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Soler, J. M.*; Kek
linen, P.*; Pulkkanen, V.-M.*; Moreno, L.*; Iraola, A.*; Trinchero, P.*; Hokr, M.*; 
ha, J.*; Havlov
, V.*; Trpko
ov, D.*; et al.
Nuclear Technology, 209(11), p.1765 - 1784, 2023/11
Times Cited Count：2 Percentile：72.91(Nuclear Science & Technology)Tachi, Yukio; Ito, Tsuyoshi*; Akagi, Yosuke*; Sato, Hisao*; Martin, A. J.*
Water Resources Research, 54(11), p.9287 - 9305, 2018/11
Times Cited Count：5 Percentile：26.57(Environmental Sciences)Effects of fine-scale surface alterations on radionuclide migration in fractured crystalline rocks were investigated by a comprehensive approach coupling a series of laboratory tests, microscopic observations and modelling, using a single fractured granodiorite sample from the Grimsel Test Site, Switzerland. Laboratory tests including through-diffusion, batch sorption and flow-through tests using five tracers indicated that tracer retention was consistently in the sequence of HDO, Se, Cs, Ni, Eu, and as well as showing the existence of a diffusion-resistance layer near the fracture surface, cation excess and anion exclusion effects for diffusion. Microscale heterogeneities in structural properties around the fracture were clarified quantitatively by coupling X-ray CT and EPMA. A three layer model including weathered vermiculite, foliated mica and undisturbed matrix layers, and their properties such as porosity, sorption and diffusion parameters, could provide a reasonable interpretation for breakthrough curves and concentration distributions near fracture surface of all tracers, measured in flow-through tests.
Pratama, M. A.; Takahara, Shogo; Hato, Shinji*
Hoken Butsuri, 52(3), p.200 - 209, 2017/09
The purpose of this study is to identify the significance of the change in the intestinal absorption rate values the (
value) to the change of dose coefficient as well as to provide a list of dose coefficients which each of the value corresponds to a specific intestinal absorption rate and age groups. In the range of 0-1, 10 different values of for 1 year, 5 years old, and adult group were chosen and used in a separate calculation by using, a biokinetic compartment model, DCAL. It was found that the lower values of intestinal absorption rate lead to a significant decrease of the committed effective coefficient for adult. Oppositely for children, the decrease of committed effective coefficient was not as significant. This study also suggests that the significance of dose coefficient change due to the variation of substantially depends on the biological half-life of the radionuclide and the mass of organs and tissues in human body.
Niunoya, Sumio*; Aoyagi, Kazuhei; Fujita, Tomoo; Shirase, Mitsuyasu*
Dai-44-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.336 - 341, 2016/01
In the Horonobe Underground Research Laboratory, rock mass classification and determination of mechanical properties of rock mass was conducted considering the effect of the density of fractures in the rock mass. In this paper, the authors report the mechanical properties of rock mass detected by plate loading tests and in situ shear tests in the 250 m and 350 m galleries. As a result, the failure criteria based on the result of in situ shear tests provides the most conservative value for the design of support pattern and assessment of stability of the gallery.
Soler, J. M.*; Landa, J.*; Havlov, V.*; Tachi, Yukio; Ebina, Takanori*; Sardini, P.*; Siitari-Kauppi, M.*; Eikenberg, J.*; Martin, A. J.*
Journal of Contaminant Hydrology, 179, p.89 - 101, 2015/08
Times Cited Count：39 Percentile：81.5(Environmental Sciences)Matrix diffusion is a key process for radionuclide retention in crystalline rocks. An in-situ diffusion experiment in granite matrix was performed at the Grimsel Test Site (Switzerland). Several tracers (HTO, Na
, Cs) were circulated through a borehole and the decrease in tracer concentrations was monitored for 2.5 years. Then, the borehole section was overcored and the tracer profiles in the rock were analyzed. Transport distances in the rock were 20 cm for HTO, 10 cm for Na and 1 cm for Cs. The dataset was analyzed with diffusion-sorption models by different teams using different codes, with the goal of obtaining effective diffusivities (De) and rock capacity factors. There was a rather good agreement between the values from different teams, implied that De and capacity factors in the borehole damaged zone are larger than those in the bulk rock. However, HTO seems to display large discrepancies between measured and modeled results.
Ono, Tomio*; Subekti, M.*; Kudo, Kazuhiko*; Takamatsu, Kuniyoshi; Nakagawa, Shigeaki; Nabeshima, Kunihiko
Nihon Genshiryoku Gakkai Wabun Rombunshi, 4(2), p.115 - 126, 2005/06
Control-rod withdrawal tests simulating reactivity insertion are carried out in the HTTR to verify the inherent safety features of HTGRs. This paper describes pre-test analysis method using artificial neural networks to predict the changes of reactor power and reactivity. The network model applied in this study is based on recurrent neural networks. The inputs of the network are the changes of the central control rods position and other significant core parameters, and the outputs are the changes of reactor power and reactivity. Furthermore, Time Synchronizing Signal(TSS) is added to input to improve the modeling of time series data. The actual tests data, which were previously carried out in the HTTR, were used for learning the model of the plant dynamics. After the learning, the network can predict the changes of reactor power and reactivity in the following tests.
Sato, Hiroyuki; Ohashi, Hirofumi; Inaba, Yoshitomo; Maeda, Yukimasa; Takeda, Tetsuaki; Nishihara, Tetsuo; Inagaki, Yoshiyuki
JAERI-Tech 2005-014, 89 Pages, 2005/03
JAERI-Tech-2005-014.pdf:7.25MB
In a hydrogen production system using HTTR, it is required to control a secondary helium gas temperature within an allowable value at an intermediate heat exchanger (IHX) inlet to prevent a reactor scram. To mitigate thermal disturbance of the secondary helium gas caused by the hydrogen production system, a cooling system of the secondary helium gas using a steam generator(SG) and a radiator will be installed at the downstream of the chemical reactor. In order to verify a numerical analysis code of the cooling system, numerical analysis has been conducted. The pressure controllability in SG is highly affected by the heat transfer characteristics of air which flows outside of the heat exchanger tube of the radiator. In order to verify a numerical analysis code of the cooling system, the heat transfer characteristics of air has been investigated with experimental results of a mock-up model test. It was confirmed that numerical analysis results were agreed well with experimental results, and the analysis code was successfully verified.
Takeda, Nobukazu; Nakahira, Masataka
JAERI-Tech 2004-073, 59 Pages, 2005/01
JAERI-Tech-2004-073.pdf:11.36MB
The ITER toamak is composed of major components such as superconducting magnet and vacuum vessel whose operation temperatures are changed from room temperature to 4 K and room temperature to 200
C, respectively. The gravity support of the tokamak is flexible in order to accept the thermal deformation caused by temperature change. This structural feature causes the complex behaviors of the tokamak during seismic events. Therefore, the mechanical characteristics of the flexible support have to be investigated in detail. The present report describes the global plan of the series of vibration tests to estimate the seismic performance of the ITER tokamak. Although it is ideal that the vibration tests are carried out using a full-scale model, scale models are planned due to the limitation of the test facilities. The test results can be estimated by a scaling law. When the scaling law cannot be applied to some performances, the test is performed using a full-scale model. In addition, the other tests such as vacuum vessel and small-scaled models of the support structure are also planned.
Takeda, Nobukazu; Kakudate, Satoshi; Nakahira, Masataka
JAERI-Tech 2004-072, 43 Pages, 2005/01
JAERI-Tech-2004-072.pdf:6.06MB
The vibration experiments of the support structures with flexible plates for the ITER major components such as the vacuum vessel (VV) and the toroidal field (TF) coil were performed aiming to obtain its basic mechanical characteristics. Based on the experimental results, numerical analysis regarding the actual support structure was performed and a simplified model of the support structure was proposed. A support structure was modeled by only two spring elements. The stiffness calculated by the spring model agrees well with that of shell model, simulating actual structures based on the experimental results. It is therefore found that the spring model with the only two values of stiffness enables to simplify the complicated support structure with flexible plates. Using the spring model, the dynamic analysis of the VV and TF coil were performed to estimate the integrity under the design earthquake. As a result, the maximum relative displacement of 8.6 mm between VV and TF coil is much less than designed clearance, 100 mm, so that the integrity of the components is ensured.
I released from HanfordThiessen, K. M.*; Napier, B. A.*; Filistovic, V.*; Homma, Toshimitsu; Kanyr, B*; Krajewski, P.*; Kryshev, A. I.*; Nedveckaite, T.*; N
nyei, A.*; Sazykina, T. G.*; et al.
Journal of Environmental Radioactivity, 84(2), p.211 - 224, 2005/00
Times Cited Count：9 Percentile：21.64(Environmental Sciences)The Hanford test scenario described an accidental release of I to the environment from the Hanford Purex Chemical Separations Plant in September 1963. Based on monitoring data collected after the release, this scenario was used by the Dose Reconstruction Working Group of BIOMASS. Predicted doses to actual children with high milk consumption ranged from 0.006 to 2 mSv. The predicted deposition at any given location varied among participants by a factor of 5 to 80. Predicted ingestion doses for children, normalized for predicted deposition, varied by about a factor of 10. The exercise provided an opportunity for comparison of assessment methods and conceptual approaches, testing model predictions against measurements, and identifying the most important contributors to uncertainty in the assessment result. Key factors affecting predictions included the approach to handling incomplete data, interpretation of input information, selection of parameter values, adjustment of models for sitespecific conditions, and treatment of uncertainties.
Cs from Chernobyl fallout in the Iput River catchment area of RussiaThiessen, K. M.*; Sazykina, T. G.*; Apostoaei, A. I.*; Balonov, M. I.*; Crawford, J.*; Domel, R.*; Fesenko, S.*; Filistovic, V.*; Galeriu, D.*; Homma, Toshimitsu; et al.
Journal of Environmental Radioactivity, 84(2), p.225 - 244, 2005/00
Times Cited Count：7 Percentile：17.22(Environmental Sciences)Data collected following the Chernobyl accident in 1986 have provided a unique opportunity to test the reliability of computer models for contamination of terrestrial and aquatic environments. The Iput River scenario was used by the Dose Reconstruction Working Group of BIOMASS. The test area was one of the most highly contaminated areas in Russia following the accident, with an average contamination density of Cs of 800, 000 Bq m
and localized contamination up to 1,500,000 Bq m, and a variety of countermeasures that were implemented in the test area had to be considered in the modelling exercise. Difficulties encountered during the exercise included averaging of data to account for uneven contamination of the test area, simulating the downward migration and decrease in bioavailability of Cs in soil, and modelling the effectiveness of countermeasures. The accuracy of model predictions is dependent at least in part on the experience and judgment of the participant in interpretation of input information, selection of parameter values, and treatment of uncertainties.
Onozuka, Masanori*; Takeda, Nobukazu; Nakahira, Masataka; Shimizu, Katsusuke*; Nakamura, Tomomichi*
Fusion Engineering and Design, 69(1-4), p.757 - 762, 2003/09
Times Cited Count：2 Percentile：19(Nuclear Science & Technology)The dynamic behavior of the ITER tokamak assembly has been investigated. Three experimental models have been considered to validate the numerical analysis methods for the dynamic events, mainly seismic events. A 1/8-scaled tokamak model, which is based on the 1998 ITER design, is under construction. Non-linear vibration characteristics, such as damping, can only be identified by a full-scale model. Therefore, a full-scale gravity support structure for the coil system has been designed and will be tested. In addition, for the sub-scaled tokamak model, the VV is assumed to be a rigid structure. This assumption is to be verified using a 1/20-scaled model. The above experimental models and their testing conditions have analytically and numerically evaluated. For example, both the static and dynamic spring constants obtained by static analysis and eigen-value analysis, respectively, were evaluated to be in good agreement.
Ueta, Shohei; Sumita, Junya; Emori, Koichi; Takahashi, Masashi*; Sawa, Kazuhiro
Journal of Nuclear Science and Technology, 40(9), p.679 - 686, 2003/09
Times Cited Count：13 Percentile：64.66(Nuclear Science & Technology)no abstracts in English
Inagaki, Yoshiyuki; Hayashi, Koji; Kato, Michio; Fujisaki, Katsuo; Aita, Hideki; Takeda, Tetsuaki; Nishihara, Tetsuo; Inaba, Yoshitomo; Ohashi, Hirofumi; Katanishi, Shoji; et al.
JAERI-Tech 2003-034, 129 Pages, 2003/05
JAERI-Tech-2003-034.pdf:7.62MB
no abstracts in English
Thiessen, K. M.*; Napier, B. A.*; Filistovic, V.*; Homma, Toshimitsu; Kanyr, B*; Krajewski, P.*; Kryshev, A. I.*; Nedveckaite, T.*; Nnyei, A.*; Sazykina, T. G.*; et al.
Proceedings from the International Conference on Radioactivity in the Environment, p.313 - 316, 2002/09
no abstracts in English
Cs from Chernobyl fallout in the Iput River catchment area of RussiaThiessen, K. M.*; Sazykina, T. G.*; Apostoaei, A. I.*; Balonov, M.*; Crawford, J.*; Domel, R.*; Fesenko, S.*; Filistovic, V.*; Galeriu, D.*; Homma, Toshimitsu; et al.
Proceedings from the International Conference on Radioactivity in the Environment, p.317 - 320, 2002/09
no abstracts in English
Martin, D. G.*; Sawa, Kazuhiro; Ueta, Shohei; Sumita, Junya
JAERI-Research 2001-033, 19 Pages, 2001/05
JAERI-Research-2001-033.pdf:1.2MB
no abstracts in English
Isono, Takaaki; Nishijima, Gen; Sugimoto, Makoto; Nunoya, Yoshihiko; Wakabayashi, Hiroshi*; Tsuji, Hiroshi
JAERI-Tech 2000-084, 393 Pages, 2001/02
JAERI-Tech-2000-084.pdf:16.39MB
no abstracts in English
Nakayama, Teruyuki; Kato, Shohei
Radiation Risk Assessment Workshop Proceedings, p.140 - 150, 2001/00
no abstracts in English
Fujimoto, Nozomu; Yamashita, Kiyonobu
JAERI-Research 99-059, p.43 - 0, 1999/11
JAERI-Research-99-059.pdf:2.51MB
no abstracts in English
