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Miura, Takatomo; Kudo, Atsunari; Koyama, Daisuke; Obu, Tomoyuki; Samoto, Hirotaka
Proceedings of 12th International Conference on Nuclear Criticality Safety (ICNC2023) (Internet), 10 Pages, 2023/10
Tokai Reprocessing Plant (TRP) had reprocessed 1,140 tons of spent fuel discharged from commercial reactors (BWR, PWR) and Advanced Thermal Reactor "Fugen" from 1977 to 2007. TRP had entered decommissioning stage in 2018. In order to reduce the risk of High Active Liquid Waste (HALW) held at the facility, the vitrification of HALW is given top priority. HALW generated from reprocessing of spent fuel contains not only fission products (FPs) but also trace amounts of uranium (U) and plutonium (Pu) within the liquid and insoluble residues (sludge). Under normal conditions, concentrations of U and Pu in HALW are very low so that it can not reach criticality. Since FPs with high neutron absorption effect coexists in HALW, even if the cooling function is lost due to serious accident and HALW evaporates to dryness, it is considered that criticality would not been reached. In order to confirm this estimation quantitatively, criticality safety evaluations were carried out for the increase of U and Pu concentrations by evaporation of HALW to the point of dryness. In this evaluation, infinite multiplication factors were calculated for each of solution system and sludge system of HALW with respect to the concentration change through evaporation to dryness. It is confirmed it could not reach criticality. The abundance ratios of U, Pu and FPs were set conservatively based on analytical data and ORIGEN calculation results. Multiplation factors for two-layer infinite slab model of solution and sludge systems of HALW were also calculated, and it was confirmed it could not reached criticality. In conclusion, the result was gaind that there could be no criticality even in the process through evaporation to dryness of HALW in TRP.
Umino, Yoshinori; Kato, Keisuke; Tanigawa, Masafumi; Kobayashi, Daisuke; Obu, Tomoyuki; Kimura, Yuichi*; Nemoto, Ryo*; Tajiri, Kazuma*
Nihon Hozen Gakkai Dai-19-Kai Gakujutsu Koenkai Yoshishu, p.33 - 36, 2023/08
In the basic laboratory of the Plutonium Conversion Development Facility in Tokai Reprocessing Plant, tests had been conducted to obtain effective data for manufacturing mixed plutonium and uranium oxide powder by irradiating a mixture of plutonium and uranium solution with microwaves. The test has already been completed, and we are currently dismantling and removing equipment. In this paper, techniques related to equipment renewal, dismantling and removal works inside the glove-box are discussed.
Sano, Tomokazu*; Matsuda, Tomoki*; Hirose, Akio*; Terai, Tomoyuki*; Kakeshita, Tomoyuki*; Inubushi, Yuichi*; Sato, Takahiro*; Yabashi, Makina*; Shobu, Takahisa; 22 of others*
Scientific Reports (Internet), 13, p.13796_1 - 13796_10, 2023/08
Shimamura, Yoshinobu*; Matsushita, Shinya*; Fujii, Tomoyuki*; Togo, Keiichiro*; Akita, Koichi*; Shobu, Takahisa; Shiro, Ayumi*
Metals, 9(5), p.527_1 - 527_9, 2019/05
Times Cited Count:4 Percentile:24.04(Materials Science, Multidisciplinary)Kudo, Atsunari; Kurabayashi, Kazuaki; Yanagibashi, Futoshi; Sasaki, Shunichi; Sato, Takehiko; Fujimoto, Ikuo; Obu, Tomoyuki
Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 6 Pages, 2017/04
The Co-processing process is the extraction process to recover Pu/U mixed product solution with given Pu/U ratio for improving of nuclear proliferation resistance. In addition, Np is also recovered with U and Pu because Np is one of minor actinides and a long-lived radionuclide and Np has the extractability into TBP solvent. Development of its flowsheet achieves to decrease environmental effect of waste materials. The orientation of development about Co-processing process is to demonstrate of reprocessing the future spent fuels from a LWR, a LWR-MOX hybrid, and a FR-MOX with one cycle. We demonstrated by use of miniature reflux-type centrifugal contactors at the partitioning unit. The test conditions of the Pu/U ratio in the loaded solvents were 1%, 3%, and 5% considering the composition of spent fuels. We used the HAN as the reductant of Np (VI) for back extraction. The results of these tests were very good. We got the prospect of U, Pu, and Np Co-processing flowsheet.
Shibano, Junichi*; Shobu, Takahisa; Suzuki, Kenji*; Hirata, Tomoyuki*; Kaneko, Hiroshi; Kobayashi, Michiaki*
Zairyo, 56(10), p.985 - 992, 2007/10
This paper presents a basic research on a measurement of strain in the bulk of materials by using high energy white X-rays from a synchrotron radiation source of SPring-8. WEL-TEN780E (JIS G3128 SHY685) whose grain size was 0.013 mm was used as a specimen. The specimen was loaded with four point bending. The white X-ray beam, which has a height of 0.05 mm and width of 0.03 mm, was incident in it. Bending strain at the surface of specimen was measured by a strain gauge. The internal strain of SHY685 of 5 mm thickness could be evaluated using white X-rays which range of energy from 60 keV to 150 keV. Furthermore, the measurement error of strain could be decreased by using the diffracted X-rays with high energy, high peak count and the profile which is close to Gaussian curve. The results showed that the high energy white X-ray is effective for internal strain measurements.
Shobu, Takahisa; Kaneko, Hiroshi; Mizuki, Junichiro; Konishi, Hiroyuki; Shibano, Junichi*; Hirata, Tomoyuki*; Suzuki, Kenji*
AIP Conference Proceedings 879, p.1581 - 1585, 2007/01
The third generation synchrotron X-ray source such as SPring-8 provides us intense beams of high energy X-rays. The techniques of non-destructive internal residual stress measurement for industrial applications are well established by angle dispersive diffractometry with high energy synchrotron radiation and provide valuable information. The energy dispersive diffraction techniques using white radiation is the advantage of a stress measurement compared with the angular dispersive one. For example, the multitudes of reflections recorded in one spectrum offers additional information that can be used for stress gradient evaluation. The purpose of present study is to apply high energy white X-rays to the measurement of the residual strain in the bulk specimen. The experiment was carried out on the beamline BL14B1 at SPring-8. A diffraction pattern was collected by a Ge Solid State Detector (SSD) mounted on the arm of a 2-axes diffractometer behind two sets of secondary collimating slits. The beam size of white X-rays was 0.05 0.3 mm. The specimens were JIS-S45C carbon steel and JIS-SUS304 austenitic stainless steel with a thickness of 5mm. The bending stress was applied with the four-point bending and the strain at the surface of the specimen was measured by a strain gauge as shown in the figure. X-rays diffraction measurement was carried out simultaneously. The figure shows each diffraction profile of SUS304 taken with white X-rays. The strain was calculated by the ratio of the energy shift to the peak energy. Though many peaks appeared in every measured positions Y, each diffraction pattern depended on the number and the orientation of crystal grains in irradiated volume by X-rays. The calculated strain by using a single peak is depending on peak quality. The accurate internal stress can be obtained with white X-rays by selecting the peak at high energy, high peak counts and close to Gaussian peak profile.
Obu, Tomoyuki; Morimoto, Kazuyuki; Yoshinari, Toshimi; Kanamori, Sadamu; Omori, Eiichi
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Kiriyama, Koji; Shibano, Junichi*; Hirata, Tomoyuki*; Kajiwara, Kentaro*; Shobu, Takahisa; Suzuki, Kenji*
no journal, ,
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Kawakami, Yoshiyuki; Nagaoka, Shinichi; Kitao, Takahiko; Morimoto, Kazuyuki; Obu, Tomoyuki; Kanamori, Sadamu; Omori, Eiichi
no journal, ,
We are trying to research how acidity and temperature influences Np behavior at extraction process in Tokai Reprocessing Plant. So we varied acidity and warmed up solution within the limit of operating parameter for second extraction cycle, and measured Np extracted.
Nagaoka, Shinichi; Morimoto, Kazuyuki; Kitao, Takahiko; Obu, Tomoyuki; Kanamori, Sadamu; Omori, Eiichi
no journal, ,
4050% of neptunium (Np) was distributed to product stream in Tokai Reprocessing Plant (TRP) at present. We tried to increase acidity of second extraction cycle within available operating parameter, and by measuring neptunium concentration at outlet stage in second extraction cycle, we verified that 6070% of neptunium was distributed to product stream. Also we warmed up solutions in contactors of second extraction cycle within available operating parameter to make sure oxidation of neptunium on actual process, and we verified that 70% of neptunium was distributed to product stream. We confirmed that increasing acidity and warming up solutions was effective for Pu-U-Np co-extraction on the engineering scale reprocessing facility.
Kiriyama, Koji; Shobu, Takahisa; Shibano, Junichi*; Fujishiro, Tomoyuki; Kaneko, Hiroshi; Miura, Setsuo*
no journal, ,
Yanagibashi, Futoshi; Nishida, Naoki; Suwa, Toshio; Fujimoto, Ikuo; Obu, Tomoyuki; Kashimura, Takao
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Yamamoto, Kohei; Kaji, Naoya; Morimoto, Kazuyuki; Obu, Tomoyuki; Sano, Yuichi; Kashimura, Takao
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Fujishiro, Tomoyuki; Shobu, Takahisa; Terasawa, Michitaka*; Yamamoto, Atsushi*; Kiriyama, Koji*; Nakahigashi, Shigeo*; Hasegawa, Tadayuki*
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Shobu, Takahisa; Akita, Koichi; Shiro, Ayumi; Fujishiro, Tomoyuki*; Kiriyama, Koji*; Kumagai, Masayoshi*; Hisamori, Noriyuki*
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Namatame, Toshihiro; Sato, Takehiko; Morimoto, Kazuyuki; Obu, Tomoyuki; Kashimura, Takao; Omori, Eiichi
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Fujimoto, Ikuo; Yanagibashi, Futoshi; Akiyama, Hideki; Morimoto, Kazuyuki; Obu, Tomoyuki; Taki, Kiyotaka
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Fujimoto, Ikuo; Yanagibashi, Futoshi; Yamamoto, Kohei; Sato, Takehiko; Obu, Tomoyuki; Taki, Kiyotaka
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Yamamoto, Kohei; Yanagibashi, Futoshi; Fujimoto, Ikuo; Sato, Takehiko; Obu, Tomoyuki; Taki, Kiyotaka; Hayashi, Shinichiro
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no abstracts in English