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JAEA Reports

Review and evaluation on the surface area of vitrified products of high-level waste; Surface area increase factors due to fracturing and their bases for the performance assessment of geological disposal

Igarashi, Hiroshi

JAEA-Review 2020-006, 261 Pages, 2020/09

JAEA-Review-2020-006.pdf:4.42MB

A literature review was conducted on the increase in surface area of vitrified products of HLW due to the fracturing caused by cooling during glass pouring process and by mechanical impact, from the perspective of a parameter of the radionuclide release model in the performance assessment of geological disposal system studied overseas. The review was focused on the value of surface area increase factor set as a parameter in the model, the experimental work to evaluate an increase in surface area, and how the parameters on surface area were determined based on the experimental results. The surface area obtained from the experiments executed in Japan was also discussed in comparison with the overseas studies. On the basis of the investigation, the effects of various conditions on the surface area were studied, such as a diameter of vitrified product, cooling condition during and after the glass pouring, impact on vitrified products during their handling, environment after the closure of disposal facility, and others. The causes of fracturing are associated with the phenomena or events in the waste management process such as production, transport, storage, and disposal. The surface area increase factors set in the nuclide release model of the glass and their bases were reviewed. In addition, the measured values and the experimental methods for surface increase factors published so far were compared. Accordingly, the methods for measuring surface area as the bases were identified for these factors set in the models. The causes of fracturing and features of these factors were studied with respect to the relation with the waste management process. The results from the review and assessment can contribute to the expanding the knowledge for the conservative and realistic application of these factors to performance assessment, and to the developing and upgrading of safety case as a consequence.

Journal Articles

Applicability study of nuclear graphite material IG-430 to VHTR

Osaki, Hirotaka; Shimazaki, Yosuke; Sumita, Junya; Shibata, Taiju; Konishi, Takashi; Ishihara, Masahiro

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 8 Pages, 2015/05

For the design on the VHTR graphite components, it is desirable to employ graphite material with higher strength. IG-430 graphite has been developed as an advanced candidate for VHTR. However, the new developed IG-430 does not have enough databases for the design of HTGR. In this paper, the compressive strength (Cs) of IG-430, one of important strengths for design data, is statistically evaluated. The component reliability is evaluated based on the safety factors defined by the graphite design code, and the applicability as the VHTR graphite material is discussed. It was found that IG-430 has higher strength (about 11%) and lower standard deviation (about 27%) than IG-110 which is one of traditional graphites used for HTGR, because the crack in IG-430 would not easy to propagate rather than IG-110. Since fracture probability for IG-430 is low, the higher reliability of core-component will be achieved using IG-430. It is expected that IG-430 is applicable for VHTR graphite material.

Journal Articles

Comparisons of small ELM H-mode regimes on the Alcator C-Mod and JFT-2M tokamaks

Hubbard, A. E.*; Kamiya, Kensaku; Oyama, Naoyuki; Basse, N.*; Biewer, T.*; Edlund, E.*; Hughes, J. W.*; Lin, L.*; Porkolab, M.*; Rowan, W.*; et al.

Plasma Physics and Controlled Fusion, 48(5A), p.A121 - A129, 2006/05

 Times Cited Count:15 Percentile:49.06(Physics, Fluids & Plasmas)

Dedicated experiments were carried out to compare the properties, fluctuation behaviour and access conditions of these regimes. A common shape was developed which scaled the plasma boundary except for aspect ratio. Scans of density and input power were carried out at several values of q95, so as to achieve ranges of dimensionless parameters. A striking similarity of access conditions was seen. These results suggest common physical mechanisms for the H-mode regimes, which do not depend critically on aspect ratio over this range. On the other hand, several differences in the details of the edge fluctuations were found, and will be reported. The effect of wall conditioning via boronization on the H-mode regimes will also be discussed.

Journal Articles

Recent RF experiments and application of RF waves to real-time control of safety factor profile in JT-60U

Suzuki, Takahiro; Isayama, Akihiko; Ide, Shunsuke; Fujita, Takaaki; Oikawa, Toshihiro; Sakata, Shinya; Sueoka, Michiharu; Hosoyama, Hiroki*; Seki, Masami; JT-60 Team

AIP Conference Proceedings 787, p.279 - 286, 2005/09

A real-time control system of safety factor (q) profile was developed in JT-60. This system, for the first time, enables 1) real time evaluation of q profile using local magnetic pitch angle measurement by motional Stark effect (MSE) diagnostic and 2) control of current drive (CD) location (rhoCD) by adjusting the parallel refractive index $$N_{rm //}$$ of lower-hybrid (LH) waves through the change of phase difference (dphi) of LH waves between multi-junction launcher modules. The method for q profile evaluation was newly developed, without time-consuming reconstruction of equilibrium, so that the method requires less computational time. The system evaluates q profile within every 10ms, which is much faster than current relaxation time, typically order of 1s. Safety factor profile by the real-time calculation agreed well with that by equilibrium reconstruction with MSE. From temporal evolution of q (or current) profile, we evaluate CD location in real-time, too. The control system controls rhoCD through $$N_{rm //}$$ (or directly dphi) in such a way to minimize difference between the real-time evaluated q profile and its reference profile. The real-time control system was applied to positive shear plasmas ($$q(0)sim 1$$), having plasma current of 0.6MA, toroidal field of 2.3T, and electron density of $$0.5times 10^{19}{rm m}^{-3}$$. In order to keep good coupling of LH waves to the plasma, gap between the launcher and the plasma surface was controlled to about 0.1m. The reference q profile was set to q(0)=1.3. The real-time q profile approached to the reference after application of real-time control; the controlled q profile was sustained for 3s, which was limited by injected LH power. RF experiments in JT-60U, such as stabilization of neo-classical tearing modes, plasma startup experiments, etc., are also presented.

Journal Articles

Study of a drift wave-zonal mode system based on global electromagnetic landau-fluid ITG simulation in toroidal plasmas

Miyato, Naoaki; Li, J. Q.*; Kishimoto, Yasuaki

Nuclear Fusion, 45(6), p.425 - 430, 2005/06

 Times Cited Count:22 Percentile:60.74(Physics, Fluids & Plasmas)

Using a global Landau fluid code in toroidal geometry, an electromagnetic ion temperature gradient (ITG) driven turbulence-zonal mode system is investigated. Two different types of zonal flows, i.e. stationary zonal flows in a low $$q$$ (safety factor) region and oscillatory ones in a high $$q$$ region which are called geodesic acoustic modes (GAM), are found to be simultaneously excited in a torus. The stationary flows efficiently suppress turbulent transport, while the oscillatory ones weakly affect the turbulence due to their time varying nature. Therefore in the low $$q$$ region where the zonal flows are almost stationary, the zonal flows are dominant over the turbulence. On the other hand, the turbulence is still active in the high $$q$$ region where the zonal flows are oscillatory.

Journal Articles

Study of drift wave-zonal mode system based on global electromagnetic landau-fluid ITG simulation in toroidal plasmas

Miyato, Naoaki; Li, J. Q.*; Kishimoto, Yasuaki

IAEA-CN-116/TH/8-5Rb (CD-ROM), 8 Pages, 2004/11

Using a global Landau fluid code in toroidal geometry, an electromagnetic ion temperature gradient (ITG) driven turbulence-zonal mode system is investigated. Two different types of zonal flows, i.e. stationary zonal flows in a low $$q$$ (safety factor) region and oscillatory ones in a high $$q$$ region which are called geodesic acoustic modes (GAM), are found to be simultaneously excited in a torus. The stationary flows efficiently suppress turbulent transport, while the oscillatory ones weakly affect the turbulence due to their time varying nature. Therefore in the low $$q$$ region where the zonal flows are stationary, the zonal flows are dominant over the turbulence. On the other hand, the turbulence is still active in the high $$q$$ region where the zonal flows are oscillatory.

Journal Articles

Observation of high recycling steady H-mode edge and compatibility with improved core confinement mode on JFT-2M

Kamiya, Kensaku; Kimura, Haruyuki; Ogawa, Hiroaki; Kawashima, Hisato; Tsuzuki, Kazuhiro; Sato, Masayasu; Miura, Yukitoshi; JFT-2M Group

Nuclear Fusion, 43(10), p.1214 - 1219, 2003/10

 Times Cited Count:34 Percentile:72.26(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

International studies on burnup credit criticality safety by an OECD/NEA working group, 2; Calculation benchmarks for BWR spent fuels

; *; Suyama, Kenya; Ando, Yoshihira*

Proceedings of 6th International Conference on Nuclear Criticality Safety (ICNC '99), 2, p.566 - 575, 1999/00

no abstracts in English

Journal Articles

Effects of organic solvent on infinite neutron multiplication factor of homogeneous plutonium nitrate solution system

Sakurai, Satoshi; Arakawa, Takuya*;

Journal of Nuclear Science and Technology, 35(5), p.365 - 369, 1998/05

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Measurement of the equivalent fundamental-mode source strength

G.D.Spriggs*; R.D.Busch*; Sakurai, Takeshi; Okajima, Shigeaki

Transactions of the American Nuclear Society, 76, p.374 - 375, 1997/06

no abstracts in English

Journal Articles

Progress of LWR safety research in Japan

Kosaka, Atsuo; ; Sugimoto, Jun

10th Pacific Basin Nuclear Conf. (10-PBNC), 1, p.341 - 346, 1996/00

no abstracts in English

Journal Articles

Summary of experiments and analyses from the JAERI/USDOE collaborative program on fusion blanket neutronics

Maekawa, Hiroshi; M.A.Abdou*

Fusion Engineering and Design, 28, p.479 - 491, 1995/00

no abstracts in English

JAEA Reports

DANKE: A Monte Carlo computer program for calculating the Dancoff correction factor for spheres, rods and slabs

Okuno, Hiroshi; Komuro, Yuichi

JAERI-M 94-049, 28 Pages, 1994/03

JAERI-M-94-049.pdf:0.55MB

no abstracts in English

JAEA Reports

Nuclear hot spot factor of JMTR-LEU core

Nagaoka, Yoshiharu; Komukai, Bunsaku; ; Saito, Minoru;

JAERI-M 92-042, 92 Pages, 1992/03

JAERI-M-92-042.pdf:2.18MB

no abstracts in English

JAEA Reports

Effect of fuel density on neutron multiplication factor

*; Naito, Yoshitaka

JAERI-M 91-164, 25 Pages, 1991/10

JAERI-M-91-164.pdf:0.73MB

no abstracts in English

Journal Articles

Evaluation Methods of resonance absorption for system with pellet surrounded by fuel solution

; ; *

Journal of Nuclear Science and Technology, 27(9), p.870 - 874, 1990/09

no abstracts in English

JAEA Reports

A Revision of MUTUAL; A Computer code for analysing nuclear criticality safety on array system

Okuno, Hiroshi; Naito, Yoshitaka; *; *

JAERI-M 89-140, 32 Pages, 1989/10

JAERI-M-89-140.pdf:0.65MB

no abstracts in English

JAEA Reports

JAEA Reports

25 (Records 1-20 displayed on this page)