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Journal Articles

Kinetic study on eutectic melting process between boron carbide and stainless steel in sodium-cooled fast reactor

Kikuchi, Shin; Sakamoto, Kan*; Takai, Toshihide; Yamano, Hidemasa

Nihon Kikai Gakkai 2020-Nendo Nenji Taikai Koen Rombunshu (Internet), 4 Pages, 2020/09

In a postulated severe accidental condition of sodium-cooled fast reactor (SFR), eutectic melting between boron carbide (B$$_{4}$$C) as control rod element and stainless steel (SS) as control rod cladding or related structure may occur. Thus, behavior of B$$_{4}$$C-SS eutectic melting is one of the phenomena to evaluate the core disruptive accidents in SFR. In order to clarify the kinetic feature of B$$_{4}$$C-SS eutectic melting process in the interface, the thinning test for SS crucibles using the pellets of B$$_{4}$$C or SS with low B$$_{4}$$C concentration were performed to obtain the rate constant with dependence of B$$_{4}$$C concentration against SS. It was found that the rate constants of eutectic melting between SS and SS low B$$_{4}$$C concentration were smaller than that of B$$_{4}$$C-SS in the high temperature range. Besides, the rate constant of eutectic melting between SS and B$$_{4}$$C containing SS became small when decreasing the B$$_{4}$$C concentration against SS.

Journal Articles

Determination of detrapping and trapping rate constants for hydrogen based on experimental thermal desorption spectra

Ebihara, Kenichi; Saito, Kei*; Takai, Kenichi*

Proceedings of 2016 International Hydrogen Conference (IHC 2016); Materials Performance in Hydrogen Environments, p.470 - 477, 2017/00

http://doi.org/10.1115/1.861387_ch53

For understanding hydrogen (H) embrittlement of steels, it is necessary to infer the state that defects trap H in the steels. Thermal desorption spectra of H obtained by the thermal desorption spectrometry (TDS) are used for inferring such a state. Because the thermal desorption spectra include the influence of experimental conditions and hydrogen diffusion as well as information of the defects trapping H, it is necessary to interpret the spectra using the numerical simulation. In the presentation, we determined the detrapping and the trapping rate constants which are necessary for the simulation from the experimental spectra obtained for plate specimens which is so small that H diffusion is ignorable. Then we confirmed that the model using the obtained rate constants can simulate the spectra of larger cylindrical specimens, so that it was found that the rate constant for small specimens can be used for the simulation of the spectra for specimens of different shape or size.

Journal Articles

Consideration of radiolytic behavior in diluted and concentrated systems of seawater for computational simulation of hydrogen generation

Nagaishi, Ryuji; Inoue, Masao; Hino, Ryutaro; Ogawa, Toru

Proceedings of 2014 Nuclear Plant Chemistry Conference (NPC 2014) (USB Flash Drive), 9 Pages, 2014/10

Since seawater has been used as a coolant for reactors and spent fuel pools in broken reactor buildings at Fukushima Daiichi NPS accident, radioactive contaminated water emitted following the accident has contained salt content of seawater at high concentrations, different from that at TMI-2 accident. Radiolysis of seawater leading to hydrogen generation and corrosion has been simulated and reported by several groups. However, the proposed radiolysis models cannot be always applied to water radiolysis at the wide range of salt concentrations present in the NPS, mainly because primary yields of radiolysis products of water and radiation-induced reactions are dependent on the salt concentration. In this study, the radiolytic behavior in diluted and concentrated systems of seawater was considered on the basis of results in steady state and pulse radiolysis experiments, in which the above salt effects were demonstrated from the obtained results.

JAEA Reports

Experimental study of pyrite oxidation in compacted sodium bentonite

JNC TN8400 2000-012, 33 Pages, 2000/04

JNC-TN8400-2000-012.pdf:1.04MB

The redox condition of near-field is expected to affect the performance of engineered barrier system. Especially, the oxygen initially existing in the pore space of compacted bentonites strongly affects the redox condition of the near-field. For assessing the influence of the oxygen, the transport parameters of it in the compacted bentonite and consumption process should be known. Therefore, following researches were conducted. In order to understand the diffusion of dissolved oxygen (DO) in compacted bentonite and to predict the effect of DO, the effective diffusion coefficients of DO in compacted sodium bentonite were measured by electrochemistry. As the results, the following relationship between the dry density of compacted sodium bentonite and the effective diffusion coefficient of DO in compacted sodium bentonite was derived: De=1.53$$pm$$0.13$$times$$10$$^{-9}$$exp(-2.15$$pm$$0.24$$times$$10$$^{-3}$$p) where De is the effective diffusion coefficient (m$$^{2}$$s$$^{-1}$$) of DO in compacted sodium bentonite and $$rho$$ is the dry density (kg m$$^{-3}$$) of compacted sodium bentonite. The oxygen concentration in the bentonite is expected to be controlled by oxidation of pyrite as impurity in the bentonite. In order to investigate the above idea, the rates of pyrite oxidation by DO in compacted sodium bentonite were estimated from the experimental data on pyrite-bentonite systems usig the obtained effective diffusion coefficient of DO. The results show that the averages of the rate constants of pyrite oxidation by DO in the bentonite for dry densities of 0.8, 0.9, 1.0, 1.1 and 1.2$$times$$10$$^{3}$$kgm$$^{3}$$ were 1.38$$pm$$0.32$$times$$10$$^{-8}$$, 1.10$$pm$$0.24$$times$$10$$^{-8}$$, 1.16$$pm$$0.35$$times$$10$$^{-8}$$, 9.36$$pm$$2.23$$times$$10$$^{-9}$$ and 7.48$$pm$$1.92$$times$$10$$^{-9}$$ms$$^{-1}$$, respectively. The relationship between the dry density ($$rho$$) and the rate constant (k') was expressed as follows: k'=3.94$$pm$$1.06$$times$$10$$^{-8}$$exp(-1.33$$pm$$0.28$$times$$10$$^{-3}$$$$rho$$) ...

JAEA Reports

Literature survey of redox reactions in the new field

Miki, Takahito*; Sasamoto, Hiroshi; Chiba, Tamotsu*; Inagaki, Manabu*; Yui, Mikazu

JNC TN8400 2000-007, 32 Pages, 2000/01

JNC-TN8400-2000-007.pdf:0.69MB

This report presents a summary of literature survey about geochemical reactions which are important to evaluate the redox conditions in the near field rock mass and buffer. The results of literature survey are summarized as follows; (1)Minerals including ferrous iron and organic materials in the rock mass are important reductants. Initial stage after closure of repository, oxygen will be consumed by pyrite, because the reaction rate between pyrite and oxygen is relatively fast. (2)It is possible to estimate the redox capacity for reductants by rock (mineral)-water iteraction experiment in a laboratory. And it is expected that the ferrous iron-rich rock and higher porosity rock may have bigger redox capacity. (3)It is possible to estimate the oxygen consumption rate by reductants such as minerals including ferrous iron. The rate law and rate constant for the oxidation reaction of ferrous iron in the solution are also determined. As a conclusion, it seems that we can evaluate kinetically the evolution of geochemical conditions in the near field rock mass and buffer by excavation of drifts, based on data derived from these existing literatures.

JAEA Reports

Compilation of Kinetic Data for Geochemical Calculations

Arthur, R. C,*; Savage, D.*; Sasamoto, Hiroshi; Shibata, Masahiro; Yui, Mikazu

JNC TN8400 2000-005, 61 Pages, 2000/01

JNC-TN8400-2000-005.pdf:2.83MB

Kinetic data, including rate constants, reaction orders and activation energies, are compiled for 34 hydrolysis reactions involving feldspars, sheet silicates, zeolites, oxides, pyroxenes and amphiboles, and for similar reactions involving calcite and pyrite. The data are compatible with a rate law consistent with surface reaction control and transition-state theoly, which is incorporated in the geochemieal software package EQ3/6 and GWB. Kinetic data for the reactions noted above are strictly compatible with the transition-state rate law only under far-from-equilibrium conditions. It is possiblethat the data are conceptually consistent with this rate law under both far-from-equilibrium and near-to-equilibrium conditions, but this should be confirmed whenever possible through analysis of original experimental results, Due to limitations in the availability of kinetic data for mineral-water reactions, and in order to simplify evaluations of geochemical models of groundwater evolution, it is convenient to assume local-equilibrium in such models whenever possible. To assess whether this assumption is reasonable, a modeling approach accounting for coupled fluid flow and water-rock interaction is described that can be used to estimate spatial and temporal scale of local equiliblium. The approach is demonstrated for conditions involving groundwater flow in fractures at JNC's Kamaishi in-situ tests site, and is also used to estimate the travel time necessary for oxidizing surface waters to migrate to the level of a HLW repository in crystalline rock. The question of whether local equilibrium is a reasonable assumption must be addressed using an appropriate modeling approach. To be appropriate for conditions at the Kamaishi site using the modeling approach noted above, the fracture fill must closely approximate a porous medium, groundwater flow must be purely advective and diffusion of solutes across the fracture-host rock boundary must not occur. Moreover, the ...

Journal Articles

Kinetics and mechanisms of the reactions of CH and CD with H$$_{2}$$S and D$$_{2}$$S

Sato, K.*; *; *; *; *; Kurosaki, Yuzuru*; Takayanagi, Toshiyuki

Chemical Physics, 242(1), p.1 - 10, 1999/00

https://doi.org/10.1016/S0301-0104(98)00420-0
 Times Cited Count：7 Percentile：22.56(Chemistry, Physical)

no abstracts in English

Journal Articles

Kinetic studies on the N($$^{2}$$D,$$^{2}$$P)+CH$$_{4}$$ and CD$$_{4}$$ reactions; The Role of nonadiabatic transitions on thermal rate constants

Takayanagi, Toshiyuki; Kurosaki, Yuzuru*; Sato, K.*; *; *; *

Journal of Physical Chemistry A, 103(2), p.250 - 255, 1999/00

https://doi.org/10.1021/jp9833146
 Times Cited Count：34 Percentile：71.42(Chemistry, Physical)

no abstracts in English

Journal Articles

Measurements of thermal rate constants for the reactions of N($$^{2}$$D,$$^{2}$$P) with C$$_{2}$$H$$_{4}$$ and C$$_{2}$$D$$_{4}$$ between 225 and 292K

Sato, K.*; *; *; *; *; Kurosaki, Yuzuru*; Takayanagi, Toshiyuki

Journal of Physical Chemistry A, 103(43), p.8650 - 8656, 1999/00

https://doi.org/10.1021/jp991742l
 Times Cited Count：27 Percentile：64.06(Chemistry, Physical)

no abstracts in English

Journal Articles

Isotope exchange reaction in Li$$_{2}$$ZrO$$_{3}$$ packed bed

Kawamura, Yoshinori; Enoeda, Mikio; Okuno, Kenji

Fusion Engineering and Design, 39-40, p.713 - 721, 1998/00

https://doi.org/10.1016/S0920-3796(97)00189-0
 Times Cited Count：8 Percentile：57.28(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Quantum-mechanical tunneling in the H$$_{2}$$ elimination from 2,3-dimethylbutane cation: (CH$$_{3}$$)$$_{2}$$CHCH(CH$$_{3}$$)$$_{2+}$$$$rightarrow$$(CH$$_{3}$$)$$_{2}$$C=C(CH$$_{3}$$)$$_{2+}$$+H$$_{2}$$; An ab initio molecular orbital study

Kurosaki, Yuzuru*; Takayanagi, Toshiyuki; Miyazaki, Tetsuro*

Journal of Molecular Structure; THEOCHEM, 452, p.209 - 218, 1998/00

no abstracts in English

Journal Articles

Measurements of thermal rate constants and theoretical calculations for the N($$^{2}$$D,$$^{2}$$P)+C$$_{2}$$H$$_{2}$$ and C$$_{2}$$D$$_{2}$$ reactions

Takayanagi, Toshiyuki; Kurosaki, Yuzuru*; *; *; *; Sato, K.*; *

Journal of Physical Chemistry A, 102(31), p.6251 - 6258, 1998/00

https://doi.org/10.1021/jp9811631
 Times Cited Count：42 Percentile：78.25(Chemistry, Physical)

no abstracts in English

Journal Articles

Theoretical calculations of potential energy surface and thermal rate constants for the H(Mu)+F$$_{2}$$ reaction

Takayanagi, Toshiyuki; Kurosaki, Yuzuru*

Journal of Physical Chemistry A, 101(38), p.7098 - 7104, 1997/00

https://doi.org/10.1021/jp971395k
 Times Cited Count：33 Percentile：73.31(Chemistry, Physical)

no abstracts in English

JAEA Reports

Reaction kinetics and reaction heat on thermal decomposition of solvent containing unstable reactive hydrocarbons with nitric acid at Tomsk-7 reprocessing plant

*; *; Koike, Tadao; Miyata, Teijiro

JAERI-Tech 96-056, 59 Pages, 1996/12

JAERI-Tech-96-056.pdf:1.87MB

no abstracts in English

JAEA Reports

Amounts of particulate radionuclides and their reaction constants in radionuclide migration test using undisturbed samples of aerated sandy soil layers

Ogawa, Hiromichi; Takebe, Shinichi;

JAERI-Research 94-002, 12 Pages, 1994/07

JAERI-Research-94-002.pdf:0.61MB

no abstracts in English

JAEA Reports

Numerical kinetic model including equilibrium and rate equations for chemical reactions of actinide elements

*; Tachimori, Shoichi; Naito, Shinjiro*

JAERI-M 93-056, 27 Pages, 1993/03

JAERI-M-93-056.pdf:0.76MB

no abstracts in English

Journal Articles

Reactions of technetium(III)-thiourea derivative complexes with pyrimidine derivatives

Hashimoto, Kazuyuki; Kudo, Hiroshi; *; *

Radiochimica Acta, 63, p.167 - 171, 1993/00

https://doi.org/10.1524/ract.1993.63.special-issue.167

no abstracts in English

JAEA Reports

Measurements of breakaway reaction between beryllium and water vapor for ITER blanket design

Yoshida, Hiroshi; *; *; Enoeda, Mikio

JAERI-M 92-083, 28 Pages, 1992/06

JAERI-M-92-083.pdf:2.41MB

no abstracts in English

Journal Articles

Overall reaction rate analysis of ion-exchange resins incineration by fluidized bed

*; Hirata, Masaru; Yahata, Taneaki

Journal of Nuclear Science and Technology, 28(8), p.739 - 747, 1991/08

https://doi.org/10.3327/jnst.28.739

no abstracts in English

Journal Articles

High temperature corrosion of iron chromium alloys by tellurium

; Tsuji, Toshihide*; *

Journal of Nuclear Science and Technology, 28(8), p.721 - 731, 1991/08

https://doi.org/10.3327/jnst.28.721

no abstracts in English

35 (Records 1-20 displayed on this page)