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Journal Articles

Deposition behavior of cesium molybdate on Type304 austenite stainless steel in severe accident

Do, Thi-Mai-Dung*; Sujatanond, S.*; Ogawa, Toru

Nuclear Science and Engineering, 196(5), p.584 - 599, 2022/05

https://doi.org/10.1080/00295639.2021.2009985

Times Cited Count：1 Percentile：8.48(Nuclear Science & Technology)

The chemical behavior of cesium molybdate (Cs $_{2}$ MoO $_{4}$ ) in light water reactors during severe nuclear accidents remains unexplored. This study demonstrated the deposition behavior of cesium molybdate (Cs $_{2}$ MoO $_{4}$ ) on stainless steel (SUS304) at 1530-530 K under dry (Ar) and humid (Ar + H $_{2}$ O) conditions. Cs $_{2}$ MoO $_{4}$ was partially decomposed on the SUS surface, thereby inducing the oxidation of iron (Fe) and chromium (Cr) under dry condition. Molybdenum metal (Mo) and molybdenum dioxide (MoO $_{2}$ ) were detected on the surface, while Cs coexisted with chromium in the oxide layer at 1500 K. Both Cs $_{2}$ MoO $_{4}$ and Mo metal were identified on the SUS surface at 1230 K. Under the humid condition, the oxidation of the SUS was affected by Cs $_{2}$ MoO $_{4}$ vapor. Molybdenum was detected in the form of spots in the iron oxide layer, while cesium was not detected at above 1500 K. Mo was detected on the surface of SUS oxide at 1230 K. Cs $_{2}$ MoO $_{4}$ was deposited on SUS at 730-530 K under both the dry and humid conditions. The results were discussed in relation with the thermodynamic model of the Cs-Fe-Cr-Mo-O system. Thus, the chemical behavior of Cs $_{2}$ MoO $_{4}$ at the interior of the reactor cooling system was elucidated.

Journal Articles

Behavior of cesium molybdate, Cs $_{2}$ MoO $_{4}$ , in severe accident conditions, 1; Partitioning of Cs and Mo among gaseous species

Do, Thi Mai Dung*; Sujatanond, S.*; Ogawa, Toru

Journal of Nuclear Science and Technology, 55(3), p.348 - 355, 2018/03

https://doi.org/10.1080/00223131.2017.1397560

Times Cited Count：7 Percentile：49.82(Nuclear Science & Technology)

In order to better understand the behavior of cesium in the severe accident of the LWR, the high-temperature chemistry of Cs $_{2}$ MoO $_{4}$ in H $_{2}$ O+H $_{2}$ gas was studied. The pseudo-binary system, Cs $_{2}$ MoO $_{4}$ -MoO $_{3}$ , was thermochemically modeled with Redlich-Kister formulation to form a basis to analyze the high-temperature behavior of Cs $_{2}$ MoO $_{4}$ . The model prediction was compared with the thermogravimetric measurements of Cs $_{2}$ MoO $_{4}$ in dry and humid argon, which revealed that the mass-loss rate was enhanced in the humid atmosphere. Thermochemical model was further applied to predict the partitioning of cesium and molybdenum among gaseous species in the BWR core degradation condition typical of Short-Term Station Blackout.

Journal Articles

Features of Zr-rich corner of the Zr-N-O ternary system by controlled low-pressure oxidation and thermodynamic analysis

Lam, Do Van*; Do, Thi Mai Dung*; Ogawa, Toru

Journal of Nuclear Science and Technology, 54(7), p.784 - 794, 2017/07

https://doi.org/10.1080/00223131.2017.1315974

Times Cited Count：1 Percentile：8.89(Nuclear Science & Technology)

In order to clarify the Zr-rich corner of the Zr-N-O ternary system, a series of nitridation and controlled low-pressure oxidation heatings were made on zirconium metal. Low-partial pressures of oxygen were obtained by using a redox couple of either Mo/MoO $_{2}$ or Cu $_{2}$ O/CuO. The heated samples were characterized by X-ray diffraction (XRD), optical microscopy and electron probe micro analysis (EPMA). Experimental results were coupled with a preliminary thermodynamic analysis with a sublattice formalism to draw a provisional ternary isotherm at 1373 K.

Journal Articles

Hydrogen generation by water radiolysis with immersion of oxidation products of zircaloy-4

Matsumoto, Yoshinobu*; Do, Thi-Mai-Dung*; Inoue, Masao; Nagaishi, Ryuji; Ogawa, Toru

Journal of Nuclear Science and Technology, 52(10), p.1303 - 1307, 2015/10

https://doi.org/10.1080/00223131.2015.1034215

Times Cited Count：4 Percentile：29.40(Nuclear Science & Technology)

Effects of zirconium oxides and oxidation products of zircaloy-4 on water radiolysis were investigated to predict the hydrogen generation from the water-immersed debris after a severe accident of a nuclear power plant. Observed yields of hydrogen in water containing the oxides were measured as a function of their weight fractions. Assuming that energies of Co-60 -ray deposited to water and the oxides brought about the water radiolysis to generate hydrogen independently, the radiolysis showed an additional term of hydrogen generation due to the energy deposition to the oxides. This term seemed to be dependent on the specific surface area or particle size of oxides, but not on the crystal structure of oxides in our experimental results. The oxides in distilled water gave the strong enhancement of term. The enhancement tended to saturate with increasing the weight fraction of oxides and was not apparent in the seawater.

Oral presentation

Comparative study of Cs silicates properties between DFT calculation and experimental data

Miradji, F.; Suzuki, Eriko; Nishioka, Shunichiro; Suzuki, Chikashi; Nakajima, Kunihisa; Oishi, Yuji*; Muta, Hiroaki*; Kurosaki, Ken*; Do, Thi Mai Dung*; Osaka, Masahiko

no journal, ,

Oral presentation

Reaction products in Cs-adsorption on concrete in the 600150 $^{circ}$ C temperature range

Do, Thi-Mai-Dung*; Nhut, V. L.*; Murakami, Kenta*; Suematsu, Hisayuki*; Nakajima, Kunihisa; Nishioka, Shunichiro; Suzuki, Eriko; Miradji, F.; Osaka, Masahiko

no journal, ,

The interaction between Cs $_{2}$ MoO $_{4}$ with concrete within the temperature range of 600150 $^{circ}$ C in Ar gas is studied. It seems that there is no reaction between Cs $_{2}$ MoO $_{4}$ aerosol particles with concrete at these temperatures. However, because of the hygroscopic property, Cs $_{2}$ MoO $_{4}$ aerosol particles change to the liquid phase and quickly diffused inside the concrete bulk.

Oral presentation

Synthesis and characterization of cesium silicate Cs $_{2}$ Si $_{4}$ O $_{9}$

Do, Thi Mai Dung*; Ngarayana, I.*; Nguyen, H. D.*; Murakami, Kenta*; Suematsu, Hisayuki*; Koide, Manabu*; Nakajima, Kunihisa; Suzuki, Eriko; Osaka, Masahiko

no journal, ,

Cs $_{2}$ Si $_{4}$ O $_{9}$ powder was synthesized by wet method using cesium carbonate powder and colloidal silica 40 wt.% suspension in H $_{2}$ O as starting materials. The characteristic of Cs $_{2}$ Si $_{4}$ O $_{9}$ is investigated by using X-ray diffraction, Raman and Thermogravimetry-differential scanning calorimetry. The structure of Cs $_{2}$ Si $_{4}$ O $_{9}$ was analyzed by Transmission Electron Microscope.

Oral presentation

Partitioning of Cs and Mo in steam environment

Do, Thi Mai Dung*; Sujatanond, S.*; Ogawa, Toru

no journal, ,

The effect of steam on the partitioning of Cs and Mo at the temperature ranged 1200 2600 K was calculated at total pressures of 75 and 3.5 bar, which correspond to those before and after RPV depressurization. The reaction of Cs $_{2}$ MoO $_{4}$ (g) with steam was better described by taking into account the participation of Cs $_{2}$ Mo $_{2}$ O $_{7}$ .

Oral presentation

Study on material properties of concrete exposed to extremely high temperature and its non-destructive evaluation

Sato, Yuma*; Do, Thi Mai Dung*; Suzuki, Masahide*; Yamada, Tomonori

no journal, ,

no abstracts in English

Oral presentation

The Characteristics of concrete after high temperature exposures simulating severe accident

Nhut, V. L.*; Do, Thi Mai Dung*; Murakami, Kenta*; Suzuki, Masahide*; Yamada, Tomonori; Shibata, Takuya

no journal, ,

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Deposition behavior of cesium molybdate on Type304 austenite stainless steel in severe accident

Behavior of cesium molybdate, Cs $_{2}$ MoO $_{4}$ , in severe accident conditions, 1; Partitioning of Cs and Mo among gaseous species

Features of Zr-rich corner of the Zr-N-O ternary system by controlled low-pressure oxidation and thermodynamic analysis

Hydrogen generation by water radiolysis with immersion of oxidation products of zircaloy-4

Comparative study of Cs silicates properties between DFT calculation and experimental data

Reaction products in Cs-adsorption on concrete in the 600150 $^{circ}$ C temperature range

Synthesis and characterization of cesium silicate Cs $_{2}$ Si $_{4}$ O $_{9}$

Partitioning of Cs and Mo in steam environment

Study on material properties of concrete exposed to extremely high temperature and its non-destructive evaluation

The Characteristics of concrete after high temperature exposures simulating severe accident