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Journal Articles

Double diffusive dissolution model of UO $_{2}$ 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

Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)

JAEA Reports

Improvement of intragranular fission gas behavior model for fuel performance code FEMAXI-8

Udagawa, Yutaka; Tasaki, Yudai

JAEA-Data/Code 2021-007, 56 Pages, 2021/07

JAEA-Data-Code-2021-007.pdf:5.05MB

Japan Atomic Energy Agency (JAEA) has released FEMAXI-8 in 2019 as the latest version of the fuel performance code FEMAXI, which has been developed to analyze thermal and mechanical behaviors of a single fuel rod in mainly normal operation conditions and anticipated transient conditions. This report summarizes a newly developed model to analyze intragranular fission gas behaviors considering size distribution of gas bubbles and their dynamics. While the intragranular fission gas behavior models implemented in the previous FEMAXI versions have supported only treating single bubble size for a given fuel element, the new model supports multiple gas groups according to their size and treats their dynamic behaviors, making the code more versatile. The model was first implemented as a general module that takes arbitrary number of bubble groups and spatial mesh division for a given fuel grain system. An interface module to connect the model to FEMAXI-8 was then developed so that it works as a 2 bubble groups model, which is the minimum configuration of the multi-grouped model to be operated with FEMAXI-8 at the minimum calculation cost. FEMAXI-8 with the new intragranular model was subjected to a systematic validation calculation against 144 irradiation test cases and recommended values for model parameters were determined so that the code makes reasonable predictions in terms of fuel center temperature, fission gas release, etc. under steady-state and power ramp conditions.

Journal Articles

Chemical state and isotope ratio analysis of individual uranium particles by a combination of micro-Raman spectroscopy and secondary ion mass spectrometry

Yomogida, Takumi; Esaka, Fumitaka; Magara, Masaaki

Analytical Methods, 9(44), p.6261 - 6266, 2017/11

https://doi.org/10.1039/C7AY01815K

Times Cited Count：8 Percentile：56.94(Chemistry, Analytical)

A combination of micro-sampling, micro-Raman spectroscopy (MRS), and secondary ion mass spectrometry (SIMS) was applied to the characterization of individual uranium particles. Reference particles with U $_{3}$ O $_{8}$ (NBL CRM U010) and UO $_{2}$ were identified by scanning electron microscopy combined with energy dispersive X-ray detection (SEM-EDX) and transferred onto grassy carbon substrates by micro-sampling. The crystalline phases of the reference particles with diameters ranging from 1 m to 5 m were determined non-destructively by using MRS thanks to the optimization of laser power at the measurement. Isotope ratios were also determined with SIMS after the MRS analysis and were consistent with values in the literature. These results indicate that chemical forms and isotope ratios of individual uranium particles as small as 1 m can be analyzed efficiently by using the proposed method.

Journal Articles

Defect chemistry and basic properties of non-stoichiometric PuO $_{2}$

Kato, Masato; Nakamura, Hiroki; Watanabe, Masashi; Matsumoto, Taku; Machida, Masahiko

Defect and Diffusion Forum, 375, p.57 - 70, 2017/05

http://doi.org/10.4028/www.scientific.net/DDF.375.57

The basic properties of PuO $_{2-x}$ were reviewed, and the equilibrium defects in PuO $_{2-x}$ were evaluated from the experimental data of the oxygen potential and electrical conductivity as well as the Ab-initio calculation results. Consistency among various properties was confirmed, and the mechanistic models for thermal property representations were derived.

Journal Articles

Chlorination of UO $_{2}$ , PuO $_{2}$ and rare earth oxides using ZrCl $_{4}$ in LiCl-KCl eutectic melt

Sakamura, Yoshiharu*; Inoue, Tadashi*; Iwai, Takashi; Moriyama, Hirotake*

Journal of Nuclear Materials, 340(1), p.39 - 51, 2005/04

https://doi.org/10.1016/j.jnucmat.2004.11.002

Times Cited Count：36 Percentile：90.36(Materials Science, Multidisciplinary)

A new chlorination method using ZrCl $_{4}$ in a molten salt has been investigated for the pyrometallurgical reprocessing of spent oxide fuels. UO $_{2}$ , PuO $_{2}$ and rare earth oxides(La $_{2}$ O $_{3}$ , CeO $_{2}$ , Nd $_{2}$ O $_{3}$ and Y $_{2}$ O $_{3}$ ) were allowed to react with ZrCl $_{4}$ in a LiCl-KCl eutectic salt at 500 $^{circ}$ C to give a metal chloride solution and a precipitate of ZrO $_{2}$ . By keeping the system quite still, the solution settled so that the ZrO $_{2}$ precipitate could be separated.

Journal Articles

Application of neutron imaging plate and neutron CT methods on nuclear fuels and materials

Yasuda, Ryo; Matsubayashi, Masahito; Nakata, Masahito; Harada, Katsuya; Amano, Hidetoshi; Sasajima, Fumio; Nishi, Masahiro; Horiguchi, Yoji

IEEE Transactions on Nuclear Science, 52(1), p.313 - 316, 2005/02

https://doi.org/10.1109/TNS.2005.844297

Times Cited Count：14 Percentile：68.11(Engineering, Electrical & Electronic)

Neutron radiography is useful to inspect macroscopic change in nuclear fuels before and after irradiation. We have been investigated the practicality of neutron imaging plate and neutron CT methods for the inspection of the spent fuels. A fresh UO2 fuel rod was examined by those methods. The test results of those samples are available to develop the system of those methods for the spent fuels and to determine the specifications of the system. Some good images of those samples are obtained by those examinations. The shape of the pellets in the fuel rod is clearly recognized in the image. Those images are analyzed to estimate the size of some parts in the fuel pellets.

JAEA Reports

Study on the prediction accuracy of nuclide generation and depletion with JENDL

Okumura, Keisuke; Oki, Shigeo*; Yamamoto, Munenari*; Matsumoto, Hideki*; Ando, Yoshihira*; Tsujimoto, Kazufumi; Sasahara, Akihiro*; Katakura, Junichi; Matsumura, Tetsuo*; Aoyama, Takafumi*; et al.

JAERI-Research 2004-025, 154 Pages, 2005/01

JAERI-Research-2004-025.pdf:19.46MB

This report summarizes the activity (FY2000-2003) of Working Group (WG) on Evaluation of Nuclide Generation and Depletion under Subcommittee on Nuclear Fuel Cycle of Japanese Nuclear Data Committee. In the WG, analyses of Post Irradiation Examinations have been carried out for UO $_{2}$ and MOX fuels irradiated in PWRs, BWRs and FBRs, and for actinide samples irradiated in fast reactors, by using ORIGEN or more detailed calculation codes with their libraries based on JENDL-3.2, JENDL-3.3 and other foreign nuclear data files. From these results, current prediction accuracy and problems for evaluation of nuclide generation and depletion are discussed. Furthermore, this report covers other products of our activity; development of the ORIGEN libraries for PWR, BWR and FBR based on JENDL-3.3, study on introduction of neutron spectrum index to ORIGEN calculations, and results of questionnaire survey on desirable accuracy of ORIGEN calculations.

JAEA Reports

Development of once-through type densitometer

Onozawa, Atsushi; Kushida, Teruo; Kanazawa, Hiroyuki

JAERI-Tech 2004-061, 39 Pages, 2004/11

JAERI-Tech-2004-061.pdf:8.64MB

The swelling observed on irradiated fuels is caused by the accumulation of fission products and irradiation defects. The swelling ratio is changed along with radius region in the pellet due to burn up difference caused by that of neutron flux. To investigate the swelling behavior at the small area of the pellet, it is needed to measure the density of fuel fragments picked from an irradiated pellet. In this circumstance, once-through type densitometer was developed to measure the density of the small irradiated specimen precisely and to handle the samples easily with remote control systems. Several kinds of metallic and ceramic standard specimens are prepared to investigate the dependence of the sample weight, density and porosity on the accuracy. The results of characteristic examination using these specimens indicate that this densitometer has enough accuracy. In addition, some parts of this apparatus are controlled by motor drive units, which made it possible to measure the density full-automatically.

Journal Articles

Magnetism of uranium dioxide UO $_{2}$ under high pressure

Sakai, Hironori; Kato, Harukazu; Tokunaga, Yo; Kambe, Shinsaku; Walstedt, R. E.; Nakamura, Akio; Tateiwa, Naoyuki*; Kobayashi, Tatsuo*

Journal of Magnetism and Magnetic Materials, 272-276(Suppl.), p.e413 - e414, 2004/05

https://doi.org/10.1016/j.jmmm.2003.11.307

Times Cited Count：2 Percentile：13.84(Materials Science, Multidisciplinary)

The d.c. magnetization of insulating UO $_{2}$ under high pressure up to about 1 GPa has been measured using a piston-cylinder cell. Pressure-induced weak ferromagnetism was found to appear at low pressure (about 0.2 GPa). Both the remanent magnetization and the coercive force increase as pressure increases. This weak ferromagnetism may come from spin canting or from uncompensated moments around grain boundaries.

JAEA Reports

Influence of plutonium contents in MOX fuel on destructive forces at fuel failure in the NSRR experiment

Nakamura, Jinichi; Sugiyama, Tomoyuki; Nakamura, Takehiko; Kanazawa, Toru; Sasajima, Hideo

JAERI-Tech 2003-008, 32 Pages, 2003/03

JAERI-Tech-2003-008.pdf:1.49MB

no abstracts in English

Journal Articles

Weak ferromagnetism induced in UO $_{2}$ -MO $_{x}$ heterogeneous multi-phase systems (M=Ti, Nb, Si, V, etc.)

Nakamura, Akio; Yoshii, Kenji

Journal of Nuclear Science and Technology, 39(Suppl.3), p.160 - 163, 2002/11

http://www.tandfonline.com/doi/abs/10.1080/00223131.2002.10875433

no abstracts in English

Journal Articles

Studies in the PuO $_{2}$ -ZrO $_{2}$ pseudo-binary phase diagram

Albiol, T.*; Serizawa, Hiroyuki; Arai, Yasuo

Journal of Nuclear Science and Technology, 39(Suppl.3), p.834 - 837, 2002/11

http://www.tandfonline.com/doi/abs/10.1080/00223131.2002.10875598

no abstracts in English

Journal Articles

Decrease of cesium release from irradiated UO $_{2}$ fuel in helium atmosphere under elevated pressure of 1.0MPa at temperature up to 2,773K

Hidaka, Akihide; Kudo, Tamotsu; Nakamura, Takehiko; Uetsuka, Hiroshi

Journal of Nuclear Science and Technology, 39(7), p.759 - 770, 2002/07

https://doi.org/10.3327/jnst.39.759

Times Cited Count：6 Percentile：39.76(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Development of advanced neutron radiography for inspection on irradiated fuels and materials, 3; Examination of neutron imaging plate and computed tomography methods on unirradiated fuel rod

Yasuda, Ryo; Matsubayashi, Masahito; Nakata, Masahito; Harada, Katsuya; Amano, Hidetoshi; Ando, Hitoshi*; Sasajima, Fumio; Nishi, Masahiro; Horiguchi, Yoji

JAERI-Tech 2002-001, 23 Pages, 2002/02

JAERI-Tech-2002-001.pdf:3.79MB

Advanced neutron radiography techniques such as neutron imaging plate (NIP) and Computed Tomography (CT) methods have been investigated the practicality for Post Irradiation Examination (PIE). In this work, an unirradiated fuel rod was examined by NIP and CT methods in order to collect the fundamental data for applying these techniques to PIE.The fuel rod is composed of seven-enriched UO2 pellet and two-natural UO2 pellet that are loaded into a Zircaloy tube. There are somewhat difference in the size and shape among those UO2 pellets. A transmitted and cross-sectional images were obtained by NIP and CT methods, respectively.In the NIP image, the difference in the size, shape, and enrichment among the UO2 pellets is obviously recognized. In the case of CT method, the images clearly show the detailed shape of the cross section in the pellets, in addition, the difference in the enrichment between the natural and enriched pellets is recognized.

JAEA Reports

Behavior of radionuclide release from irradiated fuel under severe accident conditions; Results of VEGA-1 test

Hidaka, Akihide; Nakamura, Takehiko; Kudo, Tamotsu; Uetsuka, Hiroshi

JAERI-Research 2001-055, 48 Pages, 2001/12

JAERI-Research-2001-055.pdf:3.9MB

no abstracts in English

Journal Articles

Re-evaluation of the effective delayed neutron fraction measured by the substitution technique for a light water moderated low-enriched uranium core

Nakajima, Ken

Journal of Nuclear Science and Technology, 38(12), p.1120 - 1125, 2001/12

https://doi.org/10.3327/jnst.38.1120

no abstracts in English

Journal Articles

Thermodynamics of the UO $_{2}$ solid solution with magnesium and europium oxides

Fujino, Takeo*; Sato, Nobuaki*; Yamada, Kota*; Nakama, Shohei*; Fukuda, Kosaku; Serizawa, Hiroyuki; Shiratori, Tetsuo*

Journal of Nuclear Materials, 297(3), p.332 - 340, 2001/09

https://doi.org/10.1016/S0022-3115(01)00627-4

Times Cited Count：4 Percentile：33.54(Materials Science, Multidisciplinary)

Oxygen potential of solid solution Mg $_{y}$ Eu $_{z}$ U $_{1-y-z}$ O $_{2+x}$ was examined as a function of O/Metal ratio at 1000, 1100 and 1200 $^{circ}$ C. The O/Metal ratio which gave the steepest change of the oxygen potential(GOM) was 1.995 for y=0.05, z=0.1 and y=0.05, z=0.05. The position decreased to 1.908 at higher Mg $^{2+}$ concentration of y=0.1, z=0.05. The GOM did not change with temperature in a range 1000-1200 $^{circ}$ C. At GOM, a friction of 0.473 of total Mg $^{2+}$ occupy the interstitial position of the fluorite lattice.