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Hara, Akio; Tsuji, Takashi*; Nishimura, Mizue*; Hoshi, Kazuyoshi*; Yagi, Masahiko*; Kawada, Koji*; Hou, J.-Y.*
JAERI-Conf 2005-007, p.270 - 275, 2005/08
Borehole log interpretation methods, which are usually used by petroleum exploration companies, are applied for evaluating heterogeneity of deep underground diatomaceous mudstones in the Horonobe area. Natural ray log and electrical micro image (EMI) log data were used for the log interpretation. Five sedimentary facies, A to E, were established from the EMI log interpretation. Significant correlations between the sedimentary facies, the chemical contents, the natural
ray level, and the electric conductivity in the diatomaceous mudstone were seen. Spatial distribution of the diatomaceous mudstone, in lithology and thickness, was recognized through borehole correlation, which seems to reflect the sedimentary environment change.
Takazawa, Mayumi; Negishi, Kumi; Sakamoto, Yoshifumi; Akai, Masanobu; Yamaguchi, Tetsuji; Iida, Yoshihisa; Tanaka, Tadao; Nakayama, Shinichi
JAERI-Conf 2005-007, p.236 - 241, 2005/08
no abstracts in English
Mizuno, Tsuyoshi*; Maeda, Toshikatsu; Bamba, Tsunetaka*
JAERI-Conf 2005-007, p.225 - 229, 2005/08
no abstracts in English
Abe, Hitoshi; Tashiro, Shinsuke; Morita, Yasuji
JAERI-Conf 2005-007, p.199 - 204, 2005/08
Source term data for estimating release behavior of radioactive nuclides is necessary to evaluate synthetic safety of nuclear fuel cycle facility under accident conditions, such as fire and criticality. In JAERI, the data has been obtained by performing some demonstration tests. In this paper, the data for the criticality accident in fuel solution obtained from the TRACY experiment, will be mainly reviewed. At 4.5 h after the transient criticality, the release ratio of the iodine were about 0.2% for re-insertion of transient rod at just after transient criticality and about 0.9% for not re-insertion. Similarly the release coefficient and release ratio for Xe were estimated. It was proved that the release ratio of Xe-141 from the solution was over 90% in case that the inverse period was over about 100 (1/s). Furthermore, outline of the study on the fire accident as future plan will be also mentioned.
Asakura, Toshihide; Sato, Makoto; Matsumura, Masakazu; Morita, Yasuji
JAERI-Conf 2005-007, p.345 - 347, 2005/08
This paper reviews the succeeding development and utilization of Extraction System Simulation Code for Advanced Reprocessing (ESSCAR). From the viewpoint of development, more tests with spent fuel and calculations should be performed with better understanding of the physico-chemical phenomena in a separation process. From the viewpoint of process safety research on fuel cycle facilities, it is important to know the process behavior of a key substance; being highly reactive but existing only trace amount.
Kim, S.-Y.; Asakura, Toshihide; Morita, Yasuji
JAERI-Conf 2005-007, p.341 - 344, 2005/08
Electrochemistry has been used to investigate the behavior of plutonium(IV) in 1-7 M HNO solutions. These Pu(IV) complexes were found to be reduced quasi-reversibly to Pu(III) species. The formal redox potentials (E
) for Pu(IV)/Pu(III) couples were determined to be +0.721, +0.712, +0.706, +0.705, +0.704, 0.694, and +0.696 V (vs. Ag/AgCl(SSE)) for Pu(IV) complexes in 1, 2, 3, 4, 5, 6, 7 M HNO
solutions, respectively. These results indicate that the reduction product of Pu(IV) is Pu(III), which is considerably stable in HNO
solution.
Tashiro, Shinsuke; Abe, Hitoshi; Morita, Yasuji
JAERI-Conf 2005-007, p.348 - 350, 2005/08
Hot test at Rokkasho Reprocessing plant has been started since last year. In addition, construction of the MOX fuel fabrication facility at Rokkasho site is planning. So, the importance of safety evaluation of the nuclear fuel cycle facility is increasing. Under the fire accident, one of the serious postulated accidents in the nuclear fuel cycle facility, the equipments (glove-box, ventilation system, ventilation filters etc.) for the confinement of the radioactive materials within the facility could be damaged by a large amount of heat and smoke released from the combustion source. Therefore, the fundamental data and models calculating for the amount of heat and smoke released from the combustion source under such accident are important for the safety evaluation of the facility. In JAERI, the study focused on the evaluation of amount of heat and smoke released from the combustion source is planning. In this paper, the outline of experimental apparatus, measurement items and evaluation terms are described.
Morita, Yasuji; Asakura, Toshihide; Mineo, Hideaki; Hotoku, Shinobu; Uchiyama, Gunzo
JAERI-Conf 2005-007, p.25 - 30, 2005/08
Researches on process safety of reprocessing, development of an advanced reprocessing and partitioning of high-level liquid waste(HLLW) have been conducted in NUCEF - BECKY (Back-end Fuel Cycle Key Elements Research Facility), which has alpha-gamma concrete cells and many glove-boxes. This paper presents 10 year accomplishment of the above researches and future activities to be conducted in the field of separation process development.
Mikami, Satoshi; Yoshida, Tadayoshi; Takada, Chie; Tsujimura, Norio
JAERI-Conf 2005-007, p.326 - 331, 2005/08
Feasibility study of a hard rubber named ebonite as an activation detector for fast neutron has been carried out. It contains about 30 wt% of sulphur and S(n,p)
P reaction can be utilized for fast neutron dose assessment. Characteristics of ebonite, a feasibility of it as a neutron dosemeter are investigated. According to our examination results, the neutron dose assessment method using an ebonite can be applied to dose reconstruction in the fields such as fuel fabrication plant and reprocessing plant etc., and to personal working there too. For easy dose assessment, the conversion factors to neutron tissue kerma from spectra were tabulated as a function of thickness of shielding of steel and concrete. The disc-shaped ebonite is one of the most useful tools to evaluate the dose induced by fast neutrons in case of criticality accident. It has the advantage of simple handling, measurements and rapid dose assessment.
Sanada, Yukihisa; Mikami, Satoshi; Kobayashi, Hirohide; Kurimata, Tomoyuki*; Fukazawa, Satoshi*
JAERI-Conf 2005-007, p.321 - 325, 2005/08
It researched concerning the method of evaluating the radionuclide discharged by using the gas monitor at a criticality accident. The measurement condition was set from the evaluation result of the -ray spectrum at a criticality accident of the use of the calculation code. The measurement system was developed in consideration of those conditions. The evaluation after three hours is possible at a criticality accident according to this system. The evaluation before three hours was examined about the method of doing the detector pulse by high-speed processing by digital oscilloscope.
Yamaguchi, Tetsuji; Minase, Naofumi; Iida, Yoshihisa; Tanaka, Tadao; Nakayama, Shinichi
JAERI-Conf 2005-007, p.150 - 155, 2005/08
no abstracts in English
Tanaka, Tadao; Sakamoto, Yoshifumi; Yamaguchi, Tetsuji; Takazawa, Mayumi; Akai, Masanobu; Negishi, Kumi; Iida, Yoshihisa; Nakayama, Shinichi
JAERI-Conf 2005-007, p.105 - 110, 2005/08
Highly alkaline environments induced by cementitious materials in radioactive waste repositories are likely to dissolve and to alter montmorillonite, the main constituent of bentonite buffer materials. For the prediction of the long-term variations in permeability of compacted sand-bentonite mixtures, long-term alteration of bentonite should be quantified based on information accumulated by using the compacted or powdered bentonite materials, with batch experiments or column experiments. In this study, we summarize distinctive information obtained from various experimental systems, and propose functional and effective integration of experimental approaches to prediction of bentonite alteration.
Sono, Hiroki; Kojima, Takuji; Soramasu, Noboru*; Takahashi, Fumiaki
JAERI-Conf 2005-007, p.315 - 320, 2005/08
Personal dosimeters provide a fundamental evaluation of external exposures to human bodies in radiation accidents. The dose distribution inside the body, which is needed to estimate the exposures from a result of personal dosimetry, has been evaluated mostly by computational simulations, while experimental data to verify the simulations are not sufficiently supplied, in particular, in criticality accident situations. For the purpose of obtaining the experimental data on external exposures inside the body, a preliminary experiment on criticality accident dosimetry was carried out at the Transient Experiment Critical Facility (TRACY) using a human phantom and tissue-equivalent dosimeters. The neutron and -ray absorbed doses inside the phantom could be satisfactorily measured by the combined use of an alanine dosimeter and a thermoluminescent dosimeter made of enriched lithium tetra borate. The doses measured in and on the phantom were regarded as reasonable in dose level and distribution by comparison with the doses measured in the free air.
Iida, Yoshihisa; Taki, Hiroshi; Yamaguchi, Tetsuji; Tanaka, Tadao; Negishi, Kumi; Nakayama, Shinichi
JAERI-Conf 2005-007, p.230 - 235, 2005/08
A variation in data should be quantitatively incorporated in a probabilistic safety assessment of radioactive waste disposal. We focus our experimental efforts on parameters that induce major uncertainties in the radionuclide migration analysis and that have not been quantitatively assessed. Possible sources of uncertainty includes increase in ionic strength of groundwater caused by intrusion of seawater and/or dissolution of sodium nitrate in TRU waste, highly alkaline conditions originating from cementitious materials, and a variation of porewater composition accompanied with corrosion of. This study is a summary of current status of our investigations for solubility and diffusion.
Ebashi, Katsuhiro; Yamaguchi, Tetsuji; Tanaka, Tadao; Araki, Kunio*; Saito, Masao*
JAERI-Conf 2005-007, p.242 - 247, 2005/08
no abstracts in English
Mukai, Masayuki; Ueda, Masato; Inada, Daisuke; Yukawa, Kazuhiko; Maeda, Toshikatsu; Iida, Yoshihisa
Proceedings of International Symposium NUCEF 2005, p.219 - 224, 2005/08
For better quantitative understanding of radionuclide migration for safety assessment of geologic disposal, JAERI has been conducting experimental and modeling studies on influences of humic substances, highly alkaline conditions and colloids on sorptive and diffusional behavior of TRU in geologic materials. In the absence of fulvic acid, one of humic substances, diffusion of Am through a tuff sample was not detected. By adding fulvic acid, Am was detected in the downstream cell, which indicates the diffusion through the sample. Highly alkaline conditions arisen from cementitious materials may spread by altering chemical and physical properties of geologic materials. Through-diffusion experiments of alkaline species in granite showed that the effective diffusion coefficient of Ca and OH
in a cement-equilibrated aqueous solution were found to be higher by almost two orders of magnitude than Na
and OH
in a NaOH solution. Radionuclide migration can be enhanced by colloids, and thus a calculation code describing the effect of colloids on radionuclide migration has been required.
Ishidera, Takamitsu; Miyamoto, Shinya*; Sato, Haruo
JAERI-Conf 2005-007, p.264 - 269, 2005/05
For safety assessment of TRU waste disposal, the effective diffusion coefficients (De) for CO, Cl
and I
ions in compacted bentonite (Kunigel V1) were determined as a function of silica sand contents under hyper alkaline condition. The obtained De values for three diffusants were on the order of 10
- 10
m
/s and increased with increasing silica sand content. The effective porosity for diffusion of Cl
and I
ions, estimated from the rock capacity factor values, were also increased with increasing silica sand content. This close relationship indicated that the increases in the De values were due to the increase in effective porosity with increasing silica sand content. In the case of CO
ion, the rock capacity factor values were higher than those for Cl
and I
ions. The Da values for CO
ion were approximately one order of magnitude lower than those for Cl
and I
ions. The differences in these behaviors suggested a possibility of isotopic exchange of
C with the carbon of calcite contained in Kunigel V1.
Kurosawa, Susumi; Yui, Mikazu; Yoshikawa, Hideki
International Symposium NUCEF2005, 0 Pages, 2005/02
It is reported that the nuclide migration in groundwater is enhanced according to transport behavior of colloids compared with the migration behavior as the ion when the nuclide generates colloids. For example, in the colloids and radionuclide retardation experiment (CRR experiment) in the Grimusel test site in Switzerland had been performed as collaboration of JNC and NAGRA (Switzerland), the possibility that the nuclide migration was enhanced by the influence of the colloids in the groundwater was indicated. We will present on the simulations of the analysis by numerical code COLFRAC which describes colloid-facilitated solute transport in fractured media. Moreover, in order to evaluate the impact of microorganism on the performance assessment for geological disposal of HLW, we simulated effects of microorganism on radionuclide migration by using the COLFRAC code.
Miura, Akihiko
International Symposium NUCEF2005, 0 Pages, 2005/02
Based on some lessons learned from the accidents in the reprocessing plant all over the world, Japan Nuclear Cycle Development Institute (JNC) has researched and developed the safety technologies for the reprocessing plants and its related facilities. This paper describes some accidental information around the reprocessing plants and its related research activities in JNC.
Kurosawa, Susumi; Yui, Mikazu; Yoshikawa, Hideki
International Symposium NUCEF2005, 0 Pages, 2005/02
On the geological disposal of high-level radioactive waste (HLW), it is known that the actinide ion which is released from the HLW generates true-colloids with hydrolysis reaction, and forms pseudo- colloids by sorption reaction onto the colloids in the groundwater. Recently, it is reported that the radionuclide migration in groundwater is enhanced by transport behavior of colloids compared with the migration behavior of the solute. For example, the in-situ experiment on the colloids and radionuclide retardation (CRR experiment) in the Grimsel test site in Switzerland had been performed by the collaboration among NAGRA (Switzerland), ENRESA (Spain), ANDRA (France), FZK-INE (Germany), USDoE/SNL (U.S.A) and JNC (Japan), the possibility of the radionuclide migration enhancement by the influence of the colloids was indicated. We will present the modeling results by numerical code COLFRAC which describes colloid-facilitated solute transport in fractured media. Moreover, in order to evaluate the impact of microorganisms on the performance assessment for geological disposal of HLW, we simulated effects of microorganism as a colloid on radionuclide migration by using the COLFRAC code.