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Journal Articles

Clogging properties of HEPA filter induced by loading of soot from burned glove-box panel materials

Tashiro, Shinsuke; Ono, Takuya; Amano, Yuki; Yoshida, Ryoichiro; Watanabe, Koji*; Abe, Hitoshi

Nuclear Technology, 208(10), p.1553 - 1561, 2022/10

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

To contribute to the confinement safety evaluation of the radioactive materials in the Glove box (GB) fire accident, combustion tests with the Polymethyl methacrylate (PMMA) and the Polycarbonate (PC) as typical panel materials for the GB have been conducted with a relatively large scale apparatus. As the important data for evaluating confinement safety, the release ratio and the particle size distribution of the soot generated from the burned materials were obtained. Furthermore, the rise of the differential pressure ($$Delta$$P) of the high efficiency particle air (HEPA) filter by the soot loading was also investigated. As results, the release ratio of the soot from the PC was about seven times as large as the PMMA. In addition, it was found that the behavior of the rise of the $$Delta$$P with soot loading could be represented uniformly regardless of kinds of combustion materials by considering effect of the loading volume of the soot particle in the relatively low loading region.

Journal Articles

Structure analysis and derivation of deformed electron density distribution of polydiacetylene giant single crystal by the combination of X-ray and neutron diffraction data

Tashiro, Koji*; Kusaka, Katsuhiro*; Hosoya, Takaaki*; Ohara, Takashi; Hanesaka, Makoto*; Yoshizawa, Yoshinori*; Yamamoto, Hiroko*; Niimura, Nobuo*; Tanaka, Ichiro*; Kurihara, Kazuo*; et al.

Macromolecules, 51(11), p.3911 - 3922, 2018/06

 Times Cited Count:4 Percentile:14.91(Polymer Science)

Journal Articles

HEPA filter clogging and volatile material release under solvent fire accident in fuel reprocessing facility

Ono, Takuya; Watanabe, Koji; Tashiro, Shinsuke; Amano, Yuki; Abe, Hitoshi

Proceedings of 25th International Conference on Nuclear Engineering (ICONE-25) (CD-ROM), 7 Pages, 2017/07

After the Fukushima-Daiichi accident, countermeasures against the severe accident are newly required as regulatory items for nuclear facilities. Organic solvent fire in cell was defined as one of the accidents in the fuel reprocessing plant. When the solvent burns, aerosols including soot are released. The substances clog HEPA filters in the ventilation system and their breakthrough may happen because of differential pressure rising. Moreover, the fire can also release volatile radioactive gaseous species, which can pass through HEPA filters. These phenomena are important for evaluation of confinement capability of the facility and public exposure. We have investigated, in relating to the clogging behavior, release behavior of aerosols as well as of volatile materials from burnt solvent. In the presentation, we will report experimental data and evaluation results obtained from recent research.

JAEA Reports

Solvent extraction and release behavior of ruthenium and europium in fire accident conditions in reprocessing plants (Contract research)

Amano, Yuki; Watanabe, Koji; Masaki, Tomoo; Tashiro, Shinsuke; Abe, Hitoshi

JAEA-Technology 2016-012, 21 Pages, 2016/06


To contribute to safety evaluation of fire accident in fuel reprocessing plants, solvent extraction behavior of ruthenium, which could form volatile species, was investigated. Distribution ratios of ruthenium at fire accident conditions were obtained by extraction experiments with several solvent composition at different temperature as parameters. In order to investigate release behavior of ruthenium and europium at fire accident, release ratios of ruthenium and europium were also obtained by solvent combustion experiments.

Journal Articles

Trends of nitrogen oxide release during thermal decomposition of nitrates in highly active liquid waste

Amano, Yuki; Watanabe, Koji; Tashiro, Shinsuke; Yamane, Yuichi; Ishikawa, Jun; Yoshida, Kazuo; Uchiyama, Gunzo; Abe, Hitoshi

Nihon Genshiryoku Gakkai Wabun Rombunshi, 14(2), p.86 - 94, 2015/06

Radioactive materials could be released into air due to the accidental boiling of high active liquid waste (HALW) in reprocessing plants. Volatile radioactive nuclides, such as ruthenium, are released from the tanks into the atmosphere. Nitrogen oxides (NOx) are also released due to the thermal decomposition of metal nitrates in HALW. The released NOx transport volatile ruthenium and cause redox reactions associated with the composition or decomposition of volatile ruthenium. In this study, NOx release data were obtained by heating simulated HALW up to 600$$^{circ}$$C. As a result, the release of NOx from the simulated HALW was observed from 200$$^{circ}$$C to 600$$^{circ}$$C, and the main release of NOx was observed at about 340$$^{circ}$$C. All the lanthanide nitrates were found to decompose in the simulated HALW, and the thermal decomposition temperature of the lanthanide nitrates decreased after the addition of ruthenium dioxide to the mixed lanthanide nitrates solution.

Journal Articles

Accurate structure analyses of polymer crystals on the basis of wide-angle X-ray and neutron diffractions

Tashiro, Koji*; Hanesaka, Makoto*; Yamamoto, Hiroko*; Wasanasuk, K.*; Jayaratri, P.*; Yoshizawa, Yoshinori*; Tanaka, Ichiro*; Niimura, Nobuo*; Kusaka, Katsuhiro*; Hosoya, Takaaki*; et al.

Kobunshi Rombunshu, 71(11), p.508 - 526, 2014/11

 Times Cited Count:6 Percentile:22.87(Polymer Science)

The crystal structure analysis of various polymer substances has been reviewed on the basis of wide-angle high-energy X-ray and neutron diffraction data. The progress in structural analytical techniques of polymer crystals have been reviewed at first. The structural models proposed so far were reinvestigated and new models have been proposed for various kinds of polymer crystals including polyethylene, poly(vinyl alcohol), poly(lactic acid) and its stereocomplex etc. The hydrogen atomic positions were also clarified by the quantitative analysis of wide-angle neutron diffraction data, from which the physical properties of polymer crystals have been evaluated theoretically. The bonded electron density distribution has been estimated for a polydiacetylene single crystal on the basis of the so-called X-N method or by the combination of structural information derived from X-ray and neutron diffraction data analysis. Some comments have been added about future developments in the field of structure-property relationship determination.

JAEA Reports

Experiment on evaluation of confinement capability of fuel cycle facility under combustion of combustible materials (Contract research)

Abe, Hitoshi; Tashiro, Shinsuke; Watanabe, Koji; Uchiyama, Gunzo

JAEA-Research 2012-035, 26 Pages, 2013/01


To contribute on confirmation of safety of fuel cycle facilities, an evaluation method for soundness of confinement capability of the facilities under fire accident has been investigated. Organic extraction solvents, zinc stearate, which is added into MOX powder in MOX fuel preparation process, and typical lubricating oil were considered to be examination objects as the representative combustible materials in the facilities. Combustion property data, such as mass loss rate and soot release fraction, of them and clogging property data of HEPA filter with combustion of the organic extraction solvents were measured. As the results, it was found that soot release fraction from burning 30%TBP/70%dodecane was larger than that of the other materials including dodecane and very rapid rise of differential pressure of HEPA filter, which has not been reported, would be induced in the last stage of combustion of 30%TBP/70%dodecane. Furthermore, it was confirmed that zinc stearate, of which combustibility has not been considered, burned continuously in the condition which was heated from outside.

Journal Articles

Crystal structure analysis of poly(L-lactic acid) $$alpha$$ form on the basis of the 2-dimensional wide-angle synchrotron X-ray and neutron diffraction measurements

Wasanasuk, K.*; Tashiro, Koji*; Hanesaka, Makoto*; Ohara, Takashi*; Kurihara, Kazuo; Kuroki, Ryota; Tamada, Taro; Ozeki, Tomoji*; Kanamoto, Tetsuo*

Macromolecules, 44(16), p.6441 - 6452, 2011/07

 Times Cited Count:174 Percentile:98.54(Polymer Science)

The crystal structure of poly(L-lactic acid) (PLLA) $${alpha}$$ form has been analyzed in detail by utilizing the 2-dimensional wideangle X-ray (WAXD) and neutron diffraction (WAND) data measured for the ultradrawn sample. The WAXD data were collected using a synchrotron-sourced high-energy X-ray beam of wavelength 0.328${AA}$ at SPring-8 and the WAND data were measured using a neutron beam of wavelength 1.510${AA}$ with a BIX-3 detector at JRR-3, JAEA. The initial crystal structure model was extracted successfully by a direct method under the assumption of the space group ${it P}$2$$_{1}$$2$$_{1}$$2$$_{1}$$ using about 700 X-ray reflections observed at -150$$^{circ}$$C. The crystal structure model obtained by the direct method was refined so that the best agreement between the observed and calculated integrated intensities was obtained or the reliability factor (${it R}$) became minimal: ${it R}$ was 18.2% at -150$$^{circ}$$C and 23.2% at 25$$^{circ}$$C. The obtained chain conformation took the distorted (10/3) helical form with 2$$_{1}$$ helical symmetry along the chain axis. However, the symmetrically forbidden reflections were detected in a series of the 00l reflections, requiring us to erase the 2$$_{1}$$ screw symmetry along the molecular chain. By assuming the space group symmetry ${it P}$2$$_{1}$$, the structural refinement was made furthermore and the finally obtained R factor was 19.3% at -150$$^{circ}$$C and 19.4% at 25$$^{circ}$$C. This refined model was found to reproduce the observed reflection profiles well for all the layer lines. The X-ray-analyzed crystal structure was transferred to the WAND data analysis to determine the hydrogen atomic positions. The ${it R}$ factor was 23.0% for the 92 observed reflections at 25$$^{circ}$$C. The agreement between the observed and calculated layer line profiles was good.

Journal Articles

Structural refinement and extraction of hydrogen atomic positions in polyoxymethylene crystal based on the first successful measurements of 2-dimensional high-energy synchrotron X-ray diffraction and wide-angle neutron diffraction patterns of hydrogenated and deuterated species

Tashiro, Koji*; Hanesaka, Makoto*; Ohara, Takashi; Ozeki, Tomoji*; Kitano, Toshiaki*; Nishu, Takashi*; Kurihara, Kazuo; Tamada, Taro; Kuroki, Ryota; Fujiwara, Satoru; et al.

Polymer Journal, 39(12), p.1253 - 1273, 2007/12

 Times Cited Count:18 Percentile:50.01(Polymer Science)

no abstracts in English

JAEA Reports

Study on evaluation of containment capability of grove box under fire accident, 2

Abe, Hitoshi; Watanabe, Koji; Tashiro, Shinsuke; Uchiyama, Gunzo

JAEA-Research 2007-075, 50 Pages, 2007/11


In the MOX fuel fabrication facility, MOX is required to be handled in Grove-box to sustain containment of MOX into the facility. In case of fire in the facility, the containment capability of Grove-box may be deteriorated by pyrolysis or combustion of the plastic materials as components of Grove-box caused by thermal stress from flame. The purpose of this study is to examine pyrolysis and combustion properties of the materials for applying quantitative evaluation method for the containment capability of Grove-box under fire. This report summarize experimental results about the properties under the Air condition and investigation of evaluation model for estimating time-course of deteriorating containment capability of Grove-box under fire.

Journal Articles

Startup of superheavy element chemistry at RIKEN

Haba, Hiromitsu*; Akiyama, Takahiro*; Kaji, Daiya*; Kikunaga, Hidetoshi*; Kuribayashi, Takahiro*; Morimoto, Koji*; Morita, Kosuke*; Oe, Kazuhiro*; Sato, Nozomi*; Shinohara, Atsushi*; et al.

European Physical Journal D, 45(1), p.81 - 86, 2007/10

 Times Cited Count:11 Percentile:49.8(Optics)

A review is given on the startup of the superheavy element (SHE) chemistry at RIKEN. A gas-jet transport system for the SHE chemistry has been coupled to the gas-filled recoil ion separator GARIS at the RIKEN Linear Accelerator. The performance of the system was appraised using $$^{206}$$Fr and $$^{245}$$Fm produced in the $$^{169}$$Tm($$^{40}$$Ar,3${it n}$)$$^{206}$$Fr and $$^{208}$$Pb($$^{40}$$Ar,3${it n}$)$$^{245}$$Fm reactions, respectively. The $$alpha$$ particles of $$^{206}$$Fr and $$^{245}$$Fm separated with GARIS and transported by the gas-jet were identified with a rotating wheel system for $$alpha$$ spectrometry under desired low background condition. The high gas-jet efficiencies over 80% were independent of the beam intensities up to 2 particle $$mu$$A. A gas-jet coupled target system for the production of SHEs was also installed on the beam line of the RIKEN K70 AVF cyclotron. The gas-jet transport of $$^{255}$$No and $$^{261}$$Rf produced in the $$^{238}$$U($$^{22}$$Ne,5${it n}$)$$^{255}$$No and $$^{248}$$Cm($$^{18}$$O,5${it n}$)$$^{261}$$Rf reactions, respectively, was conducted for the future chemical studies of $$^{265}$$Sg via the $$^{248}$$Cm($$^{22}$$Ne, 5${it n}$)$$^{265}$$Sg reaction.

JAEA Reports

Study on evaluation of containment capability of grove-box under fire accident

Abe, Hitoshi; Watanabe, Koji; Tashiro, Shinsuke; Uchiyama, Gunzo

JAEA-Research 2006-054, 39 Pages, 2006/09


no abstracts in English

Journal Articles

Extraction of hydrogen-atom positions in polyethylene crystal lattice from wide-angle neutron diffraction data collected by a two-dimensional imaging plate system; Comparison with the X-ray and electron diffraction results

Tashiro, Koji*; Tanaka, Ichiro*; Ohara, Takashi; Niimura, Nobuo*; Fujiwara, Satoru; Kamae, Toshiya*

Macromolecules, 37(11), p.4109 - 4117, 2004/06

 Times Cited Count:21 Percentile:55.79(Polymer Science)

Two-dimensional wide-angle neutron diffraction patterns have been measured successfully for uniaxially oriented fully deuterated and fully hydrogeneous polyethylene samples by using an imaging plate system (BIX-3) installed at the Japan Atomic Energy Research Institute. The detailed data analysis allowed us to extract the positions of hydrogen atoms in the crystal lattice accurately. The results were compared quantitatively with those obtained from the X-ray and electron diffraction experiments as well as the computer simulation result.

JAEA Reports

Differential pressure analysis for ventilation filter by smoke under fire accident with CELVA-1D

Watanabe, Koji; Tashiro, Shinsuke; Abe, Hitoshi; Takada, Junichi; Morita, Yasuji

JAERI-Tech 2004-029, 48 Pages, 2004/03


In a part of building ventilating installation of a nuclear fuel facility, a reprocessing plant for example, the pre-filters are adopted as one of the ventilation filters. In a fire accident, it is supposed that, because of the pre-filter clogging by large smoke, its differential pressure ($$Delta$$p) is evolved up to the value at its breakage. Therefore, in regard to maintaining the confinement of radioactive materials, it is important to predict the time course of $$Delta$$p of the pre-filter accurately. In the current study, it was assumed that the empirical equation for the DF of the pre-filter as function of smoke particle diameter (SPD), between 0.7-2 $$mu$$m, could be applied to estimating its DF for SPD above 2 $$mu$$m. Under this assumption, the time corresponding to its $$Delta$$p at its breakage, calculated by CELVA-1D, was agreed well with the experimental result.

JAEA Reports

Release behavior of smoke and clogging characteristics of the ventilation filter under the fire accident (Contract research)

Takada, Junichi; Hayashi, Shiro*; Watanabe, Koji; Takita, Koji*; Tsukamoto, Michio; Tashiro, Shinsuke; Abe, Hitoshi*; Uchiyama, Gunzo*

JAERI-Tech 2002-102, 87 Pages, 2003/01


no abstracts in English

Journal Articles

Outline of simulation code fact for analysis of ventilation system on criticality accident

Tsubata, Yasuhiro; Tashiro, Shinsuke; Koike, Tadao; Abe, Hitoshi*; Watanabe, Koji; Uchiyama, Gunzo

Transactions of the American Nuclear Society, 87, p.60 - 61, 2002/11

no abstracts in English

JAEA Reports

Evaluation of released source terms from burning mock combustible waste

Abe, Hitoshi; Watanabe, Koji*; Tashiro, Shinsuke; Takada, Junichi; Uchiyama, Gunzo

JAERI-Research 2001-052, 18 Pages, 2001/11


no abstracts in English

Journal Articles

Interaction of externally applied rotating helical field with tokamak plasma

Kobayashi, M.*; Tsuda, Takashi; Tashiro, Kenji*; Kojima, H.*; Zhai, K.*; Takamura, Shuichi*

Nuclear Fusion, 40(2), p.181 - 193, 2000/02

 Times Cited Count:27 Percentile:63.54(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Structure of physical gels formed in syndiotactic polystyrene/solvent systems studied by small-angle neutron scattering

Kobayashi, Masamichi*; Yoshioka, Toshimori*; Kozasa, Takehiko*; Tashiro, Koji*; Suzuki, Junichi; Funahashi, Satoru; Izumi, Yoshinobu*

Macromolecules, 27(6), p.1349 - 1354, 1994/00

 Times Cited Count:43 Percentile:84.91(Polymer Science)

no abstracts in English

Oral presentation

The Experimental study of GB containment in fire and earthquake, 2; Element experiment on source term evaluation under fire

Abe, Hitoshi; Watanabe, Koji; Tashiro, Shinsuke; Tsuchino, Susumu*; Umetsu, Hiroyuki*

no journal, , 

no abstracts in English

27 (Records 1-20 displayed on this page)