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Journal Articles

Experimental study on transport behavior of cesium iodide in the reactor coolant system under LWR severe accident conditions

Miyahara, Naoya; Miwa, Shuhei; Gou$"e$llo, M.*; Imoto, Jumpei; Horiguchi, Naoki; Sato, Isamu*; Osaka, Masahiko

Journal of Nuclear Science and Technology, 57(12), p.1287 - 1296, 2020/12

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

In order to clarify the cesium iodide (CsI) transport behavior with a focus on the mechanisms of gaseous iodine formation in the reactor coolant system of LWR under a severe accident condition, a reproductive experiment of CsI transport behavior was conducted using a facility equipped with a thermal gradient tube. Various analyses on deposits and airborne materials during transportation could elucidate two mechanisms for the gaseous iodine formation. One was the gaseous phase chemical reaction in Cs-I-O-H system at relatively high-temperature region, which led to gaseous iodine transport to the lower temperature region without any further changes in gas species due to the kinetics limitation effects. The other one was the chemical reactions related to condensed phase of CsI, namely those of CsI deposits on walls with surface of stainless steel to form Cs$$_{2}$$CrO$$_{4}$$ compound and CsI aerosol particles with steam, which were newly found in this study.

Journal Articles

Improvement in flow-sheet of extraction chromatography for trivalent minor actinides recovery

Watanabe, So; Senzaki, Tatsuya; Shibata, Atsuhiro; Nomura, Kazunori; Takeuchi, Masayuki; Nakatani, Kiyoharu*; Matsuura, Haruaki*; Horiuchi, Yusuke*; Arai, Tsuyoshi*

Journal of Radioanalytical and Nuclear Chemistry, 322(3), p.1273 - 1277, 2019/12

 Times Cited Count:0 Percentile:100(Chemistry, Analytical)

Journal Articles

STRAD project for systematic treatments of radioactive liquid wastes generated in nuclear facilities

Watanabe, So; Ogi, Hiromichi*; Arai, Yoichi; Aihara, Haruka; Takahatake, Yoko; Shibata, Atsuhiro; Nomura, Kazunori; Kamiya, Yuichi*; Asanuma, Noriko*; Matsuura, Haruaki*; et al.

Progress in Nuclear Energy, 117, p.103090_1 - 103090_8, 2019/11

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Journal Articles

Ion beam induced luminescence of complexes formed in adsorbent for MA recovery process

Watanabe, So; Katai, Yuya*; Matsuura, Haruaki*; Kada, Wataru*; Koka, Masashi*; Sato, Takahiro*; Arai, Tsuyoshi*

Nuclear Instruments and Methods in Physics Research B, 450, p.61 - 65, 2019/07

 Times Cited Count:1 Percentile:58.8(Instruments & Instrumentation)

Journal Articles

Microanalysis of silica-based adsorbent for effective recovery of radioactive elements

Sano, Yuichi; Watanabe, So; Matsuura, Haruaki*; Nagoshi, Kohei*; Arai, Tsuyoshi*

Journal of Nuclear Science and Technology, 54(10), p.1058 - 1064, 2017/10

 Times Cited Count:3 Percentile:50.46(Nuclear Science & Technology)

For effective recovery of radioactive elements by adsorbents using polymer-immobilized silica (SiO$$_{2}$$-P) supports, the microstructure of SiO$$_{2}$$-P particles impregnated with CMPO as extractants and their change with the crosslinking degree of polymer (CDP) were investigated using STXM and EXAFS analyses; further, their relation with adsorption/elution behavior was discussed. The adsorption/elution tests using adsorbents with a different CDP demonstrated that a higher CDP inhibited the elution of adsorbed metal ions from the adsorbent. The results of STXM and EXAFS analyses suggested that adsorption by CMPO proceeds through the entire area in the adsorbent and the local structure around adsorbed metal ions is similar irrespective of the CDP. Conversely, STXM analyses implied the capture of eluents such as H$$_{2}$$O by polymers with high CDP, which suppresses the prompt elution of adsorbed metal ions from the adsorbent.

Journal Articles

Local structure and distribution of remaining elements inside extraction chromatography adsorbents

Watanabe, So; Sano, Yuichi; Shiwaku, Hideaki; Yaita, Tsuyoshi; Ono, Shimpei*; Arai, Tsuyoshi*; Matsuura, Haruaki*; Koka, Masashi*; Sato, Takahiro*

Nuclear Instruments and Methods in Physics Research B, 404, p.202 - 206, 2017/08

 Times Cited Count:3 Percentile:50.46(Instruments & Instrumentation)

Journal Articles

Microscopic analyses of complexes formed in adsorbent for Mo and Zr separation chromatography

Abe, Ryoji*; Nagoshi, Kohei*; Arai, Tsuyoshi*; Watanabe, So; Sano, Yuichi; Matsuura, Haruaki*; Takagi, Hideaki*; Shimizu, Nobutaka*; Koka, Masashi*; Sato, Takahiro*

Nuclear Instruments and Methods in Physics Research B, 404, p.173 - 178, 2017/08

 Times Cited Count:1 Percentile:80.48(Instruments & Instrumentation)

Journal Articles

Probabilistic risk assessment method development for high temperature gas-cooled reactors, 3; Development plan of seismic fragility analysis method

Itoi, Tatsuya*; Nishida, Akemi; Takada, Tsuyoshi*; Hida, Takenori*; Muramatsu, Ken*; Sato, Hiroyuki

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 5 Pages, 2017/04

In this paper, an overview of development plan for seismic PRA methodology for high temperature gas-cooled reactors (HTGRs) is discussed focusing on seismic fragility analysis. The developed seismic fragility analysis has the features as follows: (1) Appropriate treatment of uncertainty in seismic fragility analysis, (2) Utilization of ground motion simulation considering fault rupture process, (3) Utilization of detailed finite element models for seismic fragility analysis. It is also intended that seismic fragility analysis method to be developed is applicable to that of light water reactors.

JAEA Reports

XAFS measurement of simulated waste glass samples (Borosilicate glass including vanadium)

Nagai, Takayuki; Kobayashi, Hidekazu; Sasage, Kenichi; Ayame, Yasuo; Okamoto, Yoshihiro; Shiwaku, Hideaki; Matsuura, Haruaki*; Uchiyama, Takafumi*; Okada, Yukiko*; Nezu, Atsushi*; et al.

JAEA-Research 2016-015, 52 Pages, 2016/11

JAEA-Research-2016-015.pdf:37.48MB

The local structure of waste elements in simulated waste glasses including V was estimated by using synchrotron XAFS measurement in this study. The results are as follows. (1) V has a high possibility which exists in the glass phase in the case of frit, and V can regard both samples as stable 4 coordination structure. (2) Zn, Ce, Nd, Zr, and Mo exist in the glass phase, and the difference is admitted by the percentage of Ce(III) and Ce(IV) by the composition. (3) Ru is separated from the glass phase as RuO$$_{2}$$ crystalline, both of metal and oxide exist in Rh, and Pd is separated out as metal. (4) It was confirmed that the regularity of the local structure of Zr and Mo in the molten glasses retreats as a result of the XAFS measurement at high temperature. (5) The XAFS measurement of molten glasses were performed at 1200$$^{circ}$$C, so it would be possible to acquire excellent data by improving the shapes of the sample cell.

Journal Articles

Predoping effects of boron and phosphorous on arsenic diffusion along grain boundaries in polycrystalline silicon investigated by atom probe tomography

Takamizawa, Hisashi; Shimizu, Yasuo*; Inoue, Koji*; Nozawa, Yasuko*; Toyama, Takeshi*; Yano, Fumiko*; Inoue, Masao*; Nishida, Akio*; Nagai, Yasuyoshi*

Applied Physics Express, 9(10), p.106601_1 - 106601_4, 2016/10

 Times Cited Count:0 Percentile:100(Physics, Applied)

Journal Articles

Reliability enhancement of seismic risk assessment of NPP as risk management fundamentals, 3; Sensitivity analysis for the quantification of epistemic uncertainty on fragility assessment

Nishida, Akemi; Choi, B.; Itoi, Tatsuya*; Takada, Tsuyoshi*; Furuya, Osamu*; Muramatsu, Ken*

Transactions of 23rd International Conference on Structural Mechanics in Reactor Technology (SMiRT-23) (USB Flash Drive), 10 Pages, 2015/08

This study focused on uncertainty-assessment frameworks and the development of relevant software to improve the reliability of seismic probabilistic risk assessment (SPRA) for NPP and promote its further use. This research aimed at contributing to development of implementation guidelines on epistemic uncertainty. Some sensitivity analyses were performed using a three dimensional reactor-building model and a conventional evaluation model by using 3D vibration simulator for NPP of JAEA, and the results were provided to the experts for expert-opinion elicitation. The results of the sensitivity analyses were related to the uncertainty evaluation of the buildings and soil to evaluate the fragility of the equipment. In this paper, those results will be shown in comparison with a conventional evaluation model.

Journal Articles

Seismic damage probability by ground motions consistent with seismic hazard

Igarashi, Sayaka*; Sakamoto, Shigehiro*; Uchiyama, Yasuo*; Yamamoto, Yu*; Nishida, Akemi; Muramatsu, Ken; Takada, Tsuyoshi*

Transactions of 23rd International Conference on Structural Mechanics in Reactor Technology (SMiRT-23) (USB Flash Drive), 10 Pages, 2015/08

In the preceding study, the methodology to generate ground-motion time histories for advanced PRA of NPPs was proposed by Nishida et al.. They are consistent with seismic hazard at reference site, and incorporate uncertainties of seismic-source characteristics. The ground motions utilized in conventional PRA are generated to fit to specified spectra such as UHS, and they are often generated without considering the variation of spectra. Even if it is considered, their inter-period correlations are generally assumed to be 1.0. In this paper, the authors prepared some cases of ground-motions sets. Ground motions are generated to fit to the response spectra calculated from hazard-consistent ground motions. While the target response spectra have the same median for all case, they have different variation and inter-period correlation. The response analyses of general RC structure and PWR building are conducted and the damage frequencies of simplified equipment system are compared.

Journal Articles

Reliability enhancement of seismic risk assessment of NPP as risk management fundamentals, 1; Uncertainty analysis with the SECOM2 code

Muta, Hitoshi*; Muramatsu, Ken*; Furuya, Osamu*; Uchiyama, Tomoaki*; Nishida, Akemi; Takada, Tsuyoshi*

Transactions of 23rd International Conference on Structural Mechanics in Reactor Technology (SMiRT-23) (USB Flash Drive), 10 Pages, 2015/08

Seismic PRA is an effective measure to consider the countermeasures and improvement plans to secure the further safety of nuclear power plants regarding to seismic risk for the earthquake exceeding the reference ground motion. However, the application of the seismic PRA has not been utilized sufficiently so far. One of the reasons is that there is not enough consensus among stakeholders regarding to the evaluation methods and consideration of uncertainty for decision-making. This study proposes the mathematic framework to treat the uncertainty properly related to the evaluation of Core Damage Frequency induced by earthquake, the method to evaluate the fragility utilizing expert knowledge, the probabilistic model to cope with the aleatory uncertainty as well as the development of analyzing code including these considerations for the improvement of the reliability of the method and enhancement of utilization of the products of Seismic PRA.

Journal Articles

Reliability enhancement of seismic risk assessment of NPP as risk management fundamentals, 2; Quantifying epistemic uncertainty in fragility assessment using expert opinions

Takada, Tsuyoshi*; Itoi, Tatsuya*; Nishida, Akemi; Furuya, Osamu*; Muramatsu, Ken*

Transactions of 23rd International Conference on Structural Mechanics in Reactor Technology (SMiRT-23) (USB Flash Drive), 10 Pages, 2015/08

The assessment of seismic safety of nuclear power plant facilities has been performed by identifying and quantifying uncertainties in seismic probabilistic risk assessment (SPRA). For the evaluation process, all uncertainties are classified into either aleatory or epistemic uncertainty for their quantification. In this study, systematic evaluation of the epistemic uncertainty on the seismic fragility of structures and equipment is studied and implemented for a model NPP. There are two expert groups formed in this project: experts in the field of buildings and soil ground (CE experts) and experts in the field of pipe and equipment (ME experts). Along with ample results from relevant sensitivity analyses conducted, elicited opinions are carefully treated and classified into several specific areas and integrated into the form of knowledge tree technique (KTT), all of which can be utilized for future fragility estimation.

Journal Articles

Structural response by ground motions from sources with stochastic characteristics

Igarashi, Sayaka*; Sakamoto, Shigehiro*; Nishida, Akemi; Muramatsu, Ken; Takada, Tsuyoshi*

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 10 Pages, 2015/05

In the preceding study, the ground-motion time histories consistent with seismic hazard were generated by Nishida et al.. In this study, structural response analyses of general RC structure are conducted with the 2,736 waves of ground motions which were generated from one seismic source, minami-kanto earthquakes. These ground motions incorporate the differences of their seismic-source characteristics. The multi-regression analyses are also conducted with the results of response analysis. As a result, the seismic moment, stress drop and Q-value coefficient showed clear positive correlation with seismic intensities and maximum structural responses. This can be expressed by the relationship between the Fourier spectra of seismic source and seismic-source characteristics. On the other hand, asperity location showed negative correlation with seismic intensities and maximum structural responses. The trend can be expressed by the relationship of location between reference site and faults.

Journal Articles

Chemical forms of uranium, thorium and trace elements in sedimentary rocks distributed in Horonobe area, Hokkaido

Kosemura, Takashi*; Honda, Teruyuki*; Mizuno, Takashi; Murakami, Hiroaki; Nomura, Masao*

Fisshion, Torakku Nyusureta, (26), p.16 - 20, 2013/00

We Analyze existence form of REE in the rock from HDB-6 borehole at the Horonobe Town, Hokkaido. As a result, U and Th is mainly sulfate at fault. REE is mainly silicate at fault.

Journal Articles

Development of a dynamic CT system for neutron radiography and consecutive visualization of three-dimensional water behavior in a PEFC stack

Murakawa, Hideki*; Hashimoto, Michinori*; Sugimoto, Katsumi*; Asano, Hitoshi*; Takenaka, Nobuyuki*; Mochiki, Koichi*; Yasuda, Ryo

Nippon Kikai Gakkai Rombunshu, B, 77(784), p.2255 - 2262, 2011/12

Journal Articles

Reverse Monte Carlo simulation approach on the amorphous structure of C$$_{59}$$N

Ferdows, M.; Suzuya, Kentaro; Kawakita, Yukinobu; Kohara, Shinji*; Kodama, Katsuaki; Yamamoto, Kazunori; Shamoto, Shinichi; Hirata, Takamichi*; Omote, Kenji*; Kasama, Yasuhiko*; et al.

Abstracts of 7th International Symposium on Advanced Materials in Asia-Pacific (NT 2010)/JAIST International Symposium on Nano Technology 2010 (7th ISAMAP), p.25 - 28, 2010/09

We performed Reverse Monte Carlo analysis (RMCA) to study amorphous structure of a heterofullerene, C$$_{59}$$N by using pulsed neutron powder diffraction data. The scattering function S(Q) shows that the structure is amorphous, while the atomic pair distribution function (PDF) shows that the local structure is similar to that of C$$_{60}$$. Obtained structures strongly depend on the initial models. Problems for this RMCA method are discussed.

Journal Articles

Natural analogue study on trace element migration in geological formation at Horonobe area, Japan

Iwatsuki, Teruki; Ishii, Eiichi; Mizuno, Takashi; Honda, Teruyuki*

Tokyo Toshi Daigaku Genshiryoku Kenkyusho Kenkyushoho, (36), p.1 - 13, 2010/07

Trace element analysis in deep rock formation of Horonobe area, Hokkaido was conducted to construct the estimation technique on trace element migration. The distribution of trace element in rock formations suggests that those has not migrate in wide area. However those concentration in and around several fault are inhomogenious indicating the faults has a role of migration path. The analysis of trace element concentration is available to estimate the migration path.

Journal Articles

Natural analogue study focused on trace elements of sedimentary and granitic rocks in Tono area, Gifu prefecture, Japan

Mizuno, Takashi; Nagata, Hiroshi; Iwatsuki, Teruki; Honda, Teruyuki*

Tokyo Toshi Daigaku Genshiryoku Kenkyusho Kenkyushoho, (36), p.14 - 24, 2010/07

This paper aims to understanding the behavior of the elements related to the change of the chemical properties of sedimentary rocks and granitic rocks distributed in the Tono area, Gifu prefecture, using natural analogue approach. As a result, in the sedimentary rocks, it is indicated that REE and U are migrated in response to the change of pH and/or redox condition. These elements will be dissolved from the rocks and introduced into clayminerals, carbonate minerals and phosphate minerals. On the other hand, ingranitic rocks, these elements do not show the systematical variation. It is needed to more detail analysis (ex. chemical analysis of each separated minerals) for understanding their behavior in the granitic rocks.

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