Development of environmental mitigation technology with novel water purification agents (Contract research); FY2020 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Shinshu University*

JAEA-Review 2021-051, 81 Pages, 2022/01

JAEA-Review-2021-051.pdf:4.03MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2020. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2020, this report summarizes the research results of the "Development of environmental mitigation technology with novel water purification agents" conducted in FY2020. The present study aims to develop a reusable adsorbent for strontium ions through joint research between Japan and the United Kingdom, and to reduce the amount of used adsorbent generated through the decontamination process. The basic strategy of this research is to produce adsorbents and examine their Sr adsorption performance at Shinshu University. The structural analyses of the adsorbents are conducted by the Institute for Molecular Science (IMS) and the UK teams.

Major element and REE compositions of Pliocene sediments in southwest Japan; Implications for paleoweathering and paleoclimate

Hatano, Nozomi*; Yoshida, Koki*; Mori, Saori*; Sasao, Eiji

Sedimentary Geology, 408, p.105751_1 - 105751_13, 2020/10

https://doi.org/10.1016/j.sedgeo.2020.105751

The history of the East Asian monsoon and the relationship between the development of the monsoon climate, tectonics and global climate are complicated and controversial. The present study clarifies the chemical weathering conditions in southwest Japan based on the concentrations of major elements and rare earth elements (REEs) in lacustrine muddy sediments. Between 3.8 and 3.4 Ma, chemical weathering significantly intensified, as indicated by the high values of the chemical index of alteration as well as the high concentrations of REEs and light REEs against heavy REEs and kaolinite-rich clay mineral compositions. The intense chemical weathering on land in southwest Japan from 3.8 to 3.4 Ma may have been regulated by alternating periods of warm and humid climate brought by the invasion of the Kuroshio Current and the intensification of the East Asian summer monsoon.

Intense chemical weathering in southwest Japan during the Pliocene warm period

Hatano, Nozomi*; Yoshida, Koki*; Adachi, Yoshiko*; Sasao, Eiji

Journal of Asian Earth Sciences, 184, p.103971_1 - 103971_13, 2019/10

https://doi.org/10.1016/j.jseaes.2019.103971

Whole rock major and REE geochemistry and mineral compositions of the Pliocene sediments in southwest Japan reveal the effects of source rock compositions and grain sizes, as well as the relationship between sedimentary environments and the degree of chemical weathering in the Pliocene warm period. A wide variation in the degree of chemical weathering, source rock compositions and grain sizes were observed with vertical and spatial changes in the sedimentary environment. Regardless of the wide variety of source rock compositions and grain sizes, REE and kaolinite-rich clay mineral concentrations in sediments, of which CIA values are generally above 90, are indicative of the intense weathering conditions that prevailed in the Pliocene period (3-4 Ma) in southwest Japan.

Effects of grain size on the chemical weathering index; A Case study of Neogene fluvial sediments in southwest Japan

Hatano, Nozomi*; Yoshida, Koki*; Sasao, Eiji

Sedimentary Geology, 386, p.1 - 8, 2019/05

https://doi.org/10.1016/j.sedgeo.2019.03.017

Grain size variation of sediments generally complicates the assessment of the degree of chemical weathering. Mineralogical and geochemical research was carried out on Miocene and Pliocene fluvial sediments in southwest Japan to evaluate the effects of grain size on the degree of chemical weathering. We indicated that the AlO/SiO ratio may be suitable as a grain size index. Most of the fine-grained sediments have higher CIA values. In contrast, coarse-grained sediments, display a wide range of CIA values. The CIA values for intermediate grain sized samples reflect distinctive differences in the degree of chemical weathering between Miocene and Pliocene sediments. In the intermediate grain sized samples, the Miocene sediments have higher CIA values than Pliocene sediments. To compare the degree of chemical weathering, it is desirable to evaluate with the AlO/SiO ratios limited to the intermediate grain size range.

A Study of efficient excavation limiting the extent of an excavation damaged zone in Horonobe URL

Aoyagi, Kazuhei; Tokiwa, Tetsuya*; Fujita, Tomoo

Rock Mechanics and Rock Engineering; From the Past to the Future (EUROCK 2016), p.1023 - 1028, 2016/07

A Study on optimum irradiation dose of -ray and carbon ion beams in grain amaranth

Nemoto, Kazuhiro*; Tsurukawa, Akiko*; Minami, Mineo*; Matsushima, Kenichi*; Hase, Yoshihiro

JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 112, 2015/03

https://jopss.jaea.go.jp/pdfdata/JAEA-Review-2014-050.pdf#page=144

https://doi.org/10.11484/jaea-review-2014-050

no abstracts in English

Velocity of entrainments formed by high velocity air jet flow in stagnant water

Akabane, Masaaki*; Koizumi, Yasuo; Uchibori, Akihiro; Kamide, Hideki; Ohshima, Hiroyuki

Proceedings of 22nd International Conference on Nuclear Engineering (ICONE-22) (DVD-ROM), 6 Pages, 2014/07

https://doi.org/10.1115/ICONE22-30806

A liquid droplet entrainment which appears under heat transfer tube failure accident in a steam generator of sodium-cooled fast reactors and causes wastage on an adjacent tube was examined in this study. The visualization experiment on a high-pressure air jet in a liquid pool was carried out. Filament-like ears and wisps pulled out from the wavy gas-liquid interface were observed. The ears and the wisps were broken off and entrained into the air jet. This process seems quite similar to the entrainment process in an annular dispersed flow in a pipe. The velocity of the entrained droplet was estimated from an image processing. The axial velocity of the entrained droplet increased as the air jet velocity increased. The Transversal directional velocity was much slower than the axial directional velocity. The data obtained from this experiment are very useful for the study of the heat transfer tube failure accident.

Entrainment into high speed air jet blowing out from a hole to stagnant water

Koizumi, Yasuo*; Nago, Kohei*; Uchibori, Akihiro; Kamide, Hideki; Ohshima, Hiroyuki

Proceedings of ASME 2013 International Mechanical Engineering Congress and Exposition (IMECE 2013) (DVD-ROM), 6 Pages, 2013/11

https://doi.org/10.1115/IMECE2013-65822

Flow visualization experiments of an air jet in liquid were performed. The air jet was blown vertically upward into stagnant water or kerosine in the test vessel from a 1 mm width nozzle which was located at the bottom of the test vessel. A flow state of the jet in the liquid was recorded with a high speed video camera. Experimental result showed that the filament-like ears and wisps were pulled out from the wavy interface between liquid and the air jet. The ears and wisps were broken off and entrained into the air jet. As the air jet velocity increased, the number of entrainments created by the air jet increased lineally. The correlation for the entrainment diameter distribution which was developed for the annular dispersed two-phase flow in a pipe predicted well the present results. Measured entrainment rates were considerably lower than the prediction of the correlation for the annular dispersed two-phase flow in a pipe.

Gas entrainment rate from free surface by vortex

Koizumi, Yasuo*; Ote, Naosuke*; Kamide, Hideki; Ohno, Shuji; Ito, Kei

Proceedings of 6th Japanese-European Two-Phase Flow Group Meeting (USB Flash Drive), 6 Pages, 2012/09

The gas entrainment rate into liquid by the vortex formed on the free surface was examined experimentally. Water, 20 cSt silicone oil and kerosene were used as test fluid in the experiments. When the liquid flow rate was low, small air bubbles were torn off from the vortex tip. The torn-off bubble flow rate was small. The gas entrainment increased drastically with the increase of the liquid flow rate. When the liquid level height in the vessel was low, only the latter type of the gas entrainment was observed. As the liquid level was increased, the former type was observed first and then the entrainment turned to the latter type. The physical properties of the viscosity and the surface tension had some effect on gas entrainment phenomena such as the gas entrainment rate and the initiation of the gas entrainment. The Kelvin-Helmholtz instability seemed to explain the inception of the bubble type and also the vortex type entrainment.

Measurement of gas entrainment rate from free surface by vortex

Koizumi, Yasuo*; Ote, Naosuke*; Kamide, Hideki; Ohno, Shuji; Ito, Kei

Proceedings of 20th International Conference on Nuclear Engineering and the ASME 2012 Power Conference (ICONE-20 & POWER 2012) (DVD-ROM), 5 Pages, 2012/07

A sodium-cooled fast breeder reactor is now at the developing stage in Japan. One concern for safety is cover gas entrainment into the sodium coolant. The gas entrainment rate into liquid by the vortex formed on the free surface was examined experimentally. In the present experiments, test fluid was changed from water in the previous experiments to 20 cSt silicone oil. The liquid level in the test vessel was 25 mm in the present experiments. Only the vortex-type gas-entrainment was observed as in the previous experiments since the liquid level was low. The flow state observed at the flow visualization section of the outlet pipe was only a semi-annular flow. The initiation of the gas entrainment was delayed in the case of silicone oil compared with the case of water. The increasing rate of the gas entrainment to the liquid velocity is milder in the case of silicone oil than in the case of water.