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Ito, Daisuke*; Ito, Kei*; Saito, Yasushi*; Aoyagi, Mitsuhiro; Matsuba, Kenichi; Kamiyama, Kenji
Nuclear Engineering and Design, 334, p.90 - 95, 2018/08
Times Cited Count：9 Percentile：62.99(Nuclear Science & Technology)Two-phase flow through porous media must be well understood to develop a severe accident analysis code not only for light water reactor but also sodium-cooled fast reactor. When a core disruptive accident occurs in sodium-cooled fast reactor, the fuel inside the core become melted and interacts with the coolant. As a result, gas-liquid two-phase flow will be formed in the debris bed, which may have porous nature depending on the cooling process. In such condition, the local porosity and its distribution are very important to characterize two-phase flow field in the porous media. In this study, X-ray radiography was applied to measure the local porosity in the packed bed of spheres. The radial profiles were estimated from the chordal profiles measured by the X-ray method and compared with the previous porosity model. In addition, the void fraction radial profiles were also obtained in air-water two-phase flow.
*; Ijiri, Yuji*; *; *
JNC TN8400 2000-021, 66 Pages, 2000/04
JNC-TN8400-2000-021.pdf:4.38MB
A reliability evaluation for radionuclide transport analysis code, MATRICS, used in radionuclide transport analysis in the natural barrier system PA in H12 report has been carried out. Sensitivity analysis to radionuclide transport parameter in MATRICS and analytical solution has been performed, and the results of each analysis have been compared. Additionally sensitivity analysis using Talbot Method, Crump method and Hosono method has been carried out, and the results of each inverse Laplace transform method has been compared. The conclusions obtained from the results of the evaluation are summarized as follows, (1)In case of the infinite matrix diffusion distance, an error among the results of each calculation is maximum about 0.4% in the range of Pe number from 1.0 to 100. And, an error among the results of each calculation is maximum about 5.5% in the range of transmissivity from 1.0
10
to 1.010
(m
/s). (2)In case of the finite matrix diffusion distance (0.03
1.0(m)), an error among the results of each calculation is maximum about 0.7% in the range of Pe number from 1.0 to 100. And, an error among the results of each calculation is maximum about 2.4% in the range of transmissivity from 1.010 to 1.010(m/s). 3)By comparing Talbot method with other inverse Laplace transform method, Talbot method is confirmed to give similar results with other inverse Laplace transform method in the range of Pe number from 5.010
to 2.010
, and that of transmissivity below 1.010
(m/s). Therefore, it is concluded that the reliability of MATRICS are confirmed by conducting sensitivity analysis in the range of Pe number and transmissivity coefficient used in H12 report.
Takemura, Morio*
JNC TJ9450 2000-002, 112 Pages, 2000/03
JNC-TJ9450-2000-002.pdf:2.55MB
This report is intended to make it easier to apply the measured data obtained from the Gap Streaming Experiment, which was conducted at the Oak Ridge National Laboratory (ORNL) during about two months beginning at the start of March, 1992 as the sixth one of a series of eight experiments planned for the Japanese-American Shielding Program for Experimental Research (JASPER) which was started in 1986. For this reason. the information presented includes specifications and measurement data for all configurations, compositions of all materials, characteristics of the measurement system. and daily-basis records of measurements. The Gap Streaming Experiment was planned to obtain the data of neutron streaming characteristics in the inclosure system above the core of an advanced fast reactor for verification and improvement of the analysis method to be applied to the shielding design. A iron-lined solid or slit concrete assembly was placed, with or without a spectrum modifier forming soft incident neutron spectrum, behind the TSR-II reactor of Tower Shielding Facility. Inserting central cylinders and cylindrical sleeves gave various gap width and offset in the slit concrete assembly. Neutron flux was measured behind the configurations with various types of detectors. The integral neutron flux in wide energy region was measured on radial traverse and on the axis behind the concrete assembly in almost all configurations. Neutron spectrum and fine radial distribution in high energy region was measured further in case of hard incident neutron spectrum, Information presented in this report is based mainly on a report issued by ORNL (ORNL/TM-12140. "Measurements for the JASPER Program Gap Streaming Experiment"). Additional information reported by the assignee is utilized also.
Muroi, Masayuki*
JNC TJ8400 2000-042, 142 Pages, 2000/02
JNC-TJ8400-2000-042.pdf:14.6MB
Hyperalkaline pore water of cementitious material used in TRU waste repository would react with bentonite and cause the increased porosity and the loss of the swelling and sorption ability. This work is a modelling study on bentonite-cement pore water. The possible extent of reaction between bentonite and cement pore water was simulated using the PRECIP reaction-transport code. Three cement pore fluid compositions (leachates 1,2 and 3) were reacted with a 1-D, 1m flowpath of bentonite (+ sand) at 25 and 70
C. Key minerals were allowed to dissolve and precipitate using kinetic reaction mechanism. Leachate 1 was the most aggressive fluid (highest pH, Na and K), and leachate 3 (1owest pH, Na and Ca) the least aggressive. Simulation with leachate 1 showed total removal of primary bentonite minerals up to 60 cm from the contact with cement after 1000 years. The maximum porosity increase observed was in leachate 1(up to 80-90%) over a narrow zone 1-2 cm. Simulations with all fluids showed total filling of pore with CSH minerals in a zone very close to the interface with the cement, whereas zeolites and sheet silicates formed far away. For a given leachate composition, there was little difference in the profiles at the two temperatures studied. It was suggested that bentonite alteration was not sensitive to the kinetic parameters over the conditions studied. The conceptual model chosen for the modelling study assumed that there was an unlimited amount of cement pore fluid available for reaction with bentonite so that the results of the simulations represent a conservative (pessimistic) estimate. There were a number of uncertainties associated with the modelling which relate to assumptions concerning: the kinetic mechanisms for dissolution and growth of minerals at elevated pH; evolving surface areas of minerals with time; thermodynamic data for CSH minerals, zeolites and aqueous species at high pH; the synergy between changing porosity and fluid ...
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.
Hashizume, Shuji*; Matsumoto, Junko; Bamba, Tsunetaka
Genshiryoku Bakkuendo Kenkyu, 6(1), p.101 - 106, 1999/12
no abstracts in English
; ; Ishiguro, Katsuhiko; Nakajima, Kunihiko*;
JNC TN8400 99-087, 41 Pages, 1999/11
Corrosion of the carbon steel overpack leads to a volume expansion since the specific gravity of corrosion products is smaller than carbon steel. The buffer material is compressed due to the corrosive swelling, reducing its thickness and porosity. On the other hand, Buffer material may be extruded into fractures of the surrounding rock and this may lead to a deterioration of the planned functions of the buffer, including retardation of nuclides migration and colloid filtration. In this study, the sensitivity analyses for the effect of volume expansion and intrusion of the buffer material on nuclide migration in the engineering barrier system are carried out. The sensitivity analyses were performed on the decrease in the thickness of the buffer material in the radial direction caused by the corrosive swelling, and the change in the porosity and dry density of the buffer caused by both compaction due to corrosive swelling and intrusion of buffer material. As results, it was found the maximum release rates of relatively shorter half-life nuclides from the outside of the buffer material decreased for taking into account of a volume expansion due to overpack corrosion. On the other hand, the maximum release rates increased when the intrusion of buffer material was also taking into account. It was, however, the maximum release rates of longer half-life nuclides, such as Cs-137 and Np-237, were insensitive to the change of buffer material thickness, and porosity and dry density of buffer.
Aoyagi, Takayoshi*; Mihara, Morihiro; Tanaka, M.*; Okutsu, Kazuo*
JNC TN8400 99-058, 55 Pages, 1999/11
For the emplaced waste in TRU waste disposal facility, it may have the void for waste bodies it. And, generating void which accompanies those component elution in concrete pit and filler in which the cement material becomes the candidate material is assumed. It is considered that the security of the diffusion control in the bentonite is not done when these voids collapsed, and when it generated the volume change inside the buffer material (bentonite). The imperfect blockage of the void by not obtaining, the sufficient swelling pameability swelling bentonite is a cause on this. Then, volume change of the bentonite inside is analyzed in this study under the conservative estimation. And the following are tested: Self-sealing, maximum swelling rate, density distribution change of the batonite. Evaluation of the engineered barrier system for volume change from the result was carried out. Prior to the evaluation, generating void was calculated based on the conservative estimation. The density of the buffer material as it assumed the blocking by buffer material uniformly awelling using this calculated data, was obtained. By the permeability got from existing research result which shows the relationship between density and permeability of the bentonite, it was confirmed to become diffusion control in the buffer material inside, in existing engineered barrier specification. Next, it was tested, when the conservative void of the superscription was assumed, in order to confirm whether it does the security, as permeability necessaly for maintaining diffusion control, puts it for the swelling of actual bentonite. As the result, it was possible to confirm sufficient swelling performance in order to do the security of the diffusion control in Na-bentonite. However, the swelling performance greatly lowered by comparing Na-bentonite in Ca-bentonite with under 1/6. The increase of the permeability not do the security of the diffusion control, when it was based on void quantity ...
Yamaguchi, Tetsuji; Isobe, Hiroshi;
Hoshasei Haikibutsu Kenkyu, 3(2), p.99 - 108, 1997/00
no abstracts in English
; Yamaguchi, Koichi; ;
Tanso, (113), p.60 - 65, 1983/00
no abstracts in English
; Iwamoto, K.
JAERI-M 5937, 30 Pages, 1974/12
no abstracts in English
Yamazaki, Akio*; Okubo, Takahiro*; Iwadate, Yasuhiko*; Tachi, Yukio
no journal, ,
A structural analysis of water-filled pores in saturated compacted sodium montmorillonite was conducted by 1H NMR spectroscopy. The pore structure including interlayer and intraparticle pores in compacted montmorillonite was characterized by relaxation time and freezing point observed by 1H NMR and their correlations with water-filled pore sizes.
Konomura, Mamoru*; Kamiyama, Kenji
no journal, ,
A behavior of a heavy metal jet which ran into a water pool was analyzed with the Moving Particle Semi-implic Method. A little pressurization proved useful to suppress unrealistic cavity which appeared in the pool.
Yamazaki, Akio*; Okubo, Takahiro*; Iwadate, Yasuhiko*; Tachi, Yukio
no journal, ,
A structural analysis of water-filled pores in saturated compacted Ca-type montmorillonite was conducted by 1H NMR spectroscopy. The pore structure including interlayer and intraparticle pores in Ca-type compacted montmorillonite was characterized by relaxation time observed by 1H NMR and their correlations with water-filled pore sizes.
