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Ikeuchi, Hirotomo
Journal of Nuclear Science and Technology, 59(6), p.768 - 780, 2022/06
Times Cited Count：1 Percentile：29.26(Nuclear Science & Technology)Guido-Garcia, F.; Sakamoto, Fuminori; David, K.*; Kozai, Naofumi; Grambow, B.
Chemosphere, 279, p.130511_1 - 130511_10, 2021/09
Times Cited Count：1 Percentile：5.8(Environmental Sciences)Cesium (Cs) accumulation by Shiitake was investigated to contribute to the elucidation of radiocesium-cycling mechanisms in forest environments. The results demonstrate that Shiitake non-specifically accumulates Cs while accumulating the essential element K and provide evidence that no selective Cs accumulation (or binding) sites exist within the Shiitake fruit body. Furthermore, the present results show that most accumulated Cs quickly leaches out from the dead fruit body with exposure to water. The leached Cs was largely adsorbable on clay minerals, suggesting that the Shiitake fruit body likely contains Cs in the cation form.
Mishima, Ria; Inaba, Yusuke*; Tachioka, Sotaro*; Harigai, Miki*; Watanabe, Shinta*; Onoe, Jun*; Nakase, Masahiko*; Matsumura, Tatsuro; Takeshita, Kenji*
Chemistry Letters, 49(1), p.83 - 86, 2020/01
Times Cited Count：4 Percentile：20.61(Chemistry, Multidisciplinary)Separation of platinum group metals (PGMs) from high-level liquid waste generated from the reprocessing of spent nuclear fuels is important to produce good quality vitrified glass for final disposal. A new sorbent, Aluminum hexacyanoferrate (AlHCF), was synthesized and the general sorption behavior of PGMs from concentrated nitric acid was examined. Nitric acid caused substantial elution of AlHCF but the sorption of Pd stabilized the structure. Consequently, Rh was sorbed in the presence of Pd, whereas single Rh sorption caused complete dissolution of AlHCF. Relation between sorbed mount of Pd vs eluted Al and Fe revealed that the elution ratio of Al and Fe was not the same as molar ratio of synthesized AlHCF, indicating the re-sorption of Fe resulted in formation of new structure. The sorption mechanism of PGMs by this new sorbent, AlHCF, not only the simple ion exchange, but also oxidation reduction reaction as well as kinetics play important rule. Understanding the general sorption and dissolution behavior will help improve the sorption performance of PGMs by AlHCF.
O and UOFidalgo, A. B.*; Kumagai, Yuta; Jonsson, M.*
Journal of Coordination Chemistry, 71(11-13), p.1799 - 1807, 2018/07
Times Cited Count：30 Percentile：88.14(Chemistry, Inorganic & Nuclear)In this work, we have studied the reaction between HO and UO with particular focus on the nature of the hydroxyl radical formed as an intermediate. Experiments were performed to study the kinetics of the reaction at different initial HO concentrations. The results show that the consumption rates at a given HO concentration are different depending on the initial HO concentration. This is attributed to an alteration of the reactive interface, likely caused by blocking of surface sites by oxidized U/surface-bound hydroxyl radicals. The U dissolution yield decreases with increasing initial HO concentration. This is expected from the mechanism of catalytic decomposition of HO on oxide surfaces. As the experiments were performed in solutions containing 10 mM and a strong concentration dependence was observed in the 0.2 - 2.0 mM HO concentration range, we conclude that the intermediate hydroxyl radical is surface bound rather than free.
Fujii, Kengo*; Ochi, Kotaro; Obuchi, Atsushi*; Koike, Yuya*
Journal of Environmental Management, 217, p.157 - 163, 2018/07
Times Cited Count：35 Percentile：77.62(Environmental Sciences)After the Fukushima Daiichi-Nuclear Power Plant accident, environmental recovery was a major issue because a considerable amount of municipal solid waste incineration (MSWI) fly ash was highly contaminated with radioactive cesium. In this study, MSWI fly ash was sampled in Fukushima Prefecture, and the physicochemical properties of radioactive cesium in MSWI fly ash were evaluated by particle size classification and the Japanese leaching test No. 13 (JLT-13). The results obtained from the classification of fly ash indicated that the activity concentration of radioactive cesium and the content of the coexisting matter (i.e., chloride, potassium, and sylvite) temporarily change in response to the particle size of fly ash. X-ray diffraction results indicated that water-soluble radioactive cesium exists as CsCl because of the cooling process and that insoluble cesium is bound to the inner sphere of amorphous matter.
Tsuji, Tomoyuki; Nakamura, Yasuo; Nakatani, Takayoshi
JAEA-Technology 2015-014, 34 Pages, 2015/06
[The article has been found to have a problem about reliability of the corrosion data acquisition, and thus it is unavailable to download the full text in accordance with authors' intentions to retract the report.] In order to dispose of radioactive wastes for sub-surface disposal, JAEA has studied the safety assessment for likely scenario and less-likely scenario. Radioactive nuclide leaching rate under the sub-surface disposal is important parameter in the safety assessment because radioactive nuclides in activated metal wastes are released with its corrosion. In this report, sensitivity of radioactive nuclide leaching rate is studied for the safety assessment. As the result, it is confirmed that Cl-36 which is dominant for the safety assessment in groundwater scenario is sensitive to radioactive nuclide leaching rate, but Nb-94 which is dominant in tunnel excavation scenario is not sensitive to radioactive nuclide leaching rate but to distribution coefficients in engineered barrier.
Kameo, Yutaka; Haraga, Tomoko; Nakashio, Nobuyuki; Hoshi, Akiko; Nakashima, Mikio
Nihon Genshiryoku Gakkai Wabun Rombunshi, 3(4), p.354 - 362, 2004/12
In order to investigate chemical stability of solidified products made from Low Level Radioactive Wastes (LLW) by plasma melting, a leaching test based on the MCC (Material Characterization Center)-3S Agitated Powder Leach Test Method was performed to determine Normalized Elemental Mass Loss (NL
) of both main components (Na, Al, Si, Ca, and Fe) of the solidified product and radioactive tracers (
Co, 
Cs, and 
Eu) incorporated into it. The results of leaching test indicated that NLi value was greatly affected by basicity defined as weight ratio of CaO to SiO in the solidified product, while effect of FeO concentration on NL value was small. In the case of basicity less than 0.8, logarithm of NL linearly increased with the basicity, implying that NL value can be estimated by chemical composition of the solidified products.
*; 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
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
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.
Kato, Hiroshige*; Sato, Mitsuyoshi*; Owada, Hitoshi*; Mihara, Morihiro;
JNC TN8430 2000-008, 53 Pages, 2000/05
Cementitious materials will be used in TRU waste disposal repository. In such cases, it is considered that the migration of alkaline leachates from cementitious materials, so called high pH plume, will cause dissolution of rock and precipitation of secondary minerals. In addition, the high pH plume will move along the flow of groundwater, so it is predicted that rock formation and components of high pH groundwater vary with time and space. However, time and spatial dependence of the variations of secondary minerals and groundwater components has not been clarified. In order to acquire the data of variations of secondary minerals and groundwater components, we carried out the rock alteration experiments with column method. The crushed granodiorite was filled into 4 meters length column (
3.7 cm) and artificial cement leachate (pH=13.3; Na=0,1 mol/l, K=0.1 mol/l, Ca=0.002 mol/l) was streamed at flow rates of 0.1 ml/min for 7 months at 80C. As the result, secondary minerals confirmed on the rock were calcite and C-S-H at upstream of column and C-S-H at mid-downstream. The pH value of the fluid dominated by Na and K did not be decreased by reaction with the rock. In this study, the data relating to the effect of high pH plume on rock over the long term was acquired.
Osaka, Masahiko; Koyama, Shinichi; Mitsugashira, Toshiaki; Morozumi, Katsufumi; Namekawa, Takashi
JNC TN9400 2000-058, 49 Pages, 2000/04
JNC-TN9400-2000-058.pdf:1.22MB
The analytical technique for Cm contained in a MOX FUEL was developed and analysis of Cm contained in irradiated fuel of experimental fast reactor "JOYO" was carried out, to contribute to evaluation of transmutation characteristics of MA nuclide in the fast reactor. The procedure of ion-exchange separation of Cm with nitric acid-methanol mixed media essential for the isotopic analysis in irradiated MOX fuel was adopted considering for being rapid and easy. The fundamental test to grasp separation characteristics of this procedure, such as Cm elution position and separation capacity between Cm and Am or Eu, was carried out. ln applying this procedure to the analysis of Cm contained in actual specimen, separation condition was evaluated and optimized, and the procedure consist of impurity removal and Am removal process was devised. This procedure resulted in high recovery rate of Cm and high removal rate of Am and impurity which becomes a problem in sample handling and mass-spectrometry such as Eu and Cs. The Cm separation test from irradiated MOX fuel was carried out using this technique, and Cm isotopic ratio analysis was enabled. The analytical technique for Cm contained in irradiated MOX fuel was established using the procedure of ion-exchange separation with nitric acid-methanol mixed media. The analysis of Cm contained in irradiated MOX fuel of experimental fast reactor "Joyo" was carried out. As a result, it was revealed from measured data that Cm content rate was 1.4
4.0
lO
atom%, small amount of 
Cm was generated and Cm isotopic ratio was constant above burn-up 60GWd/t.
Kaito, Takeji
JNC TN9400 2000-039, 19 Pages, 2000/03
JNC-TN9400-2000-039.pdf:0.66MB
The corrosion behavior of core materials in lead cooled reactor was investigated as the feasibility study for fast breeder reactor. The results are summarized as follows. (1)The corrosion of stainless steels under lead and lithium occurs mainly due to the dissolution of nickel. Consequently ferritic stainless steels have better resistance to corrosion under lead and lithium than austenitic stainless steels, and the corrosion resistance of high nickel steels is worst. (2)The dissolution rate, D(mg/m
/h), is correlated with lead and lithium temperature, T(K), as log
Da = 10.7873 - 6459.3/ T and logDf = 7.6185 - 4848.4/T, where D a is the dissolution rate for austenitic steels and D f is for ferritic steels. lt's possible to calculate the corrosion thickness, C(
m), using the following correlation: C = (Dt)/
10, where t is exposure time(hr) and is density of the core matelial (g/cm
). (3)The corrosion thickness estimated for austenitic steels using above correlations was extremely larger than ferritic steels, about 6 times at 400C and more than 20 times at above 600C. lt's considered that applicable temperature in lead cooled reactor core is below 400C (about 60m corrosion thickness after 30000 hr) for austenitic steels, and below 500C (about 80 m after 30000 hr) for ferritic steels.
; Makino, Hitoshi; Peter*
JNC TN8400 99-095, 69 Pages, 1999/12
MESHNOTE code was developed to evaluate the engineered barrier system in collaboration with QuantiSci. This code is used to simulate glass dissolution, diffusive transport of nuclides in the buffer material and release to surrounding host rock. MESHNOTE is a one-dimensional finite difference, code, which uses cylindrical co-ordinates for the solution of a radially symmetric diffusion problem. MESHNOTE has the followig characteristics: (1) MESHNOTE can solve for diffusive transport of nuclides through an annulus shaped buffer region while accounting for multiple decay chains, linear and non-linear sorption onto the buffer materials and elemental solubility limits; (2) MESHNOTE can solve for ingrowth of plural daughter nuclides from a singular parent nuclide (branching), and the ingrowth of a singular daughter nuclide from plural parent nuclides (rejoining); (3) MESHNOTE can treat the leaching of nuclide from the vitrified waste and the release of nuclide from buffer to surrounding rock, which are boundary conditions for migration in the buffer, basing on the phenomena; (4) MESHNOTE can treat principal parameters (e.g. solubility and distribution coefficient) relevant to nuclide migration as time and space-dependence parameters; (5) The time stepping scheme in MESHNOTE is controlled by tolerance defined by the user. The time stepping will increase automatically while checking the accuracy of the numerical solution. The conceptual model, the mathematical model and the numerical implementation of the MESHNOTE code are described in this report and the characteristic functions of MESHNOTE are verified by comparing with analytical solutions or simulations produced with other calculation codes.
Saito, Junichi; Morinaga, Masahiko*; Kano, Shigeki
PNC TN9410 98-072, 97 Pages, 1998/07
Research on structural materials which will be utilized even in the severe environment of high-temperature liquid alkali metals has been promoted in order to develop the frontiers of materials techniques. The super-heat resisting alloys which are based on refractory metals, Nb and Mo, are aimed as promising materials used in such an environment. The corrosion resistance in liquid Li and the mechanical properties such as creep and tensile strengths at high temperatures are important for these structural materials. On the basis of many expeliments and analyses of these properties at 1473K, the material design of Nb-based and Mo-based alloys has-been carried out successfully. In this report, all the previous experimental results of corrosion tests in liquid Li were summarized systematically for Nb-based and Mo-based alloys. The corrosion mechanism was proposed on the basis of a series of analyses, in particular, focussing on the deposition mechanism of corrosion products on the surface and also on the initiation and growth mechanism of cracks on the corroded surface of Nb-based alloys. The principal results are as follows. (1)For the deposition mechanism, a reaction took place first between dissolved metallic elements and nitrogen which existed as an impurity in liquid Li and then corrosion products (nitrides) precipitated on the metal surface. Subsequently, another reaction took place between dissolved metalic elements in liquid Li, and corrosion products (intermetallic compounds) precipitated on the metal surface. The composition of deposited corrosion products could be predicted on the basis of the deposition mechanism. (2)For the crack initiation mechanism, the chemical potential diagrams were utilized in order to understand the formation of Li-M-O ternary oxides which caused cracks to be formed on the corroded surface. Consequently, it was evident that not only the concentration of the dissolved oxygen in the alloy but also the concentration of Li which ...
Okoshi, Minoru
JAERI-Review 97-009, 32 Pages, 1997/08
JAERI-Review-97-009.pdf:1.24MB
no abstracts in English
Amano, Hikaru; Matsunaga, Takeshi; Ueno, Takashi; Nagao, Seiya; Watanabe, Miki*; *; Onuma, Yoshikazu*
KURRI-KR-18, p.201 - 212, 1997/00
no abstracts in English
Tanaka, Tadao; Onuki, Toshihiko
Geochemical Journal, 28(5), p.369 - 376, 1994/00
Times Cited Count：5 Percentile：15.93(Geochemistry & Geophysics)no abstracts in English
*; Morinaga, Masahiko*; Saito, Junichi*; *; *
PNC TJ9623 92-001, 81 Pages, 1991/07
[PURPOSE] For structural materials serviced in the Li environments, both Nb-based and Mo-based alloys are selected as the candidate materials. In this study, a simple method was proposed for evaluating the high temperature strength of these alloys. Also, the corrosion resistance in liquid metals was investigated in order to get fundamental information for the design and development of high performance alloys. [EXPERIMENTAL AND CALCULATING METHODS] With a variety of ternary alloys high temperature micro-hardness was measured systematically. The results were analyzed by referring to the relationship between the hardness and the tensile strength reported in previous publications. Also, some alloys designed last year were exposed to the liquid Na at 650 C, and the attendant changes were examined with respect to the weight, microstructure and local composition of alloys. Some of the results were understood in terms of the free energy for the oxide formation of Na and other elements in alloys. Another effort to understand the corrosion properties was made by the molecular orbital calculation of the electronic states of various elements in liquid Li, K and Na. [RESULTS] The high temperature tensile strength of both the alloys was found to be predictable by using a linear relationship between the hardness and the tensile strength of room temperature to 1200 C. The corrosion resistance was much poorer in the Nb-based alloys than in the Mo-based alloys. This is partially due to the enhancement of corrosion by the preferred oxidation of Nb and Ta in the Nb-based alloys, whereas no such oxidation took place in the Mo-based alloys. In addition, it was found from the molecular orbital calculation that Li is the liquid metal of more strongly-bonded with every alloying element, compared to K and Na liquid metals. Futhermore, it was shown that the hardness of each alloy correlated well with the atomic-size difference and also the young's modulus difference ...
;
Analytica Chimica Acta, 172, p.39 - 47, 1985/00
Times Cited Count：7 Percentile：43.07(Chemistry, Analytical)no abstracts in English
