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JAEA Reports

Deuterium Critical Assembly (DCA) Decommissioning work in 2013

Morita, Kenji; Morimoto, Makoto; Hisada, Masaki; Fukui, Yasutaka

JAEA-Technology 2015-037, 28 Pages, 2016/01


Deuterium Critical Assembly (DCA) achieved first critically in 1969 and used for research and development program of Advanced Thermal Reactor. To achieved the aim of facility, DCA decommissioning work started in 2002. Decommissioning schedule consists of 4 stages. The third stage, which is the main work (To dismantle and remove reactor vessel and main equipment), was started in 2008 and will be finished at 2023. This report describes DCA decommissioning work and data (Ability of cutting tools and Man-hours) in 2013.

Journal Articles

Investigation of hydrogen isotope permeation through F82H steel with and without a ceramic coating of Cr$$_{2}$$O$$_{3}$$-SiO$$_{2}$$ including CrPO$$_{4}$$, Out-of-pile tests

Kulsartov, T. V.*; Hayashi, Kimio; Nakamichi, Masaru*; Afanasyev, S. E.*; Shestakov, V. P.*; Chikhray, Y. V.*; Kenzhin, E. A.*; Kolbaenkov, A. N.*

Fusion Engineering and Design, 81(1-7), p.701 - 705, 2006/02

 Times Cited Count:33 Percentile:90.23(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Deuterium depth profiling in JT-60U W-shaped divertor tiles by nuclear reaction analysis

Hayashi, Takao; Ochiai, Kentaro; Masaki, Kei; Goto, Yoshitaka*; Kutsukake, Chuzo; Arai, Takashi; Nishitani, Takeo; Miya, Naoyuki

Journal of Nuclear Materials, 349(1-2), p.6 - 16, 2006/02

 Times Cited Count:10 Percentile:59.81(Materials Science, Multidisciplinary)

Deuterium concentrations and depth profiles in plasma-facing graphite tiles used in the divertor of JT-60U were investigated by NRA. The highest deuterium concentration of D/$$^{12}$$C of 0.053 was found in the outer dome wing tile, where the deuterium accumulated probably through the deuterium-carbon co-deposition. In the outer and inner divertor target tiles, the D/$$^{12}$$C data were lower than 0.006. Additionally, the maximum (H+D)/$$^{12}$$C in the dome top tile was estimated to be 0.023 from the results of NRA and SIMS. OFMC simulation showed energetic deuterons caused by NBI were implanted into the dome region with high heat flux. Furthermore, the surface temperature and conditions such as deposition and erosion significantly influenced the accumulation process of deuterium. The deuterium depth profile, SEM observation and OFMC simulation indicated the deuterium was considered to accumulate through three processes: the deuterium-carbon co-deposition, the implantation of energetic deuterons and the deuterium diffusion into the bulk.

Journal Articles

Incident energy dependence of blistering at tungsten irradiated by low energy high flux deuterium plasma beams

Luo, G.; Shu, Wataru; Nishi, Masataka

Journal of Nuclear Materials, 347(1-2), p.111 - 117, 2005/12

 Times Cited Count:74 Percentile:98.03(Materials Science, Multidisciplinary)

Polycrystalline tungsten samples have been irradiated at room temperature by high flux (1$$times$$10$$^{22}$$ D/m$$^{2}$$/s) deuterium plasma beams with incident energies ranging 7 $$sim$$ 98 eV/D. Surface blistering occurred at all energies. The critical fluence for blistering $$Phi$$$$_{cr}$$ was found to increase with decreasing the incident energy. At energies $$<$$ 20 eV/D, $$Phi$$$$_{cr}$$ increased more rapidly. This energy dependence of $$Phi$$$$_{cr}$$ may be explained by a proposed model dealing with the oxide barrier to deuterium uptake into and release from the bulk W. At all energies, the blisters increased in their size and number with fluence within the corresponding low fluence ranges. However the size stopped increasing at certain fluences, while the number kept increasing within the experimental fluence range, which could be attributed to rupturing of blisters at a certain size of about 2$$mu$$m.

Journal Articles

Formation of organically bound deuterium at each growing stage of rice

Atarashi-Andoh, Mariko; Kumakura, Yasuharu*; Amano, Hikaru; Fukui, Masami*

Fusion Science and Technology, 48(1), p.771 - 774, 2005/07

 Times Cited Count:2 Percentile:18.81(Nuclear Science & Technology)

Uptake of tritium by food plants is an important pathway in transferring tritium to the human body. Plants take up tritium as the form of water and a part of tritiated water (HTO) is converted to organically bound tritium (OBT). The formation of OBT in plants depends on the growth stage when the contamination occurs. Potted rice plants were exposed to deuterated water vapor, as a substitute for HTO vapor, for 4 h at 5 different times during the grain ripening period to estimate the influence of the growth stage on the formation and retention of organically bound deuterium (OBD) in rice. The plants were grown outside before and after the exposure experiments and were exposed to deuterated water vapor in a laboratory in a small chamber equipped with controllers of temperature, humidity and light intensity.The mass of OBD in grain at harvest showed the highest value when the exposure was carried out in the early stage of the ripening period. When the exposure was carried out after 26 day from the heading, the increase of OBD in the grain was a little.

Journal Articles

Intelligible seminor on fusion reactors, 1; Introduction to fusion reactors

Ueda, Yoshio*; Inoue, Takashi; Kurihara, Kenichi

Nihon Genshiryoku Gakkai-Shi, 46(12), p.845 - 852, 2004/12

no abstracts in English

Journal Articles

CARS study of deuterium clusters stabilized in solid helium

Gordon, E. B.*; Kumada, Takayuki; Ishiguro, Masazumi; Aratono, Yasuyuki

Journal of Experimental and Theoretical Physics, 99(4), p.776 - 783, 2004/10

The solid Deuterium clusters for the first time isolated in a matrix of solid Helium have been investigated at T = 1.3K and P = 3 MPa by CARS (Coherent anti-Stokes Raman spectroscopy) technique. The Q1(J=0) and Q1(J=1) lines intensity, shape and positions have been studied as the functions of ortho- para content in the solid, as well as of clusters size. The strong effect of Raman scattering cross section sensitivity to the molecular environment nuclear spin state has been found in CARS; the ratio of probabilities for the scattering by para (J=1) and ortho (J=0) deuterium being equal to 1 in a gas is as high as 10,000 in nearly pure o-D2, whereas it is about 50 in spontaneous Raman scattering. This effect has been shown to give rise starting from cluster size corresponding to the phonon band onset.

Journal Articles

A Neutron crystallographic analysis of a rubredoxin mutant at 1.6 ${AA}$ resolution

Chatake, Toshiyuki*; Kurihara, Kazuo; Tanaka, Ichiro*; Tsyba, I.*; Bau, R.*; Jenney, F. E. Jr.*; Adams, M. W. W.*; Niimura, Nobuo

Acta Crystallographica Section D, 60(8), p.1364 - 1373, 2004/08

 Times Cited Count:31 Percentile:88.46(Biochemical Research Methods)

A neutron diffraction study has been carried out at 1.6 ${AA}$ resolution on a mutant rubredoxin from ${it Pyrococcus furiosus}$ using the BIX-3 single-crystal diffractometer at the JRR-3 reactor of JAERI. In order to study the unusual thermostability of rubredoxin from ${it P. furiosus}$, the hydrogen-bonding patterns were compared between the native and a 'triple-mutant' variant where three residues were changed so that they are identical to those in a mesophilic rubredoxin. In the present study, some minor changes were found between the wild-type and mutant proteins in the hydrogen-bonding patterns of the Trp3/Tyr3 region. The H/D-exchange ratios in the protein were also studied. The results suggest that the backbone amide bonds near the four Cys residues of the FeS$$_{4}$$ redox center are most resistant to H/D exchange. In addition, the 1.6 ${AA}$ resolution of the present neutron structure determination has revealed a more detailed picture than previously available of some portions of the water structure, including ordered and disordered O-D bonds.

Journal Articles

Measurement of deuterium and tritium retentions on the surface of JT-60 divertor tiles by means of nuclear reaction analysis

Ochiai, Kentaro; Hayashi, Takao; Kutsukake, Chuzo; Goto, Yoshitaka*; Masaki, Kei; Arai, Takashi; Miya, Naoyuki; Nishitani, Takeo

Journal of Nuclear Materials, 329-333(Part1), p.836 - 839, 2004/08

 Times Cited Count:4 Percentile:30.82(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Energetic deuterium and helium irradiation effects on chemical structure of CVD diamond

Sasaki, Masayoshi*; Morimoto, Yasutomi*; Kimura, Hiromi*; Takahashi, Koji; Sakamoto, Keishi; Imai, Tsuyoshi; Okuno, Kenji*

Journal of Nuclear Materials, 329-333(Part1), p.899 - 903, 2004/08

A CVD diamond has been the reference material of a torus widow for a rf heating system in a fusion reactor. Since the window is in the circumstance of tritium, helium and radio activated dust, it is important to elucidate the effect of ions on chemical structure of the diamond, existing states of tritium and tritium inventory. Polycrystalline CVD diamond disks($$phi$$=10.0mm, t=0.21mm) used in this study are the same grade as rf windows. After sputtering the surface with 1.0 keV Ar$$^{+}$$ to remove oxygen impurity, the sample was irradiated with deuterium (D$$_{2}$$$$^{+}$$) or helium ions (He$$^{+}$$) at an angle of 0 degrees to the surface normal. The irradiation energies of deuterium and helium are 0.25 keV D$$^{+}$$ and 0.45 keV He$$^{+}$$, respectively. The structural change of the irradiated sample was measured by X-ray Photoelectron Spectroscopy (XPS) technique. The C1s peak shift toward lower binding energy side was observed when deuterium ions irradiated. This result indicates that the diamond changes to amorphous carbon due to formation of C-D bond.

Journal Articles

Irradiation test on Mo- and W-mirrors for ITER by low energy deuterium ions

Sugie, Tatsuo; Kasai, Satoshi; Taniguchi, Masaki; Nagatsu, Masaaki*; Nishitani, Takeo

Journal of Nuclear Materials, 329-333(2), p.1481 - 1485, 2004/08

 Times Cited Count:30 Percentile:87.54(Materials Science, Multidisciplinary)

In ITER, the effect of lower energy particle bombardment is important for mirrors located near the divertor where the low temperature plasma is formed. The test pieces of molybdenum mirrors and a tungsten mirror were irradiated by high flux and low energy (67-80 eV) deuterium ions using SLEIS (Super Low Energy Ion Source with High Ion Flux) facility at the temperature of around 100 $$^{circ}$$C. The molybdenum mirror manufactured by sintering and melting the thin layer of the surface by electron beam in order to eliminate holes on the surface has a higher reflectivity before irradiation than the mirrors without melting the surface, but the reflectivity decreases rapidly with the irradiation fluence due to the generation of blisters on the mirror surface. The reflectivity of molybdenum mirror manufactured by sintering only did not decrease so significantly (less than 10 % at the fluence of 1.3 $$times$$ 10$$^{25}$$ m$$^{-2}$$). The molybdenum and tungsten mirrors manufactured by sintering without melting the surface have a potential for plasma facing mirrors in ITER.

Journal Articles

Neutron crystallographic study on rubredoxin from ${it Pyrococcus furiosus}$ by BIX-3, a single-crystal diffractometer for biomacromolecules

Kurihara, Kazuo; Tanaka, Ichiro*; Chatake, Toshiyuki*; Adams, M. W. W.*; Jenney, F. E. Jr.*; Moiseeva, N.*; Bau, R.*; Niimura, Nobuo

Proceedings of the National Academy of Sciences of the United States of America, 101(31), p.11215 - 11220, 2004/08

 Times Cited Count:46 Percentile:62.17(Multidisciplinary Sciences)

The structure of a rubredoxin (Rd) from ${it Pyrococcus furiosus}$, an organism that grows optimally at 100 $$^{circ}$$C, was determined using the neutron single-crystal diffractometer for biological macromolecules (BIX-3) at the JRR-3 reactor of JAERI. Data were collected at room temperature up to a resolution of 1.5 ${AA}$, and the completeness of the data set was 81.9 %. The model contains 306 H atoms and 50 D atoms. A total of 37 hydration water molecules were identified. The model has been refined to final agreement factors of ${it R}$ = 18.6 % and ${it R}$$$_{free}$$ = 21.7 %. Several orientations of the O-D bonds of side chains, whose assignments from X-ray data were previously ambiguous, were clearly visible in the neutron structure. While most backbone N-H bonds had undergone some degree of H/D exchange throughout the molecule, five H atom positions still had distinctly negative (H) peaks. The neutron Fourier maps clearly showed the details of an extensive set of H bonds involving the ND$$_{3}$$$$^{+}$$ terminus that may contribute to the unusual thermostability of this molecule.

Journal Articles

Counter-permeation of deuterium and hydrogen through INCONEL 600

Takeda, Tetsuaki; Iwatsuki, Jin*

Nuclear Technology, 146(1), p.83 - 95, 2004/04

 Times Cited Count:6 Percentile:36.97(Nuclear Science & Technology)

The objective of this study is to investigate the effect of the existence of hydrogen in a pipe outside on the amount of permeated deuterium through the pipe. It was found that the amount of permeated deuterium decreases with increasing the partial pressure of hydrogen in the pipe outside when the partial pressure of deuterium in the pipe is lower than 100 Pa and that of hydrogen in the pipe outside is higher than 10 kPa. The amount of permeated deuterium on counter permeation was predicted quantitatively by using an effectiveness factor for diffusivity of deuterium in metals and by taking into account the equilibrium state for hydrogen, deuterium and HD molecules on the metal surface. From the results obtained in this study, it is supposed that the amount of tritium transferred from the primary circuit of the HTTR to the hydrogen production system will be reduced by the existence of high-pressure hydrogen in the catalyst pipe of the steam reformer.

Journal Articles

Permeability of hydrogen and deuterium of Hastelloy XR

Takeda, Tetsuaki; Iwatsuki, Jin*; Inagaki, Yoshiyuki

Journal of Nuclear Materials, 326(1), p.47 - 58, 2004/03

 Times Cited Count:17 Percentile:74.24(Materials Science, Multidisciplinary)

Permeation of hydrogen isotope through a high-temperature alloy used as heat exchanger and steam reformer pipes is an important problem in the hydrogen production system connected to be a High-Temperature Engineering Test Reactor (HTTR). An experiment of hydrogen (H$$_{2}$$) and deuterium (D$$_{2}$$) permeation was performed to obtain permeability of H$$_{2}$$ and D$$_{2}$$ of Hastelloy XR, which is adopted as heat transfer pipe of an intermediate heat exchanger of the HTTR. Permeability of H$$_{2}$$ and D$$_{2}$$ of Hastelloy XR were obtained as follows. The activation energy E$$_{0}$$ and pre-exponential factor F$$_{0}$$ of the permeability of H$$_{2}$$ was E$$_{0}$$=67.2$$pm$$1.2 kJ/mol and F$$_{0}$$=(1.0$$pm$$0.2)$$times$$10$$^{-8}$$m$$^{3}$$(STP)/m$$^{-1}$$/s$$^{-1}$$/Pa$$^{-0.5}$$, respectively, in the pipe temperature ranging from 843K-1093K.

Journal Articles

Application of glow discharges for tritium removal from JT-60U vacuum vessel

Nakamura, Hirofumi; Higashijima, Satoru; Isobe, Kanetsugu; Kaminaga, Atsushi; Horikawa, Toyohiko*; Kubo, Hirotaka; Miya, Naoyuki; Nishi, Masataka; Konishi, Satoshi*; Tanabe, Tetsuo*

Fusion Engineering and Design, 70(2), p.163 - 173, 2004/02

 Times Cited Count:19 Percentile:77.18(Nuclear Science & Technology)

In order to establish the effective and conventional in-vessel tritium removal method, glow discharge methods, usually used as wall conditioning, have been applied and examined in vacuum vessel of JT-60U for tritium removal characteristics and kinetics. Release rates of all hydrogen isotopes as well as hydrocarbons from JT-60U vacuum vessel induced by Glow Discharge Cleaning (GDC) with He and H$$_{2}$$ were measured. Release characteristics of hydrogen isotopes were classified into three different release processes each of which is well described by a simple exponential decay with time. It was found that H$$_{2}$$ GDC showed the superior hydrogen isotope release characteristics than the He GDC, probably because chemical processes, such as isotope exchanges assisted by the chemical sputtering process between discharged hydrogen and hydrogen isotopes plasma facing carbon tiles are enhanced by the H$$_{2}$$ glow discharge. Based on the release kinetics observed in the present work, it is estimated that it will take several days to reduce tritium inventory in the surface area of JT-60U to a half by continuous H$$_{2}$$ GDC at 573 K.

JAEA Reports

Measurement and evaluation of isotope effect between tritium and deuterium on diffusion and surface recombination in/on nickel using ion driven permeation method (Cooperative research)

Nakamura, Hirofumi; Nishi, Masataka; Sugisaki, Masayasu*

JAERI-Research 2003-018, 32 Pages, 2003/09


Tritium transport behavior in materials, which is essential for the safety evaluation of the fusion reactor, has to be evaluated by either tritium properties or extrapolated value from protium or deuterium (D) to tritium (T) using the isotope effect theory. However, there are still some uncertainties on estimation of T behavior in materials, because there are only a few T transport properties data in materials, and it is not completely proven the application of the isotope effect theory to T due to the lack of T data. Therefore, in order to understand the tritium transport properties in materials, isotope effects on diffusion and surface recombination between T and D in/on nickel, whose hydrogen transport properties were well known, were investigated by comparing the obtained properties of T with those of D measured under the same conditions with the ion driven permeation method. Though obtained diffusion coefficient of T was larger than that of D, and activation energy of diffusion of T was smaller than that of D as the contrary to the classical diffusion theory, those were shown to be explained with a modified diffusion theory by introducing higher vibration temperatures in nickel than previous reported values. In addition, the isotope effect on surface recombination coefficient between D and T was shown to be explained using a modified solution model as well as diffusion.

Journal Articles

Deuterium effect on the subcritical limit for fissile-to-hydrogen ratio

Okuno, Hiroshi; Akiyama, Hideo*; Mochizuki, Hiroki*

Journal of Nuclear Science and Technology, 40(1), p.57 - 60, 2003/01

 Times Cited Count:1 Percentile:11.39(Nuclear Science & Technology)

Low-level waste (LLW) drums are required to transport as fissile material if the current IAEA's Regulations for the Safe Transport of Radioactive Material are rigorously applied. This problem is a consequence that water contents of concrete in LLW drums contained deuterium (D) in quantities more than 0.1% of fissile material mass, therefore they are not excepted from packages containing fissile material. Consideration of differences in the absorption cross sections of light hydrogen and D shows that the relative increase in the neutron multiplication factor by a presence of D in natural water for hydrogen (H)-moderated systems is not larger than 0.015%. A numerical calculation confirms that the infinite multiplication factor of a mixture of $$^{235}$$U-metal and water in a $$^{235}$$U/H mass ratio of 5% increases proportionally to the D/H atomic ratio, and that its relative increase is less than 0.03% for the D/H atomic ratio of 0.015%. The limiting fissile-to-H mass ratio of 5% in the exception rule is concluded to be applicable to H-moderated systems including D in natural water.

JAEA Reports

Study on hydrogen isotope permeation in the HTTR hydrogen production system, 2; Effectiveness of reducing the amount of permeated deuterium by oxidized film (Contract research)

Takeda, Tetsuaki; Iwatsuki, Jin*; Nishihara, Tetsuo

JAERI-Tech 2002-090, 30 Pages, 2002/11


Permeation of hydrogen isotope through a high-temperature alloy as used a heat transfer pipe of an intermediate heat exchanger and a steam reformer is an important problem in the hydrogen production system connected to be the high-temperature engineering test reactor (HTTR). In order to obtain detailed data for safety review and development of analytical codes, a test of permeation of hydrogen isotope was carried out as one of essential tests. The objective of this study is to obtain a permeability of hydrogen isotope through Hastelloy XR and other high temperature alloys and to evaluate quantitatively an effect of oxidized film on reducing the amount of permeated hydrogen through the pipe. From the results obtained in this experiment, it is supposed that the oxidized film produced on the surface of the heat transfer pipe during an early stage of the reactor operation will reduce the amount of tritium permeated from the primary circuit of the HTTR to the utilization system.

Journal Articles

In-situ observation of surface blistering in silicon by deuterium and helium ion irradiation

Igarashi, Shinichi; Muto, Shunsuke*; Tanabe, Tetsuo*; Aihara, Jun; Hojo, Kiichi

Surface & Coatings Technology, 158-159, p.421 - 425, 2002/09

no abstracts in English

Journal Articles

Formation and retention of organically bound deuterium in rice in deuterium water release experiment

Atarashi-Andoh, Mariko; Amano, Hikaru; Kakiuchi, Hideki; Ichimasa, Michiko*; Ichimasa, Yusuke*

Health Physics, 82(6), p.863 - 868, 2002/06

 Times Cited Count:6 Percentile:41.16(Environmental Sciences)

As a substitute of tritium, deuterium water (D2O) vapor release experiments were performed to estimate the difference of formation and subsequent retention of organically bound deuterium (OBD) in rice plants between daytime and nighttime exposure. Potted plants were exposed to deuterium water vapor in a greenhouse for 8 hours, under day and night conditions. Deuterium concentrations in free water and organic matter in rice leaves and ears were investigated until the harvest time. Data analysis was carried out using a model in which different generating processes of organic matter were considered. The calculated results agreed with the measured value.

76 (Records 1-20 displayed on this page)