Status on the development of the fabrication and analysis equipment of the pseudo fuel debris

Kobayashi, Fuyumi; Fukaya, Hiroyuki; Izawa, Kazuhiko; Kida, Takashi; Sono, Hiroki; Suyama, Kenya

Proceedings of 12th International Conference on Nuclear Criticality Safety (ICNC2023) (Internet), 7 Pages, 2023/10

In the criticality experiment in the new STACY, pseudo fuel debris samples are used to acquire data for validation of the system used for 1F debris criticality safety assessment. The pseudo fuel debris is a pellet with a diameter of 8 mm and a height of 10 mm containing uranium oxide and structural materials (iron, silicon, zirconium, etc.). The pellets are made by mixing, pressing and sintering uranium dioxide powder and structural materials powder. The UO powder uses the same composition of uranium as the STACY driver fuel rods, in order to reduce the errors in fuel composition. The pseudo fuel debris fabrication devices and analysis equipment are installed at the BECKY in order to evaluate the critical properties of fuel debris with high accuracy in dimension and analysis. This equipment is located in the same laboratory and can quickly respond to experimental needs such as preparation of the pseudo fuel debris and analysis before and after irradiation.

Double diffusive dissolution model of UO pellet in molten Zr cladding

Ito, Ayumi*; Yamashita, Susumu; Tasaki, Yudai; Kakiuchi, Kazuo; Kobayashi, Yoshinao*

Journal of Nuclear Science and Technology, 60(4), p.450 - 459, 2023/04

https://doi.org/10.1080/00223131.2022.2114956

Low-temperature thermochronology of active arc-arc collision zone, South Fossa Magna region, central Japan

Sueoka, Shigeru; Kobayashi, Yumi*; Fukuda, Shoma; Kohn, B. P.*; Yokoyama, Tatsunori; Sano, Naomi*; Hasebe, Noriko*; Tamura, Akihiro*; Morishita, Tomoaki*; Tagami, Takahiro*

Tectonophysics, 828, p.229231_1 - 229231_17, 2022/04

https://doi.org/10.1016/j.tecto.2022.229231

The South Fossa Magna zone, central Japan, has been an active collision zone between the Honshu Arc and the Izu-Bonin Arc since the middle Miocene and provides an excellent setting for reconstructing the earliest stages of continent formation. Multi-system geo-thermochronometry was applied to different domains of the South Fossa Magna zone, together with some previously published data, to reveal mountain formation processes, i.e., vertical crustal movements. Nine granitic samples yielded zircon U-Pb ages of 10.2-5.8 Ma ( = 2), apatite (U-Th)/He (AHe) ages of 42.8-2.6 Ma ( = 7), and apatite fission-track (AFT) ages of 44.1-3.0 Ma ( = 9). Thermal history inversion modeling based on the AHe and AFT data suggested rapid cooling events confined within the study region at 6-2 Ma. The Kanto Mountains may have undergone a domal uplift in association with their collision with the Tanzawa Block at 5 Ma. However, this uplift may have slowed down following the migration of the plate boundary and late Pliocene termination of the Tanzawa collision. The Minobu Mountains and possibly adjacent mountains may have been uplifted by the motional change of the Philippine Sea plate at 3 Ma. Therefore, the mountain formation in the South Fossa Magna zone was mainly controlled by collisions of the Tanzawa and Izu Blocks and motional change of the Philippine Sea plate. Earlier collisions of the Kushigatayama Block at 13 Ma and Misaka Block at 10 Ma appeared to have had little effect on mountain formation. Together with a 90 deg. clockwise rotation of the Kanto Mountains at 12-6 Ma, these observations suggest that horizontal deformation predominated during the earlier stage of arc-arc collision, and vertical movements due to buoyancy resulting from crustal shortening and thickening developed at a later stage.

Izu-Bonin arc collision and mountain formation of the South Fossa Magna region; New insight from low-temperature thermochronometry

Kobayashi, Yumi*; Sueoka, Shigeru; Fukuda, Shoma; Hasebe, Noriko*; Tamura, Akihiro*; Morishita, Tomoaki*; Tagami, Takahiro*

Fuisshon, Torakku Nyusureta, (33), p.25 - 27, 2020/10

no abstracts in English

Uplift and denudation history of the South Fossa Magna region based on low-temperature thermochronometric methods

Kobayashi, Yumi*; Sueoka, Shigeru; Fukuda, Shoma*; Hasebe, Noriko*; Tamura, Akihiro*; Morishita, Tomoaki*; Tagami, Takahiro*

Fuisshon, Torakku Nyusureta, (32), p.8 - 11, 2019/12

http://ftrgj.org/FTNLs/FTNLall2.htm#FTNL32

no abstracts in English

Real-time observation of irradiated HeLa-cell modified by fluorescent ubiquitination-based cell-cycle indicator using synchrotron X-ray microbeam

Narita, Ayumi; Kaminaga, Kiichi; Yokoya, Akinari; Noguchi, Miho; Kobayashi, Katsumi*; Usami, Noriko*; Fujii, Kentaro

Radiation Protection Dosimetry, 166(1-4), p.192 - 196, 2015/09

https://doi.org/10.1093/rpd/ncv156

For the knowledge about irradiation effects of mammalian cells depending on the cell cycle, most of them had been analyzed by statistical approches. Our purpose is to establish the method for real-time observation of irradiated cells under a microscope. Fluorescent ubiquitination-based cell cycle indicator (FUCCI) human cancer (HeLa) cells (red indicates G1; green, S/G2) were exposed to a synchrotron X-ray microbeam. Cells in either G1 or S/G2 were selectively irradiated according to cell color observed in the same microscopic field in a culture dish. Time-lapse micrographs of the irradiated cells were acquired for 24 h after irradiation. The cell cycle was strongly arrested by irradiation at S/G2 and never progressed to G1. In contrast, cells irradiated at G1 progress to S/G2 with a similar time course as non-irradiated control cells. These results show single FUCCI cell exposure and live cell imaging are powerful methods for studying radiation effects on the cell cycle.

Development of mineralization techniques for organic solvents by the silver mediated electrochemical oxidation process with the ultrasound agitation

Kobayashi, Fuyumi; Ishii, Junichi; Shirahashi, Koichi; Umeda, Miki; Sakuraba, Koichi

Kakuhan, Kongo Gijutsu To Toraburu Taisaku, p.341 - 344, 2014/10

The silver mediated electrochemical oxidation (Ag/MEO) process with the ultrasound agitation has been developed for the purpose of the mineralization of organic wastes containing transuranium nuclides at the nuclear fuel reprocessing process. In the Ag/MEO process, organic solvents are decomposed by divalent silver cations under the relatively low temperature and the ambient pressure condition. The ultrasound agitation is effective in mixing the electrolytic solutions and the organic solvents, and is expected to promote the oxidation of the organic solvents. Therefore, the Ag/MEO process with the ultrasound agitation could be a candidate for the treatment of organic solvents. Destruction tests of TBP and dodecane by the Ag/MEO process were conducted to optimize some treatment conditions. Under optimized conditions, the destruction tests of kerosene and TODGA were carried out. It was confirmed that the Ag/MEO process is effective for the mineralization of these organic solvents.

Monitoring of airborne C discharge at RI facilities; A Comparison of collection and oxidation methods

Ueno, Yumi; Koarashi, Jun; Iwai, Yasunori; Sato, Junya; Takahashi, Teruhiko; Sawahata, Katsunori; Sekita, Tsutomu; Kobayashi, Makoto; Tsunoda, Masahiko; Kikuchi, Masamitsu

Hoken Butsuri, 49(1), p.39 - 44, 2014/03

http://doi.org/10.5453/jhps.49.39

http://doi.org/10.5453/jhps.49.2

The Japan Atomic Energy Agency has conducted a monthly monitoring of airborne C discharge at the forth research building (RI facility) of the Tokai Research and Development Center. In the current monitoring, C, which exists in various chemical forms in airborne effluent, is converted into CO with CuO catalyst and then collected using monoethanolamine (MEA) as CO absorbent. However, this collection method has some issues on safety management because the CuO catalyst requires a high heating temperature (600C) to ensure a high oxidation efficiency and the MEA is specified as a poisonous and deleterious substance. To establish a safer, manageable and reliable method for monitoring airborne C discharge, we examined collection methods that use different CO absorbents (MEA and Carbo-Sorb E) and oxidation catalysts (CuO, Pt/Alumina and Pd/ZrO). The results showed 100% CO collection efficiency of MEA during a 30-day sampling period under the condition tested. In contrast, Carbo-Sorb E was found to be unsuitable for the monthly-long CO collection because of its high volatile nature. Among the oxidation catalysts, the Pd/ZrO showed the highest oxidation efficiency for CH at a lower temperature.

Operation databook of the fuel treatment system of the Static Experiment Critical Facility (STACY) and the Transient Experiment Critical Facility (TRACY); JFY 2004 to JFY 2008

Kokusen, Junya; Sumiya, Masato; Seki, Masakazu; Kobayashi, Fuyumi; Ishii, Junichi; Umeda, Miki

JAEA-Technology 2012-041, 32 Pages, 2013/02

JAEA-Technology-2012-041.pdf:1.6MB

Uranyl nitrate solution fuel used in the STACY and the TRACY is adjusted in the Fuel Treatment System, in which such parameters are varied as concentration of uranium, free nitric acid, soluble neutron poison, and so on. Operations for concentration and denitration of the solution fuel were carried out with an evaporator from JFY 2004 to JFY 2008 in order to adjust the fuel to the experimental condition of the STACY and the TRACY. In parallel, the solution fuel in which some kinds of soluble neutron poison were doped was also adjusted in JFY 2005 and JFY 2006 for the purpose of the STACY experiments to determine neutron absorption effects brought by fission products, etc. After these experiments in the STACY, a part of the solution fuel including the soluble neutron poison was purified by the solvent extraction method with mixer-settlers in JFY 2006 and JFY 2007. This report summarizes operation data of the Fuel Treatment System from JFY 2004 to JFY 2008.

Basic study on decontamination of TRU wastes with cerium mediated electrolytic oxidation method

Ishii, Junichi; Kobayashi, Fuyumi; Uchida, Shoji; Sumiya, Masato; Kida, Takashi; Shirahashi, Koichi; Umeda, Miki; Sakuraba, Koichi

JAEA-Technology 2009-068, 20 Pages, 2010/03

JAEA-Technology-2009-068.pdf:2.49MB

At Nuclear Fuel Cycle Safety Engineering Research Facility, the cerium mediated electrolytic oxidation method which is a decontamination technique to decrease the radioactivity of TRU wastes to the clearance-level has been developed for the effective reduction of TRU wastes generated from the decommissioning of a nuclear fuel reprocessing facility and so on. This method corrodes the oxide layer and the surface of metallic TRU metal wastes by the strong oxidation power of Ce in nitric acid. In this study, parameter tests were conducted to optimize the solution condition of Ce initial concentrations and nitric acid concentrations. The target corrosion rate of metallic TRU wastes set to be 24m/h for the practical use of this method. Under the optimized solution condition, a dissolution test of stainless steel simulating wastes was carried out. From the result of the dissolution test, the average corrosion rate was 3.3 m/h during the test time of 90 hours. Based on the supposition that the corrosion depth of metallic TRU wastes was 20 m enough to achieve the clearance-level, the treatment time for the decontamination was about 6 hours. It was confirmed from the result that the decontamination could be performed within one day and the decontamination solution could repeatedly reuse 15 times.