JOPSS - Search Results

Journal Articles

Toward a robust phenomenological expression of evaporation efficiency for unsaturated soil surfaces

Komatsu, Teruhisa; Adachi, Takeo

Journal of Applied Meteorology, 42(9), p.1330 - 1334, 2003/09

no abstracts in English

JAEA Reports

A study on long term stability of bentonite; The preliminary study on the bentonite stability in the groundwater influenced by cementitious material

*; Mihara, Morihiro;

JNC TN8430 2001-007, 56 Pages, 2002/01

JNC-TN8430-2001-007.pdf:13.13MB

In the geological disposal concept of radioactive wastes, a kind of clay with sorption ability and low permeability, called bentonite, is envisaged as an engineered barrier system in the geological repository. Also, the cemetitious material is envisaged as the backfill material in the vaults and the structure material of the vaults. The groundwater in contact with the cementitious material will promote hyperalkaline conditions in the repository environment and these conditions will affect the performance of the bentonite. Therefore, it is necessary to investigate the interaction between the cementitious material and the bentonite for the evaluation of long term stability of the disposal system. In this study, for the identification and the investigation of the secondary minerals, the batch immersion experiments of the powder bentonite were carried out using synthetic cement leachates (pH=7, 12.5, 14) at 200 $^{circ}$ C. As the results, it was confirmed that Na as exchangeable cations in the bentonite can exchange relatively easily with Ca in the solution from the experiment results. And the ratio of cation exchange was estimated to be about 25% based on the amount of exchangeable cations Ca $^{2+}$ between layers. Furthermore, it was concretely shown that the generation of analcime might be affected by the Na concentration from results of the solution analyses and a stability analysis of analcime using the chemical equilibrium model, in addition to the pH in the solution.

Journal Articles

Evaporation speed of water from various soil surfaces under calm state

Komatsu, Teruhisa

Journal of the Physical Society of Japan, 70(12), p.3755 - 3756, 2001/12

https://doi.org/10.1143/JPSJ.70.3755

Times Cited Count：4 Percentile：33.15(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Creep motion in granular pile exhibiting steady surface flow

Komatsu, Teruhisa; Inagaki, Shio*; Nakagawa, Naoko*; Nasuno, Satoru*

Physical Review Letters, 86(9), p.1757 - 1760, 2001/02

https://doi.org/10.1103/PhysRevLett.86.1757

Times Cited Count：251 Percentile：97.47(Physics, Multidisciplinary)

no abstracts in English

JAEA Reports

Study on dissolution of UO $_{2}$ to obtain the high U solution

; *; Sakurai, Koji*; ; Nomura, Kazunori; *

JNC TN8400 2000-032, 98 Pages, 2000/12

JNC-TN8400-2000-032.pdf:1.94MB

Concerning the preparation of high U solution for the crystallization process and the application of UO $_{2}$ powder dissolution to that, the effects of final U concentration, dissolution temperature, nitric acid concentration and powder size on the dissolution of UO $_{2}$ powder in the nitric acid where the final U concentration was 800g/L were investigated. The experimental results showed that the solubility of UO $_{2}$ decreased with the increase of final UO $_{2}$ concentration and powder size, and with the decrease of dissolution temperature and nitric acid concentration. It was also confirmed that in the condition where the final U concentration was sufficiently lower than the solubility of U, UO $_{2}$ dissolution behavior in the high U solution could be estimated with the equation based on the fragmentation model which we had already reported. Based on these experimental results, the dissolution behavior of irradiated MOX fuel in high U solution was estimated and the possibility of supplying high U solution to the crystallization process was discussed. In the preparation of high U solution for the crystallization process, it was estimated that the present dissolution process (dissolution for fuel pieces of about 3cm long) needed a lot of time to obtain a high dissolution yield, but it was shorted drastically by the pulverization of fuel pieces. The burst of off-gas at the early in the dissolution of fuel powder seems to be avoidable with setting the appropriate dissolution condition, and it is important to optimize the dissolution condition with considering the capacity of off-gas treatment process.