, Hiroyuki; Mitsuoka, Shinichi; Nagae, Daisuke*; Nishinaka, Ichiro; et al.
European Physical Journal A, 46(2), p.157 - 160, 2010/11
Mitsuoka, Shinichi; Ikezoe, Hiroshi; Nishio, Katsuhisa; Watanabe, Yutaka*; Jeong, S. C.*; Ishiyama, Hironobu*; Hirayama, Yoshikazu*; Imai, Nobuaki*; Miyatake, Hiroari
International Journal of Modern Physics E, 19(5&6), p.989 - 996, 2010/07
We have measured quasi-elastic scattering cross sections in reactions of Ti, Cr, Fe, Ni and Zn + Pb, relating to Pb-based cold fusion reactions for super-heavy elements 104, 106, 108, 110 and 112, respectively. A thin target of Pb was bombarded by heavy-ion beams supplied from the JAEA tandem-booster accelerator with changing the beam energy in steps of 1.5 MeV. The barrier distributions were derived from the first derivative of the excitation functions measured at backward angles of 172, 168 and 162. The centroid of the barrier distributions showed a deviation from several predicted barrier heights toward the low energy side. The shape of the barrier distributions was well reproduced by the results of a coupled-channel calculation taking account of the coupling effects of the collective vibrational excitations in the projectile and target nuclei. We have recently obtained similar results in heavier reactions of Ge and Kr + Pb.
Abe, Hironobu; Takahashi, Kazuharu*; Fujishima, Atsushi
JAEA-Data/Code 2009-007, 35 Pages, 2009/07
We are carring out a geological survey to understand important geological structure as geological heterogeneity and migration pathway of material in the bedrock of around the URL area. This report summarizes method and the result of gas measurements, carried out in the Hokushin area and the Suwanosawa area, a period of the FY 2002 to FY 2006. We have investigated gas concentrations of CH and CO (methane and carbon dioxide) along the Omagari fault, and discussed correlations between the gas concentrations and the Omagari fault. The high amount of CO gas concentration were observed around the Omagari Fault.
Sumi, Mika; Abe, Katsuo; Kageyama, Tomio; Nakazawa, Hiroaki; Kacchi, Tomokazu*; Murakami, Yoshiki*; Hishi, Tomoyuki*; Ai, Hironobu*
Proceedings of INMM 50th Annual Meeting (CD-ROM), 9 Pages, 2009/07
Currently, many laboratories who measure Pu and U concentration by isotope dilution mass spectrometry (IDMS) use Large Size Dried (LSD) spikes, which contain both Pu and U in individual vials. Plutonium Fuel Development Center (PFDC) prepared LSD spikes for MOX samples and has been used while LSD spikes prepared at inspection laboratories and commercially supplied are mainly aimed to measure input solution for reprocessing. Difficulties of importing reference materials are increasing though the needs of Pu reference materials are increasing. Stable securing Pu reference material is essential for facility operation and it is considered to be important to acquire technique to prepare domestic Pu reference material. Pu were prepared from MOX powder at PFDC and used for LSD spike preparation. Practical tests were performed with JNFL. Experience of preparation and utilization of LSD spike for MOX, consideration of certification method for MOX-Pu will be explained also in this paper.