Development of "MOX weighing and Ball-mill blending" based on experience in operation and maintenance of MOX fuel manufacturing equipment

Kawasaki, Kohei; Ono, Takanori; Shibanuma, Kimikazu; Goto, Kenta; Aita, Takahiro; Okamoto, Naritoshi; Shinada, Kenta; Ichige, Hidekazu; Takase, Tatsuya; Osaka, Yuki; et al.

JAEA-Technology 2022-031, 91 Pages, 2023/02

JAEA-Technology-2022-031.pdf:6.57MB

The document for back-end policy opened to the public in 2018 by Japan Atomic Energy Agency (hereafter, JAEA) states the decommissioning of facilities of Nuclear Fuel Cycle Engineering Laboratories and JAEA have started gathering up nuclear fuel material of the facilities into Plutonium Fuel Production Facilities (hereafter, PFPF) in order to put it long-term, stable and safe storage. Because we planned to manufacture scrap assemblies almost same with Monju fuel assembly using unsealed plutonium-uranium mixed-oxide (hereafter, MOX) powder held in PFPF and transfer them to storage facilities as part of this "concentration" task of nuclear fuel material, we obtained permission to change the use of nuclear fuel material in response to the new regulatory Requirements in Japan for that. The amount of plutonium (which is neither sintered pellets nor in a lidded powder-transport container) that could be handled in the pellet-manufacturing process was limited to 50 kg Pu or less in order to decrease the facility risk in this manufacture. Therefore, we developed and installed the "MOX weighing and blending equipment" corresponding with small batch sizes that functioned in a starting process and the equipment would decrease handling amounts of plutonium on its downstream processes. The failure data based on our operation and maintenance experiences of MOX fuel production facilities was reflected in the design of the equipment to further improve reliability and maintainability in this development. The completed equipment started its operation using MOX powder in February 2022 and the design has been validated through this half-a-year operation. This report organizes the knowledge obtained through the development of the equipment, the evaluation of the design based on the half-a-year operation results and the issues in future equipment development.

Crystal structure of nesquehonite, MgCO 3H(D)O by neutron diffraction and effect of pH on structural formulas of nesquehonite

Yamamoto, Genichiro*; Kyono, Atsushi*; Abe, Jun*; Sano, Asami; Hattori, Takanori

Journal of Mineralogical and Petrological Sciences, 116(2), p.96 - 103, 2021/04

https://doi.org/10.2465/jmps.200117

Neutron diffraction, Raman spectroscopy, and thermal analysis were performed to investigate the composition, structure, and formation conditions of the magnesium carbonate hydrate nesquehonite. The time-of-flight neutron diffraction revealed the crystal structure of the monoclinic space group 2 with lattice parameters of =7.72100(12)=5.37518(7)=12.1430(3)=90.165(4), in which two deuterium atoms are coordinated to the O1, O2, and O6 atoms to form water molecules. The three water molecules in the structure suggests the structural formula of the nesquehonite should be MgCO 3HO rather than Mg(HCO)(OH) 2HO.

Crystal structure change of katoite, CaAl(OD), with temperature at high pressure

Kyono, Atsushi*; Kato, Masato*; Sano, Asami; Machida, Shinichi*; Hattori, Takanori

Physics and Chemistry of Minerals, 46(5), p.459 - 469, 2019/05

https://doi.org/10.1007/s00269-018-1016-4

To reveal the decomposition mechanism with temperature under high-pressure, crystal structure of a hydrogrossular, katoite CaAl(OD) has been studied by in-situ neutron diffraction at 8 GPa. Although unusual expansion behavior was discerned at 200-400C, the unit cell was continuously expanded up to 850C. At 900C, katoite was decomposed, indicating that pressure strongly increases dehydration temperature from 300C to 900C. On release of pressure, the katoite reappear together with corundum and portlandite. At 8 GPa, CaO and AlO polyhedra expand with temperature up to 850C by about 8% and 13%, respectively. On the other hand, tetrahedral interstices are isotopically squeezed by about 10%: due to the expansion of above polyhedra. The neighboring D-D distance remains almost unchanged in this temperature range, while the O-D bond distance shrinks drastically just before decomposition. This finding suggests that the shortening of O-D distance caused by the D-D repulsion destabilizes the O-D bond, which induces the thermal decomposition of katoite.

Verification of alternative dew point hygrometer for CV-LRT in MONJU; Short- and long-term verification for capacitance-type dew point hygrometer (Translated document)

Ichikawa, Shoichi; Chiba, Yusuke; Ono, Fumiyasu; Hatori, Masakazu; Kobayashi, Takanori; Uekura, Ryoichi; Hashiri, Nobuo*; Inuzuka, Taisuke*; Kitano, Hiroshi*; Abe, Hisashi*

JAEA-Research 2017-001, 40 Pages, 2017/03

JAEA-Research-2017-001.pdf:5.19MB

In order to reduce the influence on a plant schedule of the MONJU by the maintenance of dew point hygrometers, The JAEA examined a capacitance type dew point hygrometer as an alternative dew point hygrometer for a lithium-chloride type dew point hygrometer which had been used at the CV-LRT in the MONJU. As a result of comparing a capacitance type dew point hygrometer with a lithium-chloride type dew point hygrometer at the CV-LRT (Atmosphere: nitrogen, Testing time: 24 hours), there weren't significant difference between a capacitance type dew point hygrometer and a lithium-chloride type dew point hygrometer. As a result of comparing a capacitance dew point hygrometer with a high-mirror-surface type dew point hygrometer for long term verification (Atmosphere: air, Testing time: 24 months), the JAEA confirmed that a capacitance type dew point hygrometer satisfied the instrument specification (2.04C) required by the JEAC4203-2008.

Present state of TEM-SXES analysis and its application to SEM aiming chemical analysis of bulk materials

Terauchi, Masami*; Takahashi, Hideyuki*; Handa, Nobuo*; Murano, Takanori*; Koike, Masato; Imazono, Takashi; Koeda, Masaru*; Nagano, Tetsuya*; Sasai, Hiroyuki*; Oue, Yuki*; et al.

Microscopy and Microanalysis, 20(Suppl.3), p.682 - 683, 2014/08

https://doi.org/10.1017/S1431927614005133

X-rays originate form electronic transitions from valence bands (VB, bonding electron states) to inner-shell electron levels inform us energy states of bonding electrons. We have developed the SXES spectrometers attaching to TEM, EPMA, and SEM. A spectrometer has an energy range of 50-4000 eV by using four varied-line-spacing gratings. Applications of TEM-SXES instrument to C have revealed characteristic energy distribution of bonding electrons. Carbon K-emission spectra of C crystals showed that both the peak structures in - and -bands and the characteristic dip structure between the - and -bonding states in monomer-C disappear in the most polymerized-C crystals. Bulk specimens were examined by applying SXES to a SEM. Al L-emission spectra of intermetallic compounds of AlAu, AlCo, and aluminum showed different intensity distributions due to different band structures originating from different crystal structures.

Chemical state information of bulk specimens obtained by SEM-based soft-X-ray emission spectrometry

Terauchi, Masami*; Koshiya, Shogo*; Sato, Futami*; Takahashi, Hideyuki*; Handa, Nobuo*; Murano, Takanori*; Koike, Masato; Imazono, Takashi; Koeda, Masaru*; Nagano, Tetsuya*; et al.

Microscopy and Microanalysis, 20(3), p.692 - 697, 2014/06

https://doi.org/10.1017/S1431927614000439

Electron beam induced soft-X-ray emission spectroscopy (SXES) by using a grating spectrometer has been introduced to a conventional scanning electron microscope (SEM) for characterizing desired specimen areas of bulk materials. The spectrometer was designed as a grazing-incidence flat-field optics by using aberration corrected (varied-line-spacing) gratings and a multi-channel-plate detector combined with a charge-coupled-device camera, which has already applied for a transmission electron microscope. The best resolution was confirmed as 0.13 eV at Mg L-emission (50 eV), which value is comparable to that of recent dedicated electron energy-loss spectroscopy instruments. This SXES-SEM instrument presents density of states of simple metals of bulk Mg and Li. Apparent band structure effects have been observed in Si L-emission of Si-wafer, P L-emission of GaP-wafer, and Al L-emissions of intermetallic compounds of AlCo, AlPd, AlPt, and AlAu.

Development and applications of a new soft X-ray emission spectrometer for electron probe microanalysis and/or nanoanalysis

Takahashi, Hideyuki*; Handa, Nobuo*; Murano, Takanori*; Koike, Masato; Kawachi, Tetsuya; Imazono, Takashi; Hasegawa, Noboru; Terauchi, Masami*; Koeda, Masaru*; Nagano, Tetsuya*; et al.

JAEA-Conf 2013-001, p.13 - 15, 2013/09

https://doi.org/10.11484/jaea-conf-2013-001

A very unique high performance soft X-ray emission spectrometer (SXES) has successfully been developed which can be attached not only to transmission electron microscopes (TEMs), but also to scanning electron microscopes (SEMs) as well as electron probe microanalyzers (EPMAs). To extend the analyzed energy ranges, a newly designed laminar-type varied-line-spacing (VLS) grating JS50XL, for a lower energy range, 50-170 eV, and a multilayered VLS grating JS4000, for a higher energy range, 2000-4000 eV, have been developed and installed to this spectrometer. Application software has also been developed for a commercial use of SXES in several fields such as battery materials, steel and alloys, and electron devices. The appearance of this spectrometer attached to EPMA and a few results acquired are shown in the following figures. This development has been conducted as one of the projects of Collaborative Development of Innovative Seeds (Practicability verification stage) by Japan Science and Technology Agency.

Chemical State Mapping via soft X-rays using a Wavelength Dispersive Soft X-ray Emission Spectrometer with High Energy Resolution

Takahashi, Hideyuki*; Handa, Nobuo*; Murano, Takanori*; Terauchi, Masami*; Koike, Masato; Kawachi, Tetsuya; Imazono, Takashi; Hasegawa, Noboru; Koeda, Masaru*; Nagano, Tetsuya*; et al.

Microscopy and Microanalysis, 19(Suppl.2), p.1258 - 1259, 2013/08

https://doi.org/10.1017/S1431927613008283

A new wavelength dispersive soft X-ray emission spectrometer (WD-SXES) consisting of newly developed diffraction gratings has been developed for soft X-ray emission spectroscopy. The WD-SXES with two types of diffraction gratings nominally covering an energy range between 50 and 210 eV has been installed to electron probe X-ray microanalyzers, JEOL JXA-8100, for commercial use. The energy resolution of this WD-SXES is nominally 0.3 eV, which is one order of magnitude better than that of conventional WDSs with layered dispersion elements. It is to be noted that the corresponding edge of AlB is shifted to higher energy side by about 1 eV. One of the energy range was selected from 72 to 73.5 eV whereas the other was from 73.5 to 75 eV. The contrast in the former map is reversed in the later map as expected even though the energy difference between two maps is only 1.5 eV. The study confirms the high potential for the characterization especially for chemical state mapping.

A New grating X-ray spectrometer for 2-4 keV enabling a separate observation of In-L and Sn-L emissions of indium tin oxide

Terauchi, Masami*; Takahashi, Hideyuki*; Handa, Nobuo*; Murano, Takanori*; Koike, Masato; Kawachi, Tetsuya; Imazono, Takashi; Hasegawa, Noboru; Koeda, Masaru*; Nagano, Tetsuya*; et al.

Microscopy, 62(3), p.391 - 395, 2013/06

https://doi.org/10.1093/jmicro/dfs129

A new multilayer-coated varied line-spaced grating, JS4000, was fabricated and tested for extending the upper limit of a grating X-ray spectrometer for electron microscopy. This grating was designed for 2-3.8 keV at a grazing incidence angle of 1.35 deg. It was revealed that this new multilayer structure enables us to take soft-X-ray emission spectra continuously from 1.5 keV to 4 keV at the same optical setting. The full-width at half maximum of Te-L (3.8 keV) emission peak was 27 eV. Sn-L (3444 eV) and In-L (3487 eV) peaks, which cannot be resolved by a widely used energy-dispersive X-ray spectrometer.

Operating and maintenance experiences of rebottling equipment for plutonium dioxide powder received from foreign country

Ono, Takanori; Hatanaka, Nobuhiro; Okita, Takatoshi; Aono, Shigenori

JAEA-Technology 2012-042, 96 Pages, 2013/02

JAEA-Technology-2012-042.pdf:2.6MB

In January of 1993, plutonium dioxide powder was received from the reprocessing plant "La Hague" of COGEMA in France to Plutonium Fuel Production Facility (PFPF) of JAEA to use as feed powder of MOX fuel for FBR prototype "Monju". Since the plutonium dioxide powder was contained in COGEMA type canisters, the powder had to be rebottled from CCGEMA type canisters to JAEA type canisters which can be handled in the PFPF. Therefore feed powder rebottling equipment and temporary feed storage equipment were developed and installed in the PFPF. Rebottling work with their equipments was started from March of 1993 and completed in March of 2006. This report summarizes operating and maintenance experiences on feed powder rebottling equipment and temporary feed storage equipment. It's important to reflect the operating and maintenance experiences of the rebottling equipment into design of a new rebottling equipment for uranium-plutonium mixed oxide powder.