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Journal Articles

Study on chemical interaction between UO $_{2}$ and Zr at precisely controlled high temperatures

Shirasu, Noriko; Sato, Takumi; Suzuki, Akihiro*; Nagae, Yuji; Kurata, Masaki

Journal of Nuclear Science and Technology, 60(6), p.697 - 714, 2023/06

https://doi.org/10.1080/00223131.2022.2138602

Times Cited Count：1 Percentile：68.31(Nuclear Science & Technology)

Interaction tests between UO $_{2}$ and Zr were performed at precisely controlled high temperatures between 1840 and 2000 $^{circ}$ C to understand the interaction mechanism in detail. A Zr rod was inserted in a UO $_{2}$ crucible and then heat-treated at a fixed temperature in Ar-gas flow for 10 min. After heating in the range of 1890 to 1930 $^{circ}$ C, the Zr rod was deformed to a round shape, in which the post-analysis detected the significant diffusion of U into the Zr region and the formation of a dominant -Zr(O) matrix and a small amount of U-Zr-O precipitates. The abrupt progress of liquefaction was observed in the sample heated at around 1940 $^{circ}$ C or higher. The higher oxygen concentration in the -Zr(O) matrix suppressed the liquefaction progress, due to the variation in the equilibrium state. The U-Zr-O melt formation progressed by the selective dissolution of Zr from the matrix, and the selective diffusion of U could occur via the U-Zr-O melt.

Journal Articles

High-temperature interaction between zirconium and UO

Shirasu, Noriko; Suzuki, Akihiro*; Nagae, Yuji; Kurata, Masaki

Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR 2019) (Internet), 4 Pages, 2019/05

High temperature interaction tests between UO $_{2}$ and Zr were performed at around 2173 K, to make clear the UO $_{2}$ / -Zr(O) interaction and the mechanism of degradation, for developing the improved models for advanced severe accident analysis codes. A Zr plate was inserted in a UO $_{2}$ crucible, and heat treated at 2173 K in stream of Ar. After the heat-treatment, the samples were subjected to surface microanalysis. The middle region of Zr sample shows streak-like structures which are extended towered the top. It is confirmed that the streak-like structures were mainly consist of U from the EDX results, and the structures revealed that the U-rich phase was liquid during the heat-treatment. It seems that the U-rich liquid grew selectively toward the area where the oxygen concentration was low.

Journal Articles

Phenomenology of BWR fuel assembly degradation

Kurata, Masaki; Barrachin, M.*; Haste, T.*; Steinbrueck, M.*

Journal of Nuclear Materials, 500, p.119 - 140, 2018/03

https://doi.org/10.1016/j.jnucmat.2017.12.004

Times Cited Count：29 Percentile：66.35(Materials Science, Multidisciplinary)

Severe accidents occurred at the Fukushima-Daiichi Nuclear Power Station (FDNPS) required an immediate re-examination of fuel degradation phenomenology. The present paper reviews the updated knowledge on the phenomenology of the fuel degradation, focusing mainly on the BWR fuel assembly degradation at the macroscopic scale and that of the individual interactions at the meso-scale. Oxidation of boron carbide (B $_{4}$ C) control rods potentially generate far larger amounts of heat and hydrogen under BWR accident conditions. All integral tests with B $_{4}$ C control rods or control blades have shown early failure, liquefaction, relocation and oxidation of B $_{4}$ C starting at temperatures around 1250 $^{circ}$ C, well below the significant interaction temperatures of UO $_{2}$ -Zry. These interactions or reactions potentially influence the progress of fuel degradation in the early phase. The steam-starved conditions, which are being discussed as a likely scenario at the FDNPS accident, highly influence the individual interactions and potentially lead the fuel degradation in non-prototypical directions. The detailed phenomenology of individual interactions and their influence on the transient and on the late phase of the severe accidents are also discussed.

Journal Articles

Phase equilibria in the Be-V and Be-Ti binary systems

Onuma, Ikuo*; Kainuma, Ryosuke*; Uda, Minoru*; Iwadachi, Takaharu*; Uchida, Munenori*; Kawamura, Hiroshi; Ishida, Kiyohito*

JAERI-Conf 2004-006, p.172 - 183, 2004/03

https://jopss.jaea.go.jp/pdfdata/JAERI-Conf-2004-006.pdf

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

JAEA Reports

Estimation of thermochemical behavior of spallation products in mercury target

Kobayashi, Kaoru*; Kaminaga, Masanori; Haga, Katsuhiro; Kinoshita, Hidetaka; Aso, Tomokazu; Teshigawara, Makoto; Hino, Ryutaro

JAERI-Tech 2002-005, 118 Pages, 2002/02

JAERI-Tech-2002-005.pdf:9.71MB

In order to examine the radiation safety of a spallation mercury target system, it is necessary to clarify the chemical forms of spallation products generated by spallation reaction with proton beam. As for the chemical forms of spallation products in mercury that involves large amounts of spallation products, these forms were estimated by using the binary phase diagrams and the thermochemical equilibrium calculation based on the amounts of spallation product. Calculation results showed that the mercury would dissolve Al, As, B, Be, Bi, C, Co, Cr, Fe, Ga, Ge, Ir, Mo, Nb, Os, Re, Ru, Sb, Si, Ta, Tc, V and W in the element state, and Ag, Au, Ba, Br, Ca, Cd, Ce, Cl, Cs, Cu, Dy, Er, Eu, F, Gd, Hf, Ho, I, In, K, La, Li, Lu, Mg, Mn, Na, Nd, Ni, O, Pb, Pd, Pr, Pt, Rb, Rh, S, Sc, Se, Sm, Sn, Sr, Tb, Te, Ti, Tl, Tm, Y, Yb, Zn and Zr in the form of inorganic mercury compounds.

JAEA Reports

Physical and thermochemical properties for inorganic mercury compounds

Kobayashi, Kaoru*; Kaminaga, Masanori; Haga, Katsuhiro; Kinoshita, Hidetaka; Aso, Tomokazu; Kogawa, Hiroyuki; Hino, Ryutaro

JAERI-Data/Code 2000-037, 69 Pages, 2000/12

JAERI-Data-Code-2000-037.pdf:3.21MB

no abstracts in English

JAEA Reports

Phase diagrams for the binary systems NdCl $_{3}$ -LiCl and PrCl $_{3}$ -LiCl

I.Kim*; Okamoto, Yoshihiro

JAERI-Research 99-033, 15 Pages, 1999/04

JAERI-Research-99-033.pdf:0.69MB

no abstracts in English

JAEA Reports

Design and installation of high-temperature X-ray diffractometer for transuranium elements and its performance test (Joint research)

Arai, Yasuo; Nakajima, Kunihisa; Serizawa, Hiroyuki; ; Suzuki, Yasufumi; Inoue, Tadashi*

JAERI-Tech 98-022, 21 Pages, 1998/06

JAERI-Tech-98-022.pdf:1.07MB

no abstracts in English

JAEA Reports

Pseudo-ternary phase diagram in the Na $_{2}$ O-Na $_{2}$ O $_{2}$ -NaOH system

Saito, Junichi; Aoto, Kazumi; *

PNC TN9410 97-101, 36 Pages, 1997/10

PNC-TN9410-97-101.pdf:0.83MB

Generally, the phase diagrams are always used to understand the present state of compounds at certain temperature. In order to understand the corrosion behavior of structural material for FBR by main sodium compounds (Na $_{2}$ O, Na $_{2}$ O $_{2}$ and NaOH), it is very important to comprehend the phase diagrams of their compounds. However, only Na $_{2}$ O-NaOH pseudo-binary phase diagram had been investigated previously in this system. There is no study of other pseudo-binary or ternary phase diagrams in the Na $_{2}$ O-Na $_{2}$ O $_{2}$ -NaOH system. In this study, in order to clarify the present states of their compounds at certain temperatures, the pseudo-binary and ternary phase diagrams in the Na $_{2}$ O-Na $_{2}$ O $_{2}$ -NaOH system were prepared. A series of thermal analyses with binary and ternary component system has been carried out using the differential scanning calorimetry (DSC). The liquidus temperature and ternary eutectic temperatures were confirmed by these measurements. The beneficial indications for constructing phase diagrams were obtained from these experiments. On the basis of these results, the interaction parameters between compounds which were utilized for the Thermo-Calc calculation were optimized. Thermo-Calc is one of thermodynamic calculation software. Consequently the accurate pseudo-binary and ternary phase diagrams were indicated using the optimized parameters.

Journal Articles